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;
shutdown_thread_fn(void * data)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
show_status(struct device * d,struct device_attribute * attr,char * buf)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
mcu_power_off(void)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
mcu_gpio_set(struct gpio_chip * gc,unsigned int gpio,int val)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
mcu_gpio_dir_out(struct gpio_chip * gc,unsigned int gpio,int val)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
mcu_gpiochip_add(struct mcu * mcu)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
mcu_gpiochip_remove(struct mcu * mcu)142 static int mcu_gpiochip_remove(struct mcu *mcu)
143 {
144 gpiochip_remove(&mcu->gc);
145 return 0;
146 }
147
mcu_probe(struct i2c_client * client,const struct i2c_device_id * id)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
mcu_remove(struct i2c_client * client)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