[linux-2.6-block.git] / drivers / mfd / ntxec.c

// 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 int 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);
	}

	return 0;
}

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");
Commit	Line	Data
eceae583 JN	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/*
	3	* The Netronix embedded controller is a microcontroller found in some
	4	* e-book readers designed by the original design manufacturer Netronix, Inc.
	5	* It contains RTC, battery monitoring, system power management, and PWM
	6	* functionality.
	7	*
	8	* This driver implements register access, version detection, and system
	9	* power-off/reset.
	10	*
	11	* Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net>
	12	*/
	13
	14	#include <linux/delay.h>
	15	#include <linux/errno.h>
	16	#include <linux/i2c.h>
	17	#include <linux/mfd/core.h>
	18	#include <linux/mfd/ntxec.h>
	19	#include <linux/module.h>
	20	#include <linux/pm.h>
	21	#include <linux/reboot.h>
	22	#include <linux/regmap.h>
	23	#include <linux/types.h>
	24	#include <asm/unaligned.h>
	25
	26	#define NTXEC_REG_VERSION 0x00
	27	#define NTXEC_REG_POWEROFF 0x50
	28	#define NTXEC_REG_POWERKEEP 0x70
	29	#define NTXEC_REG_RESET 0x90
	30
	31	#define NTXEC_POWEROFF_VALUE 0x0100
	32	#define NTXEC_POWERKEEP_VALUE 0x0800
	33	#define NTXEC_RESET_VALUE 0xff00
	34
	35	static struct i2c_client *poweroff_restart_client;
	36
	37	static void ntxec_poweroff(void)
	38	{
	39	int res;
	40	u8 buf[3] = { NTXEC_REG_POWEROFF };
	41	struct i2c_msg msgs[] = {
	42	{
	43	.addr = poweroff_restart_client->addr,
	44	.flags = 0,
	45	.len = sizeof(buf),
	46	.buf = buf,
	47	},
	48	};
	49
	50	put_unaligned_be16(NTXEC_POWEROFF_VALUE, buf + 1);
	51
	52	res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
	53	if (res < 0)
	54	dev_warn(&poweroff_restart_client->dev,
	55	"Failed to power off (err = %d)\n", res);
	56
	57	/*
	58	* The time from the register write until the host CPU is powered off
	59	* has been observed to be about 2.5 to 3 seconds. Sleep long enough to
	60	* safely avoid returning from the poweroff handler.
	61	*/
	62	msleep(5000);
	63	}
	64
65	static int ntxec_restart(struct notifier_block *nb,
66	unsigned long action, void *data)
67	{
68	int res;
69	u8 buf[3] = { NTXEC_REG_RESET };
70	/*
71	* NOTE: The lower half of the reset value is not sent, because sending
72	* it causes an I2C error. (The reset handler in the downstream driver
73	* does send the full two-byte value, but doesn't check the result).
74	*/
75	struct i2c_msg msgs[] = {
76	{
77	.addr = poweroff_restart_client->addr,
78	.flags = 0,
79	.len = sizeof(buf) - 1,
80	.buf = buf,
81	},
82	};
83
84	put_unaligned_be16(NTXEC_RESET_VALUE, buf + 1);
85
86	res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
87	if (res < 0)
88	dev_warn(&poweroff_restart_client->dev,
89	"Failed to restart (err = %d)\n", res);
90
91	return NOTIFY_DONE;
92	}
93
94	static struct notifier_block ntxec_restart_handler = {
95	.notifier_call = ntxec_restart,
96	.priority = 128,
97	};
98
d1157530 AK	99	static int regmap_ignore_write(void *context,
	100	unsigned int reg, unsigned int val)
	101
	102	{
	103	struct regmap *regmap = context;
	104
	105	regmap_write(regmap, reg, val);
	106
	107	return 0;
	108	}
	109
	110	static int regmap_wrap_read(void *context, unsigned int reg,
	111	unsigned int *val)
	112	{
	113	struct regmap *regmap = context;
	114
	115	return regmap_read(regmap, reg, val);
	116	}
	117
	118	/*
	119	* Some firmware versions do not ack written data, add a wrapper. It
	120	* is used to stack another regmap on top.
	121	*/
	122	static const struct regmap_config regmap_config_noack = {
	123	.name = "ntxec_noack",
	124	.reg_bits = 8,
	125	.val_bits = 16,
	126	.cache_type = REGCACHE_NONE,
	127	.reg_write = regmap_ignore_write,
	128	.reg_read = regmap_wrap_read
	129	};
	130
eceae583 JN	131	static const struct regmap_config regmap_config = {
	132	.name = "ntxec",
	133	.reg_bits = 8,
	134	.val_bits = 16,
	135	.cache_type = REGCACHE_NONE,
	136	.val_format_endian = REGMAP_ENDIAN_BIG,
	137	};
	138
d1157530	139	static const struct mfd_cell ntxec_subdev[] = {
eceae583 JN	140	{ .name = "ntxec-rtc" },
	141	{ .name = "ntxec-pwm" },
	142	};
	143
d1157530 AK	144	static const struct mfd_cell ntxec_subdev_pwm[] = {
	145	{ .name = "ntxec-pwm" },
	146	};
	147
eceae583 JN	148	static int ntxec_probe(struct i2c_client *client)
	149	{
	150	struct ntxec *ec;
	151	unsigned int version;
	152	int res;
d1157530 AK	153	const struct mfd_cell *subdevs;
d1157530 AK	154	size_t n_subdevs;
eceae583 JN	155
	156	ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
	157	if (!ec)
	158	return -ENOMEM;
	159
	160	ec->dev = &client->dev;
	161
	162	ec->regmap = devm_regmap_init_i2c(client, &regmap_config);
	163	if (IS_ERR(ec->regmap)) {
	164	dev_err(ec->dev, "Failed to set up regmap for device\n");
	165	return PTR_ERR(ec->regmap);
	166	}
	167
	168	/* Determine the firmware version */
	169	res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version);
	170	if (res < 0) {
	171	dev_err(ec->dev, "Failed to read firmware version number\n");
	172	return res;
	173	}
	174
	175	/* Bail out if we encounter an unknown firmware version */
	176	switch (version) {
	177	case NTXEC_VERSION_KOBO_AURA:
d1157530 AK	178	subdevs = ntxec_subdev;
	179	n_subdevs = ARRAY_SIZE(ntxec_subdev);
	180	break;
	181	case NTXEC_VERSION_TOLINO_SHINE2:
	182	subdevs = ntxec_subdev_pwm;
	183	n_subdevs = ARRAY_SIZE(ntxec_subdev_pwm);
	184	/* Another regmap stacked on top of the other */
	185	ec->regmap = devm_regmap_init(ec->dev, NULL,
	186	ec->regmap,
	187	&regmap_config_noack);
	188	if (IS_ERR(ec->regmap))
	189	return PTR_ERR(ec->regmap);
eceae583 JN	190	break;
	191	default:
	192	dev_err(ec->dev,
	193	"Netronix embedded controller version %04x is not supported.\n",
	194	version);
	195	return -ENODEV;
	196	}
	197
	198	dev_info(ec->dev,
	199	"Netronix embedded controller version %04x detected.\n", version);
	200
	201	if (of_device_is_system_power_controller(ec->dev->of_node)) {
	202	/*
	203	* Set the 'powerkeep' bit. This is necessary on some boards
	204	* in order to keep the system running.
	205	*/
	206	res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP,
	207	NTXEC_POWERKEEP_VALUE);
	208	if (res < 0)
	209	return res;
	210
	211	if (poweroff_restart_client)
	212	/*
	213	* Another instance of the driver already took
	214	* poweroff/restart duties.
	215	*/
	216	dev_err(ec->dev, "poweroff_restart_client already assigned\n");
	217	else
	218	poweroff_restart_client = client;
	219
	220	if (pm_power_off)
	221	/* Another driver already registered a poweroff handler. */
	222	dev_err(ec->dev, "pm_power_off already assigned\n");
	223	else
	224	pm_power_off = ntxec_poweroff;
	225
	226	res = register_restart_handler(&ntxec_restart_handler);
	227	if (res)
	228	dev_err(ec->dev,
	229	"Failed to register restart handler: %d\n", res);
	230	}
	231
	232	i2c_set_clientdata(client, ec);
	233
d1157530 AK	234	res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE,
d1157530 AK	235	subdevs, n_subdevs, NULL, 0, NULL);
eceae583 JN	236	if (res)
	237	dev_err(ec->dev, "Failed to add subdevices: %d\n", res);
	238
	239	return res;
	240	}
	241
	242	static int ntxec_remove(struct i2c_client *client)
	243	{
	244	if (client == poweroff_restart_client) {
	245	poweroff_restart_client = NULL;
	246	pm_power_off = NULL;
	247	unregister_restart_handler(&ntxec_restart_handler);
	248	}
	249
	250	return 0;
	251	}
	252
	253	static const struct of_device_id of_ntxec_match_table[] = {
	254	{ .compatible = "netronix,ntxec", },
	255	{}
	256	};
	257	MODULE_DEVICE_TABLE(of, of_ntxec_match_table);
	258
	259	static struct i2c_driver ntxec_driver = {
	260	.driver = {
	261	.name = "ntxec",
	262	.of_match_table = of_ntxec_match_table,
	263	},
	264	.probe_new = ntxec_probe,
	265	.remove = ntxec_remove,
	266	};
	267	module_i2c_driver(ntxec_driver);
	268
	269	MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>");
	270	MODULE_DESCRIPTION("Core driver for Netronix EC");
	271	MODULE_LICENSE("GPL");