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

   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 = np->full_name;
 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         gpiochip_remove(&mcu->gc);
 145         return 0;
 146 }
 147
 148 static int mcu_probe(struct i2c_client *client, const struct i2c_device_id *id)
 149 {
 150         struct mcu *mcu;
 151         int ret;
 152
 153         mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
 154         if (!mcu)
 155                 return -ENOMEM;
 156
 157         mutex_init(&mcu->lock);
 158         mcu->client = client;
 159         i2c_set_clientdata(client, mcu);
 160
 161         ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
 162         if (ret < 0)
 163                 goto err;
 164         mcu->reg_ctrl = ret;
 165
 166         ret = mcu_gpiochip_add(mcu);
 167         if (ret)
 168                 goto err;
 169
 170         /* XXX: this is potentially racy, but there is no lock for pm_power_off */
 171         if (!pm_power_off) {
 172                 glob_mcu = mcu;
 173                 pm_power_off = mcu_power_off;
 174                 dev_info(&client->dev, "will provide power-off service\n");
 175         }
 176
 177         if (device_create_file(&client->dev, &dev_attr_status))
 178                 dev_err(&client->dev,
 179                         "couldn't create device file for status\n");
 180
 181         shutdown_thread = kthread_run(shutdown_thread_fn, NULL,
 182                                       "mcu-i2c-shdn");
 183
 184         return 0;
 185 err:
 186         kfree(mcu);
 187         return ret;
 188 }
 189
 190 static int mcu_remove(struct i2c_client *client)
 191 {
 192         struct mcu *mcu = i2c_get_clientdata(client);
 193         int ret;
 194
 195         kthread_stop(shutdown_thread);
 196
 197         device_remove_file(&client->dev, &dev_attr_status);
 198
 199         if (glob_mcu == mcu) {
 200                 pm_power_off = NULL;
 201                 glob_mcu = NULL;
 202         }
 203
 204         ret = mcu_gpiochip_remove(mcu);
 205         if (ret)
 206                 return ret;
 207         kfree(mcu);
 208         return 0;
 209 }
 210
 211 static const struct i2c_device_id mcu_ids[] = {
 212         { "mcu-mpc8349emitx", },
 213         {},
 214 };
 215 MODULE_DEVICE_TABLE(i2c, mcu_ids);
 216
 217 static const struct of_device_id mcu_of_match_table[] = {
 218         { .compatible = "fsl,mcu-mpc8349emitx", },
 219         { },
 220 };
 221
 222 static struct i2c_driver mcu_driver = {
 223         .driver = {
 224                 .name = "mcu-mpc8349emitx",
 225                 .of_match_table = mcu_of_match_table,
 226         },
 227         .probe = mcu_probe,
 228         .remove = mcu_remove,
 229         .id_table = mcu_ids,
 230 };
 231
 232 module_i2c_driver(mcu_driver);
 233
 234 MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
 235                    "MPC8349E-mITX-compatible MCU");
 236 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
 237 MODULE_LICENSE("GPL");