mcu_mpc8349emitx.c

  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 int 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	int ret;
100
101	mutex_lock(&mcu->lock);
102	if (val)
103		mcu->reg_ctrl &= ~bit;
104	else
105		mcu->reg_ctrl |= bit;
106
107	ret = i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL,
108					mcu->reg_ctrl);
109	mutex_unlock(&mcu->lock);
110
111	return ret;
112}
113
114static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
115{
116	return mcu_gpio_set(gc, gpio, val);
117}
118
119static int mcu_gpiochip_add(struct mcu *mcu)
120{
121	struct device *dev = &mcu->client->dev;
122	struct gpio_chip *gc = &mcu->gc;
123
124	gc->owner = THIS_MODULE;
125	gc->label = kasprintf(GFP_KERNEL, "%pfw", dev_fwnode(dev));
126	if (!gc->label)
127		return -ENOMEM;
128	gc->can_sleep = 1;
129	gc->ngpio = MCU_NUM_GPIO;
130	gc->base = -1;
131	gc->set = mcu_gpio_set;
132	gc->direction_output = mcu_gpio_dir_out;
133	gc->parent = dev;
134
135	return gpiochip_add_data(gc, mcu);
136}
137
138static void mcu_gpiochip_remove(struct mcu *mcu)
139{
140	kfree(mcu->gc.label);
141	gpiochip_remove(&mcu->gc);
142}
143
144static int mcu_probe(struct i2c_client *client)
145{
146	struct mcu *mcu;
147	int ret;
148
149	mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
150	if (!mcu)
151		return -ENOMEM;
152
153	mutex_init(&mcu->lock);
154	mcu->client = client;
155	i2c_set_clientdata(client, mcu);
156
157	ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
158	if (ret < 0)
159		goto err;
160	mcu->reg_ctrl = ret;
161
162	ret = mcu_gpiochip_add(mcu);
163	if (ret)
164		goto err;
165
166	/* XXX: this is potentially racy, but there is no lock for pm_power_off */
167	if (!pm_power_off) {
168		glob_mcu = mcu;
169		pm_power_off = mcu_power_off;
170		dev_info(&client->dev, "will provide power-off service\n");
171	}
172
173	if (device_create_file(&client->dev, &dev_attr_status))
174		dev_err(&client->dev,
175			"couldn't create device file for status\n");
176
177	shutdown_thread = kthread_run(shutdown_thread_fn, NULL,
178				      "mcu-i2c-shdn");
179
180	return 0;
181err:
182	kfree(mcu);
183	return ret;
184}
185
186static void mcu_remove(struct i2c_client *client)
187{
188	struct mcu *mcu = i2c_get_clientdata(client);
189
190	kthread_stop(shutdown_thread);
191
192	device_remove_file(&client->dev, &dev_attr_status);
193
194	if (glob_mcu == mcu) {
195		pm_power_off = NULL;
196		glob_mcu = NULL;
197	}
198
199	mcu_gpiochip_remove(mcu);
200	kfree(mcu);
201}
202
203static const struct i2c_device_id mcu_ids[] = {
204	{ "mcu-mpc8349emitx", },
205	{},
206};
207MODULE_DEVICE_TABLE(i2c, mcu_ids);
208
209static const struct of_device_id mcu_of_match_table[] = {
210	{ .compatible = "fsl,mcu-mpc8349emitx", },
211	{ },
212};
213
214static struct i2c_driver mcu_driver = {
215	.driver = {
216		.name = "mcu-mpc8349emitx",
217		.of_match_table = mcu_of_match_table,
218	},
219	.probe = mcu_probe,
220	.remove	= mcu_remove,
221	.id_table = mcu_ids,
222};
223
224module_i2c_driver(mcu_driver);
225
226MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
227		   "MPC8349E-mITX-compatible MCU");
228MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
229MODULE_LICENSE("GPL");