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