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Linux/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c

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  1 /*
  2  * Power Management and GPIO expander driver for MPC8349E-mITX-compatible MCU
  3  *
  4  * Copyright (c) 2008  MontaVista Software, Inc.
  5  *
  6  * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
  7  *
  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.
 12  */
 13 
 14 #include <linux/kernel.h>
 15 #include <linux/module.h>
 16 #include <linux/device.h>
 17 #include <linux/mutex.h>
 18 #include <linux/i2c.h>
 19 #include <linux/gpio/driver.h>
 20 #include <linux/of.h>
 21 #include <linux/of_gpio.h>
 22 #include <linux/slab.h>
 23 #include <linux/kthread.h>
 24 #include <linux/reboot.h>
 25 #include <asm/prom.h>
 26 #include <asm/machdep.h>
 27 
 28 /*
 29  * I don't have specifications for the MCU firmware, I found this register
 30  * and bits positions by the trial&error method.
 31  */
 32 #define MCU_REG_CTRL    0x20
 33 #define MCU_CTRL_POFF   0x40
 34 #define MCU_CTRL_BTN    0x80
 35 
 36 #define MCU_NUM_GPIO    2
 37 
 38 struct mcu {
 39         struct mutex lock;
 40         struct i2c_client *client;
 41         struct gpio_chip gc;
 42         u8 reg_ctrl;
 43 };
 44 
 45 static struct mcu *glob_mcu;
 46 
 47 struct task_struct *shutdown_thread;
 48 static int shutdown_thread_fn(void *data)
 49 {
 50         int ret;
 51         struct mcu *mcu = glob_mcu;
 52 
 53         while (!kthread_should_stop()) {
 54                 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
 55                 if (ret < 0)
 56                         pr_err("MCU status reg read failed.\n");
 57                 mcu->reg_ctrl = ret;
 58 
 59 
 60                 if (mcu->reg_ctrl & MCU_CTRL_BTN) {
 61                         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL,
 62                                                   mcu->reg_ctrl & ~MCU_CTRL_BTN);
 63 
 64                         ctrl_alt_del();
 65                 }
 66 
 67                 set_current_state(TASK_INTERRUPTIBLE);
 68                 schedule_timeout(HZ);
 69         }
 70 
 71         return 0;
 72 }
 73 
 74 static ssize_t show_status(struct device *d,
 75                            struct device_attribute *attr, char *buf)
 76 {
 77         int ret;
 78         struct mcu *mcu = glob_mcu;
 79 
 80         ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
 81         if (ret < 0)
 82                 return -ENODEV;
 83         mcu->reg_ctrl = ret;
 84 
 85         return sprintf(buf, "%02x\n", ret);
 86 }
 87 static DEVICE_ATTR(status, S_IRUGO, show_status, NULL);
 88 
 89 static void mcu_power_off(void)
 90 {
 91         struct mcu *mcu = glob_mcu;
 92 
 93         pr_info("Sending power-off request to the MCU...\n");
 94         mutex_lock(&mcu->lock);
 95         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL,
 96                                   mcu->reg_ctrl | MCU_CTRL_POFF);
 97         mutex_unlock(&mcu->lock);
 98 }
 99 
100 static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
101 {
102         struct mcu *mcu = gpiochip_get_data(gc);
103         u8 bit = 1 << (4 + gpio);
104 
105         mutex_lock(&mcu->lock);
106         if (val)
107                 mcu->reg_ctrl &= ~bit;
108         else
109                 mcu->reg_ctrl |= bit;
110 
111         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
112         mutex_unlock(&mcu->lock);
113 }
114 
115 static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
116 {
117         mcu_gpio_set(gc, gpio, val);
118         return 0;
119 }
120 
121 static int mcu_gpiochip_add(struct mcu *mcu)
122 {
123         struct device_node *np;
124         struct gpio_chip *gc = &mcu->gc;
125 
126         np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
127         if (!np)
128                 return -ENODEV;
129 
130         gc->owner = THIS_MODULE;
131         gc->label = kasprintf(GFP_KERNEL, "%pOF", np);
132         gc->can_sleep = 1;
133         gc->ngpio = MCU_NUM_GPIO;
134         gc->base = -1;
135         gc->set = mcu_gpio_set;
136         gc->direction_output = mcu_gpio_dir_out;
137         gc->of_node = np;
138 
139         return gpiochip_add_data(gc, mcu);
140 }
141 
142 static int mcu_gpiochip_remove(struct mcu *mcu)
143 {
144         kfree(mcu->gc.label);
145         gpiochip_remove(&mcu->gc);
146         return 0;
147 }
148 
149 static int mcu_probe(struct i2c_client *client, const struct i2c_device_id *id)
150 {
151         struct mcu *mcu;
152         int ret;
153 
154         mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
155         if (!mcu)
156                 return -ENOMEM;
157 
158         mutex_init(&mcu->lock);
159         mcu->client = client;
160         i2c_set_clientdata(client, mcu);
161 
162         ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
163         if (ret < 0)
164                 goto err;
165         mcu->reg_ctrl = ret;
166 
167         ret = mcu_gpiochip_add(mcu);
168         if (ret)
169                 goto err;
170 
171         /* XXX: this is potentially racy, but there is no lock for pm_power_off */
172         if (!pm_power_off) {
173                 glob_mcu = mcu;
174                 pm_power_off = mcu_power_off;
175                 dev_info(&client->dev, "will provide power-off service\n");
176         }
177 
178         if (device_create_file(&client->dev, &dev_attr_status))
179                 dev_err(&client->dev,
180                         "couldn't create device file for status\n");
181 
182         shutdown_thread = kthread_run(shutdown_thread_fn, NULL,
183                                       "mcu-i2c-shdn");
184 
185         return 0;
186 err:
187         kfree(mcu);
188         return ret;
189 }
190 
191 static int mcu_remove(struct i2c_client *client)
192 {
193         struct mcu *mcu = i2c_get_clientdata(client);
194         int ret;
195 
196         kthread_stop(shutdown_thread);
197 
198         device_remove_file(&client->dev, &dev_attr_status);
199 
200         if (glob_mcu == mcu) {
201                 pm_power_off = NULL;
202                 glob_mcu = NULL;
203         }
204 
205         ret = mcu_gpiochip_remove(mcu);
206         if (ret)
207                 return ret;
208         kfree(mcu);
209         return 0;
210 }
211 
212 static const struct i2c_device_id mcu_ids[] = {
213         { "mcu-mpc8349emitx", },
214         {},
215 };
216 MODULE_DEVICE_TABLE(i2c, mcu_ids);
217 
218 static const struct of_device_id mcu_of_match_table[] = {
219         { .compatible = "fsl,mcu-mpc8349emitx", },
220         { },
221 };
222 
223 static struct i2c_driver mcu_driver = {
224         .driver = {
225                 .name = "mcu-mpc8349emitx",
226                 .of_match_table = mcu_of_match_table,
227         },
228         .probe = mcu_probe,
229         .remove = mcu_remove,
230         .id_table = mcu_ids,
231 };
232 
233 module_i2c_driver(mcu_driver);
234 
235 MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
236                    "MPC8349E-mITX-compatible MCU");
237 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
238 MODULE_LICENSE("GPL");
239 

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