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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Power Management and GPIO expander driver for MPC8349E-mITX-compatible MCU
   4  *
   5  * Copyright (c) 2008  MontaVista Software, Inc.
   6  *
   7  * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/device.h>
  13 #include <linux/mutex.h>
  14 #include <linux/i2c.h>
  15 #include <linux/gpio/driver.h>
  16 #include <linux/of.h>
  17 #include <linux/of_gpio.h>
  18 #include <linux/slab.h>
  19 #include <linux/kthread.h>
  20 #include <linux/reboot.h>
  21 #include <asm/prom.h>
  22 #include <asm/machdep.h>
  23
  24 /*
  25  * I don't have specifications for the MCU firmware, I found this register
  26  * and bits positions by the trial&error method.
  27  */
  28 #define MCU_REG_CTRL    0x20
  29 #define MCU_CTRL_POFF   0x40
  30 #define MCU_CTRL_BTN    0x80
  31
  32 #define MCU_NUM_GPIO    2
  33
  34 struct mcu {
  35         struct mutex lock;
  36         struct i2c_client *client;
  37         struct gpio_chip gc;
  38         u8 reg_ctrl;
  39 };
  40
  41 static struct mcu *glob_mcu;
  42
  43 struct task_struct *shutdown_thread;
  44 static int shutdown_thread_fn(void *data)
  45 {
  46         int ret;
  47         struct mcu *mcu = glob_mcu;
  48
  49         while (!kthread_should_stop()) {
  50                 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
  51                 if (ret < 0)
  52                         pr_err("MCU status reg read failed.\n");
  53                 mcu->reg_ctrl = ret;
  54
  55
  56                 if (mcu->reg_ctrl & MCU_CTRL_BTN) {
  57                         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL,
  58                                                   mcu->reg_ctrl & ~MCU_CTRL_BTN);
  59
  60                         ctrl_alt_del();
  61                 }
  62
  63                 set_current_state(TASK_INTERRUPTIBLE);
  64                 schedule_timeout(HZ);
  65         }
  66
  67         return 0;
  68 }
  69
  70 static ssize_t show_status(struct device *d,
  71                            struct device_attribute *attr, char *buf)
  72 {
  73         int ret;
  74         struct mcu *mcu = glob_mcu;
  75
  76         ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
  77         if (ret < 0)
  78                 return -ENODEV;
  79         mcu->reg_ctrl = ret;
  80
  81         return sprintf(buf, "%02x\n", ret);
  82 }
  83 static DEVICE_ATTR(status, 0444, show_status, NULL);
  84
  85 static void mcu_power_off(void)
  86 {
  87         struct mcu *mcu = glob_mcu;
  88
  89         pr_info("Sending power-off request to the MCU...\n");
  90         mutex_lock(&mcu->lock);
  91         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL,
  92                                   mcu->reg_ctrl | MCU_CTRL_POFF);
  93         mutex_unlock(&mcu->lock);
  94 }
  95
  96 static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
  97 {
  98         struct mcu *mcu = gpiochip_get_data(gc);
  99         u8 bit = 1 << (4 + gpio);
 100
 101         mutex_lock(&mcu->lock);
 102         if (val)
 103                 mcu->reg_ctrl &= ~bit;
 104         else
 105                 mcu->reg_ctrl |= bit;
 106
 107         i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
 108         mutex_unlock(&mcu->lock);
 109 }
 110
 111 static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
 112 {
 113         mcu_gpio_set(gc, gpio, val);
 114         return 0;
 115 }
 116
 117 static int mcu_gpiochip_add(struct mcu *mcu)
 118 {
 119         struct device_node *np;
 120         struct gpio_chip *gc = &mcu->gc;
 121
 122         np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
 123         if (!np)
 124                 return -ENODEV;
 125
 126         gc->owner = THIS_MODULE;
 127         gc->label = kasprintf(GFP_KERNEL, "%pOF", np);
 128         gc->can_sleep = 1;
 129         gc->ngpio = MCU_NUM_GPIO;
 130         gc->base = -1;
 131         gc->set = mcu_gpio_set;
 132         gc->direction_output = mcu_gpio_dir_out;
 133         gc->of_node = np;
 134
 135         return gpiochip_add_data(gc, mcu);
 136 }
 137
 138 static int mcu_gpiochip_remove(struct mcu *mcu)
 139 {
 140         kfree(mcu->gc.label);
 141         gpiochip_remove(&mcu->gc);
 142         return 0;
 143 }
 144
 145 static int mcu_probe(struct i2c_client *client)
 146 {
 147         struct mcu *mcu;
 148         int ret;
 149
 150         mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
 151         if (!mcu)
 152                 return -ENOMEM;
 153
 154         mutex_init(&mcu->lock);
 155         mcu->client = client;
 156         i2c_set_clientdata(client, mcu);
 157
 158         ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
 159         if (ret < 0)
 160                 goto err;
 161         mcu->reg_ctrl = ret;
 162
 163         ret = mcu_gpiochip_add(mcu);
 164         if (ret)
 165                 goto err;
 166
 167         /* XXX: this is potentially racy, but there is no lock for pm_power_off */
 168         if (!pm_power_off) {
 169                 glob_mcu = mcu;
 170                 pm_power_off = mcu_power_off;
 171                 dev_info(&client->dev, "will provide power-off service\n");
 172         }
 173
 174         if (device_create_file(&client->dev, &dev_attr_status))
 175                 dev_err(&client->dev,
 176                         "couldn't create device file for status\n");
 177
 178         shutdown_thread = kthread_run(shutdown_thread_fn, NULL,
 179                                       "mcu-i2c-shdn");
 180
 181         return 0;
 182 err:
 183         kfree(mcu);
 184         return ret;
 185 }
 186
 187 static int mcu_remove(struct i2c_client *client)
 188 {
 189         struct mcu *mcu = i2c_get_clientdata(client);
 190         int ret;
 191
 192         kthread_stop(shutdown_thread);
 193
 194         device_remove_file(&client->dev, &dev_attr_status);
 195
 196         if (glob_mcu == mcu) {
 197                 pm_power_off = NULL;
 198                 glob_mcu = NULL;
 199         }
 200
 201         ret = mcu_gpiochip_remove(mcu);
 202         if (ret)
 203                 return ret;
 204         kfree(mcu);
 205         return 0;
 206 }
 207
 208 static const struct i2c_device_id mcu_ids[] = {
 209         { "mcu-mpc8349emitx", },
 210         {},
 211 };
 212 MODULE_DEVICE_TABLE(i2c, mcu_ids);
 213
 214 static const struct of_device_id mcu_of_match_table[] = {
 215         { .compatible = "fsl,mcu-mpc8349emitx", },
 216         { },
 217 };
 218
 219 static struct i2c_driver mcu_driver = {
 220         .driver = {
 221                 .name = "mcu-mpc8349emitx",
 222                 .of_match_table = mcu_of_match_table,
 223         },
 224         .probe_new = mcu_probe,
 225         .remove = mcu_remove,
 226         .id_table = mcu_ids,
 227 };
 228
 229 module_i2c_driver(mcu_driver);
 230
 231 MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
 232                    "MPC8349E-mITX-compatible MCU");
 233 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
 234 MODULE_LICENSE("GPL");