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