tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 return gpiochip_remove(&mcu->gc);
145}
146
147static int mcu_probe(struct i2c_client *client, const struct i2c_device_id *id)
148{
149 struct mcu *mcu;
150 int ret;
151
152 mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
153 if (!mcu)
154 return -ENOMEM;
155
156 mutex_init(&mcu->lock);
157 mcu->client = client;
158 i2c_set_clientdata(client, mcu);
159
160 ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
161 if (ret < 0)
162 goto err;
163 mcu->reg_ctrl = ret;
164
165 ret = mcu_gpiochip_add(mcu);
166 if (ret)
167 goto err;
168
169 /* XXX: this is potentially racy, but there is no lock for ppc_md */
170 if (!ppc_md.power_off) {
171 glob_mcu = mcu;
172 ppc_md.power_off = mcu_power_off;
173 dev_info(&client->dev, "will provide power-off service\n");
174 }
175
176 if (device_create_file(&client->dev, &dev_attr_status))
177 dev_err(&client->dev,
178 "couldn't create device file for status\n");
179
180 shutdown_thread = kthread_run(shutdown_thread_fn, NULL,
181 "mcu-i2c-shdn");
182
183 return 0;
184err:
185 kfree(mcu);
186 return ret;
187}
188
189static int mcu_remove(struct i2c_client *client)
190{
191 struct mcu *mcu = i2c_get_clientdata(client);
192 int ret;
193
194 kthread_stop(shutdown_thread);
195
196 device_remove_file(&client->dev, &dev_attr_status);
197
198 if (glob_mcu == mcu) {
199 ppc_md.power_off = NULL;
200 glob_mcu = NULL;
201 }
202
203 ret = mcu_gpiochip_remove(mcu);
204 if (ret)
205 return ret;
206 kfree(mcu);
207 return 0;
208}
209
210static const struct i2c_device_id mcu_ids[] = {
211 { "mcu-mpc8349emitx", },
212 {},
213};
214MODULE_DEVICE_TABLE(i2c, mcu_ids);
215
216static struct of_device_id mcu_of_match_table[] = {
217 { .compatible = "fsl,mcu-mpc8349emitx", },
218 { },
219};
220
221static struct i2c_driver mcu_driver = {
222 .driver = {
223 .name = "mcu-mpc8349emitx",
224 .owner = THIS_MODULE,
225 .of_match_table = mcu_of_match_table,
226 },
227 .probe = mcu_probe,
228 .remove = mcu_remove,
229 .id_table = mcu_ids,
230};
231
232module_i2c_driver(mcu_driver);
233
234MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
235 "MPC8349E-mITX-compatible MCU");
236MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
237MODULE_LICENSE("GPL");