Commit 92eba680 authored by Dmitry Osipenko's avatar Dmitry Osipenko Committed by Lee Jones
Browse files

mfd: Add driver for Embedded Controller found on Acer Iconia Tab A500 



Acer Iconia Tab A500 is an Android tablet device, it has ENE KB930
Embedded Controller which provides battery-gauge, LED, GPIO and some
other functions. The EC uses firmware that is specifically customized
for Acer A500. This patch adds MFD driver for the Embedded Controller
which allows to power-off / reboot the A500 device, it also provides
a common register read/write API that will be used by the sub-devices.

Signed-off-by: default avatarDmitry Osipenko <digetx@gmail.com>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent 0eee3048

drivers/mfd/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -2085,6 +2085,17 @@ config MFD_KHADAS_MCU 
	  additional drivers must be enabled in order to use the functionality

	  of the device.



config MFD_ACER_A500_EC

	tristate "Support for Acer Iconia Tab A500 Embedded Controller"

	depends on I2C

	depends on (ARCH_TEGRA_2x_SOC && OF) || COMPILE_TEST

	select MFD_CORE

	select REGMAP

	help

	  Support for Embedded Controller found on Acer Iconia Tab A500.

	  The controller itself is ENE KB930, it is running firmware

	  customized for the specific needs of the Acer A500 hardware.



menu "Multimedia Capabilities Port drivers"

	depends on ARCH_SA1100

drivers/mfd/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -264,6 +264,7 @@ obj-$(CONFIG_MFD_ROHM_BD71828) += rohm-bd71828.o 
obj-$(CONFIG_MFD_ROHM_BD718XX)	+= rohm-bd718x7.o

obj-$(CONFIG_MFD_STMFX) 	+= stmfx.o

obj-$(CONFIG_MFD_KHADAS_MCU) 	+= khadas-mcu.o

obj-$(CONFIG_MFD_ACER_A500_EC)	+= acer-ec-a500.o



obj-$(CONFIG_SGI_MFD_IOC3)	+= ioc3.o

obj-$(CONFIG_MFD_SIMPLE_MFD_I2C)	+= simple-mfd-i2c.o

drivers/mfd/acer-ec-a500.c

0 → 100644
+202 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0+

/*

 * Acer Iconia Tab A500 Embedded Controller Driver

 *

 * Copyright 2020 GRATE-driver project

 */



#include <linux/delay.h>

#include <linux/i2c.h>

#include <linux/mfd/core.h>

#include <linux/module.h>

#include <linux/of_device.h>

#include <linux/reboot.h>

#include <linux/regmap.h>



#define A500_EC_I2C_ERR_TIMEOUT		500

#define A500_EC_POWER_CMD_TIMEOUT	1000



/*

 * Controller's firmware expects specific command opcodes to be used for the

 * corresponding registers. Unsupported commands are skipped by the firmware.

 */

#define CMD_SHUTDOWN			0x0

#define CMD_WARM_REBOOT			0x0

#define CMD_COLD_REBOOT			0x1



enum {

	REG_CURRENT_NOW = 0x03,

	REG_SHUTDOWN = 0x52,

	REG_WARM_REBOOT = 0x54,

	REG_COLD_REBOOT = 0x55,

};



static struct i2c_client *a500_ec_client_pm_off;



static int a500_ec_read(void *context, const void *reg_buf, size_t reg_size,

			void *val_buf, size_t val_sizel)

{

	struct i2c_client *client = context;

	unsigned int reg, retries = 5;

	u16 *ret_val = val_buf;

	s32 ret = 0;



	reg = *(u8 *)reg_buf;



	while (retries-- > 0) {

		ret = i2c_smbus_read_word_data(client, reg);

		if (ret >= 0)

			break;



		msleep(A500_EC_I2C_ERR_TIMEOUT);

	}



	if (ret < 0) {

		dev_err(&client->dev, "read 0x%x failed: %d\n", reg, ret);

		return ret;

	}



	*ret_val = ret;



	if (reg == REG_CURRENT_NOW)

		fsleep(10000);



	return 0;

}



static int a500_ec_write(void *context, const void *data, size_t count)

{

	struct i2c_client *client = context;

	unsigned int reg, val, retries = 5;

	s32 ret = 0;



	reg = *(u8  *)(data + 0);

	val = *(u16 *)(data + 1);



	while (retries-- > 0) {

		ret = i2c_smbus_write_word_data(client, reg, val);

		if (ret >= 0)

			break;



		msleep(A500_EC_I2C_ERR_TIMEOUT);

	}



	if (ret < 0) {

		dev_err(&client->dev, "write 0x%x failed: %d\n", reg, ret);

		return ret;

	}



	return 0;

}



static const struct regmap_config a500_ec_regmap_config = {

	.name = "KB930",

	.reg_bits = 8,

	.val_bits = 16,

	.max_register = 0xff,

};



static const struct regmap_bus a500_ec_regmap_bus = {

	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,

	.val_format_endian_default = REGMAP_ENDIAN_LITTLE,

	.write = a500_ec_write,

	.read = a500_ec_read,

	.max_raw_read = 2,

};



static void a500_ec_poweroff(void)

{

	i2c_smbus_write_word_data(a500_ec_client_pm_off,

				  REG_SHUTDOWN, CMD_SHUTDOWN);



	mdelay(A500_EC_POWER_CMD_TIMEOUT);

}



static int a500_ec_restart_notify(struct notifier_block *this,

				  unsigned long reboot_mode, void *data)

{

	if (reboot_mode == REBOOT_WARM)

		i2c_smbus_write_word_data(a500_ec_client_pm_off,

					  REG_WARM_REBOOT, CMD_WARM_REBOOT);

	else

		i2c_smbus_write_word_data(a500_ec_client_pm_off,

					  REG_COLD_REBOOT, CMD_COLD_REBOOT);



	mdelay(A500_EC_POWER_CMD_TIMEOUT);



	return NOTIFY_DONE;

}



static struct notifier_block a500_ec_restart_handler = {

	.notifier_call = a500_ec_restart_notify,

	.priority = 200,

};



static const struct mfd_cell a500_ec_cells[] = {

	{ .name = "acer-a500-iconia-battery", },

	{ .name = "acer-a500-iconia-leds", },

};



static int a500_ec_probe(struct i2c_client *client)

{

	struct regmap *regmap;

	int err;



	regmap = devm_regmap_init(&client->dev, &a500_ec_regmap_bus,

				  client, &a500_ec_regmap_config);

	if (IS_ERR(regmap))

		return PTR_ERR(regmap);



	err = devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO,

				   a500_ec_cells, ARRAY_SIZE(a500_ec_cells),

				   NULL, 0, NULL);

	if (err) {

		dev_err(&client->dev, "failed to add sub-devices: %d\n", err);

		return err;

	}



	if (of_device_is_system_power_controller(client->dev.of_node)) {

		a500_ec_client_pm_off = client;



		err = register_restart_handler(&a500_ec_restart_handler);

		if (err)

			return err;



		if (!pm_power_off)

			pm_power_off = a500_ec_poweroff;

	}



	return 0;

}



static int a500_ec_remove(struct i2c_client *client)

{

	if (of_device_is_system_power_controller(client->dev.of_node)) {

		if (pm_power_off == a500_ec_poweroff)

			pm_power_off = NULL;



		unregister_restart_handler(&a500_ec_restart_handler);

	}



	return 0;

}



static const struct of_device_id a500_ec_match[] = {

	{ .compatible = "acer,a500-iconia-ec" },

	{ }

};

MODULE_DEVICE_TABLE(of, a500_ec_match);



static struct i2c_driver a500_ec_driver = {

	.driver = {

		.name = "acer-a500-embedded-controller",

		.of_match_table = a500_ec_match,

	},

	.probe_new = a500_ec_probe,

	.remove = a500_ec_remove,

};

module_i2c_driver(a500_ec_driver);



MODULE_DESCRIPTION("Acer Iconia Tab A500 Embedded Controller driver");

MODULE_AUTHOR("Dmitry Osipenko <digetx@gmail.com>");

MODULE_LICENSE("GPL");