// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * lm83.c - Part of lm_sensors, Linux kernel modules for hardware
 *          monitoring
 * Copyright (C) 2003-2009  Jean Delvare <jdelvare@suse.de>
 *
 * Heavily inspired from the lm78, lm75 and adm1021 drivers. The LM83 is
 * a sensor chip made by National Semiconductor. It reports up to four
 * temperatures (its own plus up to three external ones) with a 1 deg
 * resolution and a 3-4 deg accuracy. Complete datasheet can be obtained
 * from National's website at:
 *   http://www.national.com/pf/LM/LM83.html
 * Since the datasheet omits to give the chip stepping code, I give it
 * here: 0x03 (at register 0xff).
 *
 * Also supports the LM82 temp sensor, which is basically a stripped down
 * model of the LM83.  Datasheet is here:
 * http://www.national.com/pf/LM/LM82.html
 */

#include <linux/bits.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/slab.h>

/*
 * Addresses to scan
 * Address is selected using 2 three-level pins, resulting in 9 possible
 * addresses.
 */

static const unsigned short normal_i2c[] = {
	0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, 0x4c, 0x4d, 0x4e, I2C_CLIENT_END };

enum chips { lm83, lm82 };

/*
 * The LM83 registers
 * Manufacturer ID is 0x01 for National Semiconductor.
 */

#define LM83_REG_R_MAN_ID		0xFE
#define LM83_REG_R_CHIP_ID		0xFF
#define LM83_REG_R_CONFIG		0x03
#define LM83_REG_W_CONFIG		0x09
#define LM83_REG_R_STATUS1		0x02
#define LM83_REG_R_STATUS2		0x35
#define LM83_REG_R_LOCAL_TEMP		0x00
#define LM83_REG_R_LOCAL_HIGH		0x05
#define LM83_REG_W_LOCAL_HIGH		0x0B
#define LM83_REG_R_REMOTE1_TEMP		0x30
#define LM83_REG_R_REMOTE1_HIGH		0x38
#define LM83_REG_W_REMOTE1_HIGH		0x50
#define LM83_REG_R_REMOTE2_TEMP		0x01
#define LM83_REG_R_REMOTE2_HIGH		0x07
#define LM83_REG_W_REMOTE2_HIGH		0x0D
#define LM83_REG_R_REMOTE3_TEMP		0x31
#define LM83_REG_R_REMOTE3_HIGH		0x3A
#define LM83_REG_W_REMOTE3_HIGH		0x52
#define LM83_REG_R_TCRIT		0x42
#define LM83_REG_W_TCRIT		0x5A

static const u8 LM83_REG_TEMP[] = {
	LM83_REG_R_LOCAL_TEMP,
	LM83_REG_R_REMOTE1_TEMP,
	LM83_REG_R_REMOTE2_TEMP,
	LM83_REG_R_REMOTE3_TEMP,
};

static const u8 LM83_REG_MAX[] = {
	LM83_REG_R_LOCAL_HIGH,
	LM83_REG_R_REMOTE1_HIGH,
	LM83_REG_R_REMOTE2_HIGH,
	LM83_REG_R_REMOTE3_HIGH,
};

/* alarm and fault registers and bits, indexed by channel */
static const u8 LM83_ALARM_REG[] = {
	LM83_REG_R_STATUS1, LM83_REG_R_STATUS2, LM83_REG_R_STATUS1, LM83_REG_R_STATUS2
};

static const u8 LM83_MAX_ALARM_BIT[] = {
	BIT(6), BIT(7), BIT(4), BIT(4)
};

static const u8 LM83_CRIT_ALARM_BIT[] = {
	BIT(0), BIT(0), BIT(1), BIT(1)
};

static const u8 LM83_FAULT_BIT[] = {
	0, BIT(5), BIT(2), BIT(2)
};

/*
 * Client data (each client gets its own)
 */

struct lm83_data {
	struct regmap *regmap;
	enum chips type;
};

/* regmap code */

static int lm83_regmap_reg_read(void *context, unsigned int reg, unsigned int *val)
{
	struct i2c_client *client = context;
	int ret;

	ret = i2c_smbus_read_byte_data(client, reg);
	if (ret < 0)
		return ret;

	*val = ret;
	return 0;
}

/*
 * The regmap write function maps read register addresses to write register
 * addresses. This is necessary for regmap register caching to work.
 * An alternative would be to clear the regmap cache whenever a register is
 * written, but that would be much more expensive.
 */
static int lm83_regmap_reg_write(void *context, unsigned int reg, unsigned int val)
{
	struct i2c_client *client = context;

	switch (reg) {
	case LM83_REG_R_CONFIG:
	case LM83_REG_R_LOCAL_HIGH:
	case LM83_REG_R_REMOTE2_HIGH:
		reg += 0x06;
		break;
	case LM83_REG_R_REMOTE1_HIGH:
	case LM83_REG_R_REMOTE3_HIGH:
	case LM83_REG_R_TCRIT:
		reg += 0x18;
		break;
	default:
		break;
	}

	return i2c_smbus_write_byte_data(client, reg, val);
}

static bool lm83_regmap_is_volatile(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case LM83_REG_R_LOCAL_TEMP:
	case LM83_REG_R_REMOTE1_TEMP:
	case LM83_REG_R_REMOTE2_TEMP:
	case LM83_REG_R_REMOTE3_TEMP:
	case LM83_REG_R_STATUS1:
	case LM83_REG_R_STATUS2:
		return true;
	default:
		return false;
	}
}

static const struct regmap_config lm83_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.cache_type = REGCACHE_RBTREE,
	.volatile_reg = lm83_regmap_is_volatile,
	.reg_read = lm83_regmap_reg_read,
	.reg_write = lm83_regmap_reg_write,
};

/* hwmon API */

static int lm83_temp_read(struct device *dev, u32 attr, int channel, long *val)
{
	struct lm83_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;

	switch (attr) {
	case hwmon_temp_input:
		err = regmap_read(data->regmap, LM83_REG_TEMP[channel], &regval);
		if (err < 0)
			return err;
		*val = (s8)regval * 1000;
		break;
	case hwmon_temp_max:
		err = regmap_read(data->regmap, LM83_REG_MAX[channel], &regval);
		if (err < 0)
			return err;
		*val = (s8)regval * 1000;
		break;
	case hwmon_temp_crit:
		err = regmap_read(data->regmap, LM83_REG_R_TCRIT, &regval);
		if (err < 0)
			return err;
		*val = (s8)regval * 1000;
		break;
	case hwmon_temp_max_alarm:
		err = regmap_read(data->regmap, LM83_ALARM_REG[channel], &regval);
		if (err < 0)
			return err;
		*val = !!(regval & LM83_MAX_ALARM_BIT[channel]);
		break;
	case hwmon_temp_crit_alarm:
		err = regmap_read(data->regmap, LM83_ALARM_REG[channel], &regval);
		if (err < 0)
			return err;
		*val = !!(regval & LM83_CRIT_ALARM_BIT[channel]);
		break;
	case hwmon_temp_fault:
		err = regmap_read(data->regmap, LM83_ALARM_REG[channel], &regval);
		if (err < 0)
			return err;
		*val = !!(regval & LM83_FAULT_BIT[channel]);
		break;
	default:
		return -EOPNOTSUPP;
	}
	return 0;
}

static int lm83_temp_write(struct device *dev, u32 attr, int channel, long val)
{
	struct lm83_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;

	regval = DIV_ROUND_CLOSEST(clamp_val(val, -128000, 127000), 1000);

	switch (attr) {
	case hwmon_temp_max:
		err = regmap_write(data->regmap, LM83_REG_MAX[channel], regval);
		if (err < 0)
			return err;
		break;
	case hwmon_temp_crit:
		err = regmap_write(data->regmap, LM83_REG_R_TCRIT, regval);
		if (err < 0)
			return err;
		break;
	default:
		return -EOPNOTSUPP;
	}
	return 0;
}

static int lm83_chip_read(struct device *dev, u32 attr, int channel, long *val)
{
	struct lm83_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;

	switch (attr) {
	case hwmon_chip_alarms:
		err = regmap_read(data->regmap, LM83_REG_R_STATUS1, &regval);
		if (err < 0)
			return err;
		*val = regval;
		err = regmap_read(data->regmap, LM83_REG_R_STATUS2, &regval);
		if (err < 0)
			return err;
		*val |= regval << 8;
		return 0;
	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int lm83_read(struct device *dev, enum hwmon_sensor_types type,
		     u32 attr, int channel, long *val)
{
	switch (type) {
	case hwmon_chip:
		return lm83_chip_read(dev, attr, channel, val);
	case hwmon_temp:
		return lm83_temp_read(dev, attr, channel, val);
	default:
		return -EOPNOTSUPP;
	}
}

static int lm83_write(struct device *dev, enum hwmon_sensor_types type,
		      u32 attr, int channel, long val)
{
	switch (type) {
	case hwmon_temp:
		return lm83_temp_write(dev, attr, channel, val);
	default:
		return -EOPNOTSUPP;
	}
}

static umode_t lm83_is_visible(const void *_data, enum hwmon_sensor_types type,
			       u32 attr, int channel)
{
	const struct lm83_data *data = _data;

	/*
	 * LM82 only supports a single external channel, modeled as channel 2.
	 */
	if (data->type == lm82 && (channel == 1 || channel == 3))
		return 0;

	switch (type) {
	case hwmon_chip:
		if (attr == hwmon_chip_alarms)
			return 0444;
		break;
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_input:
		case hwmon_temp_max_alarm:
		case hwmon_temp_crit_alarm:
			return 0444;
		case hwmon_temp_fault:
			if (channel)
				return 0444;
			break;
		case hwmon_temp_max:
			return 0644;
		case hwmon_temp_crit:
			if (channel == 2)
				return 0644;
			return 0444;
		default:
			break;
		}
		break;
	default:
		break;
	}
	return 0;
}

static const struct hwmon_channel_info *lm83_info[] = {
	HWMON_CHANNEL_INFO(chip, HWMON_C_ALARMS),
	HWMON_CHANNEL_INFO(temp,
			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_CRIT |
			   HWMON_T_MAX_ALARM | HWMON_T_CRIT_ALARM,
			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_CRIT |
			   HWMON_T_MAX_ALARM | HWMON_T_CRIT_ALARM | HWMON_T_FAULT,
			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_CRIT |
			   HWMON_T_MAX_ALARM | HWMON_T_CRIT_ALARM | HWMON_T_FAULT,
			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_CRIT |
			   HWMON_T_MAX_ALARM | HWMON_T_CRIT_ALARM | HWMON_T_FAULT
			   ),
	NULL
};

static const struct hwmon_ops lm83_hwmon_ops = {
	.is_visible = lm83_is_visible,
	.read = lm83_read,
	.write = lm83_write,
};

static const struct hwmon_chip_info lm83_chip_info = {
	.ops = &lm83_hwmon_ops,
	.info = lm83_info,
};

/* Return 0 if detection is successful, -ENODEV otherwise */
static int lm83_detect(struct i2c_client *client,
		       struct i2c_board_info *info)
{
	struct i2c_adapter *adapter = client->adapter;
	const char *name;
	u8 man_id, chip_id;

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
		return -ENODEV;

	/* Detection */
	if ((i2c_smbus_read_byte_data(client, LM83_REG_R_STATUS1) & 0xA8) ||
	    (i2c_smbus_read_byte_data(client, LM83_REG_R_STATUS2) & 0x48) ||
	    (i2c_smbus_read_byte_data(client, LM83_REG_R_CONFIG) & 0x41)) {
		dev_dbg(&adapter->dev, "LM83 detection failed at 0x%02x\n",
			client->addr);
		return -ENODEV;
	}

	/* Identification */
	man_id = i2c_smbus_read_byte_data(client, LM83_REG_R_MAN_ID);
	if (man_id != 0x01)	/* National Semiconductor */
		return -ENODEV;

	chip_id = i2c_smbus_read_byte_data(client, LM83_REG_R_CHIP_ID);
	switch (chip_id) {
	case 0x03:
		/*
		 * According to the LM82 datasheet dated March 2013, recent
		 * revisions of LM82 have a die revision of 0x03. This was
		 * confirmed with a real chip. Further details in this revision
		 * of the LM82 datasheet strongly suggest that LM82 is just a
		 * repackaged LM83. It is therefore impossible to distinguish
		 * those chips from LM83, and they will be misdetected as LM83.
		 */
		name = "lm83";
		break;
	case 0x01:
		name = "lm82";
		break;
	default:
		/* identification failed */
		dev_dbg(&adapter->dev,
			"Unsupported chip (man_id=0x%02X, chip_id=0x%02X)\n",
			man_id, chip_id);
		return -ENODEV;
	}

	strscpy(info->type, name, I2C_NAME_SIZE);

	return 0;
}

static const struct i2c_device_id lm83_id[] = {
	{ "lm83", lm83 },
	{ "lm82", lm82 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, lm83_id);

static int lm83_probe(struct i2c_client *client)
{
	struct device *dev = &client->dev;
	struct device *hwmon_dev;
	struct lm83_data *data;

	data = devm_kzalloc(dev, sizeof(struct lm83_data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->regmap = devm_regmap_init(dev, NULL, client, &lm83_regmap_config);
	if (IS_ERR(data->regmap))
		return PTR_ERR(data->regmap);

	data->type = i2c_match_id(lm83_id, client)->driver_data;

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
							 data, &lm83_chip_info, NULL);
	return PTR_ERR_OR_ZERO(hwmon_dev);
}

/*
 * Driver data (common to all clients)
 */

static struct i2c_driver lm83_driver = {
	.class		= I2C_CLASS_HWMON,
	.driver = {
		.name	= "lm83",
	},
	.probe_new	= lm83_probe,
	.id_table	= lm83_id,
	.detect		= lm83_detect,
	.address_list	= normal_i2c,
};

module_i2c_driver(lm83_driver);

MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
MODULE_DESCRIPTION("LM83 driver");
MODULE_LICENSE("GPL");