2 * Power Management and GPIO expander driver for MPC8349E-mITX-compatible MCU
4 * Copyright (c) 2008 MontaVista Software, Inc.
6 * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
14 #include <linux/init.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/device.h>
18 #include <linux/mutex.h>
19 #include <linux/i2c.h>
20 #include <linux/gpio.h>
22 #include <linux/of_gpio.h>
23 #include <linux/slab.h>
24 #include <linux/kthread.h>
25 #include <linux/reboot.h>
27 #include <asm/machdep.h>
30 * I don't have specifications for the MCU firmware, I found this register
31 * and bits positions by the trial&error method.
33 #define MCU_REG_CTRL 0x20
34 #define MCU_CTRL_POFF 0x40
35 #define MCU_CTRL_BTN 0x80
37 #define MCU_NUM_GPIO 2
41 struct i2c_client *client;
46 static struct mcu *glob_mcu;
48 struct task_struct *shutdown_thread;
49 static int shutdown_thread_fn(void *data)
52 struct mcu *mcu = glob_mcu;
54 while (!kthread_should_stop()) {
55 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
57 pr_err("MCU status reg read failed.\n");
61 if (mcu->reg_ctrl & MCU_CTRL_BTN) {
62 i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL,
63 mcu->reg_ctrl & ~MCU_CTRL_BTN);
68 set_current_state(TASK_INTERRUPTIBLE);
75 static ssize_t show_status(struct device *d,
76 struct device_attribute *attr, char *buf)
79 struct mcu *mcu = glob_mcu;
81 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
86 return sprintf(buf, "%02x\n", ret);
88 static DEVICE_ATTR(status, S_IRUGO, show_status, NULL);
90 static void mcu_power_off(void)
92 struct mcu *mcu = glob_mcu;
94 pr_info("Sending power-off request to the MCU...\n");
95 mutex_lock(&mcu->lock);
96 i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL,
97 mcu->reg_ctrl | MCU_CTRL_POFF);
98 mutex_unlock(&mcu->lock);
101 static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
103 struct mcu *mcu = container_of(gc, struct mcu, gc);
104 u8 bit = 1 << (4 + gpio);
106 mutex_lock(&mcu->lock);
108 mcu->reg_ctrl &= ~bit;
110 mcu->reg_ctrl |= bit;
112 i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
113 mutex_unlock(&mcu->lock);
116 static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
118 mcu_gpio_set(gc, gpio, val);
122 static int mcu_gpiochip_add(struct mcu *mcu)
124 struct device_node *np;
125 struct gpio_chip *gc = &mcu->gc;
127 np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
131 gc->owner = THIS_MODULE;
132 gc->label = np->full_name;
134 gc->ngpio = MCU_NUM_GPIO;
136 gc->set = mcu_gpio_set;
137 gc->direction_output = mcu_gpio_dir_out;
140 return gpiochip_add(gc);
143 static int mcu_gpiochip_remove(struct mcu *mcu)
145 return gpiochip_remove(&mcu->gc);
148 static int __devinit mcu_probe(struct i2c_client *client,
149 const struct i2c_device_id *id)
154 mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
158 mutex_init(&mcu->lock);
159 mcu->client = client;
160 i2c_set_clientdata(client, mcu);
162 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
167 ret = mcu_gpiochip_add(mcu);
171 /* XXX: this is potentially racy, but there is no lock for ppc_md */
172 if (!ppc_md.power_off) {
174 ppc_md.power_off = mcu_power_off;
175 dev_info(&client->dev, "will provide power-off service\n");
178 if (device_create_file(&client->dev, &dev_attr_status))
179 dev_err(&client->dev,
180 "couldn't create device file for status\n");
182 shutdown_thread = kthread_run(shutdown_thread_fn, NULL,
191 static int __devexit mcu_remove(struct i2c_client *client)
193 struct mcu *mcu = i2c_get_clientdata(client);
196 kthread_stop(shutdown_thread);
198 device_remove_file(&client->dev, &dev_attr_status);
200 if (glob_mcu == mcu) {
201 ppc_md.power_off = NULL;
205 ret = mcu_gpiochip_remove(mcu);
208 i2c_set_clientdata(client, NULL);
213 static const struct i2c_device_id mcu_ids[] = {
214 { "mcu-mpc8349emitx", },
217 MODULE_DEVICE_TABLE(i2c, mcu_ids);
219 static struct of_device_id mcu_of_match_table[] __devinitdata = {
220 { .compatible = "fsl,mcu-mpc8349emitx", },
224 static struct i2c_driver mcu_driver = {
226 .name = "mcu-mpc8349emitx",
227 .owner = THIS_MODULE,
228 .of_match_table = mcu_of_match_table,
231 .remove = __devexit_p(mcu_remove),
235 static int __init mcu_init(void)
237 return i2c_add_driver(&mcu_driver);
239 module_init(mcu_init);
241 static void __exit mcu_exit(void)
243 i2c_del_driver(&mcu_driver);
245 module_exit(mcu_exit);
247 MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
248 "MPC8349E-mITX-compatible MCU");
249 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
250 MODULE_LICENSE("GPL");