/*
 * Hardware monitoring driver for Maxim MAX6621
 *
 * Copyright (c) 2017 Mellanox Technologies. All rights reserved.
 * Copyright (c) 2017 Vadim Pasternak <vadimp@mellanox.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

#include <linux/bitops.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/regmap.h>

#define MAX6621_DRV_NAME		"max6621"
#define MAX6621_TEMP_INPUT_REG_NUM	9
#define MAX6621_TEMP_INPUT_MIN		-127000
#define MAX6621_TEMP_INPUT_MAX		128000
#define MAX6621_TEMP_ALERT_CHAN_SHIFT	1

#define MAX6621_TEMP_S0D0_REG		0x00
#define MAX6621_TEMP_S0D1_REG		0x01
#define MAX6621_TEMP_S1D0_REG		0x02
#define MAX6621_TEMP_S1D1_REG		0x03
#define MAX6621_TEMP_S2D0_REG		0x04
#define MAX6621_TEMP_S2D1_REG		0x05
#define MAX6621_TEMP_S3D0_REG		0x06
#define MAX6621_TEMP_S3D1_REG		0x07
#define MAX6621_TEMP_MAX_REG		0x08
#define MAX6621_TEMP_MAX_ADDR_REG	0x0a
#define MAX6621_TEMP_ALERT_CAUSE_REG	0x0b
#define MAX6621_CONFIG0_REG		0x0c
#define MAX6621_CONFIG1_REG		0x0d
#define MAX6621_CONFIG2_REG		0x0e
#define MAX6621_CONFIG3_REG		0x0f
#define MAX6621_TEMP_S0_ALERT_REG	0x10
#define MAX6621_TEMP_S1_ALERT_REG	0x11
#define MAX6621_TEMP_S2_ALERT_REG	0x12
#define MAX6621_TEMP_S3_ALERT_REG	0x13
#define MAX6621_CLEAR_ALERT_REG		0x15
#define MAX6621_REG_MAX			(MAX6621_CLEAR_ALERT_REG + 1)
#define MAX6621_REG_TEMP_SHIFT		0x06

#define MAX6621_ENABLE_TEMP_ALERTS_BIT	4
#define MAX6621_ENABLE_I2C_CRC_BIT	5
#define MAX6621_ENABLE_ALTERNATE_DATA	6
#define MAX6621_ENABLE_LOCKUP_TO	7
#define MAX6621_ENABLE_S0D0_BIT		8
#define MAX6621_ENABLE_S3D1_BIT		15
#define MAX6621_ENABLE_TEMP_ALL		GENMASK(MAX6621_ENABLE_S3D1_BIT, \
						MAX6621_ENABLE_S0D0_BIT)
#define MAX6621_POLL_DELAY_MASK		0x5
#define MAX6621_CONFIG0_INIT		(MAX6621_ENABLE_TEMP_ALL | \
					 BIT(MAX6621_ENABLE_LOCKUP_TO) | \
					 BIT(MAX6621_ENABLE_I2C_CRC_BIT) | \
					 MAX6621_POLL_DELAY_MASK)
#define MAX6621_PECI_BIT_TIME		0x2
#define MAX6621_PECI_RETRY_NUM		0x3
#define MAX6621_CONFIG1_INIT		((MAX6621_PECI_BIT_TIME << 8) | \
					 MAX6621_PECI_RETRY_NUM)

/* Error codes */
#define MAX6621_TRAN_FAILED	0x8100	/*
					 * PECI transaction failed for more
					 * than the configured number of
					 * consecutive retries.
					 */
#define MAX6621_POOL_DIS	0x8101	/*
					 * Polling disabled for requested
					 * socket/domain.
					 */
#define MAX6621_POOL_UNCOMPLETE	0x8102	/*
					 * First poll not yet completed for
					 * requested socket/domain (on
					 * startup).
					 */
#define MAX6621_SD_DIS		0x8103	/*
					 * Read maximum temperature requested,
					 * but no sockets/domains enabled or
					 * all enabled sockets/domains have
					 * errors; or read maximum temperature
					 * address requested, but read maximum
					 * temperature was not called.
					 */
#define MAX6621_ALERT_DIS	0x8104	/*
					 * Get alert socket/domain requested,
					 * but no alert active.
					 */
#define MAX6621_PECI_ERR_MIN	0x8000	/* Intel spec PECI error min value. */
#define MAX6621_PECI_ERR_MAX	0x80ff	/* Intel spec PECI error max value. */

static const u32 max6621_temp_regs[] = {
	MAX6621_TEMP_MAX_REG, MAX6621_TEMP_S0D0_REG, MAX6621_TEMP_S1D0_REG,
	MAX6621_TEMP_S2D0_REG, MAX6621_TEMP_S3D0_REG, MAX6621_TEMP_S0D1_REG,
	MAX6621_TEMP_S1D1_REG, MAX6621_TEMP_S2D1_REG, MAX6621_TEMP_S3D1_REG,
};

static const char *const max6621_temp_labels[] = {
	"maximum",
	"socket0_0",
	"socket1_0",
	"socket2_0",
	"socket3_0",
	"socket0_1",
	"socket1_1",
	"socket2_1",
	"socket3_1",
};

static const int max6621_temp_alert_chan2reg[] = {
	MAX6621_TEMP_S0_ALERT_REG,
	MAX6621_TEMP_S1_ALERT_REG,
	MAX6621_TEMP_S2_ALERT_REG,
	MAX6621_TEMP_S3_ALERT_REG,
};

/**
 * struct max6621_data - private data:
 *
 * @client: I2C client;
 * @regmap: register map handle;
 * @input_chan2reg: mapping from channel to register;
 */
struct max6621_data {
	struct i2c_client	*client;
	struct regmap		*regmap;
	int			input_chan2reg[MAX6621_TEMP_INPUT_REG_NUM + 1];
};

static long max6621_temp_mc2reg(long val)
{
	return (val / 1000L) << MAX6621_REG_TEMP_SHIFT;
}

static umode_t
max6621_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
		   int channel)
{
	/* Skip channels which are not physically conncted. */
	if (((struct max6621_data *)data)->input_chan2reg[channel] < 0)
		return 0;

	switch (type) {
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_input:
		case hwmon_temp_label:
		case hwmon_temp_crit_alarm:
			return 0444;
		case hwmon_temp_offset:
		case hwmon_temp_crit:
			return 0644;
		default:
			break;
		}

	default:
		break;
	}

	return 0;
}

static int max6621_verify_reg_data(struct device *dev, int regval)
{
	if (regval >= MAX6621_PECI_ERR_MIN &&
	    regval <= MAX6621_PECI_ERR_MAX) {
		dev_dbg(dev, "PECI error code - err 0x%04x.\n",
			regval);

		return -EIO;
	}

	switch (regval) {
	case MAX6621_TRAN_FAILED:
		dev_dbg(dev, "PECI transaction failed - err 0x%04x.\n",
			regval);
		return -EIO;
	case MAX6621_POOL_DIS:
		dev_dbg(dev, "Polling disabled - err 0x%04x.\n", regval);
		return -EOPNOTSUPP;
	case MAX6621_POOL_UNCOMPLETE:
		dev_dbg(dev, "First poll not completed on startup - err 0x%04x.\n",
			regval);
		return -EIO;
	case MAX6621_SD_DIS:
		dev_dbg(dev, "Resource is disabled - err 0x%04x.\n", regval);
		return -EOPNOTSUPP;
	case MAX6621_ALERT_DIS:
		dev_dbg(dev, "No alert active - err 0x%04x.\n", regval);
		return -EOPNOTSUPP;
	default:
		return 0;
	}
}

static int
max6621_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
	     int channel, long *val)
{
	struct max6621_data *data = dev_get_drvdata(dev);
	u32 regval;
	int reg;
	s8 temp;
	int ret;

	switch (type) {
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_input:
			reg = data->input_chan2reg[channel];
			ret = regmap_read(data->regmap, reg, &regval);
			if (ret)
				return ret;

			ret = max6621_verify_reg_data(dev, regval);
			if (ret)
				return ret;

			/*
			 * Bit MAX6621_REG_TEMP_SHIFT represents 1 degree step.
			 * The temperature is given in two's complement and 8
			 * bits is used for the register conversion.
			 */
			temp = (regval >> MAX6621_REG_TEMP_SHIFT);
			*val = temp * 1000L;

			break;
		case hwmon_temp_offset:
			ret = regmap_read(data->regmap, MAX6621_CONFIG2_REG,
					  &regval);
			if (ret)
				return ret;

			ret = max6621_verify_reg_data(dev, regval);
			if (ret)
				return ret;

			*val = (regval >> MAX6621_REG_TEMP_SHIFT) *
			       1000L;

			break;
		case hwmon_temp_crit:
			channel -= MAX6621_TEMP_ALERT_CHAN_SHIFT;
			reg = max6621_temp_alert_chan2reg[channel];
			ret = regmap_read(data->regmap, reg, &regval);
			if (ret)
				return ret;

			ret = max6621_verify_reg_data(dev, regval);
			if (ret)
				return ret;

			*val = regval * 1000L;

			break;
		case hwmon_temp_crit_alarm:
			/*
			 * Set val to zero to recover the case, when reading
			 * MAX6621_TEMP_ALERT_CAUSE_REG results in for example
			 * MAX6621_ALERT_DIS. Reading will return with error,
			 * but in such case alarm should be returned as 0.
			 */
			*val = 0;
			ret = regmap_read(data->regmap,
					  MAX6621_TEMP_ALERT_CAUSE_REG,
					  &regval);
			if (ret)
				return ret;

			ret = max6621_verify_reg_data(dev, regval);
			if (ret) {
				/* Do not report error if alert is disabled. */
				if (regval == MAX6621_ALERT_DIS)
					return 0;
				else
					return ret;
			}

			/*
			 * Clear the alert automatically, using send-byte
			 * smbus protocol for clearing alert.
			 */
			if (regval) {
				ret = i2c_smbus_write_byte(data->client,
						MAX6621_CLEAR_ALERT_REG);
				if (!ret)
					return ret;
			}

			*val = !!regval;

			break;
		default:
			return -EOPNOTSUPP;
		}
		break;

	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int
max6621_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
	      int channel, long val)
{
	struct max6621_data *data = dev_get_drvdata(dev);
	u32 reg;

	switch (type) {
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_offset:
			/* Clamp to allowed range to prevent overflow. */
			val = clamp_val(val, MAX6621_TEMP_INPUT_MIN,
					MAX6621_TEMP_INPUT_MAX);
			val = max6621_temp_mc2reg(val);

			return regmap_write(data->regmap,
					    MAX6621_CONFIG2_REG, val);
		case hwmon_temp_crit:
			channel -= MAX6621_TEMP_ALERT_CHAN_SHIFT;
			reg = max6621_temp_alert_chan2reg[channel];
			/* Clamp to allowed range to prevent overflow. */
			val = clamp_val(val, MAX6621_TEMP_INPUT_MIN,
					MAX6621_TEMP_INPUT_MAX);
			val = val / 1000L;

			return regmap_write(data->regmap, reg, val);
		default:
			return -EOPNOTSUPP;
		}
		break;

	default:
		return -EOPNOTSUPP;
	}

	return -EOPNOTSUPP;
}

static int
max6621_read_string(struct device *dev, enum hwmon_sensor_types type, u32 attr,
		    int channel, const char **str)
{
	switch (type) {
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_label:
			*str = max6621_temp_labels[channel];
			return 0;
		default:
			return -EOPNOTSUPP;
		}
		break;
	default:
		return -EOPNOTSUPP;
	}

	return -EOPNOTSUPP;
}

static bool max6621_writeable_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MAX6621_CONFIG0_REG:
	case MAX6621_CONFIG1_REG:
	case MAX6621_CONFIG2_REG:
	case MAX6621_CONFIG3_REG:
	case MAX6621_TEMP_S0_ALERT_REG:
	case MAX6621_TEMP_S1_ALERT_REG:
	case MAX6621_TEMP_S2_ALERT_REG:
	case MAX6621_TEMP_S3_ALERT_REG:
	case MAX6621_TEMP_ALERT_CAUSE_REG:
		return true;
	}
	return false;
}

static bool max6621_readable_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MAX6621_TEMP_S0D0_REG:
	case MAX6621_TEMP_S0D1_REG:
	case MAX6621_TEMP_S1D0_REG:
	case MAX6621_TEMP_S1D1_REG:
	case MAX6621_TEMP_S2D0_REG:
	case MAX6621_TEMP_S2D1_REG:
	case MAX6621_TEMP_S3D0_REG:
	case MAX6621_TEMP_S3D1_REG:
	case MAX6621_TEMP_MAX_REG:
	case MAX6621_TEMP_MAX_ADDR_REG:
	case MAX6621_CONFIG0_REG:
	case MAX6621_CONFIG1_REG:
	case MAX6621_CONFIG2_REG:
	case MAX6621_CONFIG3_REG:
	case MAX6621_TEMP_S0_ALERT_REG:
	case MAX6621_TEMP_S1_ALERT_REG:
	case MAX6621_TEMP_S2_ALERT_REG:
	case MAX6621_TEMP_S3_ALERT_REG:
		return true;
	}
	return false;
}

static bool max6621_volatile_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MAX6621_TEMP_S0D0_REG:
	case MAX6621_TEMP_S0D1_REG:
	case MAX6621_TEMP_S1D0_REG:
	case MAX6621_TEMP_S1D1_REG:
	case MAX6621_TEMP_S2D0_REG:
	case MAX6621_TEMP_S2D1_REG:
	case MAX6621_TEMP_S3D0_REG:
	case MAX6621_TEMP_S3D1_REG:
	case MAX6621_TEMP_MAX_REG:
	case MAX6621_TEMP_S0_ALERT_REG:
	case MAX6621_TEMP_S1_ALERT_REG:
	case MAX6621_TEMP_S2_ALERT_REG:
	case MAX6621_TEMP_S3_ALERT_REG:
	case MAX6621_TEMP_ALERT_CAUSE_REG:
		return true;
	}
	return false;
}

static const struct reg_default max6621_regmap_default[] = {
	{ MAX6621_CONFIG0_REG, MAX6621_CONFIG0_INIT },
	{ MAX6621_CONFIG1_REG, MAX6621_CONFIG1_INIT },
};

static const struct regmap_config max6621_regmap_config = {
	.reg_bits = 8,
	.val_bits = 16,
	.max_register = MAX6621_REG_MAX,
	.val_format_endian = REGMAP_ENDIAN_LITTLE,
	.cache_type = REGCACHE_FLAT,
	.writeable_reg = max6621_writeable_reg,
	.readable_reg = max6621_readable_reg,
	.volatile_reg = max6621_volatile_reg,
	.reg_defaults = max6621_regmap_default,
	.num_reg_defaults = ARRAY_SIZE(max6621_regmap_default),
};

static u32 max6621_chip_config[] = {
	HWMON_C_REGISTER_TZ,
	0
};

static const struct hwmon_channel_info max6621_chip = {
	.type = hwmon_chip,
	.config = max6621_chip_config,
};

static const u32 max6621_temp_config[] = {
	HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_OFFSET,
	HWMON_T_INPUT | HWMON_T_CRIT | HWMON_T_CRIT_ALARM | HWMON_T_LABEL,
	HWMON_T_INPUT | HWMON_T_CRIT | HWMON_T_CRIT_ALARM | HWMON_T_LABEL,
	HWMON_T_INPUT | HWMON_T_CRIT | HWMON_T_CRIT_ALARM | HWMON_T_LABEL,
	HWMON_T_INPUT | HWMON_T_CRIT | HWMON_T_CRIT_ALARM | HWMON_T_LABEL,
	HWMON_T_INPUT | HWMON_T_LABEL,
	HWMON_T_INPUT | HWMON_T_LABEL,
	HWMON_T_INPUT | HWMON_T_LABEL,
	HWMON_T_INPUT | HWMON_T_LABEL,
	0
};

static const struct hwmon_channel_info max6621_temp = {
	.type = hwmon_temp,
	.config = max6621_temp_config,
};

static const struct hwmon_channel_info *max6621_info[] = {
	&max6621_chip,
	&max6621_temp,
	NULL
};

static const struct hwmon_ops max6621_hwmon_ops = {
	.read = max6621_read,
	.write = max6621_write,
	.read_string = max6621_read_string,
	.is_visible = max6621_is_visible,
};

static const struct hwmon_chip_info max6621_chip_info = {
	.ops = &max6621_hwmon_ops,
	.info = max6621_info,
};

static int max6621_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct device *dev = &client->dev;
	struct max6621_data *data;
	struct device *hwmon_dev;
	int i;
	int ret;

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

	data->regmap = devm_regmap_init_i2c(client, &max6621_regmap_config);
	if (IS_ERR(data->regmap))
		return PTR_ERR(data->regmap);

	i2c_set_clientdata(client, data);
	data->client = client;

	/* Set CONFIG0 register masking temperature alerts and PEC. */
	ret = regmap_write(data->regmap, MAX6621_CONFIG0_REG,
			   MAX6621_CONFIG0_INIT);
	if (ret)
		return ret;

	/* Set CONFIG1 register for PEC access retry number. */
	ret = regmap_write(data->regmap, MAX6621_CONFIG1_REG,
			   MAX6621_CONFIG1_INIT);
	if (ret)
		return ret;

	/* Sync registers with hardware. */
	regcache_mark_dirty(data->regmap);
	ret = regcache_sync(data->regmap);
	if (ret)
		return ret;

	/* Verify which temperature input registers are enabled. */
	for (i = 0; i < MAX6621_TEMP_INPUT_REG_NUM; i++) {
		ret = i2c_smbus_read_word_data(client, max6621_temp_regs[i]);
		if (ret < 0)
			return ret;
		ret = max6621_verify_reg_data(dev, ret);
		if (ret) {
			data->input_chan2reg[i] = -1;
			continue;
		}

		data->input_chan2reg[i] = max6621_temp_regs[i];
	}

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
							 data,
							 &max6621_chip_info,
							 NULL);

	return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id max6621_id[] = {
	{ MAX6621_DRV_NAME, 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, max6621_id);

static const struct of_device_id max6621_of_match[] = {
	{ .compatible = "maxim,max6621" },
	{ }
};
MODULE_DEVICE_TABLE(of, max6621_of_match);

static struct i2c_driver max6621_driver = {
	.class		= I2C_CLASS_HWMON,
	.driver = {
		.name = MAX6621_DRV_NAME,
		.of_match_table = of_match_ptr(max6621_of_match),
	},
	.probe		= max6621_probe,
	.id_table	= max6621_id,
};

module_i2c_driver(max6621_driver);

MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
MODULE_DESCRIPTION("Driver for Maxim MAX6621");
MODULE_LICENSE("GPL");