// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
 * (C) 2007 EADS Astrium
 *
 * This driver is based on the lm75 and other lm_sensors/hwmon drivers
 *
 * Written by Steve Hardy <shardy@redhat.com>
 *
 * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
 *
 * For further information, see the Documentation/hwmon/ads7828.rst file.
 */

#include <linux/err.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.h>
#include <linux/platform_data/ads7828.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/regulator/consumer.h>

/* The ADS7828 registers */
#define ADS7828_CMD_SD_SE       0x80    /* Single ended inputs */
#define ADS7828_CMD_PD1         0x04    /* Internal vref OFF && A/D ON */
#define ADS7828_CMD_PD3         0x0C    /* Internal vref ON && A/D ON */
#define ADS7828_INT_VREF_MV     2500    /* Internal vref is 2.5V, 2500mV */
#define ADS7828_EXT_VREF_MV_MIN 50      /* External vref min value 0.05V */
#define ADS7828_EXT_VREF_MV_MAX 5250    /* External vref max value 5.25V */

/* List of supported devices */
enum ads7828_chips { ads7828, ads7830 };

/* Client specific data */
struct ads7828_data {
        struct regmap *regmap;
        u8 cmd_byte;                    /* Command byte without channel bits */
        unsigned int lsb_resol;         /* Resolution of the ADC sample LSB */
};

/* Command byte C2,C1,C0 - see datasheet */
static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
{
        return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
}

/* sysfs callback function */
static ssize_t ads7828_in_show(struct device *dev,
                               struct device_attribute *da, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct ads7828_data *data = dev_get_drvdata(dev);
        u8 cmd = ads7828_cmd_byte(data->cmd_byte, attr->index);
        unsigned int regval;
        int err;

        err = regmap_read(data->regmap, cmd, &regval);
        if (err < 0)
                return err;

        return sprintf(buf, "%d\n",
                       DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000));
}

static SENSOR_DEVICE_ATTR_RO(in0_input, ads7828_in, 0);
static SENSOR_DEVICE_ATTR_RO(in1_input, ads7828_in, 1);
static SENSOR_DEVICE_ATTR_RO(in2_input, ads7828_in, 2);
static SENSOR_DEVICE_ATTR_RO(in3_input, ads7828_in, 3);
static SENSOR_DEVICE_ATTR_RO(in4_input, ads7828_in, 4);
static SENSOR_DEVICE_ATTR_RO(in5_input, ads7828_in, 5);
static SENSOR_DEVICE_ATTR_RO(in6_input, ads7828_in, 6);
static SENSOR_DEVICE_ATTR_RO(in7_input, ads7828_in, 7);

static struct attribute *ads7828_attrs[] = {
        &sensor_dev_attr_in0_input.dev_attr.attr,
        &sensor_dev_attr_in1_input.dev_attr.attr,
        &sensor_dev_attr_in2_input.dev_attr.attr,
        &sensor_dev_attr_in3_input.dev_attr.attr,
        &sensor_dev_attr_in4_input.dev_attr.attr,
        &sensor_dev_attr_in5_input.dev_attr.attr,
        &sensor_dev_attr_in6_input.dev_attr.attr,
        &sensor_dev_attr_in7_input.dev_attr.attr,
        NULL
};

ATTRIBUTE_GROUPS(ads7828);

static const struct regmap_config ads2828_regmap_config = {
        .reg_bits = 8,
        .val_bits = 16,
};

static const struct regmap_config ads2830_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
};

static int ads7828_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct ads7828_platform_data *pdata = dev_get_platdata(dev);
        struct ads7828_data *data;
        struct device *hwmon_dev;
        unsigned int vref_mv = ADS7828_INT_VREF_MV;
        unsigned int vref_uv;
        bool diff_input = false;
        bool ext_vref = false;
        unsigned int regval;
        enum ads7828_chips chip;
        struct regulator *reg;

        data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        if (pdata) {
                diff_input = pdata->diff_input;
                ext_vref = pdata->ext_vref;
                if (ext_vref && pdata->vref_mv)
                        vref_mv = pdata->vref_mv;
        } else if (dev->of_node) {
                diff_input = of_property_read_bool(dev->of_node,
                                                   "ti,differential-input");
                reg = devm_regulator_get_optional(dev, "vref");
                if (!IS_ERR(reg)) {
                        vref_uv = regulator_get_voltage(reg);
                        vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
                        if (vref_mv < ADS7828_EXT_VREF_MV_MIN ||
                            vref_mv > ADS7828_EXT_VREF_MV_MAX)
                                return -EINVAL;
                        ext_vref = true;
                }
        }

        chip = (uintptr_t)i2c_get_match_data(client);

        /* Bound Vref with min/max values */
        vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
                            ADS7828_EXT_VREF_MV_MAX);

        /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
        if (chip == ads7828) {
                data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 4096);
                data->regmap = devm_regmap_init_i2c(client,
                                                    &ads2828_regmap_config);
        } else {
                data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 256);
                data->regmap = devm_regmap_init_i2c(client,
                                                    &ads2830_regmap_config);
        }

        if (IS_ERR(data->regmap))
                return PTR_ERR(data->regmap);

        data->cmd_byte = ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
        if (!diff_input)
                data->cmd_byte |= ADS7828_CMD_SD_SE;

        /*
         * Datasheet specifies internal reference voltage is disabled by
         * default. The internal reference voltage needs to be enabled and
         * voltage needs to settle before getting valid ADC data. So perform a
         * dummy read to enable the internal reference voltage.
         */
        if (!ext_vref)
                regmap_read(data->regmap, data->cmd_byte, &regval);

        hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
                                                           data,
                                                           ads7828_groups);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id ads7828_device_ids[] = {
        { "ads7828", ads7828 },
        { "ads7830", ads7830 },
        { }
};
MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);

static const struct of_device_id __maybe_unused ads7828_of_match[] = {
        {
                .compatible = "ti,ads7828",
                .data = (void *)ads7828
        },
        {
                .compatible = "ti,ads7830",
                .data = (void *)ads7830
        },
        { },
};
MODULE_DEVICE_TABLE(of, ads7828_of_match);

static struct i2c_driver ads7828_driver = {
        .driver = {
                .name = "ads7828",
                .of_match_table = of_match_ptr(ads7828_of_match),
        },

        .id_table = ads7828_device_ids,
        .probe = ads7828_probe,
};

module_i2c_driver(ads7828_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");