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
38struct mcu {
39	struct mutex lock;
40	struct i2c_client *client;
41	struct gpio_chip gc;
42	u8 reg_ctrl;
43};
44
45static struct mcu *glob_mcu;
46
47struct task_struct *shutdown_thread;
48static 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
74static 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}
87static DEVICE_ATTR(status, S_IRUGO, show_status, NULL);
88
89static 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
100static 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
115static 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
121static 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
142static int mcu_gpiochip_remove(struct mcu *mcu)
143{
144	gpiochip_remove(&mcu->gc);
145	return 0;
146}
147
148static 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;
185err:
186	kfree(mcu);
187	return ret;
188}
189
190static 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
211static const struct i2c_device_id mcu_ids[] = {
212	{ "mcu-mpc8349emitx", },
213	{},
214};
215MODULE_DEVICE_TABLE(i2c, mcu_ids);
216
217static const struct of_device_id mcu_of_match_table[] = {
218	{ .compatible = "fsl,mcu-mpc8349emitx", },
219	{ },
220};
221
222static 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
233module_i2c_driver(mcu_driver);
234
235MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
236		   "MPC8349E-mITX-compatible MCU");
237MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
238MODULE_LICENSE("GPL");
239