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 device_node *np;
  39         struct i2c_client *client;
  40         struct of_gpio_chip of_gc;
  41         u8 reg_ctrl;
  42 };
  43
  44 static struct mcu *glob_mcu;
  45
  46 static void mcu_power_off(void)
  47 {
  48         struct mcu *mcu = glob_mcu;
  49
  50         pr_info("Sending power-off request to the MCU...\n");
  51         mutex_lock(&mcu->lock);
  52         i2c_smbus_write_byte_data(glob_mcu->client, MCU_REG_CTRL,
  53                                   mcu->reg_ctrl | MCU_CTRL_POFF);
  54         mutex_unlock(&mcu->lock);
  55 }
  56
  57 static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
  58 {
  59         struct of_gpio_chip *of_gc = to_of_gpio_chip(gc);
  60         struct mcu *mcu = container_of(of_gc, struct mcu, of_gc);
  61         u8 bit = 1 << (4 + gpio);
  62
  63         mutex_lock(&mcu->lock);
  64         if (val)
  65                 mcu->reg_ctrl &= ~bit;
  66         else
  67                 mcu->reg_ctrl |= bit;
  68
  69         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
  70         mutex_unlock(&mcu->lock);
  71 }
  72
  73 static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
  74 {
  75         mcu_gpio_set(gc, gpio, val);
  76         return 0;
  77 }
  78
  79 static int mcu_gpiochip_add(struct mcu *mcu)
  80 {
  81         struct device_node *np;
  82         struct of_gpio_chip *of_gc = &mcu->of_gc;
  83         struct gpio_chip *gc = &of_gc->gc;
  84         int ret;
  85
  86         np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
  87         if (!np)
  88                 return -ENODEV;
  89
  90         gc->owner = THIS_MODULE;
  91         gc->label = np->full_name;
  92         gc->can_sleep = 1;
  93         gc->ngpio = MCU_NUM_GPIO;
  94         gc->base = -1;
  95         gc->set = mcu_gpio_set;
  96         gc->direction_output = mcu_gpio_dir_out;
  97         of_gc->gpio_cells = 2;
  98         of_gc->xlate = of_gpio_simple_xlate;
  99
 100         np->data = of_gc;
 101         mcu->np = np;
 102
 103         /*
 104          * We don't want to lose the node, its ->data and ->full_name...
 105          * So, if succeeded, we don't put the node here.
 106          */
 107         ret = gpiochip_add(gc);
 108         if (ret)
 109                 of_node_put(np);
 110         return ret;
 111 }
 112
 113 static int mcu_gpiochip_remove(struct mcu *mcu)
 114 {
 115         int ret;
 116
 117         ret = gpiochip_remove(&mcu->of_gc.gc);
 118         if (ret)
 119                 return ret;
 120         of_node_put(mcu->np);
 121
 122         return 0;
 123 }
 124
 125 static int __devinit mcu_probe(struct i2c_client *client,
 126                                const struct i2c_device_id *id)
 127 {
 128         struct mcu *mcu;
 129         int ret;
 130
 131         mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
 132         if (!mcu)
 133                 return -ENOMEM;
 134
 135         mutex_init(&mcu->lock);
 136         mcu->client = client;
 137         i2c_set_clientdata(client, mcu);
 138
 139         ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
 140         if (ret < 0)
 141                 goto err;
 142         mcu->reg_ctrl = ret;
 143
 144         ret = mcu_gpiochip_add(mcu);
 145         if (ret)
 146                 goto err;
 147
 148         /* XXX: this is potentially racy, but there is no lock for ppc_md */
 149         if (!ppc_md.power_off) {
 150                 glob_mcu = mcu;
 151                 ppc_md.power_off = mcu_power_off;
 152                 dev_info(&client->dev, "will provide power-off service\n");
 153         }
 154
 155         return 0;
 156 err:
 157         kfree(mcu);
 158         return ret;
 159 }
 160
 161 static int __devexit mcu_remove(struct i2c_client *client)
 162 {
 163         struct mcu *mcu = i2c_get_clientdata(client);
 164         int ret;
 165
 166         if (glob_mcu == mcu) {
 167                 ppc_md.power_off = NULL;
 168                 glob_mcu = NULL;
 169         }
 170
 171         ret = mcu_gpiochip_remove(mcu);
 172         if (ret)
 173                 return ret;
 174         i2c_set_clientdata(client, NULL);
 175         kfree(mcu);
 176         return 0;
 177 }
 178
 179 static const struct i2c_device_id mcu_ids[] = {
 180         { "mcu-mpc8349emitx", },
 181         {},
 182 };
 183 MODULE_DEVICE_TABLE(i2c, mcu_ids);
 184
 185 static struct i2c_driver mcu_driver = {
 186         .driver = {
 187                 .name = "mcu-mpc8349emitx",
 188                 .owner = THIS_MODULE,
 189         },
 190         .probe = mcu_probe,
 191         .remove = __devexit_p(mcu_remove),
 192         .id_table = mcu_ids,
 193 };
 194
 195 static int __init mcu_init(void)
 196 {
 197         return i2c_add_driver(&mcu_driver);
 198 }
 199 module_init(mcu_init);
 200
 201 static void __exit mcu_exit(void)
 202 {
 203         i2c_del_driver(&mcu_driver);
 204 }
 205 module_exit(mcu_exit);
 206
 207 MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
 208                    "MPC8349E-mITX-compatible MCU");
 209 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
 210 MODULE_LICENSE("GPL");