2 * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
4 * Copyright (C) 2007 David Brownell
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 #include <linux/gpio.h>
22 #include <linux/i2c.h>
23 #include <linux/i2c/pcf857x.h>
24 #include <linux/interrupt.h>
25 #include <linux/irq.h>
26 #include <linux/irqdomain.h>
27 #include <linux/kernel.h>
28 #include <linux/module.h>
30 #include <linux/of_device.h>
31 #include <linux/slab.h>
32 #include <linux/spinlock.h>
35 static const struct i2c_device_id pcf857x_id[] = {
52 MODULE_DEVICE_TABLE(i2c, pcf857x_id);
55 static const struct of_device_id pcf857x_of_table[] = {
56 { .compatible = "nxp,pcf8574" },
57 { .compatible = "nxp,pcf8574a" },
58 { .compatible = "nxp,pca8574" },
59 { .compatible = "nxp,pca9670" },
60 { .compatible = "nxp,pca9672" },
61 { .compatible = "nxp,pca9674" },
62 { .compatible = "nxp,pcf8575" },
63 { .compatible = "nxp,pca8575" },
64 { .compatible = "nxp,pca9671" },
65 { .compatible = "nxp,pca9673" },
66 { .compatible = "nxp,pca9675" },
67 { .compatible = "maxim,max7328" },
68 { .compatible = "maxim,max7329" },
69 { .compatible = "ti,tca9554" },
72 MODULE_DEVICE_TABLE(of, pcf857x_of_table);
76 * The pcf857x, pca857x, and pca967x chips only expose one read and one
77 * write register. Writing a "one" bit (to match the reset state) lets
78 * that pin be used as an input; it's not an open-drain model, but acts
79 * a bit like one. This is described as "quasi-bidirectional"; read the
80 * chip documentation for details.
82 * Many other I2C GPIO expander chips (like the pca953x models) have
83 * more complex register models and more conventional circuitry using
84 * push/pull drivers. They often use the same 0x20..0x27 addresses as
85 * pcf857x parts, making the "legacy" I2C driver model problematic.
88 struct gpio_chip chip;
89 struct i2c_client *client;
90 struct mutex lock; /* protect 'out' */
91 spinlock_t slock; /* protect irq demux */
92 unsigned out; /* software latch */
93 unsigned status; /* current status */
95 int (*write)(struct i2c_client *client, unsigned data);
96 int (*read)(struct i2c_client *client);
99 /*-------------------------------------------------------------------------*/
101 /* Talk to 8-bit I/O expander */
103 static int i2c_write_le8(struct i2c_client *client, unsigned data)
105 return i2c_smbus_write_byte(client, data);
108 static int i2c_read_le8(struct i2c_client *client)
110 return (int)i2c_smbus_read_byte(client);
113 /* Talk to 16-bit I/O expander */
115 static int i2c_write_le16(struct i2c_client *client, unsigned word)
117 u8 buf[2] = { word & 0xff, word >> 8, };
120 status = i2c_master_send(client, buf, 2);
121 return (status < 0) ? status : 0;
124 static int i2c_read_le16(struct i2c_client *client)
129 status = i2c_master_recv(client, buf, 2);
132 return (buf[1] << 8) | buf[0];
135 /*-------------------------------------------------------------------------*/
137 static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
139 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
142 mutex_lock(&gpio->lock);
143 gpio->out |= (1 << offset);
144 status = gpio->write(gpio->client, gpio->out);
145 mutex_unlock(&gpio->lock);
150 static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
152 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
155 value = gpio->read(gpio->client);
156 return (value < 0) ? 0 : (value & (1 << offset));
159 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
161 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
162 unsigned bit = 1 << offset;
165 mutex_lock(&gpio->lock);
170 status = gpio->write(gpio->client, gpio->out);
171 mutex_unlock(&gpio->lock);
176 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
178 pcf857x_output(chip, offset, value);
181 /*-------------------------------------------------------------------------*/
183 static irqreturn_t pcf857x_irq(int irq, void *data)
185 struct pcf857x *gpio = data;
186 unsigned long change, i, status, flags;
188 status = gpio->read(gpio->client);
190 spin_lock_irqsave(&gpio->slock, flags);
193 * call the interrupt handler iff gpio is used as
194 * interrupt source, just to avoid bad irqs
197 change = (gpio->status ^ status);
198 for_each_set_bit(i, &change, gpio->chip.ngpio)
199 handle_nested_irq(irq_find_mapping(gpio->chip.irqdomain, i));
200 gpio->status = status;
202 spin_unlock_irqrestore(&gpio->slock, flags);
207 /*-------------------------------------------------------------------------*/
209 static int pcf857x_probe(struct i2c_client *client,
210 const struct i2c_device_id *id)
212 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
213 struct device_node *np = client->dev.of_node;
214 struct pcf857x *gpio;
215 unsigned int n_latch = 0;
218 if (IS_ENABLED(CONFIG_OF) && np)
219 of_property_read_u32(np, "lines-initial-states", &n_latch);
221 n_latch = pdata->n_latch;
223 dev_dbg(&client->dev, "no platform data\n");
225 /* Allocate, initialize, and register this gpio_chip. */
226 gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
230 mutex_init(&gpio->lock);
231 spin_lock_init(&gpio->slock);
233 gpio->chip.base = pdata ? pdata->gpio_base : -1;
234 gpio->chip.can_sleep = true;
235 gpio->chip.dev = &client->dev;
236 gpio->chip.owner = THIS_MODULE;
237 gpio->chip.get = pcf857x_get;
238 gpio->chip.set = pcf857x_set;
239 gpio->chip.direction_input = pcf857x_input;
240 gpio->chip.direction_output = pcf857x_output;
241 gpio->chip.ngpio = id->driver_data;
243 /* NOTE: the OnSemi jlc1562b is also largely compatible with
244 * these parts, notably for output. It has a low-resolution
245 * DAC instead of pin change IRQs; and its inputs can be the
246 * result of comparators.
249 /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
250 * 9670, 9672, 9764, and 9764a use quite a variety.
252 * NOTE: we don't distinguish here between *4 and *4a parts.
254 if (gpio->chip.ngpio == 8) {
255 gpio->write = i2c_write_le8;
256 gpio->read = i2c_read_le8;
258 if (!i2c_check_functionality(client->adapter,
259 I2C_FUNC_SMBUS_BYTE))
262 /* fail if there's no chip present */
264 status = i2c_smbus_read_byte(client);
266 /* '75/'75c addresses are 0x20..0x27, just like the '74;
267 * the '75c doesn't have a current source pulling high.
268 * 9671, 9673, and 9765 use quite a variety of addresses.
270 * NOTE: we don't distinguish here between '75 and '75c parts.
272 } else if (gpio->chip.ngpio == 16) {
273 gpio->write = i2c_write_le16;
274 gpio->read = i2c_read_le16;
276 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
279 /* fail if there's no chip present */
281 status = i2c_read_le16(client);
284 dev_dbg(&client->dev, "unsupported number of gpios\n");
291 gpio->chip.label = client->name;
293 gpio->client = client;
294 i2c_set_clientdata(client, gpio);
296 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
297 * We can't actually know whether a pin is configured (a) as output
298 * and driving the signal low, or (b) as input and reporting a low
299 * value ... without knowing the last value written since the chip
300 * came out of reset (if any). We can't read the latched output.
302 * In short, the only reliable solution for setting up pin direction
303 * is to do it explicitly. The setup() method can do that, but it
304 * may cause transient glitching since it can't know the last value
305 * written (some pins may need to be driven low).
307 * Using n_latch avoids that trouble. When left initialized to zero,
308 * our software copy of the "latch" then matches the chip's all-ones
309 * reset state. Otherwise it flags pins to be driven low.
311 gpio->out = ~n_latch;
312 gpio->status = gpio->out;
314 status = gpiochip_add(&gpio->chip);
318 /* Enable irqchip if we have an interrupt */
320 status = gpiochip_irqchip_add(&gpio->chip, &dummy_irq_chip, 0,
321 handle_level_irq, IRQ_TYPE_NONE);
323 dev_err(&client->dev, "cannot add irqchip\n");
327 status = devm_request_threaded_irq(&client->dev, client->irq,
328 NULL, pcf857x_irq, IRQF_ONESHOT |
329 IRQF_TRIGGER_FALLING | IRQF_SHARED,
330 dev_name(&client->dev), gpio);
334 gpiochip_set_chained_irqchip(&gpio->chip, &dummy_irq_chip,
338 /* Let platform code set up the GPIOs and their users.
339 * Now is the first time anyone could use them.
341 if (pdata && pdata->setup) {
342 status = pdata->setup(client,
343 gpio->chip.base, gpio->chip.ngpio,
346 dev_warn(&client->dev, "setup --> %d\n", status);
349 dev_info(&client->dev, "probed\n");
354 gpiochip_remove(&gpio->chip);
357 dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
363 static int pcf857x_remove(struct i2c_client *client)
365 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
366 struct pcf857x *gpio = i2c_get_clientdata(client);
369 if (pdata && pdata->teardown) {
370 status = pdata->teardown(client,
371 gpio->chip.base, gpio->chip.ngpio,
374 dev_err(&client->dev, "%s --> %d\n",
380 gpiochip_remove(&gpio->chip);
384 static struct i2c_driver pcf857x_driver = {
387 .owner = THIS_MODULE,
388 .of_match_table = of_match_ptr(pcf857x_of_table),
390 .probe = pcf857x_probe,
391 .remove = pcf857x_remove,
392 .id_table = pcf857x_id,
395 static int __init pcf857x_init(void)
397 return i2c_add_driver(&pcf857x_driver);
399 /* register after i2c postcore initcall and before
400 * subsys initcalls that may rely on these GPIOs
402 subsys_initcall(pcf857x_init);
404 static void __exit pcf857x_exit(void)
406 i2c_del_driver(&pcf857x_driver);
408 module_exit(pcf857x_exit);
410 MODULE_LICENSE("GPL");
411 MODULE_AUTHOR("David Brownell");