// 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 int mcu_gpiochip_remove(struct mcu *mcu) { kfree(mcu->gc.label); gpiochip_remove(&mcu->gc); return 0; } static int mcu_probe(struct i2c_client *client, const struct i2c_device_id *id) { 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; } ret = mcu_gpiochip_remove(mcu); if (ret) return ret; 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 = 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");