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 <linux/kthread.h> 25 #include <linux/reboot.h> 26 #include <asm/prom.h> 27 #include <asm/machdep.h> 28 29 /* 30 * I don't have specifications for the MCU firmware, I found this register 31 * and bits positions by the trial&error method. 32 */ 33 #define MCU_REG_CTRL 0x20 34 #define MCU_CTRL_POFF 0x40 35 #define MCU_CTRL_BTN 0x80 36 37 #define MCU_NUM_GPIO 2 38 39 struct mcu { 40 struct mutex lock; 41 struct i2c_client *client; 42 struct gpio_chip gc; 43 u8 reg_ctrl; 44 }; 45 46 static struct mcu *glob_mcu; 47 48 struct task_struct *shutdown_thread; 49 static int shutdown_thread_fn(void *data) 50 { 51 int ret; 52 struct mcu *mcu = glob_mcu; 53 54 while (!kthread_should_stop()) { 55 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL); 56 if (ret < 0) 57 pr_err("MCU status reg read failed.\n"); 58 mcu->reg_ctrl = ret; 59 60 61 if (mcu->reg_ctrl & MCU_CTRL_BTN) { 62 i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, 63 mcu->reg_ctrl & ~MCU_CTRL_BTN); 64 65 ctrl_alt_del(); 66 } 67 68 set_current_state(TASK_INTERRUPTIBLE); 69 schedule_timeout(HZ); 70 } 71 72 return 0; 73 } 74 75 static ssize_t show_status(struct device *d, 76 struct device_attribute *attr, char *buf) 77 { 78 int ret; 79 struct mcu *mcu = glob_mcu; 80 81 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL); 82 if (ret < 0) 83 return -ENODEV; 84 mcu->reg_ctrl = ret; 85 86 return sprintf(buf, "%02x\n", ret); 87 } 88 static DEVICE_ATTR(status, S_IRUGO, show_status, NULL); 89 90 static void mcu_power_off(void) 91 { 92 struct mcu *mcu = glob_mcu; 93 94 pr_info("Sending power-off request to the MCU...\n"); 95 mutex_lock(&mcu->lock); 96 i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, 97 mcu->reg_ctrl | MCU_CTRL_POFF); 98 mutex_unlock(&mcu->lock); 99 } 100 101 static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val) 102 { 103 struct mcu *mcu = container_of(gc, struct mcu, gc); 104 u8 bit = 1 << (4 + gpio); 105 106 mutex_lock(&mcu->lock); 107 if (val) 108 mcu->reg_ctrl &= ~bit; 109 else 110 mcu->reg_ctrl |= bit; 111 112 i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl); 113 mutex_unlock(&mcu->lock); 114 } 115 116 static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val) 117 { 118 mcu_gpio_set(gc, gpio, val); 119 return 0; 120 } 121 122 static int mcu_gpiochip_add(struct mcu *mcu) 123 { 124 struct device_node *np; 125 struct gpio_chip *gc = &mcu->gc; 126 127 np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx"); 128 if (!np) 129 return -ENODEV; 130 131 gc->owner = THIS_MODULE; 132 gc->label = np->full_name; 133 gc->can_sleep = 1; 134 gc->ngpio = MCU_NUM_GPIO; 135 gc->base = -1; 136 gc->set = mcu_gpio_set; 137 gc->direction_output = mcu_gpio_dir_out; 138 gc->of_node = np; 139 140 return gpiochip_add(gc); 141 } 142 143 static int mcu_gpiochip_remove(struct mcu *mcu) 144 { 145 return gpiochip_remove(&mcu->gc); 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 ppc_md */ 171 if (!ppc_md.power_off) { 172 glob_mcu = mcu; 173 ppc_md.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 ppc_md.power_off = NULL; 201 glob_mcu = NULL; 202 } 203 204 ret = mcu_gpiochip_remove(mcu); 205 if (ret) 206 return ret; 207 i2c_set_clientdata(client, NULL); 208 kfree(mcu); 209 return 0; 210 } 211 212 static const struct i2c_device_id mcu_ids[] = { 213 { "mcu-mpc8349emitx", }, 214 {}, 215 }; 216 MODULE_DEVICE_TABLE(i2c, mcu_ids); 217 218 static struct of_device_id mcu_of_match_table[] = { 219 { .compatible = "fsl,mcu-mpc8349emitx", }, 220 { }, 221 }; 222 223 static struct i2c_driver mcu_driver = { 224 .driver = { 225 .name = "mcu-mpc8349emitx", 226 .owner = THIS_MODULE, 227 .of_match_table = mcu_of_match_table, 228 }, 229 .probe = mcu_probe, 230 .remove = mcu_remove, 231 .id_table = mcu_ids, 232 }; 233 234 static int __init mcu_init(void) 235 { 236 return i2c_add_driver(&mcu_driver); 237 } 238 module_init(mcu_init); 239 240 static void __exit mcu_exit(void) 241 { 242 i2c_del_driver(&mcu_driver); 243 } 244 module_exit(mcu_exit); 245 246 MODULE_DESCRIPTION("Power Management and GPIO expander driver for " 247 "MPC8349E-mITX-compatible MCU"); 248 MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>"); 249 MODULE_LICENSE("GPL"); 250