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
33struct mcu {
34	struct mutex lock;
35	struct i2c_client *client;
36	struct gpio_chip gc;
37	u8 reg_ctrl;
38};
39
40static struct mcu *glob_mcu;
41
42struct task_struct *shutdown_thread;
43static 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
69static 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}
82static DEVICE_ATTR(status, 0444, show_status, NULL);
83
84static 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
95static 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
110static 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
116static 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
133static void mcu_gpiochip_remove(struct mcu *mcu)
134{
135	kfree(mcu->gc.label);
136	gpiochip_remove(&mcu->gc);
137}
138
139static 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;
176err:
177	kfree(mcu);
178	return ret;
179}
180
181static 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
198static const struct i2c_device_id mcu_ids[] = {
199	{ "mcu-mpc8349emitx", },
200	{},
201};
202MODULE_DEVICE_TABLE(i2c, mcu_ids);
203
204static const struct of_device_id mcu_of_match_table[] = {
205	{ .compatible = "fsl,mcu-mpc8349emitx", },
206	{ },
207};
208
209static struct i2c_driver mcu_driver = {
210	.driver = {
211		.name = "mcu-mpc8349emitx",
212		.of_match_table = mcu_of_match_table,
213	},
214	.probe = mcu_probe,
215	.remove	= mcu_remove,
216	.id_table = mcu_ids,
217};
218
219module_i2c_driver(mcu_driver);
220
221MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
222		   "MPC8349E-mITX-compatible MCU");
223MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
224MODULE_LICENSE("GPL");
225