1 /* i2c-core.c - a device driver for the iic-bus interface */
2 /* ------------------------------------------------------------------------- */
3 /* Copyright (C) 1995-99 Simon G. Vogl
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details. */
14 /* ------------------------------------------------------------------------- */
16 /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
17 All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
18 SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
19 Jean Delvare <jdelvare@suse.de>
20 Mux support by Rodolfo Giometti <giometti@enneenne.com> and
21 Michael Lawnick <michael.lawnick.ext@nsn.com>
22 OF support is copyright (c) 2008 Jochen Friedrich <jochen@scram.de>
23 (based on a previous patch from Jon Smirl <jonsmirl@gmail.com>) and
24 (c) 2013 Wolfram Sang <wsa@the-dreams.de>
25 I2C ACPI code Copyright (C) 2014 Intel Corp
26 Author: Lan Tianyu <tianyu.lan@intel.com>
27 I2C slave support (c) 2014 by Wolfram Sang <wsa@sang-engineering.com>
30 #include <dt-bindings/i2c/i2c.h>
31 #include <linux/module.h>
32 #include <linux/kernel.h>
33 #include <linux/delay.h>
34 #include <linux/errno.h>
35 #include <linux/gpio.h>
36 #include <linux/slab.h>
37 #include <linux/i2c.h>
38 #include <linux/init.h>
39 #include <linux/idr.h>
40 #include <linux/mutex.h>
42 #include <linux/of_device.h>
43 #include <linux/of_irq.h>
44 #include <linux/clk/clk-conf.h>
45 #include <linux/completion.h>
46 #include <linux/hardirq.h>
47 #include <linux/irqflags.h>
48 #include <linux/rwsem.h>
49 #include <linux/pm_runtime.h>
50 #include <linux/pm_domain.h>
51 #include <linux/pm_wakeirq.h>
52 #include <linux/acpi.h>
53 #include <linux/jump_label.h>
54 #include <asm/uaccess.h>
55 #include <linux/err.h>
56 #include <linux/property.h>
60 #define CREATE_TRACE_POINTS
61 #include <trace/events/i2c.h>
63 #define I2C_ADDR_OFFSET_TEN_BIT 0xa000
64 #define I2C_ADDR_OFFSET_SLAVE 0x1000
66 /* core_lock protects i2c_adapter_idr, and guarantees
67 that device detection, deletion of detected devices, and attach_adapter
68 calls are serialized */
69 static DEFINE_MUTEX(core_lock);
70 static DEFINE_IDR(i2c_adapter_idr);
72 static struct device_type i2c_client_type;
73 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
75 static struct static_key i2c_trace_msg = STATIC_KEY_INIT_FALSE;
77 void i2c_transfer_trace_reg(void)
79 static_key_slow_inc(&i2c_trace_msg);
82 void i2c_transfer_trace_unreg(void)
84 static_key_slow_dec(&i2c_trace_msg);
87 #if defined(CONFIG_ACPI)
88 struct acpi_i2c_handler_data {
89 struct acpi_connection_info info;
90 struct i2c_adapter *adapter;
103 struct acpi_i2c_lookup {
104 struct i2c_board_info *info;
105 acpi_handle adapter_handle;
106 acpi_handle device_handle;
109 static int acpi_i2c_find_address(struct acpi_resource *ares, void *data)
111 struct acpi_i2c_lookup *lookup = data;
112 struct i2c_board_info *info = lookup->info;
113 struct acpi_resource_i2c_serialbus *sb;
114 acpi_handle adapter_handle;
117 if (info->addr || ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
120 sb = &ares->data.i2c_serial_bus;
121 if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
125 * Extract the ResourceSource and make sure that the handle matches
126 * with the I2C adapter handle.
128 status = acpi_get_handle(lookup->device_handle,
129 sb->resource_source.string_ptr,
131 if (ACPI_SUCCESS(status) && adapter_handle == lookup->adapter_handle) {
132 info->addr = sb->slave_address;
133 if (sb->access_mode == ACPI_I2C_10BIT_MODE)
134 info->flags |= I2C_CLIENT_TEN;
140 static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
141 void *data, void **return_value)
143 struct i2c_adapter *adapter = data;
144 struct list_head resource_list;
145 struct acpi_i2c_lookup lookup;
146 struct resource_entry *entry;
147 struct i2c_board_info info;
148 struct acpi_device *adev;
151 if (acpi_bus_get_device(handle, &adev))
153 if (acpi_bus_get_status(adev) || !adev->status.present)
156 memset(&info, 0, sizeof(info));
157 info.fwnode = acpi_fwnode_handle(adev);
159 memset(&lookup, 0, sizeof(lookup));
160 lookup.adapter_handle = ACPI_HANDLE(&adapter->dev);
161 lookup.device_handle = handle;
165 * Look up for I2cSerialBus resource with ResourceSource that
166 * matches with this adapter.
168 INIT_LIST_HEAD(&resource_list);
169 ret = acpi_dev_get_resources(adev, &resource_list,
170 acpi_i2c_find_address, &lookup);
171 acpi_dev_free_resource_list(&resource_list);
173 if (ret < 0 || !info.addr)
176 /* Then fill IRQ number if any */
177 ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
181 resource_list_for_each_entry(entry, &resource_list) {
182 if (resource_type(entry->res) == IORESOURCE_IRQ) {
183 info.irq = entry->res->start;
188 acpi_dev_free_resource_list(&resource_list);
190 adev->power.flags.ignore_parent = true;
191 strlcpy(info.type, dev_name(&adev->dev), sizeof(info.type));
192 if (!i2c_new_device(adapter, &info)) {
193 adev->power.flags.ignore_parent = false;
194 dev_err(&adapter->dev,
195 "failed to add I2C device %s from ACPI\n",
196 dev_name(&adev->dev));
202 #define ACPI_I2C_MAX_SCAN_DEPTH 32
205 * acpi_i2c_register_devices - enumerate I2C slave devices behind adapter
206 * @adap: pointer to adapter
208 * Enumerate all I2C slave devices behind this adapter by walking the ACPI
209 * namespace. When a device is found it will be added to the Linux device
210 * model and bound to the corresponding ACPI handle.
212 static void acpi_i2c_register_devices(struct i2c_adapter *adap)
216 if (!has_acpi_companion(&adap->dev))
219 status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
220 ACPI_I2C_MAX_SCAN_DEPTH,
221 acpi_i2c_add_device, NULL,
223 if (ACPI_FAILURE(status))
224 dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");
227 #else /* CONFIG_ACPI */
228 static inline void acpi_i2c_register_devices(struct i2c_adapter *adap) { }
229 #endif /* CONFIG_ACPI */
231 #ifdef CONFIG_ACPI_I2C_OPREGION
232 static int acpi_gsb_i2c_read_bytes(struct i2c_client *client,
233 u8 cmd, u8 *data, u8 data_len)
236 struct i2c_msg msgs[2];
240 buffer = kzalloc(data_len, GFP_KERNEL);
244 msgs[0].addr = client->addr;
245 msgs[0].flags = client->flags;
249 msgs[1].addr = client->addr;
250 msgs[1].flags = client->flags | I2C_M_RD;
251 msgs[1].len = data_len;
252 msgs[1].buf = buffer;
254 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
256 dev_err(&client->adapter->dev, "i2c read failed\n");
258 memcpy(data, buffer, data_len);
264 static int acpi_gsb_i2c_write_bytes(struct i2c_client *client,
265 u8 cmd, u8 *data, u8 data_len)
268 struct i2c_msg msgs[1];
272 buffer = kzalloc(data_len + 1, GFP_KERNEL);
277 memcpy(buffer + 1, data, data_len);
279 msgs[0].addr = client->addr;
280 msgs[0].flags = client->flags;
281 msgs[0].len = data_len + 1;
282 msgs[0].buf = buffer;
284 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
286 dev_err(&client->adapter->dev, "i2c write failed\n");
293 acpi_i2c_space_handler(u32 function, acpi_physical_address command,
294 u32 bits, u64 *value64,
295 void *handler_context, void *region_context)
297 struct gsb_buffer *gsb = (struct gsb_buffer *)value64;
298 struct acpi_i2c_handler_data *data = handler_context;
299 struct acpi_connection_info *info = &data->info;
300 struct acpi_resource_i2c_serialbus *sb;
301 struct i2c_adapter *adapter = data->adapter;
302 struct i2c_client *client;
303 struct acpi_resource *ares;
304 u32 accessor_type = function >> 16;
305 u8 action = function & ACPI_IO_MASK;
309 ret = acpi_buffer_to_resource(info->connection, info->length, &ares);
310 if (ACPI_FAILURE(ret))
313 client = kzalloc(sizeof(*client), GFP_KERNEL);
319 if (!value64 || ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS) {
320 ret = AE_BAD_PARAMETER;
324 sb = &ares->data.i2c_serial_bus;
325 if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C) {
326 ret = AE_BAD_PARAMETER;
330 client->adapter = adapter;
331 client->addr = sb->slave_address;
333 if (sb->access_mode == ACPI_I2C_10BIT_MODE)
334 client->flags |= I2C_CLIENT_TEN;
336 switch (accessor_type) {
337 case ACPI_GSB_ACCESS_ATTRIB_SEND_RCV:
338 if (action == ACPI_READ) {
339 status = i2c_smbus_read_byte(client);
345 status = i2c_smbus_write_byte(client, gsb->bdata);
349 case ACPI_GSB_ACCESS_ATTRIB_BYTE:
350 if (action == ACPI_READ) {
351 status = i2c_smbus_read_byte_data(client, command);
357 status = i2c_smbus_write_byte_data(client, command,
362 case ACPI_GSB_ACCESS_ATTRIB_WORD:
363 if (action == ACPI_READ) {
364 status = i2c_smbus_read_word_data(client, command);
370 status = i2c_smbus_write_word_data(client, command,
375 case ACPI_GSB_ACCESS_ATTRIB_BLOCK:
376 if (action == ACPI_READ) {
377 status = i2c_smbus_read_block_data(client, command,
384 status = i2c_smbus_write_block_data(client, command,
385 gsb->len, gsb->data);
389 case ACPI_GSB_ACCESS_ATTRIB_MULTIBYTE:
390 if (action == ACPI_READ) {
391 status = acpi_gsb_i2c_read_bytes(client, command,
392 gsb->data, info->access_length);
396 status = acpi_gsb_i2c_write_bytes(client, command,
397 gsb->data, info->access_length);
402 pr_info("protocol(0x%02x) is not supported.\n", accessor_type);
403 ret = AE_BAD_PARAMETER;
407 gsb->status = status;
416 static int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
419 struct acpi_i2c_handler_data *data;
422 if (!adapter->dev.parent)
425 handle = ACPI_HANDLE(adapter->dev.parent);
430 data = kzalloc(sizeof(struct acpi_i2c_handler_data),
435 data->adapter = adapter;
436 status = acpi_bus_attach_private_data(handle, (void *)data);
437 if (ACPI_FAILURE(status)) {
442 status = acpi_install_address_space_handler(handle,
443 ACPI_ADR_SPACE_GSBUS,
444 &acpi_i2c_space_handler,
447 if (ACPI_FAILURE(status)) {
448 dev_err(&adapter->dev, "Error installing i2c space handler\n");
449 acpi_bus_detach_private_data(handle);
454 acpi_walk_dep_device_list(handle);
458 static void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter)
461 struct acpi_i2c_handler_data *data;
464 if (!adapter->dev.parent)
467 handle = ACPI_HANDLE(adapter->dev.parent);
472 acpi_remove_address_space_handler(handle,
473 ACPI_ADR_SPACE_GSBUS,
474 &acpi_i2c_space_handler);
476 status = acpi_bus_get_private_data(handle, (void **)&data);
477 if (ACPI_SUCCESS(status))
480 acpi_bus_detach_private_data(handle);
482 #else /* CONFIG_ACPI_I2C_OPREGION */
483 static inline void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter)
486 static inline int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
488 #endif /* CONFIG_ACPI_I2C_OPREGION */
490 /* ------------------------------------------------------------------------- */
492 static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
493 const struct i2c_client *client)
495 while (id->name[0]) {
496 if (strcmp(client->name, id->name) == 0)
503 static int i2c_device_match(struct device *dev, struct device_driver *drv)
505 struct i2c_client *client = i2c_verify_client(dev);
506 struct i2c_driver *driver;
511 /* Attempt an OF style match */
512 if (of_driver_match_device(dev, drv))
515 /* Then ACPI style match */
516 if (acpi_driver_match_device(dev, drv))
519 driver = to_i2c_driver(drv);
520 /* match on an id table if there is one */
521 if (driver->id_table)
522 return i2c_match_id(driver->id_table, client) != NULL;
528 /* uevent helps with hotplug: modprobe -q $(MODALIAS) */
529 static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
531 struct i2c_client *client = to_i2c_client(dev);
534 rc = acpi_device_uevent_modalias(dev, env);
538 if (add_uevent_var(env, "MODALIAS=%s%s",
539 I2C_MODULE_PREFIX, client->name))
541 dev_dbg(dev, "uevent\n");
545 /* i2c bus recovery routines */
546 static int get_scl_gpio_value(struct i2c_adapter *adap)
548 return gpio_get_value(adap->bus_recovery_info->scl_gpio);
551 static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
553 gpio_set_value(adap->bus_recovery_info->scl_gpio, val);
556 static int get_sda_gpio_value(struct i2c_adapter *adap)
558 return gpio_get_value(adap->bus_recovery_info->sda_gpio);
561 static int i2c_get_gpios_for_recovery(struct i2c_adapter *adap)
563 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
564 struct device *dev = &adap->dev;
567 ret = gpio_request_one(bri->scl_gpio, GPIOF_OPEN_DRAIN |
568 GPIOF_OUT_INIT_HIGH, "i2c-scl");
570 dev_warn(dev, "Can't get SCL gpio: %d\n", bri->scl_gpio);
575 if (gpio_request_one(bri->sda_gpio, GPIOF_IN, "i2c-sda")) {
576 /* work without SDA polling */
577 dev_warn(dev, "Can't get SDA gpio: %d. Not using SDA polling\n",
586 static void i2c_put_gpios_for_recovery(struct i2c_adapter *adap)
588 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
591 gpio_free(bri->sda_gpio);
593 gpio_free(bri->scl_gpio);
597 * We are generating clock pulses. ndelay() determines durating of clk pulses.
598 * We will generate clock with rate 100 KHz and so duration of both clock levels
599 * is: delay in ns = (10^6 / 100) / 2
601 #define RECOVERY_NDELAY 5000
602 #define RECOVERY_CLK_CNT 9
604 static int i2c_generic_recovery(struct i2c_adapter *adap)
606 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
607 int i = 0, val = 1, ret = 0;
609 if (bri->prepare_recovery)
610 bri->prepare_recovery(adap);
612 bri->set_scl(adap, val);
613 ndelay(RECOVERY_NDELAY);
616 * By this time SCL is high, as we need to give 9 falling-rising edges
618 while (i++ < RECOVERY_CLK_CNT * 2) {
620 /* Break if SDA is high */
621 if (bri->get_sda && bri->get_sda(adap))
623 /* SCL shouldn't be low here */
624 if (!bri->get_scl(adap)) {
626 "SCL is stuck low, exit recovery\n");
633 bri->set_scl(adap, val);
634 ndelay(RECOVERY_NDELAY);
637 if (bri->unprepare_recovery)
638 bri->unprepare_recovery(adap);
643 int i2c_generic_scl_recovery(struct i2c_adapter *adap)
645 return i2c_generic_recovery(adap);
647 EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
649 int i2c_generic_gpio_recovery(struct i2c_adapter *adap)
653 ret = i2c_get_gpios_for_recovery(adap);
657 ret = i2c_generic_recovery(adap);
658 i2c_put_gpios_for_recovery(adap);
662 EXPORT_SYMBOL_GPL(i2c_generic_gpio_recovery);
664 int i2c_recover_bus(struct i2c_adapter *adap)
666 if (!adap->bus_recovery_info)
669 dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
670 return adap->bus_recovery_info->recover_bus(adap);
672 EXPORT_SYMBOL_GPL(i2c_recover_bus);
674 static int i2c_device_probe(struct device *dev)
676 struct i2c_client *client = i2c_verify_client(dev);
677 struct i2c_driver *driver;
687 irq = of_irq_get_byname(dev->of_node, "irq");
688 if (irq == -EINVAL || irq == -ENODATA)
689 irq = of_irq_get(dev->of_node, 0);
690 } else if (ACPI_COMPANION(dev)) {
691 irq = acpi_dev_gpio_irq_get(ACPI_COMPANION(dev), 0);
693 if (irq == -EPROBE_DEFER)
701 driver = to_i2c_driver(dev->driver);
702 if (!driver->probe || !driver->id_table)
705 if (client->flags & I2C_CLIENT_WAKE) {
706 int wakeirq = -ENOENT;
709 wakeirq = of_irq_get_byname(dev->of_node, "wakeup");
710 if (wakeirq == -EPROBE_DEFER)
714 device_init_wakeup(&client->dev, true);
716 if (wakeirq > 0 && wakeirq != client->irq)
717 status = dev_pm_set_dedicated_wake_irq(dev, wakeirq);
718 else if (client->irq > 0)
719 status = dev_pm_set_wake_irq(dev, client->irq);
724 dev_warn(&client->dev, "failed to set up wakeup irq");
727 dev_dbg(dev, "probe\n");
729 status = of_clk_set_defaults(dev->of_node, false);
731 goto err_clear_wakeup_irq;
733 status = dev_pm_domain_attach(&client->dev, true);
734 if (status == -EPROBE_DEFER)
735 goto err_clear_wakeup_irq;
737 status = driver->probe(client, i2c_match_id(driver->id_table, client));
739 goto err_detach_pm_domain;
743 err_detach_pm_domain:
744 dev_pm_domain_detach(&client->dev, true);
745 err_clear_wakeup_irq:
746 dev_pm_clear_wake_irq(&client->dev);
747 device_init_wakeup(&client->dev, false);
751 static int i2c_device_remove(struct device *dev)
753 struct i2c_client *client = i2c_verify_client(dev);
754 struct i2c_driver *driver;
757 if (!client || !dev->driver)
760 driver = to_i2c_driver(dev->driver);
761 if (driver->remove) {
762 dev_dbg(dev, "remove\n");
763 status = driver->remove(client);
766 dev_pm_domain_detach(&client->dev, true);
768 dev_pm_clear_wake_irq(&client->dev);
769 device_init_wakeup(&client->dev, false);
774 static void i2c_device_shutdown(struct device *dev)
776 struct i2c_client *client = i2c_verify_client(dev);
777 struct i2c_driver *driver;
779 if (!client || !dev->driver)
781 driver = to_i2c_driver(dev->driver);
782 if (driver->shutdown)
783 driver->shutdown(client);
786 static void i2c_client_dev_release(struct device *dev)
788 kfree(to_i2c_client(dev));
792 show_name(struct device *dev, struct device_attribute *attr, char *buf)
794 return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
795 to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
797 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
800 show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
802 struct i2c_client *client = to_i2c_client(dev);
805 len = acpi_device_modalias(dev, buf, PAGE_SIZE -1);
809 return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
811 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
813 static struct attribute *i2c_dev_attrs[] = {
815 /* modalias helps coldplug: modprobe $(cat .../modalias) */
816 &dev_attr_modalias.attr,
819 ATTRIBUTE_GROUPS(i2c_dev);
821 struct bus_type i2c_bus_type = {
823 .match = i2c_device_match,
824 .probe = i2c_device_probe,
825 .remove = i2c_device_remove,
826 .shutdown = i2c_device_shutdown,
828 EXPORT_SYMBOL_GPL(i2c_bus_type);
830 static struct device_type i2c_client_type = {
831 .groups = i2c_dev_groups,
832 .uevent = i2c_device_uevent,
833 .release = i2c_client_dev_release,
838 * i2c_verify_client - return parameter as i2c_client, or NULL
839 * @dev: device, probably from some driver model iterator
841 * When traversing the driver model tree, perhaps using driver model
842 * iterators like @device_for_each_child(), you can't assume very much
843 * about the nodes you find. Use this function to avoid oopses caused
844 * by wrongly treating some non-I2C device as an i2c_client.
846 struct i2c_client *i2c_verify_client(struct device *dev)
848 return (dev->type == &i2c_client_type)
852 EXPORT_SYMBOL(i2c_verify_client);
855 /* Return a unique address which takes the flags of the client into account */
856 static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client)
858 unsigned short addr = client->addr;
860 /* For some client flags, add an arbitrary offset to avoid collisions */
861 if (client->flags & I2C_CLIENT_TEN)
862 addr |= I2C_ADDR_OFFSET_TEN_BIT;
864 if (client->flags & I2C_CLIENT_SLAVE)
865 addr |= I2C_ADDR_OFFSET_SLAVE;
870 /* This is a permissive address validity check, I2C address map constraints
871 * are purposely not enforced, except for the general call address. */
872 static int i2c_check_addr_validity(unsigned addr, unsigned short flags)
874 if (flags & I2C_CLIENT_TEN) {
875 /* 10-bit address, all values are valid */
879 /* 7-bit address, reject the general call address */
880 if (addr == 0x00 || addr > 0x7f)
886 /* And this is a strict address validity check, used when probing. If a
887 * device uses a reserved address, then it shouldn't be probed. 7-bit
888 * addressing is assumed, 10-bit address devices are rare and should be
889 * explicitly enumerated. */
890 static int i2c_check_7bit_addr_validity_strict(unsigned short addr)
893 * Reserved addresses per I2C specification:
894 * 0x00 General call address / START byte
896 * 0x02 Reserved for different bus format
897 * 0x03 Reserved for future purposes
898 * 0x04-0x07 Hs-mode master code
899 * 0x78-0x7b 10-bit slave addressing
900 * 0x7c-0x7f Reserved for future purposes
902 if (addr < 0x08 || addr > 0x77)
907 static int __i2c_check_addr_busy(struct device *dev, void *addrp)
909 struct i2c_client *client = i2c_verify_client(dev);
910 int addr = *(int *)addrp;
912 if (client && i2c_encode_flags_to_addr(client) == addr)
917 /* walk up mux tree */
918 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
920 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
923 result = device_for_each_child(&adapter->dev, &addr,
924 __i2c_check_addr_busy);
926 if (!result && parent)
927 result = i2c_check_mux_parents(parent, addr);
932 /* recurse down mux tree */
933 static int i2c_check_mux_children(struct device *dev, void *addrp)
937 if (dev->type == &i2c_adapter_type)
938 result = device_for_each_child(dev, addrp,
939 i2c_check_mux_children);
941 result = __i2c_check_addr_busy(dev, addrp);
946 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
948 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
952 result = i2c_check_mux_parents(parent, addr);
955 result = device_for_each_child(&adapter->dev, &addr,
956 i2c_check_mux_children);
962 * i2c_lock_adapter - Get exclusive access to an I2C bus segment
963 * @adapter: Target I2C bus segment
965 void i2c_lock_adapter(struct i2c_adapter *adapter)
967 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
970 i2c_lock_adapter(parent);
972 rt_mutex_lock(&adapter->bus_lock);
974 EXPORT_SYMBOL_GPL(i2c_lock_adapter);
977 * i2c_trylock_adapter - Try to get exclusive access to an I2C bus segment
978 * @adapter: Target I2C bus segment
980 static int i2c_trylock_adapter(struct i2c_adapter *adapter)
982 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
985 return i2c_trylock_adapter(parent);
987 return rt_mutex_trylock(&adapter->bus_lock);
991 * i2c_unlock_adapter - Release exclusive access to an I2C bus segment
992 * @adapter: Target I2C bus segment
994 void i2c_unlock_adapter(struct i2c_adapter *adapter)
996 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
999 i2c_unlock_adapter(parent);
1001 rt_mutex_unlock(&adapter->bus_lock);
1003 EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
1005 static void i2c_dev_set_name(struct i2c_adapter *adap,
1006 struct i2c_client *client)
1008 struct acpi_device *adev = ACPI_COMPANION(&client->dev);
1011 dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev));
1015 dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
1016 i2c_encode_flags_to_addr(client));
1020 * i2c_new_device - instantiate an i2c device
1021 * @adap: the adapter managing the device
1022 * @info: describes one I2C device; bus_num is ignored
1023 * Context: can sleep
1025 * Create an i2c device. Binding is handled through driver model
1026 * probe()/remove() methods. A driver may be bound to this device when we
1027 * return from this function, or any later moment (e.g. maybe hotplugging will
1028 * load the driver module). This call is not appropriate for use by mainboard
1029 * initialization logic, which usually runs during an arch_initcall() long
1030 * before any i2c_adapter could exist.
1032 * This returns the new i2c client, which may be saved for later use with
1033 * i2c_unregister_device(); or NULL to indicate an error.
1036 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
1038 struct i2c_client *client;
1041 client = kzalloc(sizeof *client, GFP_KERNEL);
1045 client->adapter = adap;
1047 client->dev.platform_data = info->platform_data;
1050 client->dev.archdata = *info->archdata;
1052 client->flags = info->flags;
1053 client->addr = info->addr;
1054 client->irq = info->irq;
1056 strlcpy(client->name, info->type, sizeof(client->name));
1058 status = i2c_check_addr_validity(client->addr, client->flags);
1060 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
1061 client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
1062 goto out_err_silent;
1065 /* Check for address business */
1066 status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client));
1070 client->dev.parent = &client->adapter->dev;
1071 client->dev.bus = &i2c_bus_type;
1072 client->dev.type = &i2c_client_type;
1073 client->dev.of_node = info->of_node;
1074 client->dev.fwnode = info->fwnode;
1076 i2c_dev_set_name(adap, client);
1077 status = device_register(&client->dev);
1081 dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
1082 client->name, dev_name(&client->dev));
1087 dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x "
1088 "(%d)\n", client->name, client->addr, status);
1093 EXPORT_SYMBOL_GPL(i2c_new_device);
1097 * i2c_unregister_device - reverse effect of i2c_new_device()
1098 * @client: value returned from i2c_new_device()
1099 * Context: can sleep
1101 void i2c_unregister_device(struct i2c_client *client)
1103 if (client->dev.of_node)
1104 of_node_clear_flag(client->dev.of_node, OF_POPULATED);
1105 device_unregister(&client->dev);
1107 EXPORT_SYMBOL_GPL(i2c_unregister_device);
1110 static const struct i2c_device_id dummy_id[] = {
1115 static int dummy_probe(struct i2c_client *client,
1116 const struct i2c_device_id *id)
1121 static int dummy_remove(struct i2c_client *client)
1126 static struct i2c_driver dummy_driver = {
1127 .driver.name = "dummy",
1128 .probe = dummy_probe,
1129 .remove = dummy_remove,
1130 .id_table = dummy_id,
1134 * i2c_new_dummy - return a new i2c device bound to a dummy driver
1135 * @adapter: the adapter managing the device
1136 * @address: seven bit address to be used
1137 * Context: can sleep
1139 * This returns an I2C client bound to the "dummy" driver, intended for use
1140 * with devices that consume multiple addresses. Examples of such chips
1141 * include various EEPROMS (like 24c04 and 24c08 models).
1143 * These dummy devices have two main uses. First, most I2C and SMBus calls
1144 * except i2c_transfer() need a client handle; the dummy will be that handle.
1145 * And second, this prevents the specified address from being bound to a
1148 * This returns the new i2c client, which should be saved for later use with
1149 * i2c_unregister_device(); or NULL to indicate an error.
1151 struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
1153 struct i2c_board_info info = {
1154 I2C_BOARD_INFO("dummy", address),
1157 return i2c_new_device(adapter, &info);
1159 EXPORT_SYMBOL_GPL(i2c_new_dummy);
1161 /* ------------------------------------------------------------------------- */
1163 /* I2C bus adapters -- one roots each I2C or SMBUS segment */
1165 static void i2c_adapter_dev_release(struct device *dev)
1167 struct i2c_adapter *adap = to_i2c_adapter(dev);
1168 complete(&adap->dev_released);
1172 * This function is only needed for mutex_lock_nested, so it is never
1173 * called unless locking correctness checking is enabled. Thus we
1174 * make it inline to avoid a compiler warning. That's what gcc ends up
1177 static inline unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
1179 unsigned int depth = 0;
1181 while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
1188 * Let users instantiate I2C devices through sysfs. This can be used when
1189 * platform initialization code doesn't contain the proper data for
1190 * whatever reason. Also useful for drivers that do device detection and
1191 * detection fails, either because the device uses an unexpected address,
1192 * or this is a compatible device with different ID register values.
1194 * Parameter checking may look overzealous, but we really don't want
1195 * the user to provide incorrect parameters.
1198 i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
1199 const char *buf, size_t count)
1201 struct i2c_adapter *adap = to_i2c_adapter(dev);
1202 struct i2c_board_info info;
1203 struct i2c_client *client;
1207 memset(&info, 0, sizeof(struct i2c_board_info));
1209 blank = strchr(buf, ' ');
1211 dev_err(dev, "%s: Missing parameters\n", "new_device");
1214 if (blank - buf > I2C_NAME_SIZE - 1) {
1215 dev_err(dev, "%s: Invalid device name\n", "new_device");
1218 memcpy(info.type, buf, blank - buf);
1220 /* Parse remaining parameters, reject extra parameters */
1221 res = sscanf(++blank, "%hi%c", &info.addr, &end);
1223 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
1226 if (res > 1 && end != '\n') {
1227 dev_err(dev, "%s: Extra parameters\n", "new_device");
1231 if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) {
1232 info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT;
1233 info.flags |= I2C_CLIENT_TEN;
1236 if (info.addr & I2C_ADDR_OFFSET_SLAVE) {
1237 info.addr &= ~I2C_ADDR_OFFSET_SLAVE;
1238 info.flags |= I2C_CLIENT_SLAVE;
1241 client = i2c_new_device(adap, &info);
1245 /* Keep track of the added device */
1246 mutex_lock(&adap->userspace_clients_lock);
1247 list_add_tail(&client->detected, &adap->userspace_clients);
1248 mutex_unlock(&adap->userspace_clients_lock);
1249 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
1250 info.type, info.addr);
1254 static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
1257 * And of course let the users delete the devices they instantiated, if
1258 * they got it wrong. This interface can only be used to delete devices
1259 * instantiated by i2c_sysfs_new_device above. This guarantees that we
1260 * don't delete devices to which some kernel code still has references.
1262 * Parameter checking may look overzealous, but we really don't want
1263 * the user to delete the wrong device.
1266 i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
1267 const char *buf, size_t count)
1269 struct i2c_adapter *adap = to_i2c_adapter(dev);
1270 struct i2c_client *client, *next;
1271 unsigned short addr;
1275 /* Parse parameters, reject extra parameters */
1276 res = sscanf(buf, "%hi%c", &addr, &end);
1278 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
1281 if (res > 1 && end != '\n') {
1282 dev_err(dev, "%s: Extra parameters\n", "delete_device");
1286 /* Make sure the device was added through sysfs */
1288 mutex_lock_nested(&adap->userspace_clients_lock,
1289 i2c_adapter_depth(adap));
1290 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1292 if (i2c_encode_flags_to_addr(client) == addr) {
1293 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
1294 "delete_device", client->name, client->addr);
1296 list_del(&client->detected);
1297 i2c_unregister_device(client);
1302 mutex_unlock(&adap->userspace_clients_lock);
1305 dev_err(dev, "%s: Can't find device in list\n",
1309 static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
1310 i2c_sysfs_delete_device);
1312 static struct attribute *i2c_adapter_attrs[] = {
1313 &dev_attr_name.attr,
1314 &dev_attr_new_device.attr,
1315 &dev_attr_delete_device.attr,
1318 ATTRIBUTE_GROUPS(i2c_adapter);
1320 struct device_type i2c_adapter_type = {
1321 .groups = i2c_adapter_groups,
1322 .release = i2c_adapter_dev_release,
1324 EXPORT_SYMBOL_GPL(i2c_adapter_type);
1327 * i2c_verify_adapter - return parameter as i2c_adapter or NULL
1328 * @dev: device, probably from some driver model iterator
1330 * When traversing the driver model tree, perhaps using driver model
1331 * iterators like @device_for_each_child(), you can't assume very much
1332 * about the nodes you find. Use this function to avoid oopses caused
1333 * by wrongly treating some non-I2C device as an i2c_adapter.
1335 struct i2c_adapter *i2c_verify_adapter(struct device *dev)
1337 return (dev->type == &i2c_adapter_type)
1338 ? to_i2c_adapter(dev)
1341 EXPORT_SYMBOL(i2c_verify_adapter);
1343 #ifdef CONFIG_I2C_COMPAT
1344 static struct class_compat *i2c_adapter_compat_class;
1347 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
1349 struct i2c_devinfo *devinfo;
1351 down_read(&__i2c_board_lock);
1352 list_for_each_entry(devinfo, &__i2c_board_list, list) {
1353 if (devinfo->busnum == adapter->nr
1354 && !i2c_new_device(adapter,
1355 &devinfo->board_info))
1356 dev_err(&adapter->dev,
1357 "Can't create device at 0x%02x\n",
1358 devinfo->board_info.addr);
1360 up_read(&__i2c_board_lock);
1363 /* OF support code */
1365 #if IS_ENABLED(CONFIG_OF)
1366 static struct i2c_client *of_i2c_register_device(struct i2c_adapter *adap,
1367 struct device_node *node)
1369 struct i2c_client *result;
1370 struct i2c_board_info info = {};
1371 struct dev_archdata dev_ad = {};
1372 const __be32 *addr_be;
1376 dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);
1378 if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
1379 dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
1381 return ERR_PTR(-EINVAL);
1384 addr_be = of_get_property(node, "reg", &len);
1385 if (!addr_be || (len < sizeof(*addr_be))) {
1386 dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
1388 return ERR_PTR(-EINVAL);
1391 addr = be32_to_cpup(addr_be);
1392 if (addr & I2C_TEN_BIT_ADDRESS) {
1393 addr &= ~I2C_TEN_BIT_ADDRESS;
1394 info.flags |= I2C_CLIENT_TEN;
1397 if (addr & I2C_OWN_SLAVE_ADDRESS) {
1398 addr &= ~I2C_OWN_SLAVE_ADDRESS;
1399 info.flags |= I2C_CLIENT_SLAVE;
1402 if (i2c_check_addr_validity(addr, info.flags)) {
1403 dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
1404 addr, node->full_name);
1405 return ERR_PTR(-EINVAL);
1409 info.of_node = of_node_get(node);
1410 info.archdata = &dev_ad;
1412 if (of_get_property(node, "wakeup-source", NULL))
1413 info.flags |= I2C_CLIENT_WAKE;
1415 result = i2c_new_device(adap, &info);
1416 if (result == NULL) {
1417 dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
1420 return ERR_PTR(-EINVAL);
1425 static void of_i2c_register_devices(struct i2c_adapter *adap)
1427 struct device_node *node;
1429 /* Only register child devices if the adapter has a node pointer set */
1430 if (!adap->dev.of_node)
1433 dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
1435 for_each_available_child_of_node(adap->dev.of_node, node) {
1436 if (of_node_test_and_set_flag(node, OF_POPULATED))
1438 of_i2c_register_device(adap, node);
1442 static int of_dev_node_match(struct device *dev, void *data)
1444 return dev->of_node == data;
1447 /* must call put_device() when done with returned i2c_client device */
1448 struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
1451 struct i2c_client *client;
1453 dev = bus_find_device(&i2c_bus_type, NULL, node, of_dev_node_match);
1457 client = i2c_verify_client(dev);
1463 EXPORT_SYMBOL(of_find_i2c_device_by_node);
1465 /* must call put_device() when done with returned i2c_adapter device */
1466 struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
1469 struct i2c_adapter *adapter;
1471 dev = bus_find_device(&i2c_bus_type, NULL, node, of_dev_node_match);
1475 adapter = i2c_verify_adapter(dev);
1481 EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
1483 /* must call i2c_put_adapter() when done with returned i2c_adapter device */
1484 struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node)
1486 struct i2c_adapter *adapter;
1488 adapter = of_find_i2c_adapter_by_node(node);
1492 if (!try_module_get(adapter->owner)) {
1493 put_device(&adapter->dev);
1499 EXPORT_SYMBOL(of_get_i2c_adapter_by_node);
1501 static void of_i2c_register_devices(struct i2c_adapter *adap) { }
1502 #endif /* CONFIG_OF */
1504 static int i2c_do_add_adapter(struct i2c_driver *driver,
1505 struct i2c_adapter *adap)
1507 /* Detect supported devices on that bus, and instantiate them */
1508 i2c_detect(adap, driver);
1510 /* Let legacy drivers scan this bus for matching devices */
1511 if (driver->attach_adapter) {
1512 dev_warn(&adap->dev, "%s: attach_adapter method is deprecated\n",
1513 driver->driver.name);
1514 dev_warn(&adap->dev, "Please use another way to instantiate "
1515 "your i2c_client\n");
1516 /* We ignore the return code; if it fails, too bad */
1517 driver->attach_adapter(adap);
1522 static int __process_new_adapter(struct device_driver *d, void *data)
1524 return i2c_do_add_adapter(to_i2c_driver(d), data);
1527 static int i2c_register_adapter(struct i2c_adapter *adap)
1531 /* Can't register until after driver model init */
1532 if (unlikely(WARN_ON(!i2c_bus_type.p))) {
1538 if (unlikely(adap->name[0] == '\0')) {
1539 pr_err("i2c-core: Attempt to register an adapter with "
1543 if (unlikely(!adap->algo)) {
1544 pr_err("i2c-core: Attempt to register adapter '%s' with "
1545 "no algo!\n", adap->name);
1549 rt_mutex_init(&adap->bus_lock);
1550 mutex_init(&adap->userspace_clients_lock);
1551 INIT_LIST_HEAD(&adap->userspace_clients);
1553 /* Set default timeout to 1 second if not already set */
1554 if (adap->timeout == 0)
1557 dev_set_name(&adap->dev, "i2c-%d", adap->nr);
1558 adap->dev.bus = &i2c_bus_type;
1559 adap->dev.type = &i2c_adapter_type;
1560 res = device_register(&adap->dev);
1564 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
1566 pm_runtime_no_callbacks(&adap->dev);
1568 #ifdef CONFIG_I2C_COMPAT
1569 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
1572 dev_warn(&adap->dev,
1573 "Failed to create compatibility class link\n");
1576 /* bus recovery specific initialization */
1577 if (adap->bus_recovery_info) {
1578 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
1580 if (!bri->recover_bus) {
1581 dev_err(&adap->dev, "No recover_bus() found, not using recovery\n");
1582 adap->bus_recovery_info = NULL;
1586 /* Generic GPIO recovery */
1587 if (bri->recover_bus == i2c_generic_gpio_recovery) {
1588 if (!gpio_is_valid(bri->scl_gpio)) {
1589 dev_err(&adap->dev, "Invalid SCL gpio, not using recovery\n");
1590 adap->bus_recovery_info = NULL;
1594 if (gpio_is_valid(bri->sda_gpio))
1595 bri->get_sda = get_sda_gpio_value;
1597 bri->get_sda = NULL;
1599 bri->get_scl = get_scl_gpio_value;
1600 bri->set_scl = set_scl_gpio_value;
1601 } else if (!bri->set_scl || !bri->get_scl) {
1602 /* Generic SCL recovery */
1603 dev_err(&adap->dev, "No {get|set}_gpio() found, not using recovery\n");
1604 adap->bus_recovery_info = NULL;
1609 /* create pre-declared device nodes */
1610 of_i2c_register_devices(adap);
1611 acpi_i2c_register_devices(adap);
1612 acpi_i2c_install_space_handler(adap);
1614 if (adap->nr < __i2c_first_dynamic_bus_num)
1615 i2c_scan_static_board_info(adap);
1617 /* Notify drivers */
1618 mutex_lock(&core_lock);
1619 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
1620 mutex_unlock(&core_lock);
1625 mutex_lock(&core_lock);
1626 idr_remove(&i2c_adapter_idr, adap->nr);
1627 mutex_unlock(&core_lock);
1632 * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
1633 * @adap: the adapter to register (with adap->nr initialized)
1634 * Context: can sleep
1636 * See i2c_add_numbered_adapter() for details.
1638 static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
1642 mutex_lock(&core_lock);
1643 id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1,
1645 mutex_unlock(&core_lock);
1647 return id == -ENOSPC ? -EBUSY : id;
1649 return i2c_register_adapter(adap);
1653 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
1654 * @adapter: the adapter to add
1655 * Context: can sleep
1657 * This routine is used to declare an I2C adapter when its bus number
1658 * doesn't matter or when its bus number is specified by an dt alias.
1659 * Examples of bases when the bus number doesn't matter: I2C adapters
1660 * dynamically added by USB links or PCI plugin cards.
1662 * When this returns zero, a new bus number was allocated and stored
1663 * in adap->nr, and the specified adapter became available for clients.
1664 * Otherwise, a negative errno value is returned.
1666 int i2c_add_adapter(struct i2c_adapter *adapter)
1668 struct device *dev = &adapter->dev;
1672 id = of_alias_get_id(dev->of_node, "i2c");
1675 return __i2c_add_numbered_adapter(adapter);
1679 mutex_lock(&core_lock);
1680 id = idr_alloc(&i2c_adapter_idr, adapter,
1681 __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
1682 mutex_unlock(&core_lock);
1688 return i2c_register_adapter(adapter);
1690 EXPORT_SYMBOL(i2c_add_adapter);
1693 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
1694 * @adap: the adapter to register (with adap->nr initialized)
1695 * Context: can sleep
1697 * This routine is used to declare an I2C adapter when its bus number
1698 * matters. For example, use it for I2C adapters from system-on-chip CPUs,
1699 * or otherwise built in to the system's mainboard, and where i2c_board_info
1700 * is used to properly configure I2C devices.
1702 * If the requested bus number is set to -1, then this function will behave
1703 * identically to i2c_add_adapter, and will dynamically assign a bus number.
1705 * If no devices have pre-been declared for this bus, then be sure to
1706 * register the adapter before any dynamically allocated ones. Otherwise
1707 * the required bus ID may not be available.
1709 * When this returns zero, the specified adapter became available for
1710 * clients using the bus number provided in adap->nr. Also, the table
1711 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
1712 * and the appropriate driver model device nodes are created. Otherwise, a
1713 * negative errno value is returned.
1715 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
1717 if (adap->nr == -1) /* -1 means dynamically assign bus id */
1718 return i2c_add_adapter(adap);
1720 return __i2c_add_numbered_adapter(adap);
1722 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
1724 static void i2c_do_del_adapter(struct i2c_driver *driver,
1725 struct i2c_adapter *adapter)
1727 struct i2c_client *client, *_n;
1729 /* Remove the devices we created ourselves as the result of hardware
1730 * probing (using a driver's detect method) */
1731 list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1732 if (client->adapter == adapter) {
1733 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1734 client->name, client->addr);
1735 list_del(&client->detected);
1736 i2c_unregister_device(client);
1741 static int __unregister_client(struct device *dev, void *dummy)
1743 struct i2c_client *client = i2c_verify_client(dev);
1744 if (client && strcmp(client->name, "dummy"))
1745 i2c_unregister_device(client);
1749 static int __unregister_dummy(struct device *dev, void *dummy)
1751 struct i2c_client *client = i2c_verify_client(dev);
1753 i2c_unregister_device(client);
1757 static int __process_removed_adapter(struct device_driver *d, void *data)
1759 i2c_do_del_adapter(to_i2c_driver(d), data);
1764 * i2c_del_adapter - unregister I2C adapter
1765 * @adap: the adapter being unregistered
1766 * Context: can sleep
1768 * This unregisters an I2C adapter which was previously registered
1769 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1771 void i2c_del_adapter(struct i2c_adapter *adap)
1773 struct i2c_adapter *found;
1774 struct i2c_client *client, *next;
1776 /* First make sure that this adapter was ever added */
1777 mutex_lock(&core_lock);
1778 found = idr_find(&i2c_adapter_idr, adap->nr);
1779 mutex_unlock(&core_lock);
1780 if (found != adap) {
1781 pr_debug("i2c-core: attempting to delete unregistered "
1782 "adapter [%s]\n", adap->name);
1786 acpi_i2c_remove_space_handler(adap);
1787 /* Tell drivers about this removal */
1788 mutex_lock(&core_lock);
1789 bus_for_each_drv(&i2c_bus_type, NULL, adap,
1790 __process_removed_adapter);
1791 mutex_unlock(&core_lock);
1793 /* Remove devices instantiated from sysfs */
1794 mutex_lock_nested(&adap->userspace_clients_lock,
1795 i2c_adapter_depth(adap));
1796 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1798 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1800 list_del(&client->detected);
1801 i2c_unregister_device(client);
1803 mutex_unlock(&adap->userspace_clients_lock);
1805 /* Detach any active clients. This can't fail, thus we do not
1806 * check the returned value. This is a two-pass process, because
1807 * we can't remove the dummy devices during the first pass: they
1808 * could have been instantiated by real devices wishing to clean
1809 * them up properly, so we give them a chance to do that first. */
1810 device_for_each_child(&adap->dev, NULL, __unregister_client);
1811 device_for_each_child(&adap->dev, NULL, __unregister_dummy);
1813 #ifdef CONFIG_I2C_COMPAT
1814 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1818 /* device name is gone after device_unregister */
1819 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1821 /* wait until all references to the device are gone
1823 * FIXME: This is old code and should ideally be replaced by an
1824 * alternative which results in decoupling the lifetime of the struct
1825 * device from the i2c_adapter, like spi or netdev do. Any solution
1826 * should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled!
1828 init_completion(&adap->dev_released);
1829 device_unregister(&adap->dev);
1830 wait_for_completion(&adap->dev_released);
1833 mutex_lock(&core_lock);
1834 idr_remove(&i2c_adapter_idr, adap->nr);
1835 mutex_unlock(&core_lock);
1837 /* Clear the device structure in case this adapter is ever going to be
1839 memset(&adap->dev, 0, sizeof(adap->dev));
1841 EXPORT_SYMBOL(i2c_del_adapter);
1844 * i2c_parse_fw_timings - get I2C related timing parameters from firmware
1845 * @dev: The device to scan for I2C timing properties
1846 * @t: the i2c_timings struct to be filled with values
1847 * @use_defaults: bool to use sane defaults derived from the I2C specification
1848 * when properties are not found, otherwise use 0
1850 * Scan the device for the generic I2C properties describing timing parameters
1851 * for the signal and fill the given struct with the results. If a property was
1852 * not found and use_defaults was true, then maximum timings are assumed which
1853 * are derived from the I2C specification. If use_defaults is not used, the
1854 * results will be 0, so drivers can apply their own defaults later. The latter
1855 * is mainly intended for avoiding regressions of existing drivers which want
1856 * to switch to this function. New drivers almost always should use the defaults.
1859 void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_defaults)
1863 memset(t, 0, sizeof(*t));
1865 ret = device_property_read_u32(dev, "clock-frequency", &t->bus_freq_hz);
1866 if (ret && use_defaults)
1867 t->bus_freq_hz = 100000;
1869 ret = device_property_read_u32(dev, "i2c-scl-rising-time-ns", &t->scl_rise_ns);
1870 if (ret && use_defaults) {
1871 if (t->bus_freq_hz <= 100000)
1872 t->scl_rise_ns = 1000;
1873 else if (t->bus_freq_hz <= 400000)
1874 t->scl_rise_ns = 300;
1876 t->scl_rise_ns = 120;
1879 ret = device_property_read_u32(dev, "i2c-scl-falling-time-ns", &t->scl_fall_ns);
1880 if (ret && use_defaults) {
1881 if (t->bus_freq_hz <= 400000)
1882 t->scl_fall_ns = 300;
1884 t->scl_fall_ns = 120;
1887 device_property_read_u32(dev, "i2c-scl-internal-delay-ns", &t->scl_int_delay_ns);
1889 ret = device_property_read_u32(dev, "i2c-sda-falling-time-ns", &t->sda_fall_ns);
1890 if (ret && use_defaults)
1891 t->sda_fall_ns = t->scl_fall_ns;
1893 EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
1895 /* ------------------------------------------------------------------------- */
1897 int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *))
1901 mutex_lock(&core_lock);
1902 res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn);
1903 mutex_unlock(&core_lock);
1907 EXPORT_SYMBOL_GPL(i2c_for_each_dev);
1909 static int __process_new_driver(struct device *dev, void *data)
1911 if (dev->type != &i2c_adapter_type)
1913 return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1917 * An i2c_driver is used with one or more i2c_client (device) nodes to access
1918 * i2c slave chips, on a bus instance associated with some i2c_adapter.
1921 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1925 /* Can't register until after driver model init */
1926 if (unlikely(WARN_ON(!i2c_bus_type.p)))
1929 /* add the driver to the list of i2c drivers in the driver core */
1930 driver->driver.owner = owner;
1931 driver->driver.bus = &i2c_bus_type;
1932 INIT_LIST_HEAD(&driver->clients);
1934 /* When registration returns, the driver core
1935 * will have called probe() for all matching-but-unbound devices.
1937 res = driver_register(&driver->driver);
1941 pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
1943 /* Walk the adapters that are already present */
1944 i2c_for_each_dev(driver, __process_new_driver);
1948 EXPORT_SYMBOL(i2c_register_driver);
1950 static int __process_removed_driver(struct device *dev, void *data)
1952 if (dev->type == &i2c_adapter_type)
1953 i2c_do_del_adapter(data, to_i2c_adapter(dev));
1958 * i2c_del_driver - unregister I2C driver
1959 * @driver: the driver being unregistered
1960 * Context: can sleep
1962 void i2c_del_driver(struct i2c_driver *driver)
1964 i2c_for_each_dev(driver, __process_removed_driver);
1966 driver_unregister(&driver->driver);
1967 pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
1969 EXPORT_SYMBOL(i2c_del_driver);
1971 /* ------------------------------------------------------------------------- */
1974 * i2c_use_client - increments the reference count of the i2c client structure
1975 * @client: the client being referenced
1977 * Each live reference to a client should be refcounted. The driver model does
1978 * that automatically as part of driver binding, so that most drivers don't
1979 * need to do this explicitly: they hold a reference until they're unbound
1982 * A pointer to the client with the incremented reference counter is returned.
1984 struct i2c_client *i2c_use_client(struct i2c_client *client)
1986 if (client && get_device(&client->dev))
1990 EXPORT_SYMBOL(i2c_use_client);
1993 * i2c_release_client - release a use of the i2c client structure
1994 * @client: the client being no longer referenced
1996 * Must be called when a user of a client is finished with it.
1998 void i2c_release_client(struct i2c_client *client)
2001 put_device(&client->dev);
2003 EXPORT_SYMBOL(i2c_release_client);
2005 struct i2c_cmd_arg {
2010 static int i2c_cmd(struct device *dev, void *_arg)
2012 struct i2c_client *client = i2c_verify_client(dev);
2013 struct i2c_cmd_arg *arg = _arg;
2014 struct i2c_driver *driver;
2016 if (!client || !client->dev.driver)
2019 driver = to_i2c_driver(client->dev.driver);
2020 if (driver->command)
2021 driver->command(client, arg->cmd, arg->arg);
2025 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
2027 struct i2c_cmd_arg cmd_arg;
2031 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
2033 EXPORT_SYMBOL(i2c_clients_command);
2035 #if IS_ENABLED(CONFIG_OF_DYNAMIC)
2036 static int of_i2c_notify(struct notifier_block *nb, unsigned long action,
2039 struct of_reconfig_data *rd = arg;
2040 struct i2c_adapter *adap;
2041 struct i2c_client *client;
2043 switch (of_reconfig_get_state_change(action, rd)) {
2044 case OF_RECONFIG_CHANGE_ADD:
2045 adap = of_find_i2c_adapter_by_node(rd->dn->parent);
2047 return NOTIFY_OK; /* not for us */
2049 if (of_node_test_and_set_flag(rd->dn, OF_POPULATED)) {
2050 put_device(&adap->dev);
2054 client = of_i2c_register_device(adap, rd->dn);
2055 put_device(&adap->dev);
2057 if (IS_ERR(client)) {
2058 pr_err("%s: failed to create for '%s'\n",
2059 __func__, rd->dn->full_name);
2060 return notifier_from_errno(PTR_ERR(client));
2063 case OF_RECONFIG_CHANGE_REMOVE:
2064 /* already depopulated? */
2065 if (!of_node_check_flag(rd->dn, OF_POPULATED))
2068 /* find our device by node */
2069 client = of_find_i2c_device_by_node(rd->dn);
2071 return NOTIFY_OK; /* no? not meant for us */
2073 /* unregister takes one ref away */
2074 i2c_unregister_device(client);
2076 /* and put the reference of the find */
2077 put_device(&client->dev);
2083 static struct notifier_block i2c_of_notifier = {
2084 .notifier_call = of_i2c_notify,
2087 extern struct notifier_block i2c_of_notifier;
2088 #endif /* CONFIG_OF_DYNAMIC */
2090 static int __init i2c_init(void)
2094 retval = of_alias_get_highest_id("i2c");
2096 down_write(&__i2c_board_lock);
2097 if (retval >= __i2c_first_dynamic_bus_num)
2098 __i2c_first_dynamic_bus_num = retval + 1;
2099 up_write(&__i2c_board_lock);
2101 retval = bus_register(&i2c_bus_type);
2104 #ifdef CONFIG_I2C_COMPAT
2105 i2c_adapter_compat_class = class_compat_register("i2c-adapter");
2106 if (!i2c_adapter_compat_class) {
2111 retval = i2c_add_driver(&dummy_driver);
2115 if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2116 WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier));
2121 #ifdef CONFIG_I2C_COMPAT
2122 class_compat_unregister(i2c_adapter_compat_class);
2125 bus_unregister(&i2c_bus_type);
2129 static void __exit i2c_exit(void)
2131 if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2132 WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier));
2133 i2c_del_driver(&dummy_driver);
2134 #ifdef CONFIG_I2C_COMPAT
2135 class_compat_unregister(i2c_adapter_compat_class);
2137 bus_unregister(&i2c_bus_type);
2138 tracepoint_synchronize_unregister();
2141 /* We must initialize early, because some subsystems register i2c drivers
2142 * in subsys_initcall() code, but are linked (and initialized) before i2c.
2144 postcore_initcall(i2c_init);
2145 module_exit(i2c_exit);
2147 /* ----------------------------------------------------
2148 * the functional interface to the i2c busses.
2149 * ----------------------------------------------------
2152 /* Check if val is exceeding the quirk IFF quirk is non 0 */
2153 #define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
2155 static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
2157 dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
2158 err_msg, msg->addr, msg->len,
2159 msg->flags & I2C_M_RD ? "read" : "write");
2163 static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
2165 const struct i2c_adapter_quirks *q = adap->quirks;
2166 int max_num = q->max_num_msgs, i;
2167 bool do_len_check = true;
2169 if (q->flags & I2C_AQ_COMB) {
2172 /* special checks for combined messages */
2174 if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD)
2175 return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write");
2177 if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD))
2178 return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read");
2180 if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr)
2181 return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr");
2183 if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len))
2184 return i2c_quirk_error(adap, &msgs[0], "msg too long");
2186 if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len))
2187 return i2c_quirk_error(adap, &msgs[1], "msg too long");
2189 do_len_check = false;
2193 if (i2c_quirk_exceeded(num, max_num))
2194 return i2c_quirk_error(adap, &msgs[0], "too many messages");
2196 for (i = 0; i < num; i++) {
2197 u16 len = msgs[i].len;
2199 if (msgs[i].flags & I2C_M_RD) {
2200 if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
2201 return i2c_quirk_error(adap, &msgs[i], "msg too long");
2203 if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
2204 return i2c_quirk_error(adap, &msgs[i], "msg too long");
2212 * __i2c_transfer - unlocked flavor of i2c_transfer
2213 * @adap: Handle to I2C bus
2214 * @msgs: One or more messages to execute before STOP is issued to
2215 * terminate the operation; each message begins with a START.
2216 * @num: Number of messages to be executed.
2218 * Returns negative errno, else the number of messages executed.
2220 * Adapter lock must be held when calling this function. No debug logging
2221 * takes place. adap->algo->master_xfer existence isn't checked.
2223 int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
2225 unsigned long orig_jiffies;
2228 if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
2231 /* i2c_trace_msg gets enabled when tracepoint i2c_transfer gets
2232 * enabled. This is an efficient way of keeping the for-loop from
2233 * being executed when not needed.
2235 if (static_key_false(&i2c_trace_msg)) {
2237 for (i = 0; i < num; i++)
2238 if (msgs[i].flags & I2C_M_RD)
2239 trace_i2c_read(adap, &msgs[i], i);
2241 trace_i2c_write(adap, &msgs[i], i);
2244 /* Retry automatically on arbitration loss */
2245 orig_jiffies = jiffies;
2246 for (ret = 0, try = 0; try <= adap->retries; try++) {
2247 ret = adap->algo->master_xfer(adap, msgs, num);
2250 if (time_after(jiffies, orig_jiffies + adap->timeout))
2254 if (static_key_false(&i2c_trace_msg)) {
2256 for (i = 0; i < ret; i++)
2257 if (msgs[i].flags & I2C_M_RD)
2258 trace_i2c_reply(adap, &msgs[i], i);
2259 trace_i2c_result(adap, i, ret);
2264 EXPORT_SYMBOL(__i2c_transfer);
2267 * i2c_transfer - execute a single or combined I2C message
2268 * @adap: Handle to I2C bus
2269 * @msgs: One or more messages to execute before STOP is issued to
2270 * terminate the operation; each message begins with a START.
2271 * @num: Number of messages to be executed.
2273 * Returns negative errno, else the number of messages executed.
2275 * Note that there is no requirement that each message be sent to
2276 * the same slave address, although that is the most common model.
2278 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
2282 /* REVISIT the fault reporting model here is weak:
2284 * - When we get an error after receiving N bytes from a slave,
2285 * there is no way to report "N".
2287 * - When we get a NAK after transmitting N bytes to a slave,
2288 * there is no way to report "N" ... or to let the master
2289 * continue executing the rest of this combined message, if
2290 * that's the appropriate response.
2292 * - When for example "num" is two and we successfully complete
2293 * the first message but get an error part way through the
2294 * second, it's unclear whether that should be reported as
2295 * one (discarding status on the second message) or errno
2296 * (discarding status on the first one).
2299 if (adap->algo->master_xfer) {
2301 for (ret = 0; ret < num; ret++) {
2302 dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
2303 "len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
2304 ? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
2305 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
2309 if (in_atomic() || irqs_disabled()) {
2310 ret = i2c_trylock_adapter(adap);
2312 /* I2C activity is ongoing. */
2315 i2c_lock_adapter(adap);
2318 ret = __i2c_transfer(adap, msgs, num);
2319 i2c_unlock_adapter(adap);
2323 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
2327 EXPORT_SYMBOL(i2c_transfer);
2330 * i2c_master_send - issue a single I2C message in master transmit mode
2331 * @client: Handle to slave device
2332 * @buf: Data that will be written to the slave
2333 * @count: How many bytes to write, must be less than 64k since msg.len is u16
2335 * Returns negative errno, or else the number of bytes written.
2337 int i2c_master_send(const struct i2c_client *client, const char *buf, int count)
2340 struct i2c_adapter *adap = client->adapter;
2343 msg.addr = client->addr;
2344 msg.flags = client->flags & I2C_M_TEN;
2346 msg.buf = (char *)buf;
2348 ret = i2c_transfer(adap, &msg, 1);
2351 * If everything went ok (i.e. 1 msg transmitted), return #bytes
2352 * transmitted, else error code.
2354 return (ret == 1) ? count : ret;
2356 EXPORT_SYMBOL(i2c_master_send);
2359 * i2c_master_recv - issue a single I2C message in master receive mode
2360 * @client: Handle to slave device
2361 * @buf: Where to store data read from slave
2362 * @count: How many bytes to read, must be less than 64k since msg.len is u16
2364 * Returns negative errno, or else the number of bytes read.
2366 int i2c_master_recv(const struct i2c_client *client, char *buf, int count)
2368 struct i2c_adapter *adap = client->adapter;
2372 msg.addr = client->addr;
2373 msg.flags = client->flags & I2C_M_TEN;
2374 msg.flags |= I2C_M_RD;
2378 ret = i2c_transfer(adap, &msg, 1);
2381 * If everything went ok (i.e. 1 msg received), return #bytes received,
2384 return (ret == 1) ? count : ret;
2386 EXPORT_SYMBOL(i2c_master_recv);
2388 /* ----------------------------------------------------
2389 * the i2c address scanning function
2390 * Will not work for 10-bit addresses!
2391 * ----------------------------------------------------
2395 * Legacy default probe function, mostly relevant for SMBus. The default
2396 * probe method is a quick write, but it is known to corrupt the 24RF08
2397 * EEPROMs due to a state machine bug, and could also irreversibly
2398 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
2399 * we use a short byte read instead. Also, some bus drivers don't implement
2400 * quick write, so we fallback to a byte read in that case too.
2401 * On x86, there is another special case for FSC hardware monitoring chips,
2402 * which want regular byte reads (address 0x73.) Fortunately, these are the
2403 * only known chips using this I2C address on PC hardware.
2404 * Returns 1 if probe succeeded, 0 if not.
2406 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
2409 union i2c_smbus_data dummy;
2412 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
2413 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
2414 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2415 I2C_SMBUS_BYTE_DATA, &dummy);
2418 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
2419 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
2420 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
2421 I2C_SMBUS_QUICK, NULL);
2422 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
2423 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2424 I2C_SMBUS_BYTE, &dummy);
2426 dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
2434 static int i2c_detect_address(struct i2c_client *temp_client,
2435 struct i2c_driver *driver)
2437 struct i2c_board_info info;
2438 struct i2c_adapter *adapter = temp_client->adapter;
2439 int addr = temp_client->addr;
2442 /* Make sure the address is valid */
2443 err = i2c_check_7bit_addr_validity_strict(addr);
2445 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
2450 /* Skip if already in use (7 bit, no need to encode flags) */
2451 if (i2c_check_addr_busy(adapter, addr))
2454 /* Make sure there is something at this address */
2455 if (!i2c_default_probe(adapter, addr))
2458 /* Finally call the custom detection function */
2459 memset(&info, 0, sizeof(struct i2c_board_info));
2461 err = driver->detect(temp_client, &info);
2463 /* -ENODEV is returned if the detection fails. We catch it
2464 here as this isn't an error. */
2465 return err == -ENODEV ? 0 : err;
2468 /* Consistency check */
2469 if (info.type[0] == '\0') {
2470 dev_err(&adapter->dev, "%s detection function provided "
2471 "no name for 0x%x\n", driver->driver.name,
2474 struct i2c_client *client;
2476 /* Detection succeeded, instantiate the device */
2477 if (adapter->class & I2C_CLASS_DEPRECATED)
2478 dev_warn(&adapter->dev,
2479 "This adapter will soon drop class based instantiation of devices. "
2480 "Please make sure client 0x%02x gets instantiated by other means. "
2481 "Check 'Documentation/i2c/instantiating-devices' for details.\n",
2484 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
2485 info.type, info.addr);
2486 client = i2c_new_device(adapter, &info);
2488 list_add_tail(&client->detected, &driver->clients);
2490 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
2491 info.type, info.addr);
2496 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
2498 const unsigned short *address_list;
2499 struct i2c_client *temp_client;
2501 int adap_id = i2c_adapter_id(adapter);
2503 address_list = driver->address_list;
2504 if (!driver->detect || !address_list)
2507 /* Warn that the adapter lost class based instantiation */
2508 if (adapter->class == I2C_CLASS_DEPRECATED) {
2509 dev_dbg(&adapter->dev,
2510 "This adapter dropped support for I2C classes and "
2511 "won't auto-detect %s devices anymore. If you need it, check "
2512 "'Documentation/i2c/instantiating-devices' for alternatives.\n",
2513 driver->driver.name);
2517 /* Stop here if the classes do not match */
2518 if (!(adapter->class & driver->class))
2521 /* Set up a temporary client to help detect callback */
2522 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
2525 temp_client->adapter = adapter;
2527 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
2528 dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
2529 "addr 0x%02x\n", adap_id, address_list[i]);
2530 temp_client->addr = address_list[i];
2531 err = i2c_detect_address(temp_client, driver);
2540 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
2542 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2543 I2C_SMBUS_QUICK, NULL) >= 0;
2545 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
2548 i2c_new_probed_device(struct i2c_adapter *adap,
2549 struct i2c_board_info *info,
2550 unsigned short const *addr_list,
2551 int (*probe)(struct i2c_adapter *, unsigned short addr))
2556 probe = i2c_default_probe;
2558 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
2559 /* Check address validity */
2560 if (i2c_check_7bit_addr_validity_strict(addr_list[i]) < 0) {
2561 dev_warn(&adap->dev, "Invalid 7-bit address "
2562 "0x%02x\n", addr_list[i]);
2566 /* Check address availability (7 bit, no need to encode flags) */
2567 if (i2c_check_addr_busy(adap, addr_list[i])) {
2568 dev_dbg(&adap->dev, "Address 0x%02x already in "
2569 "use, not probing\n", addr_list[i]);
2573 /* Test address responsiveness */
2574 if (probe(adap, addr_list[i]))
2578 if (addr_list[i] == I2C_CLIENT_END) {
2579 dev_dbg(&adap->dev, "Probing failed, no device found\n");
2583 info->addr = addr_list[i];
2584 return i2c_new_device(adap, info);
2586 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
2588 struct i2c_adapter *i2c_get_adapter(int nr)
2590 struct i2c_adapter *adapter;
2592 mutex_lock(&core_lock);
2593 adapter = idr_find(&i2c_adapter_idr, nr);
2597 if (try_module_get(adapter->owner))
2598 get_device(&adapter->dev);
2603 mutex_unlock(&core_lock);
2606 EXPORT_SYMBOL(i2c_get_adapter);
2608 void i2c_put_adapter(struct i2c_adapter *adap)
2613 put_device(&adap->dev);
2614 module_put(adap->owner);
2616 EXPORT_SYMBOL(i2c_put_adapter);
2618 /* The SMBus parts */
2620 #define POLY (0x1070U << 3)
2621 static u8 crc8(u16 data)
2625 for (i = 0; i < 8; i++) {
2630 return (u8)(data >> 8);
2633 /* Incremental CRC8 over count bytes in the array pointed to by p */
2634 static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
2638 for (i = 0; i < count; i++)
2639 crc = crc8((crc ^ p[i]) << 8);
2643 /* Assume a 7-bit address, which is reasonable for SMBus */
2644 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
2646 /* The address will be sent first */
2647 u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
2648 pec = i2c_smbus_pec(pec, &addr, 1);
2650 /* The data buffer follows */
2651 return i2c_smbus_pec(pec, msg->buf, msg->len);
2654 /* Used for write only transactions */
2655 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
2657 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
2661 /* Return <0 on CRC error
2662 If there was a write before this read (most cases) we need to take the
2663 partial CRC from the write part into account.
2664 Note that this function does modify the message (we need to decrease the
2665 message length to hide the CRC byte from the caller). */
2666 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
2668 u8 rpec = msg->buf[--msg->len];
2669 cpec = i2c_smbus_msg_pec(cpec, msg);
2672 pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
2680 * i2c_smbus_read_byte - SMBus "receive byte" protocol
2681 * @client: Handle to slave device
2683 * This executes the SMBus "receive byte" protocol, returning negative errno
2684 * else the byte received from the device.
2686 s32 i2c_smbus_read_byte(const struct i2c_client *client)
2688 union i2c_smbus_data data;
2691 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2693 I2C_SMBUS_BYTE, &data);
2694 return (status < 0) ? status : data.byte;
2696 EXPORT_SYMBOL(i2c_smbus_read_byte);
2699 * i2c_smbus_write_byte - SMBus "send byte" protocol
2700 * @client: Handle to slave device
2701 * @value: Byte to be sent
2703 * This executes the SMBus "send byte" protocol, returning negative errno
2704 * else zero on success.
2706 s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
2708 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2709 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
2711 EXPORT_SYMBOL(i2c_smbus_write_byte);
2714 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
2715 * @client: Handle to slave device
2716 * @command: Byte interpreted by slave
2718 * This executes the SMBus "read byte" protocol, returning negative errno
2719 * else a data byte received from the device.
2721 s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
2723 union i2c_smbus_data data;
2726 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2727 I2C_SMBUS_READ, command,
2728 I2C_SMBUS_BYTE_DATA, &data);
2729 return (status < 0) ? status : data.byte;
2731 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
2734 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
2735 * @client: Handle to slave device
2736 * @command: Byte interpreted by slave
2737 * @value: Byte being written
2739 * This executes the SMBus "write byte" protocol, returning negative errno
2740 * else zero on success.
2742 s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
2745 union i2c_smbus_data data;
2747 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2748 I2C_SMBUS_WRITE, command,
2749 I2C_SMBUS_BYTE_DATA, &data);
2751 EXPORT_SYMBOL(i2c_smbus_write_byte_data);
2754 * i2c_smbus_read_word_data - SMBus "read word" protocol
2755 * @client: Handle to slave device
2756 * @command: Byte interpreted by slave
2758 * This executes the SMBus "read word" protocol, returning negative errno
2759 * else a 16-bit unsigned "word" received from the device.
2761 s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
2763 union i2c_smbus_data data;
2766 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2767 I2C_SMBUS_READ, command,
2768 I2C_SMBUS_WORD_DATA, &data);
2769 return (status < 0) ? status : data.word;
2771 EXPORT_SYMBOL(i2c_smbus_read_word_data);
2774 * i2c_smbus_write_word_data - SMBus "write word" protocol
2775 * @client: Handle to slave device
2776 * @command: Byte interpreted by slave
2777 * @value: 16-bit "word" being written
2779 * This executes the SMBus "write word" protocol, returning negative errno
2780 * else zero on success.
2782 s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
2785 union i2c_smbus_data data;
2787 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2788 I2C_SMBUS_WRITE, command,
2789 I2C_SMBUS_WORD_DATA, &data);
2791 EXPORT_SYMBOL(i2c_smbus_write_word_data);
2794 * i2c_smbus_read_block_data - SMBus "block read" protocol
2795 * @client: Handle to slave device
2796 * @command: Byte interpreted by slave
2797 * @values: Byte array into which data will be read; big enough to hold
2798 * the data returned by the slave. SMBus allows at most 32 bytes.
2800 * This executes the SMBus "block read" protocol, returning negative errno
2801 * else the number of data bytes in the slave's response.
2803 * Note that using this function requires that the client's adapter support
2804 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
2805 * support this; its emulation through I2C messaging relies on a specific
2806 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
2808 s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
2811 union i2c_smbus_data data;
2814 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2815 I2C_SMBUS_READ, command,
2816 I2C_SMBUS_BLOCK_DATA, &data);
2820 memcpy(values, &data.block[1], data.block[0]);
2821 return data.block[0];
2823 EXPORT_SYMBOL(i2c_smbus_read_block_data);
2826 * i2c_smbus_write_block_data - SMBus "block write" protocol
2827 * @client: Handle to slave device
2828 * @command: Byte interpreted by slave
2829 * @length: Size of data block; SMBus allows at most 32 bytes
2830 * @values: Byte array which will be written.
2832 * This executes the SMBus "block write" protocol, returning negative errno
2833 * else zero on success.
2835 s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
2836 u8 length, const u8 *values)
2838 union i2c_smbus_data data;
2840 if (length > I2C_SMBUS_BLOCK_MAX)
2841 length = I2C_SMBUS_BLOCK_MAX;
2842 data.block[0] = length;
2843 memcpy(&data.block[1], values, length);
2844 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2845 I2C_SMBUS_WRITE, command,
2846 I2C_SMBUS_BLOCK_DATA, &data);
2848 EXPORT_SYMBOL(i2c_smbus_write_block_data);
2850 /* Returns the number of read bytes */
2851 s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
2852 u8 length, u8 *values)
2854 union i2c_smbus_data data;
2857 if (length > I2C_SMBUS_BLOCK_MAX)
2858 length = I2C_SMBUS_BLOCK_MAX;
2859 data.block[0] = length;
2860 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2861 I2C_SMBUS_READ, command,
2862 I2C_SMBUS_I2C_BLOCK_DATA, &data);
2866 memcpy(values, &data.block[1], data.block[0]);
2867 return data.block[0];
2869 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
2871 s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
2872 u8 length, const u8 *values)
2874 union i2c_smbus_data data;
2876 if (length > I2C_SMBUS_BLOCK_MAX)
2877 length = I2C_SMBUS_BLOCK_MAX;
2878 data.block[0] = length;
2879 memcpy(data.block + 1, values, length);
2880 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2881 I2C_SMBUS_WRITE, command,
2882 I2C_SMBUS_I2C_BLOCK_DATA, &data);
2884 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
2886 /* Simulate a SMBus command using the i2c protocol
2887 No checking of parameters is done! */
2888 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
2889 unsigned short flags,
2890 char read_write, u8 command, int size,
2891 union i2c_smbus_data *data)
2893 /* So we need to generate a series of msgs. In the case of writing, we
2894 need to use only one message; when reading, we need two. We initialize
2895 most things with sane defaults, to keep the code below somewhat
2897 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
2898 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
2899 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
2903 struct i2c_msg msg[2] = {
2911 .flags = flags | I2C_M_RD,
2917 msgbuf0[0] = command;
2919 case I2C_SMBUS_QUICK:
2921 /* Special case: The read/write field is used as data */
2922 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
2926 case I2C_SMBUS_BYTE:
2927 if (read_write == I2C_SMBUS_READ) {
2928 /* Special case: only a read! */
2929 msg[0].flags = I2C_M_RD | flags;
2933 case I2C_SMBUS_BYTE_DATA:
2934 if (read_write == I2C_SMBUS_READ)
2938 msgbuf0[1] = data->byte;
2941 case I2C_SMBUS_WORD_DATA:
2942 if (read_write == I2C_SMBUS_READ)
2946 msgbuf0[1] = data->word & 0xff;
2947 msgbuf0[2] = data->word >> 8;
2950 case I2C_SMBUS_PROC_CALL:
2951 num = 2; /* Special case */
2952 read_write = I2C_SMBUS_READ;
2955 msgbuf0[1] = data->word & 0xff;
2956 msgbuf0[2] = data->word >> 8;
2958 case I2C_SMBUS_BLOCK_DATA:
2959 if (read_write == I2C_SMBUS_READ) {
2960 msg[1].flags |= I2C_M_RECV_LEN;
2961 msg[1].len = 1; /* block length will be added by
2962 the underlying bus driver */
2964 msg[0].len = data->block[0] + 2;
2965 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
2966 dev_err(&adapter->dev,
2967 "Invalid block write size %d\n",
2971 for (i = 1; i < msg[0].len; i++)
2972 msgbuf0[i] = data->block[i-1];
2975 case I2C_SMBUS_BLOCK_PROC_CALL:
2976 num = 2; /* Another special case */
2977 read_write = I2C_SMBUS_READ;
2978 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
2979 dev_err(&adapter->dev,
2980 "Invalid block write size %d\n",
2984 msg[0].len = data->block[0] + 2;
2985 for (i = 1; i < msg[0].len; i++)
2986 msgbuf0[i] = data->block[i-1];
2987 msg[1].flags |= I2C_M_RECV_LEN;
2988 msg[1].len = 1; /* block length will be added by
2989 the underlying bus driver */
2991 case I2C_SMBUS_I2C_BLOCK_DATA:
2992 if (read_write == I2C_SMBUS_READ) {
2993 msg[1].len = data->block[0];
2995 msg[0].len = data->block[0] + 1;
2996 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
2997 dev_err(&adapter->dev,
2998 "Invalid block write size %d\n",
3002 for (i = 1; i <= data->block[0]; i++)
3003 msgbuf0[i] = data->block[i];
3007 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
3011 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
3012 && size != I2C_SMBUS_I2C_BLOCK_DATA);
3014 /* Compute PEC if first message is a write */
3015 if (!(msg[0].flags & I2C_M_RD)) {
3016 if (num == 1) /* Write only */
3017 i2c_smbus_add_pec(&msg[0]);
3018 else /* Write followed by read */
3019 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
3021 /* Ask for PEC if last message is a read */
3022 if (msg[num-1].flags & I2C_M_RD)
3026 status = i2c_transfer(adapter, msg, num);
3030 /* Check PEC if last message is a read */
3031 if (i && (msg[num-1].flags & I2C_M_RD)) {
3032 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
3037 if (read_write == I2C_SMBUS_READ)
3039 case I2C_SMBUS_BYTE:
3040 data->byte = msgbuf0[0];
3042 case I2C_SMBUS_BYTE_DATA:
3043 data->byte = msgbuf1[0];
3045 case I2C_SMBUS_WORD_DATA:
3046 case I2C_SMBUS_PROC_CALL:
3047 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
3049 case I2C_SMBUS_I2C_BLOCK_DATA:
3050 for (i = 0; i < data->block[0]; i++)
3051 data->block[i+1] = msgbuf1[i];
3053 case I2C_SMBUS_BLOCK_DATA:
3054 case I2C_SMBUS_BLOCK_PROC_CALL:
3055 for (i = 0; i < msgbuf1[0] + 1; i++)
3056 data->block[i] = msgbuf1[i];
3063 * i2c_smbus_xfer - execute SMBus protocol operations
3064 * @adapter: Handle to I2C bus
3065 * @addr: Address of SMBus slave on that bus
3066 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
3067 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
3068 * @command: Byte interpreted by slave, for protocols which use such bytes
3069 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
3070 * @data: Data to be read or written
3072 * This executes an SMBus protocol operation, and returns a negative
3073 * errno code else zero on success.
3075 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
3076 char read_write, u8 command, int protocol,
3077 union i2c_smbus_data *data)
3079 unsigned long orig_jiffies;
3083 /* If enabled, the following two tracepoints are conditional on
3084 * read_write and protocol.
3086 trace_smbus_write(adapter, addr, flags, read_write,
3087 command, protocol, data);
3088 trace_smbus_read(adapter, addr, flags, read_write,
3091 flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB;
3093 if (adapter->algo->smbus_xfer) {
3094 i2c_lock_adapter(adapter);
3096 /* Retry automatically on arbitration loss */
3097 orig_jiffies = jiffies;
3098 for (res = 0, try = 0; try <= adapter->retries; try++) {
3099 res = adapter->algo->smbus_xfer(adapter, addr, flags,
3100 read_write, command,
3104 if (time_after(jiffies,
3105 orig_jiffies + adapter->timeout))
3108 i2c_unlock_adapter(adapter);
3110 if (res != -EOPNOTSUPP || !adapter->algo->master_xfer)
3113 * Fall back to i2c_smbus_xfer_emulated if the adapter doesn't
3114 * implement native support for the SMBus operation.
3118 res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
3119 command, protocol, data);
3122 /* If enabled, the reply tracepoint is conditional on read_write. */
3123 trace_smbus_reply(adapter, addr, flags, read_write,
3124 command, protocol, data);
3125 trace_smbus_result(adapter, addr, flags, read_write,
3126 command, protocol, res);
3130 EXPORT_SYMBOL(i2c_smbus_xfer);
3133 * i2c_smbus_read_i2c_block_data_or_emulated - read block or emulate
3134 * @client: Handle to slave device
3135 * @command: Byte interpreted by slave
3136 * @length: Size of data block; SMBus allows at most I2C_SMBUS_BLOCK_MAX bytes
3137 * @values: Byte array into which data will be read; big enough to hold
3138 * the data returned by the slave. SMBus allows at most
3139 * I2C_SMBUS_BLOCK_MAX bytes.
3141 * This executes the SMBus "block read" protocol if supported by the adapter.
3142 * If block read is not supported, it emulates it using either word or byte
3143 * read protocols depending on availability.
3145 * The addresses of the I2C slave device that are accessed with this function
3146 * must be mapped to a linear region, so that a block read will have the same
3147 * effect as a byte read. Before using this function you must double-check
3148 * if the I2C slave does support exchanging a block transfer with a byte
3151 s32 i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
3152 u8 command, u8 length, u8 *values)
3157 if (length > I2C_SMBUS_BLOCK_MAX)
3158 length = I2C_SMBUS_BLOCK_MAX;
3160 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
3161 return i2c_smbus_read_i2c_block_data(client, command, length, values);
3163 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA))
3166 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) {
3167 while ((i + 2) <= length) {
3168 status = i2c_smbus_read_word_data(client, command + i);
3171 values[i] = status & 0xff;
3172 values[i + 1] = status >> 8;
3177 while (i < length) {
3178 status = i2c_smbus_read_byte_data(client, command + i);
3187 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data_or_emulated);
3189 #if IS_ENABLED(CONFIG_I2C_SLAVE)
3190 int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
3194 if (!client || !slave_cb) {
3195 WARN(1, "insufficent data\n");
3199 if (!(client->flags & I2C_CLIENT_SLAVE))
3200 dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
3203 if (!(client->flags & I2C_CLIENT_TEN)) {
3204 /* Enforce stricter address checking */
3205 ret = i2c_check_7bit_addr_validity_strict(client->addr);
3207 dev_err(&client->dev, "%s: invalid address\n", __func__);
3212 if (!client->adapter->algo->reg_slave) {
3213 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
3217 client->slave_cb = slave_cb;
3219 i2c_lock_adapter(client->adapter);
3220 ret = client->adapter->algo->reg_slave(client);
3221 i2c_unlock_adapter(client->adapter);
3224 client->slave_cb = NULL;
3225 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
3230 EXPORT_SYMBOL_GPL(i2c_slave_register);
3232 int i2c_slave_unregister(struct i2c_client *client)
3236 if (!client->adapter->algo->unreg_slave) {
3237 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
3241 i2c_lock_adapter(client->adapter);
3242 ret = client->adapter->algo->unreg_slave(client);
3243 i2c_unlock_adapter(client->adapter);
3246 client->slave_cb = NULL;
3248 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
3252 EXPORT_SYMBOL_GPL(i2c_slave_unregister);
3255 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
3256 MODULE_DESCRIPTION("I2C-Bus main module");
3257 MODULE_LICENSE("GPL");