// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for Texas Instruments INA260 power monitor chip
 * Datasheet: https://www.ti.com/lit/gpn/INA260
 *
 * Copyright (C) 2023 GUEGAN Loic <loic.guegan@mailbox.org>
 */

#include "linux/module.h"
#include "linux/uaccess.h"
#include "linux/i2c.h"
#include "linux/kobject.h"
#include "linux/slab.h"
#include "linux/kernel.h"
#include <linux/sysfs.h>
#include <linux/hwmon.h>
#include <linux/regmap.h>

// INA260 registers
#define INA260_REG_CONFIGURATION 0x00
#define INA260_REG_CURRENT 0x01
#define INA260_REG_VOLTAGE 0x02
#define INA260_REG_POWER 0x03
#define INA260_REG_MASKENABLE 0x06
#define INA260_REG_ALERTLIMIT 0x07
#define INA260_REG_MANUFACTURER 0xFE
#define INA260_REG_DIE 0xFF

static struct regmap_config ina260_regmap_config = {
    .max_register = INA260_REG_DIE,
	.reg_bits = 8,
	.val_bits = 16,
};

#define INA260_REG_SHOW(_attr,_reg) \
static ssize_t _attr##_show(struct device *dev, struct device_attribute *attr, char *buf) \
{ \
    unsigned int rvalue; \
    int err; \
    struct client_data *cdata=dev_get_drvdata(dev); \
    err = regmap_read(cdata->regmap, (_reg), &rvalue); \
    if(err>0) \
        return err; \
    return sprintf(buf, "%x\n", rvalue); \
}

#define INA260_REG_STORE(_attr,_reg) \
static ssize_t _attr##_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) \
{ \
    int uvalue, err; \
    struct client_data *cdata=dev_get_drvdata(dev); \
    if(kstrtoint(buf, 0,&uvalue)) \
        return -EINVAL; \
    err = regmap_write(cdata->regmap, (_reg), uvalue); \
    if(err>0) \
        return err; \
    return count; \
}

/**
 * @brief This macro is not available on old kernel especially the one
 * used by Beaglebones Single Board Computers
 */
#define HWMON_CHANNEL_INFO(stype, ...)	\
	(&(struct hwmon_channel_info) {	\
		.type = hwmon_##stype,	\
		.config = (u32 []) {	\
			__VA_ARGS__, 0	\
		}			\
	})

/**
 * @brief Embedded user data
 */
struct client_data {
    struct i2c_client *client;
    struct regmap *regmap;
};

static int ina260_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
		       u32 attr, int channel, long *val)
{
    int rvalue, reg, err, rem;
    struct client_data *cdata=dev_get_drvdata(dev);
    switch(type){
        case hwmon_power:
            reg=INA260_REG_POWER;
            break;
        case hwmon_curr:
            reg=INA260_REG_CURRENT;
            break;
        case hwmon_in:
            reg=INA260_REG_VOLTAGE;
            break;
        default:
            return -EOPNOTSUPP;
    }
    err=regmap_read(cdata->regmap, reg, &rvalue);
    if(err<0){
        return err;
    } else if(type == hwmon_power) {
        *val=10*rvalue*1000;
    } else{
        *val=div_u64_rem(rvalue*25,100,&rem)+rvalue+div_u64(rem,10);
    }
    return 0;
}

static int ina260_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
		       u32 attr, int channel, long val)
{
    return -EOPNOTSUPP;
}

INA260_REG_SHOW(configuration,INA260_REG_CONFIGURATION)
INA260_REG_SHOW(curr,INA260_REG_CURRENT)
INA260_REG_SHOW(bus_voltage,INA260_REG_VOLTAGE)
INA260_REG_SHOW(power,INA260_REG_POWER)
INA260_REG_SHOW(mask_enable,INA260_REG_MASKENABLE)
INA260_REG_SHOW(alert_limit,INA260_REG_ALERTLIMIT)
INA260_REG_SHOW(manufacturer_id,INA260_REG_MANUFACTURER)
INA260_REG_SHOW(die_id,INA260_REG_DIE)

INA260_REG_STORE(configuration,INA260_REG_CONFIGURATION)
INA260_REG_STORE(curr,INA260_REG_CURRENT)
INA260_REG_STORE(bus_voltage,INA260_REG_VOLTAGE)
INA260_REG_STORE(power,INA260_REG_POWER)
INA260_REG_STORE(mask_enable,INA260_REG_MASKENABLE)
INA260_REG_STORE(alert_limit,INA260_REG_ALERTLIMIT)

static umode_t ina260_hwmon_is_visible(const void *drvdata,
				 enum hwmon_sensor_types type,
				 u32 attr, int channel){
	switch (type) {
	case hwmon_in:
		switch (attr) {
		case hwmon_in_input:
			return 0444;
		default:
			return 0;
		}
	case hwmon_curr:
		switch (attr) {
		case hwmon_curr_input:
			return 0444;
		default:
			return 0;
		}
	case hwmon_power:
		switch (attr) {
		case hwmon_power_input:
			return 0444;
		default:
			return 0;
		}
	default:
		return 0;
	}
}
static const struct hwmon_channel_info *  ina260_hwmon_info[] = {
    HWMON_CHANNEL_INFO(in,HWMON_I_INPUT),
	HWMON_CHANNEL_INFO(power,HWMON_P_INPUT),
    HWMON_CHANNEL_INFO(curr,HWMON_C_INPUT),
	NULL
};
static const struct hwmon_ops ina260_hwmon_ops = {
    .is_visible = ina260_hwmon_is_visible,
	.read = ina260_hwmon_read,
	.write = ina260_hwmon_write,
};

static const struct hwmon_chip_info ina260_chip_info = {
	.ops = &ina260_hwmon_ops,
	.info = ina260_hwmon_info,
};
// ----- Registers -----
static DEVICE_ATTR_RW(configuration);
static DEVICE_ATTR_RW(curr);
static DEVICE_ATTR_RW(bus_voltage);
static DEVICE_ATTR_RW(power);
static DEVICE_ATTR_RW(mask_enable);
static DEVICE_ATTR_RW(alert_limit);
static DEVICE_ATTR_RO(manufacturer_id);
static DEVICE_ATTR_RO(die_id);
static struct attribute *registers_attrs[] = {
    &dev_attr_configuration.attr,
    &dev_attr_curr.attr,
    &dev_attr_bus_voltage.attr,
    &dev_attr_power.attr,
    &dev_attr_mask_enable.attr,
    &dev_attr_alert_limit.attr,
    &dev_attr_manufacturer_id.attr,
    &dev_attr_die_id.attr,
    NULL,   
};
static const struct attribute_group registers_group = {
	.attrs = registers_attrs,
    .name = "registers"
};

const struct attribute_group *extra_groups[] = {
    &registers_group,
    NULL
};

static int ina260_probe_new(struct i2c_client *client){
    struct client_data *p;
    struct device *hwmon_dev;

    // Initialize client data:
    printk("Adding ina260 [bus=%d address=0x%02x]\n",client->adapter->nr,client->addr);
    p=kzalloc(sizeof(struct client_data),GFP_KERNEL);
    p->client=client;
	p->regmap = devm_regmap_init_i2c(client, &ina260_regmap_config);

    hwmon_dev=hwmon_device_register_with_info(&client->dev,client->name,p,
    &ina260_chip_info,extra_groups);
	if (IS_ERR(hwmon_dev))
		return PTR_ERR(hwmon_dev);
    return 0;
}

static int ina260_remove(struct i2c_client *client){
    struct client_data *p=i2c_get_clientdata(client);
    kfree(p);
    hwmon_device_unregister(&client->dev);
    printk("Removing ina260 [bus=%d address=0x%02x]\n",client->adapter->nr,client->addr);
    return 0;
}

static const struct i2c_device_id ina260_ids[] = {
    { "ina260", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c,ina260_ids);

static struct i2c_driver ina260_driver = {
    .class = I2C_CLASS_HWMON,
	.driver = {
		.name = "ina260"
	},
	.probe_new = ina260_probe_new,
	.remove = ina260_remove,
	.id_table = ina260_ids
};

static int __init ina260_init(void){
    i2c_add_driver(&ina260_driver);
    return 0;
}

static void __exit ina260_exit(void){
    i2c_del_driver(&ina260_driver);
}

module_init(ina260_init);
module_exit(ina260_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Loïc Guegan");
MODULE_DESCRIPTION("INA260 Texas Instruments");
MODULE_VERSION("1.0");