drivers/i2c/chips/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 <asm/prom.h>
  24 #include <asm/machdep.h>
  25
  26 /*
  27  * I don't have specifications for the MCU firmware, I found this register
  28  * and bits positions by the trial&error method.
  29  */
  30 #define MCU_REG_CTRL    0x20
  31 #define MCU_CTRL_POFF   0x40
  32
  33 #define MCU_NUM_GPIO    2
  34
  35 struct mcu {
  36         struct mutex lock;
  37         struct device_node *np;
  38         struct i2c_client *client;
  39         struct of_gpio_chip of_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 of_gpio_chip *of_gc = to_of_gpio_chip(gc);
  59         struct mcu *mcu = container_of(of_gc, struct mcu, of_gc);
  60         u8 bit = 1 << (4 + gpio);
  61
  62         mutex_lock(&mcu->lock);
  63         if (val)
  64                 mcu->reg_ctrl &= ~bit;
  65         else
  66                 mcu->reg_ctrl |= bit;
  67
  68         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
  69         mutex_unlock(&mcu->lock);
  70 }
  71
  72 static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
  73 {
  74         mcu_gpio_set(gc, gpio, val);
  75         return 0;
  76 }
  77
  78 static int mcu_gpiochip_add(struct mcu *mcu)
  79 {
  80         struct device_node *np;
  81         struct of_gpio_chip *of_gc = &mcu->of_gc;
  82         struct gpio_chip *gc = &of_gc->gc;
  83         int ret;
  84
  85         np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
  86         if (!np)
  87                 return -ENODEV;
  88
  89         gc->owner = THIS_MODULE;
  90         gc->label = np->full_name;
  91         gc->can_sleep = 1;
  92         gc->ngpio = MCU_NUM_GPIO;
  93         gc->base = -1;
  94         gc->set = mcu_gpio_set;
  95         gc->direction_output = mcu_gpio_dir_out;
  96         of_gc->gpio_cells = 2;
  97         of_gc->xlate = of_gpio_simple_xlate;
  98
  99         np->data = of_gc;
 100         mcu->np = np;
 101
 102         /*
 103          * We don't want to lose the node, its ->data and ->full_name...
 104          * So, if succeeded, we don't put the node here.
 105          */
 106         ret = gpiochip_add(gc);
 107         if (ret)
 108                 of_node_put(np);
 109         return ret;
 110 }
 111
 112 static int mcu_gpiochip_remove(struct mcu *mcu)
 113 {
 114         int ret;
 115
 116         ret = gpiochip_remove(&mcu->of_gc.gc);
 117         if (ret)
 118                 return ret;
 119         of_node_put(mcu->np);
 120
 121         return 0;
 122 }
 123
 124 static int __devinit mcu_probe(struct i2c_client *client,
 125                                const struct i2c_device_id *id)
 126 {
 127         struct mcu *mcu;
 128         int ret;
 129
 130         mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
 131         if (!mcu)
 132                 return -ENOMEM;
 133
 134         mutex_init(&mcu->lock);
 135         mcu->client = client;
 136         i2c_set_clientdata(client, mcu);
 137
 138         ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
 139         if (ret < 0)
 140                 goto err;
 141         mcu->reg_ctrl = ret;
 142
 143         ret = mcu_gpiochip_add(mcu);
 144         if (ret)
 145                 goto err;
 146
 147         /* XXX: this is potentially racy, but there is no lock for ppc_md */
 148         if (!ppc_md.power_off) {
 149                 glob_mcu = mcu;
 150                 ppc_md.power_off = mcu_power_off;
 151                 dev_info(&client->dev, "will provide power-off service\n");
 152         }
 153
 154         return 0;
 155 err:
 156         kfree(mcu);
 157         return ret;
 158 }
 159
 160 static int __devexit mcu_remove(struct i2c_client *client)
 161 {
 162         struct mcu *mcu = i2c_get_clientdata(client);
 163         int ret;
 164
 165         if (glob_mcu == mcu) {
 166                 ppc_md.power_off = NULL;
 167                 glob_mcu = NULL;
 168         }
 169
 170         ret = mcu_gpiochip_remove(mcu);
 171         if (ret)
 172                 return ret;
 173         i2c_set_clientdata(client, NULL);
 174         kfree(mcu);
 175         return 0;
 176 }
 177
 178 static const struct i2c_device_id mcu_ids[] = {
 179         { "mcu-mpc8349emitx", },
 180         {},
 181 };
 182 MODULE_DEVICE_TABLE(i2c, mcu_ids);
 183
 184 static struct i2c_driver mcu_driver = {
 185         .driver = {
 186                 .name = "mcu-mpc8349emitx",
 187                 .owner = THIS_MODULE,
 188         },
 189         .probe = mcu_probe,
 190         .remove = __devexit_p(mcu_remove),
 191         .id_table = mcu_ids,
 192 };
 193
 194 static int __init mcu_init(void)
 195 {
 196         return i2c_add_driver(&mcu_driver);
 197 }
 198 module_init(mcu_init);
 199
 200 static void __exit mcu_exit(void)
 201 {
 202         i2c_del_driver(&mcu_driver);
 203 }
 204 module_exit(mcu_exit);
 205
 206 MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
 207                    "MPC8349E-mITX-compatible MCU");
 208 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
 209 MODULE_LICENSE("GPL");