// SPDX-License-Identifier: GPL-2.0-or-later

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pmbus.h>
#include "pmbus.h"

/* LTC4286 register */
#define LTC4286_MFR_CONFIG1	0xF2

/* LTC4286 configuration */
#define VRANGE_SELECT_BIT	BIT(1)

#define LTC4286_MFR_ID_SIZE	3

/*
 * Initialize the MBR as default settings which is referred to LTC4286 datasheet
 * (March 22, 2022 version) table 3 page 16
 */
static struct pmbus_driver_info ltc4286_info = {
	.pages = 1,
	.format[PSC_VOLTAGE_IN] = direct,
	.format[PSC_VOLTAGE_OUT] = direct,
	.format[PSC_CURRENT_OUT] = direct,
	.format[PSC_POWER] = direct,
	.format[PSC_TEMPERATURE] = direct,
	.m[PSC_VOLTAGE_IN] = 32,
	.b[PSC_VOLTAGE_IN] = 0,
	.R[PSC_VOLTAGE_IN] = 1,
	.m[PSC_VOLTAGE_OUT] = 32,
	.b[PSC_VOLTAGE_OUT] = 0,
	.R[PSC_VOLTAGE_OUT] = 1,
	.m[PSC_CURRENT_OUT] = 1024,
	.b[PSC_CURRENT_OUT] = 0,
	/*
	 * The rsense value used in MBR formula in LTC4286 datasheet should be ohm unit.
	 * However, the rsense value that user input is micro ohm.
	 * Thus, the MBR setting which involves rsense should be shifted by 6 digits.
	 */
	.R[PSC_CURRENT_OUT] = 3 - 6,
	.m[PSC_POWER] = 1,
	.b[PSC_POWER] = 0,
	/*
	 * The rsense value used in MBR formula in LTC4286 datasheet should be ohm unit.
	 * However, the rsense value that user input is micro ohm.
	 * Thus, the MBR setting which involves rsense should be shifted by 6 digits.
	 */
	.R[PSC_POWER] = 4 - 6,
	.m[PSC_TEMPERATURE] = 1,
	.b[PSC_TEMPERATURE] = 273,
	.R[PSC_TEMPERATURE] = 0,
	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
		   PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_VOUT |
		   PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_STATUS_TEMP,
};

static const struct i2c_device_id ltc4286_id[] = {
	{ "ltc4286", 0 },
	{ "ltc4287", 1 },
	{}
};
MODULE_DEVICE_TABLE(i2c, ltc4286_id);

static int ltc4286_probe(struct i2c_client *client)
{
	int ret;
	const struct i2c_device_id *mid;
	u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
	struct pmbus_driver_info *info;
	u32 rsense;
	int vrange_nval, vrange_oval;

	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);
	if (ret < 0) {
		return dev_err_probe(&client->dev, ret,
				     "Failed to read manufacturer id\n");
	}

	/*
	 * Refer to ltc4286 datasheet page 20
	 * the manufacturer id is LTC
	 */
	if (ret != LTC4286_MFR_ID_SIZE ||
	    strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
		return dev_err_probe(&client->dev, -ENODEV,
				     "Manufacturer id mismatch\n");
	}

	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
	if (ret < 0) {
		return dev_err_probe(&client->dev, ret,
				     "Failed to read manufacturer model\n");
	}

	for (mid = ltc4286_id; mid->name[0]; mid++) {
		if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))
			break;
	}
	if (!mid->name[0])
		return dev_err_probe(&client->dev, -ENODEV,
				     "Unsupported device\n");

	if (of_property_read_u32(client->dev.of_node,
				 "shunt-resistor-micro-ohms", &rsense))
		rsense = 300; /* 0.3 mOhm if not set via DT */

	if (rsense == 0)
		return -EINVAL;

	/* Check for the latter MBR value won't overflow */
	if (rsense > (INT_MAX / 1024))
		return -EINVAL;

	info = devm_kmemdup(&client->dev, &ltc4286_info, sizeof(*info),
			    GFP_KERNEL);
	if (!info)
		return -ENOMEM;

	/* Check MFR1 CONFIG register bit 1 VRANGE_SELECT before driver loading */
	vrange_oval = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);
	if (vrange_oval < 0)
		return dev_err_probe(&client->dev, vrange_oval,
				     "Failed to read manufacturer configuration one\n");
	vrange_nval = vrange_oval;

	if (device_property_read_bool(&client->dev, "adi,vrange-low-enable")) {
		vrange_nval &=
			~VRANGE_SELECT_BIT; /* VRANGE_SELECT = 0, 25.6 volts */

		info->m[PSC_VOLTAGE_IN] = 128;
		info->m[PSC_VOLTAGE_OUT] = 128;
		info->m[PSC_POWER] = 4 * rsense;
	} else {
		vrange_nval |=
			VRANGE_SELECT_BIT; /* VRANGE_SELECT = 1, 102.4 volts */

		info->m[PSC_POWER] = rsense;
	}
	if (vrange_nval != vrange_oval) {
		/* Set MFR1 CONFIG register bit 1 VRANGE_SELECT */
		ret = i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1,
						vrange_nval);
		if (ret < 0)
			return dev_err_probe(&client->dev, ret,
					     "Failed to set vrange\n");
	}

	info->m[PSC_CURRENT_OUT] = 1024 * rsense;

	return pmbus_do_probe(client, info);
}

static const struct of_device_id ltc4286_of_match[] = {
	{ .compatible = "lltc,ltc4286" },
	{ .compatible = "lltc,ltc4287" },
	{}
};

static struct i2c_driver ltc4286_driver = {
	.driver = {
		.name = "ltc4286",
		.of_match_table = ltc4286_of_match,
	},
	.probe = ltc4286_probe,
	.id_table = ltc4286_id,
};

module_i2c_driver(ltc4286_driver);

MODULE_AUTHOR("Delphine CC Chiu <Delphine_CC_Chiu@wiwynn.com>");
MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
MODULE_LICENSE("GPL");