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 <asm/prom.h>
  25 #include <asm/machdep.h>
  26
  27 /*
  28  * I don't have specifications for the MCU firmware, I found this register
  29  * and bits positions by the trial&error method.
  30  */
  31 #define MCU_REG_CTRL    0x20
  32 #define MCU_CTRL_POFF   0x40
  33
  34 #define MCU_NUM_GPIO    2
  35
  36 struct mcu {
  37         struct mutex lock;
  38         struct i2c_client *client;
  39         struct gpio_chip gc;
  40         u8 reg_ctrl;
  41 };
  42
  43 static struct mcu *glob_mcu;
  44
  45 static void mcu_power_off(void)
  46 {
  47         struct mcu *mcu = glob_mcu;
  48
  49         pr_info("Sending power-off request to the MCU...\n");
  50         mutex_lock(&mcu->lock);
  51         i2c_smbus_write_byte_data(glob_mcu->client, MCU_REG_CTRL,
  52                                   mcu->reg_ctrl | MCU_CTRL_POFF);
  53         mutex_unlock(&mcu->lock);
  54 }
  55
  56 static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
  57 {
  58         struct mcu *mcu = container_of(gc, struct mcu, gc);
  59         u8 bit = 1 << (4 + gpio);
  60
  61         mutex_lock(&mcu->lock);
  62         if (val)
  63                 mcu->reg_ctrl &= ~bit;
  64         else
  65                 mcu->reg_ctrl |= bit;
  66
  67         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
  68         mutex_unlock(&mcu->lock);
  69 }
  70
  71 static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
  72 {
  73         mcu_gpio_set(gc, gpio, val);
  74         return 0;
  75 }
  76
  77 static int mcu_gpiochip_add(struct mcu *mcu)
  78 {
  79         struct device_node *np;
  80         struct gpio_chip *gc = &mcu->gc;
  81
  82         np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
  83         if (!np)
  84                 return -ENODEV;
  85
  86         gc->owner = THIS_MODULE;
  87         gc->label = np->full_name;
  88         gc->can_sleep = 1;
  89         gc->ngpio = MCU_NUM_GPIO;
  90         gc->base = -1;
  91         gc->set = mcu_gpio_set;
  92         gc->direction_output = mcu_gpio_dir_out;
  93         gc->of_node = np;
  94
  95         return gpiochip_add(gc);
  96 }
  97
  98 static int mcu_gpiochip_remove(struct mcu *mcu)
  99 {
 100         return gpiochip_remove(&mcu->gc);
 101 }
 102
 103 static int __devinit mcu_probe(struct i2c_client *client,
 104                                const struct i2c_device_id *id)
 105 {
 106         struct mcu *mcu;
 107         int ret;
 108
 109         mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
 110         if (!mcu)
 111                 return -ENOMEM;
 112
 113         mutex_init(&mcu->lock);
 114         mcu->client = client;
 115         i2c_set_clientdata(client, mcu);
 116
 117         ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
 118         if (ret < 0)
 119                 goto err;
 120         mcu->reg_ctrl = ret;
 121
 122         ret = mcu_gpiochip_add(mcu);
 123         if (ret)
 124                 goto err;
 125
 126         /* XXX: this is potentially racy, but there is no lock for ppc_md */
 127         if (!ppc_md.power_off) {
 128                 glob_mcu = mcu;
 129                 ppc_md.power_off = mcu_power_off;
 130                 dev_info(&client->dev, "will provide power-off service\n");
 131         }
 132
 133         return 0;
 134 err:
 135         kfree(mcu);
 136         return ret;
 137 }
 138
 139 static int __devexit mcu_remove(struct i2c_client *client)
 140 {
 141         struct mcu *mcu = i2c_get_clientdata(client);
 142         int ret;
 143
 144         if (glob_mcu == mcu) {
 145                 ppc_md.power_off = NULL;
 146                 glob_mcu = NULL;
 147         }
 148
 149         ret = mcu_gpiochip_remove(mcu);
 150         if (ret)
 151                 return ret;
 152         i2c_set_clientdata(client, NULL);
 153         kfree(mcu);
 154         return 0;
 155 }
 156
 157 static const struct i2c_device_id mcu_ids[] = {
 158         { "mcu-mpc8349emitx", },
 159         {},
 160 };
 161 MODULE_DEVICE_TABLE(i2c, mcu_ids);
 162
 163 static struct i2c_driver mcu_driver = {
 164         .driver = {
 165                 .name = "mcu-mpc8349emitx",
 166                 .owner = THIS_MODULE,
 167         },
 168         .probe = mcu_probe,
 169         .remove = __devexit_p(mcu_remove),
 170         .id_table = mcu_ids,
 171 };
 172
 173 static int __init mcu_init(void)
 174 {
 175         return i2c_add_driver(&mcu_driver);
 176 }
 177 module_init(mcu_init);
 178
 179 static void __exit mcu_exit(void)
 180 {
 181         i2c_del_driver(&mcu_driver);
 182 }
 183 module_exit(mcu_exit);
 184
 185 MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
 186                    "MPC8349E-mITX-compatible MCU");
 187 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
 188 MODULE_LICENSE("GPL");