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(client: 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(client: mcu->client, MCU_REG_CTRL,
57 value: 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(client: mcu->client, MCU_REG_CTRL);
76 if (ret < 0)
77 return -ENODEV;
78 mcu->reg_ctrl = ret;
79
80 return sprintf(buf, fmt: "%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(client: mcu->client, MCU_REG_CTRL,
91 value: mcu->reg_ctrl | MCU_CTRL_POFF);
92 mutex_unlock(lock: &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(client: mcu->client, MCU_REG_CTRL,
108 value: mcu->reg_ctrl);
109 mutex_unlock(lock: &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, fmt: "%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(objp: mcu->gc.label);
141 gpiochip_remove(gc: &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, data: mcu);
156
157 ret = i2c_smbus_read_byte_data(client: 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(device: &client->dev, entry: &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(objp: 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(k: shutdown_thread);
191
192 device_remove_file(dev: &client->dev, attr: &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(objp: 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");
230

source code of linux/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c