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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Power Management and GPIO expander driver for MPC8349E-mITX-compatible MCU
*
* Copyright (c) 2008 MontaVista Software, Inc.
*
* Author: Anton Vorontsov <avorontsov@ru.mvista.com>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/i2c.h>
#include <linux/gpio/driver.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/reboot.h>
#include <asm/prom.h>
#include <asm/machdep.h>
/*
* I don't have specifications for the MCU firmware, I found this register
* and bits positions by the trial&error method.
*/
#define MCU_REG_CTRL 0x20
#define MCU_CTRL_POFF 0x40
#define MCU_CTRL_BTN 0x80
#define MCU_NUM_GPIO 2
struct mcu {
struct mutex lock;
struct i2c_client *client;
struct gpio_chip gc;
u8 reg_ctrl;
};
static struct mcu *glob_mcu;
struct task_struct *shutdown_thread;
static int shutdown_thread_fn(void *data)
{
int ret;
struct mcu *mcu = glob_mcu;
while (!kthread_should_stop()) {
ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
if (ret < 0)
pr_err("MCU status reg read failed.\n");
mcu->reg_ctrl = ret;
if (mcu->reg_ctrl & MCU_CTRL_BTN) {
i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL,
mcu->reg_ctrl & ~MCU_CTRL_BTN);
ctrl_alt_del();
}
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(HZ);
}
return 0;
}
static ssize_t show_status(struct device *d,
struct device_attribute *attr, char *buf)
{
int ret;
struct mcu *mcu = glob_mcu;
ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
if (ret < 0)
return -ENODEV;
mcu->reg_ctrl = ret;
return sprintf(buf, "%02x\n", ret);
}
static DEVICE_ATTR(status, 0444, show_status, NULL);
static void mcu_power_off(void)
{
struct mcu *mcu = glob_mcu;
pr_info("Sending power-off request to the MCU...\n");
mutex_lock(&mcu->lock);
i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL,
mcu->reg_ctrl | MCU_CTRL_POFF);
mutex_unlock(&mcu->lock);
}
static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
{
struct mcu *mcu = gpiochip_get_data(gc);
u8 bit = 1 << (4 + gpio);
mutex_lock(&mcu->lock);
if (val)
mcu->reg_ctrl &= ~bit;
else
mcu->reg_ctrl |= bit;
i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
mutex_unlock(&mcu->lock);
}
static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
{
mcu_gpio_set(gc, gpio, val);
return 0;
}
static int mcu_gpiochip_add(struct mcu *mcu)
{
struct device_node *np;
struct gpio_chip *gc = &mcu->gc;
np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
if (!np)
return -ENODEV;
gc->owner = THIS_MODULE;
gc->label = kasprintf(GFP_KERNEL, "%pOF", np);
gc->can_sleep = 1;
gc->ngpio = MCU_NUM_GPIO;
gc->base = -1;
gc->set = mcu_gpio_set;
gc->direction_output = mcu_gpio_dir_out;
gc->of_node = np;
return gpiochip_add_data(gc, mcu);
}
static void mcu_gpiochip_remove(struct mcu *mcu)
{
kfree(mcu->gc.label);
gpiochip_remove(&mcu->gc);
}
static int mcu_probe(struct i2c_client *client)
{
struct mcu *mcu;
int ret;
mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
if (!mcu)
return -ENOMEM;
mutex_init(&mcu->lock);
mcu->client = client;
i2c_set_clientdata(client, mcu);
ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
if (ret < 0)
goto err;
mcu->reg_ctrl = ret;
ret = mcu_gpiochip_add(mcu);
if (ret)
goto err;
/* XXX: this is potentially racy, but there is no lock for pm_power_off */
if (!pm_power_off) {
glob_mcu = mcu;
pm_power_off = mcu_power_off;
dev_info(&client->dev, "will provide power-off service\n");
}
if (device_create_file(&client->dev, &dev_attr_status))
dev_err(&client->dev,
"couldn't create device file for status\n");
shutdown_thread = kthread_run(shutdown_thread_fn, NULL,
"mcu-i2c-shdn");
return 0;
err:
kfree(mcu);
return ret;
}
static int mcu_remove(struct i2c_client *client)
{
struct mcu *mcu = i2c_get_clientdata(client);
int ret;
kthread_stop(shutdown_thread);
device_remove_file(&client->dev, &dev_attr_status);
if (glob_mcu == mcu) {
pm_power_off = NULL;
glob_mcu = NULL;
}
mcu_gpiochip_remove(mcu);
kfree(mcu);
return 0;
}
static const struct i2c_device_id mcu_ids[] = {
{ "mcu-mpc8349emitx", },
{},
};
MODULE_DEVICE_TABLE(i2c, mcu_ids);
static const struct of_device_id mcu_of_match_table[] = {
{ .compatible = "fsl,mcu-mpc8349emitx", },
{ },
};
static struct i2c_driver mcu_driver = {
.driver = {
.name = "mcu-mpc8349emitx",
.of_match_table = mcu_of_match_table,
},
.probe_new = mcu_probe,
.remove = mcu_remove,
.id_table = mcu_ids,
};
module_i2c_driver(mcu_driver);
MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
"MPC8349E-mITX-compatible MCU");
MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
MODULE_LICENSE("GPL");
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