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/kernel.h> 15 #include <linux/module.h> 16 #include <linux/device.h> 17 #include <linux/mutex.h> 18 #include <linux/i2c.h> 19 #include <linux/gpio.h> 20 #include <linux/of.h> 21 #include <linux/of_gpio.h> 22 #include <linux/slab.h> 23 #include <linux/kthread.h> 24 #include <linux/reboot.h> 25 #include <asm/prom.h> 26 #include <asm/machdep.h> 27 28 /* 29 * I don't have specifications for the MCU firmware, I found this register 30 * and bits positions by the trial&error method. 31 */ 32 #define MCU_REG_CTRL 0x20 33 #define MCU_CTRL_POFF 0x40 34 #define MCU_CTRL_BTN 0x80 35 36 #define MCU_NUM_GPIO 2 37 38 struct mcu { 39 struct mutex lock; 40 struct i2c_client *client; 41 struct gpio_chip gc; 42 u8 reg_ctrl; 43 }; 44 45 static struct mcu *glob_mcu; 46 47 struct task_struct *shutdown_thread; 48 static int shutdown_thread_fn(void *data) 49 { 50 int ret; 51 struct mcu *mcu = glob_mcu; 52 53 while (!kthread_should_stop()) { 54 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL); 55 if (ret < 0) 56 pr_err("MCU status reg read failed.\n"); 57 mcu->reg_ctrl = ret; 58 59 60 if (mcu->reg_ctrl & MCU_CTRL_BTN) { 61 i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, 62 mcu->reg_ctrl & ~MCU_CTRL_BTN); 63 64 ctrl_alt_del(); 65 } 66 67 set_current_state(TASK_INTERRUPTIBLE); 68 schedule_timeout(HZ); 69 } 70 71 return 0; 72 } 73 74 static ssize_t show_status(struct device *d, 75 struct device_attribute *attr, char *buf) 76 { 77 int ret; 78 struct mcu *mcu = glob_mcu; 79 80 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL); 81 if (ret < 0) 82 return -ENODEV; 83 mcu->reg_ctrl = ret; 84 85 return sprintf(buf, "%02x\n", ret); 86 } 87 static DEVICE_ATTR(status, S_IRUGO, show_status, NULL); 88 89 static void mcu_power_off(void) 90 { 91 struct mcu *mcu = glob_mcu; 92 93 pr_info("Sending power-off request to the MCU...\n"); 94 mutex_lock(&mcu->lock); 95 i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, 96 mcu->reg_ctrl | MCU_CTRL_POFF); 97 mutex_unlock(&mcu->lock); 98 } 99 100 static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val) 101 { 102 struct mcu *mcu = container_of(gc, struct mcu, gc); 103 u8 bit = 1 << (4 + gpio); 104 105 mutex_lock(&mcu->lock); 106 if (val) 107 mcu->reg_ctrl &= ~bit; 108 else 109 mcu->reg_ctrl |= bit; 110 111 i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl); 112 mutex_unlock(&mcu->lock); 113 } 114 115 static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val) 116 { 117 mcu_gpio_set(gc, gpio, val); 118 return 0; 119 } 120 121 static int mcu_gpiochip_add(struct mcu *mcu) 122 { 123 struct device_node *np; 124 struct gpio_chip *gc = &mcu->gc; 125 126 np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx"); 127 if (!np) 128 return -ENODEV; 129 130 gc->owner = THIS_MODULE; 131 gc->label = np->full_name; 132 gc->can_sleep = 1; 133 gc->ngpio = MCU_NUM_GPIO; 134 gc->base = -1; 135 gc->set = mcu_gpio_set; 136 gc->direction_output = mcu_gpio_dir_out; 137 gc->of_node = np; 138 139 return gpiochip_add(gc); 140 } 141 142 static int mcu_gpiochip_remove(struct mcu *mcu) 143 { 144 gpiochip_remove(&mcu->gc); 145 return 0; 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 pm_power_off */ 171 if (!pm_power_off) { 172 glob_mcu = mcu; 173 pm_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 pm_power_off = NULL; 201 glob_mcu = NULL; 202 } 203 204 ret = mcu_gpiochip_remove(mcu); 205 if (ret) 206 return ret; 207 kfree(mcu); 208 return 0; 209 } 210 211 static const struct i2c_device_id mcu_ids[] = { 212 { "mcu-mpc8349emitx", }, 213 {}, 214 }; 215 MODULE_DEVICE_TABLE(i2c, mcu_ids); 216 217 static const struct of_device_id mcu_of_match_table[] = { 218 { .compatible = "fsl,mcu-mpc8349emitx", }, 219 { }, 220 }; 221 222 static struct i2c_driver mcu_driver = { 223 .driver = { 224 .name = "mcu-mpc8349emitx", 225 .owner = THIS_MODULE, 226 .of_match_table = mcu_of_match_table, 227 }, 228 .probe = mcu_probe, 229 .remove = mcu_remove, 230 .id_table = mcu_ids, 231 }; 232 233 module_i2c_driver(mcu_driver); 234 235 MODULE_DESCRIPTION("Power Management and GPIO expander driver for " 236 "MPC8349E-mITX-compatible MCU"); 237 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>"); 238 MODULE_LICENSE("GPL"); 239