drivers/mfd/ntxec.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * The Netronix embedded controller is a microcontroller found in some
  * e-book readers designed by the original design manufacturer Netronix, Inc.
  * It contains RTC, battery monitoring, system power management, and PWM
  * functionality.
  *
  * This driver implements register access, version detection, and system
  * power-off/reset.
  *
  * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net>
  */

 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/i2c.h>
 #include <linux/mfd/core.h>
 #include <linux/mfd/ntxec.h>
 #include <linux/module.h>
 #include <linux/pm.h>
 #include <linux/reboot.h>
 #include <linux/regmap.h>
 #include <linux/types.h>
 #include <asm/unaligned.h>

 #define NTXEC_REG_VERSION	0x00
 #define NTXEC_REG_POWEROFF	0x50
 #define NTXEC_REG_POWERKEEP	0x70
 #define NTXEC_REG_RESET		0x90

 #define NTXEC_POWEROFF_VALUE	0x0100
 #define NTXEC_POWERKEEP_VALUE	0x0800
 #define NTXEC_RESET_VALUE	0xff00

 static struct i2c_client *poweroff_restart_client;

 static void ntxec_poweroff(void)
 {
 	int res;
 	u8 buf[3] = { NTXEC_REG_POWEROFF };
 	struct i2c_msg msgs[] = {
 		{
 			.addr = poweroff_restart_client->addr,
 			.flags = 0,
 			.len = sizeof(buf),
 			.buf = buf,
 		},
 	};

 	put_unaligned_be16(NTXEC_POWEROFF_VALUE, buf + 1);

 	res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
 	if (res < 0)
 		dev_warn(&poweroff_restart_client->dev,
 			 "Failed to power off (err = %d)\n", res);

 	/*
 	 * The time from the register write until the host CPU is powered off
 	 * has been observed to be about 2.5 to 3 seconds. Sleep long enough to
 	 * safely avoid returning from the poweroff handler.
 	 */
 	msleep(5000);
 }

 static int ntxec_restart(struct notifier_block *nb,
 			 unsigned long action, void *data)
 {
 	int res;
 	u8 buf[3] = { NTXEC_REG_RESET };
 	/*
 	 * NOTE: The lower half of the reset value is not sent, because sending
 	 * it causes an I2C error. (The reset handler in the downstream driver
 	 * does send the full two-byte value, but doesn't check the result).
 	 */
 	struct i2c_msg msgs[] = {
 		{
 			.addr = poweroff_restart_client->addr,
 			.flags = 0,
 			.len = sizeof(buf) - 1,
 			.buf = buf,
 		},
 	};

 	put_unaligned_be16(NTXEC_RESET_VALUE, buf + 1);

 	res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
 	if (res < 0)
 		dev_warn(&poweroff_restart_client->dev,
 			 "Failed to restart (err = %d)\n", res);

 	return NOTIFY_DONE;
 }

 static struct notifier_block ntxec_restart_handler = {
 	.notifier_call = ntxec_restart,
 	.priority = 128,
 };

 static int regmap_ignore_write(void *context,
 			       unsigned int reg, unsigned int val)

 {
 	struct regmap *regmap = context;

 	regmap_write(regmap, reg, val);

 	return 0;
 }

 static int regmap_wrap_read(void *context, unsigned int reg,
 			    unsigned int *val)
 {
 	struct regmap *regmap = context;

 	return regmap_read(regmap, reg, val);
 }

 /*
  * Some firmware versions do not ack written data, add a wrapper. It
  * is used to stack another regmap on top.
  */
 static const struct regmap_config regmap_config_noack = {
 	.name = "ntxec_noack",
 	.reg_bits = 8,
 	.val_bits = 16,
 	.cache_type = REGCACHE_NONE,
 	.reg_write = regmap_ignore_write,
 	.reg_read = regmap_wrap_read
 };

 static const struct regmap_config regmap_config = {
 	.name = "ntxec",
 	.reg_bits = 8,
 	.val_bits = 16,
 	.cache_type = REGCACHE_NONE,
 	.val_format_endian = REGMAP_ENDIAN_BIG,
 };

 static const struct mfd_cell ntxec_subdev[] = {
 	{ .name = "ntxec-rtc" },
 	{ .name = "ntxec-pwm" },
 };

 static const struct mfd_cell ntxec_subdev_pwm[] = {
 	{ .name = "ntxec-pwm" },
 };

 static int ntxec_probe(struct i2c_client *client)
 {
 	struct ntxec *ec;
 	unsigned int version;
 	int res;
 	const struct mfd_cell *subdevs;
 	size_t n_subdevs;

 	ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
 	if (!ec)
 		return -ENOMEM;

 	ec->dev = &client->dev;

 	ec->regmap = devm_regmap_init_i2c(client, &regmap_config);
 	if (IS_ERR(ec->regmap)) {
 		dev_err(ec->dev, "Failed to set up regmap for device\n");
 		return PTR_ERR(ec->regmap);
 	}

 	/* Determine the firmware version */
 	res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version);
 	if (res < 0) {
 		dev_err(ec->dev, "Failed to read firmware version number\n");
 		return res;
 	}

 	/* Bail out if we encounter an unknown firmware version */
 	switch (version) {
 	case NTXEC_VERSION_KOBO_AURA:
 		subdevs = ntxec_subdev;
 		n_subdevs = ARRAY_SIZE(ntxec_subdev);
 		break;
 	case NTXEC_VERSION_TOLINO_SHINE2:
 		subdevs = ntxec_subdev_pwm;
 		n_subdevs = ARRAY_SIZE(ntxec_subdev_pwm);
 		/* Another regmap stacked on top of the other */
 		ec->regmap = devm_regmap_init(ec->dev, NULL,
 					      ec->regmap,
 					      &regmap_config_noack);
 		if (IS_ERR(ec->regmap))
 			return PTR_ERR(ec->regmap);
 		break;
 	default:
 		dev_err(ec->dev,
 			"Netronix embedded controller version %04x is not supported.\n",
 			version);
 		return -ENODEV;
 	}

 	dev_info(ec->dev,
 		 "Netronix embedded controller version %04x detected.\n", version);

 	if (of_device_is_system_power_controller(ec->dev->of_node)) {
 		/*
 		 * Set the 'powerkeep' bit. This is necessary on some boards
 		 * in order to keep the system running.
 		 */
 		res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP,
 				   NTXEC_POWERKEEP_VALUE);
 		if (res < 0)
 			return res;

 		if (poweroff_restart_client)
 			/*
 			 * Another instance of the driver already took
 			 * poweroff/restart duties.
 			 */
 			dev_err(ec->dev, "poweroff_restart_client already assigned\n");
 		else
 			poweroff_restart_client = client;

 		if (pm_power_off)
 			/* Another driver already registered a poweroff handler. */
 			dev_err(ec->dev, "pm_power_off already assigned\n");
 		else
 			pm_power_off = ntxec_poweroff;

 		res = register_restart_handler(&ntxec_restart_handler);
 		if (res)
 			dev_err(ec->dev,
 				"Failed to register restart handler: %d\n", res);
 	}

 	i2c_set_clientdata(client, ec);

 	res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE,
 				   subdevs, n_subdevs, NULL, 0, NULL);
 	if (res)
 		dev_err(ec->dev, "Failed to add subdevices: %d\n", res);

 	return res;
 }

 static void ntxec_remove(struct i2c_client *client)
 {
 	if (client == poweroff_restart_client) {
 		poweroff_restart_client = NULL;
 		pm_power_off = NULL;
 		unregister_restart_handler(&ntxec_restart_handler);
 	}
 }

 static const struct of_device_id of_ntxec_match_table[] = {
 	{ .compatible = "netronix,ntxec", },
 	{}
 };
 MODULE_DEVICE_TABLE(of, of_ntxec_match_table);

 static struct i2c_driver ntxec_driver = {
 	.driver = {
 		.name = "ntxec",
 		.of_match_table = of_ntxec_match_table,
 	},
 	.probe_new = ntxec_probe,
 	.remove = ntxec_remove,
 };
 module_i2c_driver(ntxec_driver);

 MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>");
 MODULE_DESCRIPTION("Core driver for Netronix EC");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* The Netronix embedded controller is a microcontroller found in some
	* e-book readers designed by the original design manufacturer Netronix, Inc.
	* It contains RTC, battery monitoring, system power management, and PWM
	* functionality.
	*
	* This driver implements register access, version detection, and system
	* power-off/reset.
	*
	* Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net>
	*/

	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <linux/i2c.h>
	#include <linux/mfd/core.h>
	#include <linux/mfd/ntxec.h>
	#include <linux/module.h>
	#include <linux/pm.h>
	#include <linux/reboot.h>
	#include <linux/regmap.h>
	#include <linux/types.h>
	#include <asm/unaligned.h>

	#define NTXEC_REG_VERSION 0x00
	#define NTXEC_REG_POWEROFF 0x50
	#define NTXEC_REG_POWERKEEP 0x70
	#define NTXEC_REG_RESET 0x90

	#define NTXEC_POWEROFF_VALUE 0x0100
	#define NTXEC_POWERKEEP_VALUE 0x0800
	#define NTXEC_RESET_VALUE 0xff00

	static struct i2c_client *poweroff_restart_client;

	static void ntxec_poweroff(void)
	{
	int res;
	u8 buf[3] = { NTXEC_REG_POWEROFF };
	struct i2c_msg msgs[] = {
	{
	.addr = poweroff_restart_client->addr,
	.flags = 0,
	.len = sizeof(buf),
	.buf = buf,
	},
	};

	put_unaligned_be16(NTXEC_POWEROFF_VALUE, buf + 1);

	res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
	if (res < 0)
	dev_warn(&poweroff_restart_client->dev,
	"Failed to power off (err = %d)\n", res);

	/*
	* The time from the register write until the host CPU is powered off
	* has been observed to be about 2.5 to 3 seconds. Sleep long enough to
	* safely avoid returning from the poweroff handler.
	*/
	msleep(5000);
	}

	static int ntxec_restart(struct notifier_block *nb,
	unsigned long action, void *data)
	{
	int res;
	u8 buf[3] = { NTXEC_REG_RESET };
	/*
	* NOTE: The lower half of the reset value is not sent, because sending
	* it causes an I2C error. (The reset handler in the downstream driver
	* does send the full two-byte value, but doesn't check the result).
	*/
	struct i2c_msg msgs[] = {
	{
	.addr = poweroff_restart_client->addr,
	.flags = 0,
	.len = sizeof(buf) - 1,
	.buf = buf,
	},
	};

	put_unaligned_be16(NTXEC_RESET_VALUE, buf + 1);

	res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
	if (res < 0)
	dev_warn(&poweroff_restart_client->dev,
	"Failed to restart (err = %d)\n", res);

	return NOTIFY_DONE;
	}

	static struct notifier_block ntxec_restart_handler = {
	.notifier_call = ntxec_restart,
	.priority = 128,
	};

	static int regmap_ignore_write(void *context,
	unsigned int reg, unsigned int val)

	{
	struct regmap *regmap = context;

	regmap_write(regmap, reg, val);

	return 0;
	}

	static int regmap_wrap_read(void *context, unsigned int reg,
	unsigned int *val)
	{
	struct regmap *regmap = context;

	return regmap_read(regmap, reg, val);
	}

	/*
	* Some firmware versions do not ack written data, add a wrapper. It
	* is used to stack another regmap on top.
	*/
	static const struct regmap_config regmap_config_noack = {
	.name = "ntxec_noack",
	.reg_bits = 8,
	.val_bits = 16,
	.cache_type = REGCACHE_NONE,
	.reg_write = regmap_ignore_write,
	.reg_read = regmap_wrap_read
	};

	static const struct regmap_config regmap_config = {
	.name = "ntxec",
	.reg_bits = 8,
	.val_bits = 16,
	.cache_type = REGCACHE_NONE,
	.val_format_endian = REGMAP_ENDIAN_BIG,
	};

	static const struct mfd_cell ntxec_subdev[] = {
	{ .name = "ntxec-rtc" },
	{ .name = "ntxec-pwm" },
	};

	static const struct mfd_cell ntxec_subdev_pwm[] = {
	{ .name = "ntxec-pwm" },
	};

	static int ntxec_probe(struct i2c_client *client)
	{
	struct ntxec *ec;
	unsigned int version;
	int res;
	const struct mfd_cell *subdevs;
	size_t n_subdevs;

	ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
	if (!ec)
	return -ENOMEM;

	ec->dev = &client->dev;

	ec->regmap = devm_regmap_init_i2c(client, &regmap_config);
	if (IS_ERR(ec->regmap)) {
	dev_err(ec->dev, "Failed to set up regmap for device\n");
	return PTR_ERR(ec->regmap);
	}

	/* Determine the firmware version */
	res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version);
	if (res < 0) {
	dev_err(ec->dev, "Failed to read firmware version number\n");
	return res;
	}

	/* Bail out if we encounter an unknown firmware version */
	switch (version) {
	case NTXEC_VERSION_KOBO_AURA:
	subdevs = ntxec_subdev;
	n_subdevs = ARRAY_SIZE(ntxec_subdev);
	break;
	case NTXEC_VERSION_TOLINO_SHINE2:
	subdevs = ntxec_subdev_pwm;
	n_subdevs = ARRAY_SIZE(ntxec_subdev_pwm);
	/* Another regmap stacked on top of the other */
	ec->regmap = devm_regmap_init(ec->dev, NULL,
	ec->regmap,
	&regmap_config_noack);
	if (IS_ERR(ec->regmap))
	return PTR_ERR(ec->regmap);
	break;
	default:
	dev_err(ec->dev,
	"Netronix embedded controller version %04x is not supported.\n",
	version);
	return -ENODEV;
	}

	dev_info(ec->dev,
	"Netronix embedded controller version %04x detected.\n", version);

	if (of_device_is_system_power_controller(ec->dev->of_node)) {
	/*
	* Set the 'powerkeep' bit. This is necessary on some boards
	* in order to keep the system running.
	*/
	res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP,
	NTXEC_POWERKEEP_VALUE);
	if (res < 0)
	return res;

	if (poweroff_restart_client)
	/*
	* Another instance of the driver already took
	* poweroff/restart duties.
	*/
	dev_err(ec->dev, "poweroff_restart_client already assigned\n");
	else
	poweroff_restart_client = client;

	if (pm_power_off)
	/* Another driver already registered a poweroff handler. */
	dev_err(ec->dev, "pm_power_off already assigned\n");
	else
	pm_power_off = ntxec_poweroff;

	res = register_restart_handler(&ntxec_restart_handler);
	if (res)
	dev_err(ec->dev,
	"Failed to register restart handler: %d\n", res);
	}

	i2c_set_clientdata(client, ec);

	res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE,
	subdevs, n_subdevs, NULL, 0, NULL);
	if (res)
	dev_err(ec->dev, "Failed to add subdevices: %d\n", res);

	return res;
	}

	static void ntxec_remove(struct i2c_client *client)
	{
	if (client == poweroff_restart_client) {
	poweroff_restart_client = NULL;
	pm_power_off = NULL;
	unregister_restart_handler(&ntxec_restart_handler);
	}
	}

	static const struct of_device_id of_ntxec_match_table[] = {
	{ .compatible = "netronix,ntxec", },
	{}
	};
	MODULE_DEVICE_TABLE(of, of_ntxec_match_table);

	static struct i2c_driver ntxec_driver = {
	.driver = {
	.name = "ntxec",
	.of_match_table = of_ntxec_match_table,
	},
	.probe_new = ntxec_probe,
	.remove = ntxec_remove,
	};
	module_i2c_driver(ntxec_driver);

	MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>");
	MODULE_DESCRIPTION("Core driver for Netronix EC");
	MODULE_LICENSE("GPL");