// 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 <linux/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:	case NTXEC_VERSION_TOLINO_VISION:		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 = 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");