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/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>
  21 #include <linux/of.h>
  22 #include <linux/of_gpio.h>
  23 #include <linux/slab.h>
  24 #include <linux/kthread.h>
  25 #include <linux/reboot.h>
  26 #include <asm/prom.h>
  27 #include <asm/machdep.h>
  28
  29 /*
  30  * I don't have specifications for the MCU firmware, I found this register
  31  * and bits positions by the trial&error method.
  32  */
  33 #define MCU_REG_CTRL    0x20
  34 #define MCU_CTRL_POFF   0x40
  35 #define MCU_CTRL_BTN    0x80
  36
  37 #define MCU_NUM_GPIO    2
  38
  39 struct mcu {
  40         struct mutex lock;
  41         struct i2c_client *client;
  42         struct gpio_chip gc;
  43         u8 reg_ctrl;
  44 };
  45
  46 static struct mcu *glob_mcu;
  47
  48 struct task_struct *shutdown_thread;
  49 static int shutdown_thread_fn(void *data)
  50 {
  51         int ret;
  52         struct mcu *mcu = glob_mcu;
  53
  54         while (!kthread_should_stop()) {
  55                 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
  56                 if (ret < 0)
  57                         pr_err("MCU status reg read failed.\n");
  58                 mcu->reg_ctrl = ret;
  59
  60
  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);
  64
  65                         ctrl_alt_del();
  66                 }
  67
  68                 set_current_state(TASK_INTERRUPTIBLE);
  69                 schedule_timeout(HZ);
  70         }
  71
  72         return 0;
  73 }
  74
  75 static ssize_t show_status(struct device *d,
  76                            struct device_attribute *attr, char *buf)
  77 {
  78         int ret;
  79         struct mcu *mcu = glob_mcu;
  80
  81         ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
  82         if (ret < 0)
  83                 return -ENODEV;
  84         mcu->reg_ctrl = ret;
  85
  86         return sprintf(buf, "%02x\n", ret);
  87 }
  88 static DEVICE_ATTR(status, S_IRUGO, show_status, NULL);
  89
  90 static void mcu_power_off(void)
  91 {
  92         struct mcu *mcu = glob_mcu;
  93
  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);
  99 }
 100
 101 static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
 102 {
 103         struct mcu *mcu = container_of(gc, struct mcu, gc);
 104         u8 bit = 1 << (4 + gpio);
 105
 106         mutex_lock(&mcu->lock);
 107         if (val)
 108                 mcu->reg_ctrl &= ~bit;
 109         else
 110                 mcu->reg_ctrl |= bit;
 111
 112         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
 113         mutex_unlock(&mcu->lock);
 114 }
 115
 116 static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
 117 {
 118         mcu_gpio_set(gc, gpio, val);
 119         return 0;
 120 }
 121
 122 static int mcu_gpiochip_add(struct mcu *mcu)
 123 {
 124         struct device_node *np;
 125         struct gpio_chip *gc = &mcu->gc;
 126
 127         np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
 128         if (!np)
 129                 return -ENODEV;
 130
 131         gc->owner = THIS_MODULE;
 132         gc->label = np->full_name;
 133         gc->can_sleep = 1;
 134         gc->ngpio = MCU_NUM_GPIO;
 135         gc->base = -1;
 136         gc->set = mcu_gpio_set;
 137         gc->direction_output = mcu_gpio_dir_out;
 138         gc->of_node = np;
 139
 140         return gpiochip_add(gc);
 141 }
 142
 143 static int mcu_gpiochip_remove(struct mcu *mcu)
 144 {
 145         return gpiochip_remove(&mcu->gc);
 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 ppc_md */
 171         if (!ppc_md.power_off) {
 172                 glob_mcu = mcu;
 173                 ppc_md.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                 ppc_md.power_off = NULL;
 201                 glob_mcu = NULL;
 202         }
 203
 204         ret = mcu_gpiochip_remove(mcu);
 205         if (ret)
 206                 return ret;
 207         i2c_set_clientdata(client, NULL);
 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 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                 .owner = THIS_MODULE,
 227                 .of_match_table = mcu_of_match_table,
 228         },
 229         .probe = mcu_probe,
 230         .remove = mcu_remove,
 231         .id_table = mcu_ids,
 232 };
 233
 234 static int __init mcu_init(void)
 235 {
 236         return i2c_add_driver(&mcu_driver);
 237 }
 238 module_init(mcu_init);
 239
 240 static void __exit mcu_exit(void)
 241 {
 242         i2c_del_driver(&mcu_driver);
 243 }
 244 module_exit(mcu_exit);
 245
 246 MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
 247                    "MPC8349E-mITX-compatible MCU");
 248 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
 249 MODULE_LICENSE("GPL");