// SPDX-License-Identifier: GPL-2.0
/*
 * A driver for the I2C members of the Abracon AB x8xx RTC family,
 * and compatible: AB 1805 and AB 0805
 *
 * Copyright 2014-2015 Macq S.A.
 *
 * Author: Philippe De Muyter <phdm@macqel.be>
 * Author: Alexandre Belloni <alexandre.belloni@bootlin.com>
 *
 */

#include <linux/bcd.h>
#include <linux/bitfield.h>
#include <linux/i2c.h>
#include <linux/kstrtox.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/rtc.h>
#include <linux/watchdog.h>

#define ABX8XX_REG_HTH          0x00
#define ABX8XX_REG_SC           0x01
#define ABX8XX_REG_MN           0x02
#define ABX8XX_REG_HR           0x03
#define ABX8XX_REG_DA           0x04
#define ABX8XX_REG_MO           0x05
#define ABX8XX_REG_YR           0x06
#define ABX8XX_REG_WD           0x07

#define ABX8XX_REG_AHTH         0x08
#define ABX8XX_REG_ASC          0x09
#define ABX8XX_REG_AMN          0x0a
#define ABX8XX_REG_AHR          0x0b
#define ABX8XX_REG_ADA          0x0c
#define ABX8XX_REG_AMO          0x0d
#define ABX8XX_REG_AWD          0x0e

#define ABX8XX_REG_STATUS       0x0f
#define ABX8XX_STATUS_AF        BIT(2)
#define ABX8XX_STATUS_BLF       BIT(4)
#define ABX8XX_STATUS_WDT       BIT(5)

#define ABX8XX_REG_CTRL1        0x10
#define ABX8XX_CTRL_WRITE       BIT(0)
#define ABX8XX_CTRL_ARST        BIT(2)
#define ABX8XX_CTRL_12_24       BIT(6)

#define ABX8XX_REG_CTRL2        0x11
#define ABX8XX_CTRL2_RSVD       BIT(5)

#define ABX8XX_REG_IRQ          0x12
#define ABX8XX_IRQ_AIE          BIT(2)
#define ABX8XX_IRQ_IM_1_4       (0x3 << 5)

#define ABX8XX_REG_CD_TIMER_CTL 0x18

#define ABX8XX_REG_OSC          0x1c
#define ABX8XX_OSC_FOS          BIT(3)
#define ABX8XX_OSC_BOS          BIT(4)
#define ABX8XX_OSC_ACAL_512     BIT(5)
#define ABX8XX_OSC_ACAL_1024    BIT(6)

#define ABX8XX_OSC_OSEL         BIT(7)

#define ABX8XX_REG_OSS          0x1d
#define ABX8XX_OSS_OF           BIT(1)
#define ABX8XX_OSS_OMODE        BIT(4)

#define ABX8XX_REG_WDT          0x1b
#define ABX8XX_WDT_WDS          BIT(7)
#define ABX8XX_WDT_BMB_MASK     0x7c
#define ABX8XX_WDT_BMB_SHIFT    2
#define ABX8XX_WDT_MAX_TIME     (ABX8XX_WDT_BMB_MASK >> ABX8XX_WDT_BMB_SHIFT)
#define ABX8XX_WDT_WRB_MASK     0x03
#define ABX8XX_WDT_WRB_1HZ      0x02

#define ABX8XX_REG_CFG_KEY      0x1f
#define ABX8XX_CFG_KEY_OSC      0xa1
#define ABX8XX_CFG_KEY_MISC     0x9d

#define ABX8XX_REG_ID0          0x28

#define ABX8XX_REG_OUT_CTRL     0x30
#define ABX8XX_OUT_CTRL_EXDS    BIT(4)

#define ABX8XX_REG_TRICKLE      0x20
#define ABX8XX_TRICKLE_CHARGE_ENABLE    0xa0
#define ABX8XX_TRICKLE_STANDARD_DIODE   0x8
#define ABX8XX_TRICKLE_SCHOTTKY_DIODE   0x4

#define ABX8XX_REG_EXTRAM       0x3f
#define ABX8XX_EXTRAM_XADS      GENMASK(1, 0)

#define ABX8XX_SRAM_BASE        0x40
#define ABX8XX_SRAM_WIN_SIZE    0x40
#define ABX8XX_RAM_SIZE         256

#define NVMEM_ADDR_LOWER        GENMASK(5, 0)
#define NVMEM_ADDR_UPPER        GENMASK(7, 6)

static u8 trickle_resistors[] = {0, 3, 6, 11};

enum abx80x_chip {AB0801, AB0803, AB0804, AB0805,
        AB1801, AB1803, AB1804, AB1805, RV1805, ABX80X};

struct abx80x_cap {
        u16 pn;
        bool has_tc;
        bool has_wdog;
};

static struct abx80x_cap abx80x_caps[] = {
        [AB0801] = {.pn = 0x0801},
        [AB0803] = {.pn = 0x0803},
        [AB0804] = {.pn = 0x0804, .has_tc = true, .has_wdog = true},
        [AB0805] = {.pn = 0x0805, .has_tc = true, .has_wdog = true},
        [AB1801] = {.pn = 0x1801},
        [AB1803] = {.pn = 0x1803},
        [AB1804] = {.pn = 0x1804, .has_tc = true, .has_wdog = true},
        [AB1805] = {.pn = 0x1805, .has_tc = true, .has_wdog = true},
        [RV1805] = {.pn = 0x1805, .has_tc = true, .has_wdog = true},
        [ABX80X] = {.pn = 0}
};

struct abx80x_priv {
        struct rtc_device *rtc;
        struct i2c_client *client;
        struct watchdog_device wdog;
};

static int abx80x_write_config_key(struct i2c_client *client, u8 key)
{
        if (i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY, key) < 0) {
                dev_err(&client->dev, "Unable to write configuration key\n");
                return -EIO;
        }

        return 0;
}

static int abx80x_is_rc_mode(struct i2c_client *client)
{
        int flags = 0;

        flags =  i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);
        if (flags < 0) {
                dev_err(&client->dev,
                        "Failed to read autocalibration attribute\n");
                return flags;
        }

        return (flags & ABX8XX_OSS_OMODE) ? 1 : 0;
}

static int abx80x_enable_trickle_charger(struct i2c_client *client,
                                         u8 trickle_cfg)
{
        int err;

        /*
         * Write the configuration key register to enable access to the Trickle
         * register
         */
        if (abx80x_write_config_key(client, ABX8XX_CFG_KEY_MISC) < 0)
                return -EIO;

        err = i2c_smbus_write_byte_data(client, ABX8XX_REG_TRICKLE,
                                        ABX8XX_TRICKLE_CHARGE_ENABLE |
                                        trickle_cfg);
        if (err < 0) {
                dev_err(&client->dev, "Unable to write trickle register\n");
                return -EIO;
        }

        return 0;
}

static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        unsigned char buf[8];
        int err, flags, rc_mode = 0;

        /* Read the Oscillator Failure only in XT mode */
        rc_mode = abx80x_is_rc_mode(client);
        if (rc_mode < 0)
                return rc_mode;

        if (!rc_mode) {
                flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);
                if (flags < 0)
                        return flags;

                if (flags & ABX8XX_OSS_OF) {
                        dev_err(dev, "Oscillator failure, data is invalid.\n");
                        return -EINVAL;
                }
        }

        err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_HTH,
                                            sizeof(buf), buf);
        if (err < 0) {
                dev_err(&client->dev, "Unable to read date\n");
                return -EIO;
        }

        tm->tm_sec = bcd2bin(buf[ABX8XX_REG_SC] & 0x7F);
        tm->tm_min = bcd2bin(buf[ABX8XX_REG_MN] & 0x7F);
        tm->tm_hour = bcd2bin(buf[ABX8XX_REG_HR] & 0x3F);
        tm->tm_wday = buf[ABX8XX_REG_WD] & 0x7;
        tm->tm_mday = bcd2bin(buf[ABX8XX_REG_DA] & 0x3F);
        tm->tm_mon = bcd2bin(buf[ABX8XX_REG_MO] & 0x1F) - 1;
        tm->tm_year = bcd2bin(buf[ABX8XX_REG_YR]) + 100;

        return 0;
}

static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        unsigned char buf[8];
        int err, flags;

        if (tm->tm_year < 100)
                return -EINVAL;

        buf[ABX8XX_REG_HTH] = 0;
        buf[ABX8XX_REG_SC] = bin2bcd(tm->tm_sec);
        buf[ABX8XX_REG_MN] = bin2bcd(tm->tm_min);
        buf[ABX8XX_REG_HR] = bin2bcd(tm->tm_hour);
        buf[ABX8XX_REG_DA] = bin2bcd(tm->tm_mday);
        buf[ABX8XX_REG_MO] = bin2bcd(tm->tm_mon + 1);
        buf[ABX8XX_REG_YR] = bin2bcd(tm->tm_year - 100);
        buf[ABX8XX_REG_WD] = tm->tm_wday;

        err = i2c_smbus_write_i2c_block_data(client, ABX8XX_REG_HTH,
                                             sizeof(buf), buf);
        if (err < 0) {
                dev_err(&client->dev, "Unable to write to date registers\n");
                return -EIO;
        }

        /* Clear the OF bit of Oscillator Status Register */
        flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);
        if (flags < 0)
                return flags;

        err = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSS,
                                        flags & ~ABX8XX_OSS_OF);
        if (err < 0) {
                dev_err(&client->dev, "Unable to write oscillator status register\n");
                return err;
        }

        return 0;
}

static irqreturn_t abx80x_handle_irq(int irq, void *dev_id)
{
        struct i2c_client *client = dev_id;
        struct abx80x_priv *priv = i2c_get_clientdata(client);
        struct rtc_device *rtc = priv->rtc;
        int status;

        status = i2c_smbus_read_byte_data(client, ABX8XX_REG_STATUS);
        if (status < 0)
                return IRQ_NONE;

        if (status & ABX8XX_STATUS_AF)
                rtc_update_irq(rtc, 1, RTC_AF | RTC_IRQF);

        /*
         * It is unclear if we'll get an interrupt before the external
         * reset kicks in.
         */
        if (status & ABX8XX_STATUS_WDT)
                dev_alert(&client->dev, "watchdog timeout interrupt.\n");

        i2c_smbus_write_byte_data(client, ABX8XX_REG_STATUS, 0);

        return IRQ_HANDLED;
}

static int abx80x_read_alarm(struct device *dev, struct rtc_wkalrm *t)
{
        struct i2c_client *client = to_i2c_client(dev);
        unsigned char buf[7];

        int irq_mask, err;

        if (client->irq <= 0)
                return -EINVAL;

        err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_ASC,
                                            sizeof(buf), buf);
        if (err)
                return err;

        irq_mask = i2c_smbus_read_byte_data(client, ABX8XX_REG_IRQ);
        if (irq_mask < 0)
                return irq_mask;

        t->time.tm_sec = bcd2bin(buf[0] & 0x7F);
        t->time.tm_min = bcd2bin(buf[1] & 0x7F);
        t->time.tm_hour = bcd2bin(buf[2] & 0x3F);
        t->time.tm_mday = bcd2bin(buf[3] & 0x3F);
        t->time.tm_mon = bcd2bin(buf[4] & 0x1F) - 1;
        t->time.tm_wday = buf[5] & 0x7;

        t->enabled = !!(irq_mask & ABX8XX_IRQ_AIE);
        t->pending = (buf[6] & ABX8XX_STATUS_AF) && t->enabled;

        return err;
}

static int abx80x_set_alarm(struct device *dev, struct rtc_wkalrm *t)
{
        struct i2c_client *client = to_i2c_client(dev);
        u8 alarm[6];
        int err;

        if (client->irq <= 0)
                return -EINVAL;

        alarm[0] = 0x0;
        alarm[1] = bin2bcd(t->time.tm_sec);
        alarm[2] = bin2bcd(t->time.tm_min);
        alarm[3] = bin2bcd(t->time.tm_hour);
        alarm[4] = bin2bcd(t->time.tm_mday);
        alarm[5] = bin2bcd(t->time.tm_mon + 1);

        err = i2c_smbus_write_i2c_block_data(client, ABX8XX_REG_AHTH,
                                             sizeof(alarm), alarm);
        if (err < 0) {
                dev_err(&client->dev, "Unable to write alarm registers\n");
                return -EIO;
        }

        if (t->enabled) {
                err = i2c_smbus_write_byte_data(client, ABX8XX_REG_IRQ,
                                                (ABX8XX_IRQ_IM_1_4 |
                                                 ABX8XX_IRQ_AIE));
                if (err)
                        return err;
        }

        return 0;
}

static int abx80x_rtc_set_autocalibration(struct device *dev,
                                          int autocalibration)
{
        struct i2c_client *client = to_i2c_client(dev);
        int retval, flags = 0;

        if ((autocalibration != 0) && (autocalibration != 1024) &&
            (autocalibration != 512)) {
                dev_err(dev, "autocalibration value outside permitted range\n");
                return -EINVAL;
        }

        flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);
        if (flags < 0)
                return flags;

        if (autocalibration == 0) {
                flags &= ~(ABX8XX_OSC_ACAL_512 | ABX8XX_OSC_ACAL_1024);
        } else if (autocalibration == 1024) {
                /* 1024 autocalibration is 0x10 */
                flags |= ABX8XX_OSC_ACAL_1024;
                flags &= ~(ABX8XX_OSC_ACAL_512);
        } else {
                /* 512 autocalibration is 0x11 */
                flags |= (ABX8XX_OSC_ACAL_1024 | ABX8XX_OSC_ACAL_512);
        }

        /* Unlock write access to Oscillator Control Register */
        if (abx80x_write_config_key(client, ABX8XX_CFG_KEY_OSC) < 0)
                return -EIO;

        retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSC, flags);

        return retval;
}

static int abx80x_rtc_get_autocalibration(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        int flags = 0, autocalibration;

        flags =  i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);
        if (flags < 0)
                return flags;

        if (flags & ABX8XX_OSC_ACAL_512)
                autocalibration = 512;
        else if (flags & ABX8XX_OSC_ACAL_1024)
                autocalibration = 1024;
        else
                autocalibration = 0;

        return autocalibration;
}

static ssize_t autocalibration_store(struct device *dev,
                                     struct device_attribute *attr,
                                     const char *buf, size_t count)
{
        int retval;
        unsigned long autocalibration = 0;

        retval = kstrtoul(buf, 10, &autocalibration);
        if (retval < 0) {
                dev_err(dev, "Failed to store RTC autocalibration attribute\n");
                return -EINVAL;
        }

        retval = abx80x_rtc_set_autocalibration(dev->parent, autocalibration);

        return retval ? retval : count;
}

static ssize_t autocalibration_show(struct device *dev,
                                    struct device_attribute *attr, char *buf)
{
        int autocalibration = 0;

        autocalibration = abx80x_rtc_get_autocalibration(dev->parent);
        if (autocalibration < 0) {
                dev_err(dev, "Failed to read RTC autocalibration\n");
                sprintf(buf, "0\n");
                return autocalibration;
        }

        return sprintf(buf, "%d\n", autocalibration);
}

static DEVICE_ATTR_RW(autocalibration);

static ssize_t oscillator_store(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct i2c_client *client = to_i2c_client(dev->parent);
        int retval, flags, rc_mode = 0;

        if (strncmp(buf, "rc", 2) == 0) {
                rc_mode = 1;
        } else if (strncmp(buf, "xtal", 4) == 0) {
                rc_mode = 0;
        } else {
                dev_err(dev, "Oscillator selection value outside permitted ones\n");
                return -EINVAL;
        }

        flags =  i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);
        if (flags < 0)
                return flags;

        if (rc_mode == 0)
                flags &= ~(ABX8XX_OSC_OSEL);
        else
                flags |= (ABX8XX_OSC_OSEL);

        /* Unlock write access on Oscillator Control register */
        if (abx80x_write_config_key(client, ABX8XX_CFG_KEY_OSC) < 0)
                return -EIO;

        retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSC, flags);
        if (retval < 0) {
                dev_err(dev, "Failed to write Oscillator Control register\n");
                return retval;
        }

        return retval ? retval : count;
}

static ssize_t oscillator_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        int rc_mode = 0;
        struct i2c_client *client = to_i2c_client(dev->parent);

        rc_mode = abx80x_is_rc_mode(client);

        if (rc_mode < 0) {
                dev_err(dev, "Failed to read RTC oscillator selection\n");
                sprintf(buf, "\n");
                return rc_mode;
        }

        if (rc_mode)
                return sprintf(buf, "rc\n");
        else
                return sprintf(buf, "xtal\n");
}

static DEVICE_ATTR_RW(oscillator);

static struct attribute *rtc_calib_attrs[] = {
        &dev_attr_autocalibration.attr,
        &dev_attr_oscillator.attr,
        NULL,
};

static const struct attribute_group rtc_calib_attr_group = {
        .attrs          = rtc_calib_attrs,
};

static int abx80x_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct i2c_client *client = to_i2c_client(dev);
        int err;

        if (enabled)
                err = i2c_smbus_write_byte_data(client, ABX8XX_REG_IRQ,
                                                (ABX8XX_IRQ_IM_1_4 |
                                                 ABX8XX_IRQ_AIE));
        else
                err = i2c_smbus_write_byte_data(client, ABX8XX_REG_IRQ,
                                                ABX8XX_IRQ_IM_1_4);
        return err;
}

static int abx80x_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
        struct i2c_client *client = to_i2c_client(dev);
        int status, tmp;

        switch (cmd) {
        case RTC_VL_READ:
                status = i2c_smbus_read_byte_data(client, ABX8XX_REG_STATUS);
                if (status < 0)
                        return status;

                tmp = status & ABX8XX_STATUS_BLF ? RTC_VL_BACKUP_LOW : 0;

                return put_user(tmp, (unsigned int __user *)arg);

        case RTC_VL_CLR:
                status = i2c_smbus_read_byte_data(client, ABX8XX_REG_STATUS);
                if (status < 0)
                        return status;

                status &= ~ABX8XX_STATUS_BLF;

                tmp = i2c_smbus_write_byte_data(client, ABX8XX_REG_STATUS, 0);
                if (tmp < 0)
                        return tmp;

                return 0;

        default:
                return -ENOIOCTLCMD;
        }
}

static const struct rtc_class_ops abx80x_rtc_ops = {
        .read_time      = abx80x_rtc_read_time,
        .set_time       = abx80x_rtc_set_time,
        .read_alarm     = abx80x_read_alarm,
        .set_alarm      = abx80x_set_alarm,
        .alarm_irq_enable = abx80x_alarm_irq_enable,
        .ioctl          = abx80x_ioctl,
};

static int abx80x_dt_trickle_cfg(struct i2c_client *client)
{
        struct device_node *np = client->dev.of_node;
        const char *diode;
        int trickle_cfg = 0;
        int i, ret;
        u32 tmp;

        ret = of_property_read_string(np, "abracon,tc-diode", &diode);
        if (ret)
                return ret;

        if (!strcmp(diode, "standard")) {
                trickle_cfg |= ABX8XX_TRICKLE_STANDARD_DIODE;
        } else if (!strcmp(diode, "schottky")) {
                trickle_cfg |= ABX8XX_TRICKLE_SCHOTTKY_DIODE;
        } else {
                dev_dbg(&client->dev, "Invalid tc-diode value: %s\n", diode);
                return -EINVAL;
        }

        ret = of_property_read_u32(np, "abracon,tc-resistor", &tmp);
        if (ret)
                return ret;

        for (i = 0; i < sizeof(trickle_resistors); i++)
                if (trickle_resistors[i] == tmp)
                        break;

        if (i == sizeof(trickle_resistors)) {
                dev_dbg(&client->dev, "Invalid tc-resistor value: %u\n", tmp);
                return -EINVAL;
        }

        return (trickle_cfg | i);
}

#ifdef CONFIG_WATCHDOG

static inline u8 timeout_bits(unsigned int timeout)
{
        return ((timeout << ABX8XX_WDT_BMB_SHIFT) & ABX8XX_WDT_BMB_MASK) |
                 ABX8XX_WDT_WRB_1HZ;
}

static int __abx80x_wdog_set_timeout(struct watchdog_device *wdog,
                                     unsigned int timeout)
{
        struct abx80x_priv *priv = watchdog_get_drvdata(wdog);
        u8 val = ABX8XX_WDT_WDS | timeout_bits(timeout);

        /*
         * Writing any timeout to the WDT register resets the watchdog timer.
         * Writing 0 disables it.
         */
        return i2c_smbus_write_byte_data(priv->client, ABX8XX_REG_WDT, val);
}

static int abx80x_wdog_set_timeout(struct watchdog_device *wdog,
                                   unsigned int new_timeout)
{
        int err = 0;

        if (watchdog_hw_running(wdog))
                err = __abx80x_wdog_set_timeout(wdog, new_timeout);

        if (err == 0)
                wdog->timeout = new_timeout;

        return err;
}

static int abx80x_wdog_ping(struct watchdog_device *wdog)
{
        return __abx80x_wdog_set_timeout(wdog, wdog->timeout);
}

static int abx80x_wdog_start(struct watchdog_device *wdog)
{
        return __abx80x_wdog_set_timeout(wdog, wdog->timeout);
}

static int abx80x_wdog_stop(struct watchdog_device *wdog)
{
        return __abx80x_wdog_set_timeout(wdog, 0);
}

static const struct watchdog_info abx80x_wdog_info = {
        .identity = "abx80x watchdog",
        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
};

static const struct watchdog_ops abx80x_wdog_ops = {
        .owner = THIS_MODULE,
        .start = abx80x_wdog_start,
        .stop = abx80x_wdog_stop,
        .ping = abx80x_wdog_ping,
        .set_timeout = abx80x_wdog_set_timeout,
};

static int abx80x_setup_watchdog(struct abx80x_priv *priv)
{
        priv->wdog.parent = &priv->client->dev;
        priv->wdog.ops = &abx80x_wdog_ops;
        priv->wdog.info = &abx80x_wdog_info;
        priv->wdog.min_timeout = 1;
        priv->wdog.max_timeout = ABX8XX_WDT_MAX_TIME;
        priv->wdog.timeout = ABX8XX_WDT_MAX_TIME;

        watchdog_set_drvdata(&priv->wdog, priv);

        return devm_watchdog_register_device(&priv->client->dev, &priv->wdog);
}
#else
static int abx80x_setup_watchdog(struct abx80x_priv *priv)
{
        return 0;
}
#endif

static int abx80x_nvmem_xfer(struct abx80x_priv *priv, unsigned int offset,
                             void *val, size_t bytes, bool write)
{
        int ret;

        while (bytes) {
                u8 extram, reg, len, lower, upper;

                lower = FIELD_GET(NVMEM_ADDR_LOWER, offset);
                upper = FIELD_GET(NVMEM_ADDR_UPPER, offset);
                extram = FIELD_PREP(ABX8XX_EXTRAM_XADS, upper);
                reg = ABX8XX_SRAM_BASE + lower;
                len = min(lower + bytes, (size_t)ABX8XX_SRAM_WIN_SIZE) - lower;
                len = min_t(u8, len, I2C_SMBUS_BLOCK_MAX);

                ret = i2c_smbus_write_byte_data(priv->client, ABX8XX_REG_EXTRAM,
                                                extram);
                if (ret)
                        return ret;

                if (write) {
                        ret = i2c_smbus_write_i2c_block_data(priv->client, reg,
                                                             len, val);
                        if (ret)
                                return ret;
                } else {
                        ret = i2c_smbus_read_i2c_block_data(priv->client, reg,
                                                            len, val);
                        if (ret <= 0)
                                return ret ? ret : -EIO;
                        len = ret;
                }

                offset += len;
                val += len;
                bytes -= len;
        }

        return 0;
}

static int abx80x_nvmem_read(void *priv, unsigned int offset, void *val,
                             size_t bytes)
{
        return abx80x_nvmem_xfer(priv, offset, val, bytes, false);
}

static int abx80x_nvmem_write(void *priv, unsigned int offset, void *val,
                              size_t bytes)
{
        return abx80x_nvmem_xfer(priv, offset, val, bytes, true);
}

static int abx80x_setup_nvmem(struct abx80x_priv *priv)
{
        struct nvmem_config config = {
                .type = NVMEM_TYPE_BATTERY_BACKED,
                .reg_read = abx80x_nvmem_read,
                .reg_write = abx80x_nvmem_write,
                .size = ABX8XX_RAM_SIZE,
                .priv = priv,
        };

        return devm_rtc_nvmem_register(priv->rtc, &config);
}

static const struct i2c_device_id abx80x_id[] = {
        { "abx80x", ABX80X },
        { "ab0801", AB0801 },
        { "ab0803", AB0803 },
        { "ab0804", AB0804 },
        { "ab0805", AB0805 },
        { "ab1801", AB1801 },
        { "ab1803", AB1803 },
        { "ab1804", AB1804 },
        { "ab1805", AB1805 },
        { "rv1805", RV1805 },
        { }
};
MODULE_DEVICE_TABLE(i2c, abx80x_id);

static int abx80x_probe(struct i2c_client *client)
{
        struct device_node *np = client->dev.of_node;
        struct abx80x_priv *priv;
        int i, data, err, trickle_cfg = -EINVAL;
        char buf[7];
        const struct i2c_device_id *id = i2c_match_id(abx80x_id, client);
        unsigned int part = id->driver_data;
        unsigned int partnumber;
        unsigned int majrev, minrev;
        unsigned int lot;
        unsigned int wafer;
        unsigned int uid;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
                return -ENODEV;

        err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_ID0,
                                            sizeof(buf), buf);
        if (err < 0) {
                dev_err(&client->dev, "Unable to read partnumber\n");
                return -EIO;
        }

        partnumber = (buf[0] << 8) | buf[1];
        majrev = buf[2] >> 3;
        minrev = buf[2] & 0x7;
        lot = ((buf[4] & 0x80) << 2) | ((buf[6] & 0x80) << 1) | buf[3];
        uid = ((buf[4] & 0x7f) << 8) | buf[5];
        wafer = (buf[6] & 0x7c) >> 2;
        dev_info(&client->dev, "model %04x, revision %u.%u, lot %x, wafer %x, uid %x\n",
                 partnumber, majrev, minrev, lot, wafer, uid);

        data = i2c_smbus_read_byte_data(client, ABX8XX_REG_CTRL1);
        if (data < 0) {
                dev_err(&client->dev, "Unable to read control register\n");
                return -EIO;
        }

        err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CTRL1,
                                        ((data & ~(ABX8XX_CTRL_12_24 |
                                                   ABX8XX_CTRL_ARST)) |
                                         ABX8XX_CTRL_WRITE));
        if (err < 0) {
                dev_err(&client->dev, "Unable to write control register\n");
                return -EIO;
        }

        /* Configure RV1805 specifics */
        if (part == RV1805) {
                /*
                 * Avoid accidentally entering test mode. This can happen
                 * on the RV1805 in case the reserved bit 5 in control2
                 * register is set. RV-1805-C3 datasheet indicates that
                 * the bit should be cleared in section 11h - Control2.
                 */
                data = i2c_smbus_read_byte_data(client, ABX8XX_REG_CTRL2);
                if (data < 0) {
                        dev_err(&client->dev,
                                "Unable to read control2 register\n");
                        return -EIO;
                }

                err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CTRL2,
                                                data & ~ABX8XX_CTRL2_RSVD);
                if (err < 0) {
                        dev_err(&client->dev,
                                "Unable to write control2 register\n");
                        return -EIO;
                }

                /*
                 * Avoid extra power leakage. The RV1805 uses smaller
                 * 10pin package and the EXTI input is not present.
                 * Disable it to avoid leakage.
                 */
                data = i2c_smbus_read_byte_data(client, ABX8XX_REG_OUT_CTRL);
                if (data < 0) {
                        dev_err(&client->dev,
                                "Unable to read output control register\n");
                        return -EIO;
                }

                /*
                 * Write the configuration key register to enable access to
                 * the config2 register
                 */
                if (abx80x_write_config_key(client, ABX8XX_CFG_KEY_MISC) < 0)
                        return -EIO;

                err = i2c_smbus_write_byte_data(client, ABX8XX_REG_OUT_CTRL,
                                                data | ABX8XX_OUT_CTRL_EXDS);
                if (err < 0) {
                        dev_err(&client->dev,
                                "Unable to write output control register\n");
                        return -EIO;
                }
        }

        /* part autodetection */
        if (part == ABX80X) {
                for (i = 0; abx80x_caps[i].pn; i++)
                        if (partnumber == abx80x_caps[i].pn)
                                break;
                if (abx80x_caps[i].pn == 0) {
                        dev_err(&client->dev, "Unknown part: %04x\n",
                                partnumber);
                        return -EINVAL;
                }
                part = i;
        }

        if (partnumber != abx80x_caps[part].pn) {
                dev_err(&client->dev, "partnumber mismatch %04x != %04x\n",
                        partnumber, abx80x_caps[part].pn);
                return -EINVAL;
        }

        if (np && abx80x_caps[part].has_tc)
                trickle_cfg = abx80x_dt_trickle_cfg(client);

        if (trickle_cfg > 0) {
                dev_info(&client->dev, "Enabling trickle charger: %02x\n",
                         trickle_cfg);
                abx80x_enable_trickle_charger(client, trickle_cfg);
        }

        err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CD_TIMER_CTL,
                                        BIT(2));
        if (err)
                return err;

        priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
        if (priv == NULL)
                return -ENOMEM;

        priv->rtc = devm_rtc_allocate_device(&client->dev);
        if (IS_ERR(priv->rtc))
                return PTR_ERR(priv->rtc);

        priv->rtc->ops = &abx80x_rtc_ops;
        priv->client = client;

        i2c_set_clientdata(client, priv);

        if (abx80x_caps[part].has_wdog) {
                err = abx80x_setup_watchdog(priv);
                if (err)
                        return err;
        }

        err = abx80x_setup_nvmem(priv);
        if (err)
                return err;

        if (client->irq > 0) {
                dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
                err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
                                                abx80x_handle_irq,
                                                IRQF_SHARED | IRQF_ONESHOT,
                                                "abx8xx",
                                                client);
                if (err) {
                        dev_err(&client->dev, "unable to request IRQ, alarms disabled\n");
                        client->irq = 0;
                }
        }

        err = rtc_add_group(priv->rtc, &rtc_calib_attr_group);
        if (err) {
                dev_err(&client->dev, "Failed to create sysfs group: %d\n",
                        err);
                return err;
        }

        return devm_rtc_register_device(priv->rtc);
}

#ifdef CONFIG_OF
static const struct of_device_id abx80x_of_match[] = {
        {
                .compatible = "abracon,abx80x",
                .data = (void *)ABX80X
        },
        {
                .compatible = "abracon,ab0801",
                .data = (void *)AB0801
        },
        {
                .compatible = "abracon,ab0803",
                .data = (void *)AB0803
        },
        {
                .compatible = "abracon,ab0804",
                .data = (void *)AB0804
        },
        {
                .compatible = "abracon,ab0805",
                .data = (void *)AB0805
        },
        {
                .compatible = "abracon,ab1801",
                .data = (void *)AB1801
        },
        {
                .compatible = "abracon,ab1803",
                .data = (void *)AB1803
        },
        {
                .compatible = "abracon,ab1804",
                .data = (void *)AB1804
        },
        {
                .compatible = "abracon,ab1805",
                .data = (void *)AB1805
        },
        {
                .compatible = "microcrystal,rv1805",
                .data = (void *)RV1805
        },
        { }
};
MODULE_DEVICE_TABLE(of, abx80x_of_match);
#endif

static struct i2c_driver abx80x_driver = {
        .driver         = {
                .name   = "rtc-abx80x",
                .of_match_table = of_match_ptr(abx80x_of_match),
        },
        .probe          = abx80x_probe,
        .id_table       = abx80x_id,
};

module_i2c_driver(abx80x_driver);

MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@bootlin.com>");
MODULE_DESCRIPTION("Abracon ABX80X RTC driver");
MODULE_LICENSE("GPL v2");