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/driver.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 = gpiochip_get_data(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 = kasprintf(GFP_KERNEL, "%pOF", np);
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_data(gc, mcu);
140 }
141 
142 static int mcu_gpiochip_remove(struct mcu *mcu)
143 {
144 	kfree(mcu->gc.label);
145 	gpiochip_remove(&mcu->gc);
146 	return 0;
147 }
148 
149 static int mcu_probe(struct i2c_client *client, const struct i2c_device_id *id)
150 {
151 	struct mcu *mcu;
152 	int ret;
153 
154 	mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
155 	if (!mcu)
156 		return -ENOMEM;
157 
158 	mutex_init(&mcu->lock);
159 	mcu->client = client;
160 	i2c_set_clientdata(client, mcu);
161 
162 	ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
163 	if (ret < 0)
164 		goto err;
165 	mcu->reg_ctrl = ret;
166 
167 	ret = mcu_gpiochip_add(mcu);
168 	if (ret)
169 		goto err;
170 
171 	/* XXX: this is potentially racy, but there is no lock for pm_power_off */
172 	if (!pm_power_off) {
173 		glob_mcu = mcu;
174 		pm_power_off = mcu_power_off;
175 		dev_info(&client->dev, "will provide power-off service\n");
176 	}
177 
178 	if (device_create_file(&client->dev, &dev_attr_status))
179 		dev_err(&client->dev,
180 			"couldn't create device file for status\n");
181 
182 	shutdown_thread = kthread_run(shutdown_thread_fn, NULL,
183 				      "mcu-i2c-shdn");
184 
185 	return 0;
186 err:
187 	kfree(mcu);
188 	return ret;
189 }
190 
191 static int mcu_remove(struct i2c_client *client)
192 {
193 	struct mcu *mcu = i2c_get_clientdata(client);
194 	int ret;
195 
196 	kthread_stop(shutdown_thread);
197 
198 	device_remove_file(&client->dev, &dev_attr_status);
199 
200 	if (glob_mcu == mcu) {
201 		pm_power_off = NULL;
202 		glob_mcu = NULL;
203 	}
204 
205 	ret = mcu_gpiochip_remove(mcu);
206 	if (ret)
207 		return ret;
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 const 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 		.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