// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      w1_therm.c
 *
 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
 */

#include <asm/types.h>

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/hwmon.h>
#include <linux/string.h>
#include <linux/jiffies.h>

#include <linux/w1.h>

#define W1_THERM_DS18S20        0x10
#define W1_THERM_DS1822         0x22
#define W1_THERM_DS18B20        0x28
#define W1_THERM_DS1825         0x3B
#define W1_THERM_DS28EA00       0x42

/*
 * Allow the strong pullup to be disabled, but default to enabled.
 * If it was disabled a parasite powered device might not get the require
 * current to do a temperature conversion.  If it is enabled parasite powered
 * devices have a better chance of getting the current required.
 * In case the parasite power-detection is not working (seems to be the case
 * for some DS18S20) the strong pullup can also be forced, regardless of the
 * power state of the devices.
 *
 * Summary of options:
 * - strong_pullup = 0  Disable strong pullup completely
 * - strong_pullup = 1  Enable automatic strong pullup detection
 * - strong_pullup = 2  Force strong pullup
 */
static int w1_strong_pullup = 1;
module_param_named(strong_pullup, w1_strong_pullup, int, 0);

/* Counter for devices supporting bulk reading */
static u16 bulk_read_device_counter; /* =0 as per C standard */

/* This command should be in public header w1.h but is not */
#define W1_RECALL_EEPROM        0xB8

/* Nb of try for an operation */
#define W1_THERM_MAX_TRY                5

/* ms delay to retry bus mutex */
#define W1_THERM_RETRY_DELAY            20

/* delay in ms to write in EEPROM */
#define W1_THERM_EEPROM_WRITE_DELAY     10

#define EEPROM_CMD_WRITE    "save"      /* cmd for write eeprom sysfs */
#define EEPROM_CMD_READ     "restore"   /* cmd for read eeprom sysfs */
#define BULK_TRIGGER_CMD    "trigger"   /* cmd to trigger a bulk read */

#define MIN_TEMP        -55     /* min temperature that can be measured */
#define MAX_TEMP        125     /* max temperature that can be measured */

/* Allowed values for sysfs conv_time attribute */
#define CONV_TIME_DEFAULT 0
#define CONV_TIME_MEASURE 1

/* Bits in sysfs "features" value */
#define W1_THERM_CHECK_RESULT 1 /* Enable conversion success check */
#define W1_THERM_POLL_COMPLETION 2      /* Poll for conversion completion */
#define W1_THERM_FEATURES_MASK 3                /* All values mask */

/* Poll period in milliseconds. Should be less then a shortest operation on the device */
#define W1_POLL_PERIOD 32
#define W1_POLL_CONVERT_TEMP 2000       /* Timeout for W1_CONVERT_TEMP, ms */
#define W1_POLL_RECALL_EEPROM 500       /* Timeout for W1_RECALL_EEPROM, ms*/

/* Masks for resolution functions, work with all devices */
/* Bit mask for config register for all devices, bits 7,6,5 */
#define W1_THERM_RESOLUTION_MASK 0xE0
/* Bit offset of resolution in config register for all devices */
#define W1_THERM_RESOLUTION_SHIFT 5
/* Bit offset of resolution in config register for all devices */
#define W1_THERM_RESOLUTION_SHIFT 5
/* Add this to bit value to get resolution */
#define W1_THERM_RESOLUTION_MIN 9
/* Maximum allowed value */
#define W1_THERM_RESOLUTION_MAX 14

/* Helpers Macros */

/*
 * return a pointer on the slave w1_therm_family_converter struct:
 * always test family data existence before using this macro
 */
#define SLAVE_SPECIFIC_FUNC(sl) \
        (((struct w1_therm_family_data *)(sl->family_data))->specific_functions)

/*
 * return the power mode of the sl slave : 1-ext, 0-parasite, <0 unknown
 * always test family data existence before using this macro
 */
#define SLAVE_POWERMODE(sl) \
        (((struct w1_therm_family_data *)(sl->family_data))->external_powered)

/*
 * return the resolution in bit of the sl slave : <0 unknown
 * always test family data existence before using this macro
 */
#define SLAVE_RESOLUTION(sl) \
        (((struct w1_therm_family_data *)(sl->family_data))->resolution)

/*
 * return the conv_time_override of the sl slave
 * always test family data existence before using this macro
 */
 #define SLAVE_CONV_TIME_OVERRIDE(sl) \
        (((struct w1_therm_family_data *)(sl->family_data))->conv_time_override)

/*
 * return the features of the sl slave
 * always test family data existence before using this macro
 */
 #define SLAVE_FEATURES(sl) \
        (((struct w1_therm_family_data *)(sl->family_data))->features)

/*
 * return whether or not a converT command has been issued to the slave
 * * 0: no bulk read is pending
 * * -1: conversion is in progress
 * * 1: conversion done, result to be read
 */
#define SLAVE_CONVERT_TRIGGERED(sl) \
        (((struct w1_therm_family_data *)(sl->family_data))->convert_triggered)

/* return the address of the refcnt in the family data */
#define THERM_REFCNT(family_data) \
        (&((struct w1_therm_family_data *)family_data)->refcnt)

/* Structs definition */

/**
 * struct w1_therm_family_converter - bind device specific functions
 * @broken: flag for non-registred families
 * @reserved: not used here
 * @f: pointer to the device binding structure
 * @convert: pointer to the device conversion function
 * @get_conversion_time: pointer to the device conversion time function
 * @set_resolution: pointer to the device set_resolution function
 * @get_resolution: pointer to the device get_resolution function
 * @write_data: pointer to the device writing function (2 or 3 bytes)
 * @bulk_read: true if device family support bulk read, false otherwise
 */
struct w1_therm_family_converter {
        u8              broken;
        u16             reserved;
        struct w1_family        *f;
        int             (*convert)(u8 rom[9]);
        int             (*get_conversion_time)(struct w1_slave *sl);
        int             (*set_resolution)(struct w1_slave *sl, int val);
        int             (*get_resolution)(struct w1_slave *sl);
        int             (*write_data)(struct w1_slave *sl, const u8 *data);
        bool            bulk_read;
};

/**
 * struct w1_therm_family_data - device data
 * @rom: ROM device id (64bit Lasered ROM code + 1 CRC byte)
 * @refcnt: ref count
 * @external_powered:   1 device powered externally,
 *                              0 device parasite powered,
 *                              -x error or undefined
 * @resolution: current device resolution
 * @convert_triggered: conversion state of the device
 * @conv_time_override: user selected conversion time or CONV_TIME_DEFAULT
 * @features: bit mask - enable temperature validity check, poll for completion
 * @specific_functions: pointer to struct of device specific function
 */
struct w1_therm_family_data {
        uint8_t rom[9];
        atomic_t refcnt;
        int external_powered;
        int resolution;
        int convert_triggered;
        int conv_time_override;
        unsigned int features;
        struct w1_therm_family_converter *specific_functions;
};

/**
 * struct therm_info - store temperature reading
 * @rom: read device data (8 data bytes + 1 CRC byte)
 * @crc: computed crc from rom
 * @verdict: 1 crc checked, 0 crc not matching
 */
struct therm_info {
        u8 rom[9];
        u8 crc;
        u8 verdict;
};

/* Hardware Functions declaration */

/**
 * reset_select_slave() - reset and select a slave
 * @sl: the slave to select
 *
 * Resets the bus and select the slave by sending a ROM MATCH cmd
 * w1_reset_select_slave() from w1_io.c could not be used here because
 * it sent a SKIP ROM command if only one device is on the line.
 * At the beginning of the such process, sl->master->slave_count is 1 even if
 * more devices are on the line, causing collision on the line.
 *
 * Context: The w1 master lock must be held.
 *
 * Return: 0 if success, negative kernel error code otherwise.
 */
static int reset_select_slave(struct w1_slave *sl);

/**
 * convert_t() - Query the device for temperature conversion and read
 * @sl: pointer to the slave to read
 * @info: pointer to a structure to store the read results
 *
 * Return: 0 if success, -kernel error code otherwise
 */
static int convert_t(struct w1_slave *sl, struct therm_info *info);

/**
 * read_scratchpad() - read the data in device RAM
 * @sl: pointer to the slave to read
 * @info: pointer to a structure to store the read results
 *
 * Return: 0 if success, -kernel error code otherwise
 */
static int read_scratchpad(struct w1_slave *sl, struct therm_info *info);

/**
 * write_scratchpad() - write nb_bytes in the device RAM
 * @sl: pointer to the slave to write in
 * @data: pointer to an array of 3 bytes, as 3 bytes MUST be written
 * @nb_bytes: number of bytes to be written (2 for DS18S20, 3 otherwise)
 *
 * Return: 0 if success, -kernel error code otherwise
 */
static int write_scratchpad(struct w1_slave *sl, const u8 *data, u8 nb_bytes);

/**
 * copy_scratchpad() - Copy the content of scratchpad in device EEPROM
 * @sl: slave involved
 *
 * Return: 0 if success, -kernel error code otherwise
 */
static int copy_scratchpad(struct w1_slave *sl);

/**
 * recall_eeprom() - Restore EEPROM data to device RAM
 * @sl: slave involved
 *
 * Return: 0 if success, -kernel error code otherwise
 */
static int recall_eeprom(struct w1_slave *sl);

/**
 * read_powermode() - Query the power mode of the slave
 * @sl: slave to retrieve the power mode
 *
 * Ask the device to get its power mode (external or parasite)
 * and store the power status in the &struct w1_therm_family_data.
 *
 * Return:
 * * 0 parasite powered device
 * * 1 externally powered device
 * * <0 kernel error code
 */
static int read_powermode(struct w1_slave *sl);

/**
 * trigger_bulk_read() - function to trigger a bulk read on the bus
 * @dev_master: the device master of the bus
 *
 * Send a SKIP ROM follow by a CONVERT T commmand on the bus.
 * It also set the status flag in each slave &struct w1_therm_family_data
 * to signal that a conversion is in progress.
 *
 * Return: 0 if success, -kernel error code otherwise
 */
static int trigger_bulk_read(struct w1_master *dev_master);

/* Sysfs interface declaration */

static ssize_t w1_slave_show(struct device *device,
        struct device_attribute *attr, char *buf);

static ssize_t w1_slave_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size);

static ssize_t w1_seq_show(struct device *device,
        struct device_attribute *attr, char *buf);

static ssize_t temperature_show(struct device *device,
        struct device_attribute *attr, char *buf);

static ssize_t ext_power_show(struct device *device,
        struct device_attribute *attr, char *buf);

static ssize_t resolution_show(struct device *device,
        struct device_attribute *attr, char *buf);

static ssize_t resolution_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size);

static ssize_t eeprom_cmd_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size);

static ssize_t alarms_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size);

static ssize_t alarms_show(struct device *device,
        struct device_attribute *attr, char *buf);

static ssize_t therm_bulk_read_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size);

static ssize_t therm_bulk_read_show(struct device *device,
        struct device_attribute *attr, char *buf);

static ssize_t conv_time_show(struct device *device,
                              struct device_attribute *attr, char *buf);

static ssize_t conv_time_store(struct device *device,
                               struct device_attribute *attr, const char *buf,
                               size_t size);

static ssize_t features_show(struct device *device,
                              struct device_attribute *attr, char *buf);

static ssize_t features_store(struct device *device,
                               struct device_attribute *attr, const char *buf,
                               size_t size);
/* Attributes declarations */

static DEVICE_ATTR_RW(w1_slave);
static DEVICE_ATTR_RO(w1_seq);
static DEVICE_ATTR_RO(temperature);
static DEVICE_ATTR_RO(ext_power);
static DEVICE_ATTR_RW(resolution);
static DEVICE_ATTR_WO(eeprom_cmd);
static DEVICE_ATTR_RW(alarms);
static DEVICE_ATTR_RW(conv_time);
static DEVICE_ATTR_RW(features);

static DEVICE_ATTR_RW(therm_bulk_read); /* attribut at master level */

/* Interface Functions declaration */

/**
 * w1_therm_add_slave() - Called when a new slave is discovered
 * @sl: slave just discovered by the master.
 *
 * Called by the master when the slave is discovered on the bus. Used to
 * initialize slave state before the beginning of any communication.
 *
 * Return: 0 - If success, negative kernel code otherwise
 */
static int w1_therm_add_slave(struct w1_slave *sl);

/**
 * w1_therm_remove_slave() - Called when a slave is removed
 * @sl: slave to be removed.
 *
 * Called by the master when the slave is considered not to be on the bus
 * anymore. Used to free memory.
 */
static void w1_therm_remove_slave(struct w1_slave *sl);

/* Family attributes */

static struct attribute *w1_therm_attrs[] = {
        &dev_attr_w1_slave.attr,
        &dev_attr_temperature.attr,
        &dev_attr_ext_power.attr,
        &dev_attr_resolution.attr,
        &dev_attr_eeprom_cmd.attr,
        &dev_attr_alarms.attr,
        &dev_attr_conv_time.attr,
        &dev_attr_features.attr,
        NULL,
};

static struct attribute *w1_ds18s20_attrs[] = {
        &dev_attr_w1_slave.attr,
        &dev_attr_temperature.attr,
        &dev_attr_ext_power.attr,
        &dev_attr_eeprom_cmd.attr,
        &dev_attr_alarms.attr,
        &dev_attr_conv_time.attr,
        &dev_attr_features.attr,
        NULL,
};

static struct attribute *w1_ds28ea00_attrs[] = {
        &dev_attr_w1_slave.attr,
        &dev_attr_w1_seq.attr,
        &dev_attr_temperature.attr,
        &dev_attr_ext_power.attr,
        &dev_attr_resolution.attr,
        &dev_attr_eeprom_cmd.attr,
        &dev_attr_alarms.attr,
        &dev_attr_conv_time.attr,
        &dev_attr_features.attr,
        NULL,
};

/* Attribute groups */

ATTRIBUTE_GROUPS(w1_therm);
ATTRIBUTE_GROUPS(w1_ds18s20);
ATTRIBUTE_GROUPS(w1_ds28ea00);

#if IS_REACHABLE(CONFIG_HWMON)
static int w1_read_temp(struct device *dev, u32 attr, int channel,
                        long *val);

static umode_t w1_is_visible(const void *_data, enum hwmon_sensor_types type,
                             u32 attr, int channel)
{
        return attr == hwmon_temp_input ? 0444 : 0;
}

static int w1_read(struct device *dev, enum hwmon_sensor_types type,
                   u32 attr, int channel, long *val)
{
        switch (type) {
        case hwmon_temp:
                return w1_read_temp(dev, attr, channel, val);
        default:
                return -EOPNOTSUPP;
        }
}

static const u32 w1_temp_config[] = {
        HWMON_T_INPUT,
        0
};

static const struct hwmon_channel_info w1_temp = {
        .type = hwmon_temp,
        .config = w1_temp_config,
};

static const struct hwmon_channel_info *w1_info[] = {
        &w1_temp,
        NULL
};

static const struct hwmon_ops w1_hwmon_ops = {
        .is_visible = w1_is_visible,
        .read = w1_read,
};

static const struct hwmon_chip_info w1_chip_info = {
        .ops = &w1_hwmon_ops,
        .info = w1_info,
};
#define W1_CHIPINFO     (&w1_chip_info)
#else
#define W1_CHIPINFO     NULL
#endif

/* Family operations */

static const struct w1_family_ops w1_therm_fops = {
        .add_slave      = w1_therm_add_slave,
        .remove_slave   = w1_therm_remove_slave,
        .groups         = w1_therm_groups,
        .chip_info      = W1_CHIPINFO,
};

static const struct w1_family_ops w1_ds18s20_fops = {
        .add_slave      = w1_therm_add_slave,
        .remove_slave   = w1_therm_remove_slave,
        .groups         = w1_ds18s20_groups,
        .chip_info      = W1_CHIPINFO,
};

static const struct w1_family_ops w1_ds28ea00_fops = {
        .add_slave      = w1_therm_add_slave,
        .remove_slave   = w1_therm_remove_slave,
        .groups         = w1_ds28ea00_groups,
        .chip_info      = W1_CHIPINFO,
};

/* Family binding operations struct */

static struct w1_family w1_therm_family_DS18S20 = {
        .fid = W1_THERM_DS18S20,
        .fops = &w1_ds18s20_fops,
};

static struct w1_family w1_therm_family_DS18B20 = {
        .fid = W1_THERM_DS18B20,
        .fops = &w1_therm_fops,
};

static struct w1_family w1_therm_family_DS1822 = {
        .fid = W1_THERM_DS1822,
        .fops = &w1_therm_fops,
};

static struct w1_family w1_therm_family_DS28EA00 = {
        .fid = W1_THERM_DS28EA00,
        .fops = &w1_ds28ea00_fops,
};

static struct w1_family w1_therm_family_DS1825 = {
        .fid = W1_THERM_DS1825,
        .fops = &w1_therm_fops,
};

/* Device dependent func */

static inline int w1_DS18B20_convert_time(struct w1_slave *sl)
{
        int ret;

        if (!sl->family_data)
                return -ENODEV; /* device unknown */

        if (SLAVE_CONV_TIME_OVERRIDE(sl) != CONV_TIME_DEFAULT)
                return SLAVE_CONV_TIME_OVERRIDE(sl);

        /* Return the conversion time, depending on resolution,
         * select maximum conversion time among all compatible devices
         */
        switch (SLAVE_RESOLUTION(sl)) {
        case 9:
                ret = 95;
                break;
        case 10:
                ret = 190;
                break;
        case 11:
                ret = 375;
                break;
        case 12:
                ret = 750;
                break;
        case 13:
                ret = 850;  /* GX20MH01 only. Datasheet says 500ms, but that's not enough. */
                break;
        case 14:
                ret = 1600; /* GX20MH01 only. Datasheet says 1000ms - not enough */
                break;
        default:
                ret = 750;
        }
        return ret;
}

static inline int w1_DS18S20_convert_time(struct w1_slave *sl)
{
        if (!sl->family_data)
                return -ENODEV; /* device unknown */

        if (SLAVE_CONV_TIME_OVERRIDE(sl) == CONV_TIME_DEFAULT)
                return 750; /* default for DS18S20 */
        else
                return SLAVE_CONV_TIME_OVERRIDE(sl);
}

static inline int w1_DS18B20_write_data(struct w1_slave *sl,
                                const u8 *data)
{
        return write_scratchpad(sl, data, 3);
}

static inline int w1_DS18S20_write_data(struct w1_slave *sl,
                                const u8 *data)
{
        /* No config register */
        return write_scratchpad(sl, data, 2);
}

static inline int w1_DS18B20_set_resolution(struct w1_slave *sl, int val)
{
        int ret;
        struct therm_info info, info2;

        /* DS18B20 resolution is 9 to 12 bits */
        /* GX20MH01 resolution is 9 to 14 bits */
        if (val < W1_THERM_RESOLUTION_MIN || val > W1_THERM_RESOLUTION_MAX)
                return -EINVAL;

        /* Calc bit value from resolution */
        val = (val - W1_THERM_RESOLUTION_MIN) << W1_THERM_RESOLUTION_SHIFT;

        /*
         * Read the scratchpad to change only the required bits
         * (bit5 & bit 6 from byte 4)
         */
        ret = read_scratchpad(sl, &info);

        if (ret)
                return ret;


        info.rom[4] &= ~W1_THERM_RESOLUTION_MASK;
        info.rom[4] |= val;

        /* Write data in the device RAM */
        ret = w1_DS18B20_write_data(sl, info.rom + 2);
        if (ret)
                return ret;

        /* Have to read back the resolution to verify an actual value
         * GX20MH01 and DS18B20 are indistinguishable by family number, but resolutions differ
         * Some DS18B20 clones don't support resolution change
         */
        ret = read_scratchpad(sl, &info2);
        if (ret)
                /* Scratchpad read fail */
                return ret;

        if ((info2.rom[4] & W1_THERM_RESOLUTION_MASK) == (info.rom[4] & W1_THERM_RESOLUTION_MASK))
                return 0;

        /* Resolution verify error */
        return -EIO;
}

static inline int w1_DS18B20_get_resolution(struct w1_slave *sl)
{
        int ret;
        int resolution;
        struct therm_info info;

        ret = read_scratchpad(sl, &info);

        if (ret)
                return ret;

        resolution = ((info.rom[4] & W1_THERM_RESOLUTION_MASK) >> W1_THERM_RESOLUTION_SHIFT)
                + W1_THERM_RESOLUTION_MIN;
        /* GX20MH01 has one special case:
         *   >=14 means 14 bits when getting resolution from bit value.
         * Other devices have no more then 12 bits.
         */
        if (resolution > W1_THERM_RESOLUTION_MAX)
                resolution = W1_THERM_RESOLUTION_MAX;

        return resolution;
}

/**
 * w1_DS18B20_convert_temp() - temperature computation for DS18B20
 * @rom: data read from device RAM (8 data bytes + 1 CRC byte)
 *
 * Can be called for any DS18B20 compliant device.
 *
 * Return: value in millidegrees Celsius.
 */
static inline int w1_DS18B20_convert_temp(u8 rom[9])
{
        u16 bv;
        s16 t;

        /* Signed 16-bit value to unsigned, cpu order */
        bv = le16_to_cpup((__le16 *)rom);

        /* Config register bit R2 = 1 - GX20MH01 in 13 or 14 bit resolution mode */
        if (rom[4] & 0x80) {
                /* Insert two temperature bits from config register */
                /* Avoid arithmetic shift of signed value */
                bv = (bv << 2) | (rom[4] & 3);
                t = (s16) bv;   /* Degrees, lowest bit is 2^-6 */
                return (int)t * 1000 / 64;      /* Sign-extend to int; millidegrees */
        }
        t = (s16)bv;    /* Degrees, lowest bit is 2^-4 */
        return (int)t * 1000 / 16;      /* Sign-extend to int; millidegrees */
}

/**
 * w1_DS18S20_convert_temp() - temperature computation for DS18S20
 * @rom: data read from device RAM (8 data bytes + 1 CRC byte)
 *
 * Can be called for any DS18S20 compliant device.
 *
 * Return: value in millidegrees Celsius.
 */
static inline int w1_DS18S20_convert_temp(u8 rom[9])
{
        int t, h;

        if (!rom[7]) {
                pr_debug("%s: Invalid argument for conversion\n", __func__);
                return 0;
        }

        if (rom[1] == 0)
                t = ((s32)rom[0] >> 1)*1000;
        else
                t = 1000*(-1*(s32)(0x100-rom[0]) >> 1);

        t -= 250;
        h = 1000*((s32)rom[7] - (s32)rom[6]);
        h /= (s32)rom[7];
        t += h;

        return t;
}

/* Device capability description */
/* GX20MH01 device shares family number and structure with DS18B20 */

static struct w1_therm_family_converter w1_therm_families[] = {
        {
                .f                              = &w1_therm_family_DS18S20,
                .convert                        = w1_DS18S20_convert_temp,
                .get_conversion_time    = w1_DS18S20_convert_time,
                .set_resolution         = NULL, /* no config register */
                .get_resolution         = NULL, /* no config register */
                .write_data                     = w1_DS18S20_write_data,
                .bulk_read                      = true
        },
        {
                .f                              = &w1_therm_family_DS1822,
                .convert                        = w1_DS18B20_convert_temp,
                .get_conversion_time    = w1_DS18B20_convert_time,
                .set_resolution         = w1_DS18B20_set_resolution,
                .get_resolution         = w1_DS18B20_get_resolution,
                .write_data                     = w1_DS18B20_write_data,
                .bulk_read                      = true
        },
        {
                /* Also used for GX20MH01 */
                .f                              = &w1_therm_family_DS18B20,
                .convert                        = w1_DS18B20_convert_temp,
                .get_conversion_time    = w1_DS18B20_convert_time,
                .set_resolution         = w1_DS18B20_set_resolution,
                .get_resolution         = w1_DS18B20_get_resolution,
                .write_data                     = w1_DS18B20_write_data,
                .bulk_read                      = true
        },
        {
                .f                              = &w1_therm_family_DS28EA00,
                .convert                        = w1_DS18B20_convert_temp,
                .get_conversion_time    = w1_DS18B20_convert_time,
                .set_resolution         = w1_DS18B20_set_resolution,
                .get_resolution         = w1_DS18B20_get_resolution,
                .write_data                     = w1_DS18B20_write_data,
                .bulk_read                      = false
        },
        {
                .f                              = &w1_therm_family_DS1825,
                .convert                        = w1_DS18B20_convert_temp,
                .get_conversion_time    = w1_DS18B20_convert_time,
                .set_resolution         = w1_DS18B20_set_resolution,
                .get_resolution         = w1_DS18B20_get_resolution,
                .write_data                     = w1_DS18B20_write_data,
                .bulk_read                      = true
        }
};

/* Helpers Functions */

/**
 * device_family() - Retrieve a pointer on &struct w1_therm_family_converter
 * @sl: slave to retrieve the device specific structure
 *
 * Return: pointer to the slaves's family converter, NULL if not known
 */
static struct w1_therm_family_converter *device_family(struct w1_slave *sl)
{
        struct w1_therm_family_converter *ret = NULL;
        int i;

        for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
                if (w1_therm_families[i].f->fid == sl->family->fid) {
                        ret = &w1_therm_families[i];
                        break;
                }
        }
        return ret;
}

/**
 * bus_mutex_lock() - Acquire the mutex
 * @lock: w1 bus mutex to acquire
 *
 * It try to acquire the mutex W1_THERM_MAX_TRY times and wait
 * W1_THERM_RETRY_DELAY between 2 attempts.
 *
 * Return: true is mutex is acquired and lock, false otherwise
 */
static inline bool bus_mutex_lock(struct mutex *lock)
{
        int max_trying = W1_THERM_MAX_TRY;

        /* try to acquire the mutex, if not, sleep retry_delay before retry) */
        while (mutex_lock_interruptible(lock) != 0 && max_trying > 0) {
                unsigned long sleep_rem;

                sleep_rem = msleep_interruptible(W1_THERM_RETRY_DELAY);
                if (!sleep_rem)
                        max_trying--;
        }

        if (!max_trying)
                return false;   /* Didn't acquire the bus mutex */

        return true;
}

/**
 * check_family_data() - Check if family data and specific functions are present
 * @sl: W1 device data
 *
 * Return: 0 - OK, negative value - error
 */
static int check_family_data(struct w1_slave *sl)
{
        if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
                dev_info(&sl->dev,
                         "%s: Device is not supported by the driver\n", __func__);
                return -EINVAL;  /* No device family */
        }
        return 0;
}

/**
 * bulk_read_support() - check if slave support bulk read
 * @sl: device to check the ability
 *
 * Return: true if bulk read is supported, false if not or error
 */
static inline bool bulk_read_support(struct w1_slave *sl)
{
        if (SLAVE_SPECIFIC_FUNC(sl))
                return SLAVE_SPECIFIC_FUNC(sl)->bulk_read;

        dev_info(&sl->dev,
                "%s: Device not supported by the driver\n", __func__);

        return false;  /* No device family */
}

/**
 * conversion_time() - get the Tconv for the slave
 * @sl: device to get the conversion time
 *
 * On device supporting resolution settings, conversion time depend
 * on the resolution setting. This helper function get the slave timing,
 * depending on its current setting.
 *
 * Return: conversion time in ms, negative values are kernel error code
 */
static inline int conversion_time(struct w1_slave *sl)
{
        if (SLAVE_SPECIFIC_FUNC(sl))
                return SLAVE_SPECIFIC_FUNC(sl)->get_conversion_time(sl);

        dev_info(&sl->dev,
                "%s: Device not supported by the driver\n", __func__);

        return -ENODEV;  /* No device family */
}

/**
 * temperature_from_RAM() - Convert the read info to temperature
 * @sl: device that sent the RAM data
 * @rom: read value on the slave device RAM
 *
 * Device dependent, the function bind the correct computation method.
 *
 * Return: temperature in 1/1000degC, 0 on error.
 */
static inline int temperature_from_RAM(struct w1_slave *sl, u8 rom[9])
{
        if (SLAVE_SPECIFIC_FUNC(sl))
                return SLAVE_SPECIFIC_FUNC(sl)->convert(rom);

        dev_info(&sl->dev,
                "%s: Device not supported by the driver\n", __func__);

        return 0;  /* No device family */
}

/**
 * int_to_short() - Safe casting of int to short
 *
 * @i: integer to be converted to short
 *
 * Device register use 1 byte to store signed integer.
 * This helper function convert the int in a signed short,
 * using the min/max values that device can measure as limits.
 * min/max values are defined by macro.
 *
 * Return: a short in the range of min/max value
 */
static inline s8 int_to_short(int i)
{
        /* Prepare to cast to short by eliminating out of range values */
        i = clamp(i, MIN_TEMP, MAX_TEMP);
        return (s8) i;
}

/* Interface Functions */

static int w1_therm_add_slave(struct w1_slave *sl)
{
        struct w1_therm_family_converter *sl_family_conv;

        /* Allocate memory */
        sl->family_data = kzalloc(sizeof(struct w1_therm_family_data),
                GFP_KERNEL);
        if (!sl->family_data)
                return -ENOMEM;

        atomic_set(THERM_REFCNT(sl->family_data), 1);

        /* Get a pointer to the device specific function struct */
        sl_family_conv = device_family(sl);
        if (!sl_family_conv) {
                kfree(sl->family_data);
                return -ENODEV;
        }
        /* save this pointer to the device structure */
        SLAVE_SPECIFIC_FUNC(sl) = sl_family_conv;

        if (bulk_read_support(sl)) {
                /*
                 * add the sys entry to trigger bulk_read
                 * at master level only the 1st time
                 */
                if (!bulk_read_device_counter) {
                        int err = device_create_file(&sl->master->dev,
                                &dev_attr_therm_bulk_read);

                        if (err)
                                dev_warn(&sl->dev,
                                "%s: Device has been added, but bulk read is unavailable. err=%d\n",
                                __func__, err);
                }
                /* Increment the counter */
                bulk_read_device_counter++;
        }

        /* Getting the power mode of the device {external, parasite} */
        SLAVE_POWERMODE(sl) = read_powermode(sl);

        if (SLAVE_POWERMODE(sl) < 0) {
                /* no error returned as device has been added */
                dev_warn(&sl->dev,
                        "%s: Device has been added, but power_mode may be corrupted. err=%d\n",
                         __func__, SLAVE_POWERMODE(sl));
        }

        /* Getting the resolution of the device */
        if (SLAVE_SPECIFIC_FUNC(sl)->get_resolution) {
                SLAVE_RESOLUTION(sl) =
                        SLAVE_SPECIFIC_FUNC(sl)->get_resolution(sl);
                if (SLAVE_RESOLUTION(sl) < 0) {
                        /* no error returned as device has been added */
                        dev_warn(&sl->dev,
                                "%s:Device has been added, but resolution may be corrupted. err=%d\n",
                                __func__, SLAVE_RESOLUTION(sl));
                }
        }

        /* Finally initialize convert_triggered flag */
        SLAVE_CONVERT_TRIGGERED(sl) = 0;

        return 0;
}

static void w1_therm_remove_slave(struct w1_slave *sl)
{
        int refcnt = atomic_sub_return(1, THERM_REFCNT(sl->family_data));

        if (bulk_read_support(sl)) {
                bulk_read_device_counter--;
                /* Delete the entry if no more device support the feature */
                if (!bulk_read_device_counter)
                        device_remove_file(&sl->master->dev,
                                &dev_attr_therm_bulk_read);
        }

        while (refcnt) {
                msleep(1000);
                refcnt = atomic_read(THERM_REFCNT(sl->family_data));
        }
        kfree(sl->family_data);
        sl->family_data = NULL;
}

/* Hardware Functions */

/* Safe version of reset_select_slave - avoid using the one in w_io.c */
static int reset_select_slave(struct w1_slave *sl)
{
        u8 match[9] = { W1_MATCH_ROM, };
        u64 rn = le64_to_cpu(*((u64 *)&sl->reg_num));

        if (w1_reset_bus(sl->master))
                return -ENODEV;

        memcpy(&match[1], &rn, 8);
        w1_write_block(sl->master, match, 9);

        return 0;
}

/**
 * w1_poll_completion - Poll for operation completion, with timeout
 * @dev_master: the device master of the bus
 * @tout_ms: timeout in milliseconds
 *
 * The device is answering 0's while an operation is in progress and 1's after it completes
 * Timeout may happen if the previous command was not recognised due to a line noise
 *
 * Return: 0 - OK, negative error - timeout
 */
static int w1_poll_completion(struct w1_master *dev_master, int tout_ms)
{
        int i;

        for (i = 0; i < tout_ms/W1_POLL_PERIOD; i++) {
                /* Delay is before poll, for device to recognize a command */
                msleep(W1_POLL_PERIOD);

                /* Compare all 8 bits to mitigate a noise on the bus */
                if (w1_read_8(dev_master) == 0xFF)
                        break;
        }
        if (i == tout_ms/W1_POLL_PERIOD)
                return -EIO;

        return 0;
}

static int convert_t(struct w1_slave *sl, struct therm_info *info)
{
        struct w1_master *dev_master = sl->master;
        int max_trying = W1_THERM_MAX_TRY;
        int t_conv;
        int ret = -ENODEV;
        bool strong_pullup;

        if (!sl->family_data)
                goto error;

        strong_pullup = (w1_strong_pullup == 2 ||
                                        (!SLAVE_POWERMODE(sl) &&
                                        w1_strong_pullup));

        if (strong_pullup && SLAVE_FEATURES(sl) & W1_THERM_POLL_COMPLETION) {
                dev_warn(&sl->dev,
                        "%s: Disabling W1_THERM_POLL_COMPLETION in parasite power mode.\n",
                        __func__);
                SLAVE_FEATURES(sl) &= ~W1_THERM_POLL_COMPLETION;
        }

        /* get conversion duration device and id dependent */
        t_conv = conversion_time(sl);

        memset(info->rom, 0, sizeof(info->rom));

        /* prevent the slave from going away in sleep */
        atomic_inc(THERM_REFCNT(sl->family_data));

        if (!bus_mutex_lock(&dev_master->bus_mutex)) {
                ret = -EAGAIN;  /* Didn't acquire the mutex */
                goto dec_refcnt;
        }

        while (max_trying-- && ret) { /* ret should be 0 */

                info->verdict = 0;
                info->crc = 0;
                /* safe version to select slave */
                if (!reset_select_slave(sl)) {
                        unsigned long sleep_rem;

                        /* 750ms strong pullup (or delay) after the convert */
                        if (strong_pullup)
                                w1_next_pullup(dev_master, t_conv);

                        w1_write_8(dev_master, W1_CONVERT_TEMP);

                        if (strong_pullup) { /*some device need pullup */
                                sleep_rem = msleep_interruptible(t_conv);
                                if (sleep_rem != 0) {
                                        ret = -EINTR;
                                        goto mt_unlock;
                                }
                                mutex_unlock(&dev_master->bus_mutex);
                        } else { /*no device need pullup */
                                if (SLAVE_FEATURES(sl) & W1_THERM_POLL_COMPLETION) {
                                        ret = w1_poll_completion(dev_master, W1_POLL_CONVERT_TEMP);
                                        if (ret) {
                                                dev_dbg(&sl->dev, "%s: Timeout\n", __func__);
                                                goto mt_unlock;
                                        }
                                        mutex_unlock(&dev_master->bus_mutex);
                                } else {
                                        /* Fixed delay */
                                        mutex_unlock(&dev_master->bus_mutex);
                                        sleep_rem = msleep_interruptible(t_conv);
                                        if (sleep_rem != 0) {
                                                ret = -EINTR;
                                                goto dec_refcnt;
                                        }
                                }
                        }
                        ret = read_scratchpad(sl, info);

                        /* If enabled, check for conversion success */
                        if ((SLAVE_FEATURES(sl) & W1_THERM_CHECK_RESULT) &&
                                (info->rom[6] == 0xC) &&
                                ((info->rom[1] == 0x5 && info->rom[0] == 0x50) ||
                                (info->rom[1] == 0x7 && info->rom[0] == 0xFF))
                        ) {
                                /* Invalid reading (scratchpad byte 6 = 0xC)
                                 * due to insufficient conversion time
                                 * or power failure.
                                 */
                                ret = -EIO;
                        }

                        goto dec_refcnt;
                }

        }

mt_unlock:
        mutex_unlock(&dev_master->bus_mutex);
dec_refcnt:
        atomic_dec(THERM_REFCNT(sl->family_data));
error:
        return ret;
}

static int conv_time_measure(struct w1_slave *sl, int *conv_time)
{
        struct therm_info inf,
                *info = &inf;
        struct w1_master *dev_master = sl->master;
        int max_trying = W1_THERM_MAX_TRY;
        int ret = -ENODEV;
        bool strong_pullup;

        if (!sl->family_data)
                goto error;

        strong_pullup = (w1_strong_pullup == 2 ||
                (!SLAVE_POWERMODE(sl) &&
                w1_strong_pullup));

        if (strong_pullup) {
                pr_info("%s: Measure with strong_pullup is not supported.\n", __func__);
                return -EINVAL;
        }

        memset(info->rom, 0, sizeof(info->rom));

        /* prevent the slave from going away in sleep */
        atomic_inc(THERM_REFCNT(sl->family_data));

        if (!bus_mutex_lock(&dev_master->bus_mutex)) {
                ret = -EAGAIN;  /* Didn't acquire the mutex */
                goto dec_refcnt;
        }

        while (max_trying-- && ret) { /* ret should be 0 */
                info->verdict = 0;
                info->crc = 0;
                /* safe version to select slave */
                if (!reset_select_slave(sl)) {
                        int j_start, j_end;

                        /*no device need pullup */
                        w1_write_8(dev_master, W1_CONVERT_TEMP);

                        j_start = jiffies;
                        ret = w1_poll_completion(dev_master, W1_POLL_CONVERT_TEMP);
                        if (ret) {
                                dev_dbg(&sl->dev, "%s: Timeout\n", __func__);
                                goto mt_unlock;
                        }
                        j_end = jiffies;
                        /* 1.2x increase for variation and changes over temperature range */
                        *conv_time = jiffies_to_msecs(j_end-j_start)*12/10;
                        pr_debug("W1 Measure complete, conv_time = %d, HZ=%d.\n",
                                *conv_time, HZ);
                        if (*conv_time <= CONV_TIME_MEASURE) {
                                ret = -EIO;
                                goto mt_unlock;
                        }
                        mutex_unlock(&dev_master->bus_mutex);
                        ret = read_scratchpad(sl, info);
                        goto dec_refcnt;
                }

        }
mt_unlock:
        mutex_unlock(&dev_master->bus_mutex);
dec_refcnt:
        atomic_dec(THERM_REFCNT(sl->family_data));
error:
        return ret;
}

static int read_scratchpad(struct w1_slave *sl, struct therm_info *info)
{
        struct w1_master *dev_master = sl->master;
        int max_trying = W1_THERM_MAX_TRY;
        int ret = -ENODEV;

        info->verdict = 0;

        if (!sl->family_data)
                goto error;

        memset(info->rom, 0, sizeof(info->rom));

        /* prevent the slave from going away in sleep */
        atomic_inc(THERM_REFCNT(sl->family_data));

        if (!bus_mutex_lock(&dev_master->bus_mutex)) {
                ret = -EAGAIN;  /* Didn't acquire the mutex */
                goto dec_refcnt;
        }

        while (max_trying-- && ret) { /* ret should be 0 */
                /* safe version to select slave */
                if (!reset_select_slave(sl)) {
                        u8 nb_bytes_read;

                        w1_write_8(dev_master, W1_READ_SCRATCHPAD);

                        nb_bytes_read = w1_read_block(dev_master, info->rom, 9);
                        if (nb_bytes_read != 9) {
                                dev_warn(&sl->dev,
                                        "w1_read_block(): returned %u instead of 9.\n",
                                        nb_bytes_read);
                                ret = -EIO;
                        }

                        info->crc = w1_calc_crc8(info->rom, 8);

                        if (info->rom[8] == info->crc) {
                                info->verdict = 1;
                                ret = 0;
                        } else
                                ret = -EIO; /* CRC not checked */
                }

        }
        mutex_unlock(&dev_master->bus_mutex);

dec_refcnt:
        atomic_dec(THERM_REFCNT(sl->family_data));
error:
        return ret;
}

static int write_scratchpad(struct w1_slave *sl, const u8 *data, u8 nb_bytes)
{
        struct w1_master *dev_master = sl->master;
        int max_trying = W1_THERM_MAX_TRY;
        int ret = -ENODEV;

        if (!sl->family_data)
                goto error;

        /* prevent the slave from going away in sleep */
        atomic_inc(THERM_REFCNT(sl->family_data));

        if (!bus_mutex_lock(&dev_master->bus_mutex)) {
                ret = -EAGAIN;  /* Didn't acquire the mutex */
                goto dec_refcnt;
        }

        while (max_trying-- && ret) { /* ret should be 0 */
                /* safe version to select slave */
                if (!reset_select_slave(sl)) {
                        w1_write_8(dev_master, W1_WRITE_SCRATCHPAD);
                        w1_write_block(dev_master, data, nb_bytes);
                        ret = 0;
                }
        }
        mutex_unlock(&dev_master->bus_mutex);

dec_refcnt:
        atomic_dec(THERM_REFCNT(sl->family_data));
error:
        return ret;
}

static int copy_scratchpad(struct w1_slave *sl)
{
        struct w1_master *dev_master = sl->master;
        int max_trying = W1_THERM_MAX_TRY;
        int t_write, ret = -ENODEV;
        bool strong_pullup;

        if (!sl->family_data)
                goto error;

        t_write = W1_THERM_EEPROM_WRITE_DELAY;
        strong_pullup = (w1_strong_pullup == 2 ||
                                        (!SLAVE_POWERMODE(sl) &&
                                        w1_strong_pullup));

        /* prevent the slave from going away in sleep */
        atomic_inc(THERM_REFCNT(sl->family_data));

        if (!bus_mutex_lock(&dev_master->bus_mutex)) {
                ret = -EAGAIN;  /* Didn't acquire the mutex */
                goto dec_refcnt;
        }

        while (max_trying-- && ret) { /* ret should be 0 */
                /* safe version to select slave */
                if (!reset_select_slave(sl)) {
                        unsigned long sleep_rem;

                        /* 10ms strong pullup (or delay) after the convert */
                        if (strong_pullup)
                                w1_next_pullup(dev_master, t_write);

                        w1_write_8(dev_master, W1_COPY_SCRATCHPAD);

                        if (strong_pullup) {
                                sleep_rem = msleep_interruptible(t_write);
                                if (sleep_rem != 0) {
                                        ret = -EINTR;
                                        goto mt_unlock;
                                }
                        }
                        ret = 0;
                }

        }

mt_unlock:
        mutex_unlock(&dev_master->bus_mutex);
dec_refcnt:
        atomic_dec(THERM_REFCNT(sl->family_data));
error:
        return ret;
}

static int recall_eeprom(struct w1_slave *sl)
{
        struct w1_master *dev_master = sl->master;
        int max_trying = W1_THERM_MAX_TRY;
        int ret = -ENODEV;

        if (!sl->family_data)
                goto error;

        /* prevent the slave from going away in sleep */
        atomic_inc(THERM_REFCNT(sl->family_data));

        if (!bus_mutex_lock(&dev_master->bus_mutex)) {
                ret = -EAGAIN;  /* Didn't acquire the mutex */
                goto dec_refcnt;
        }

        while (max_trying-- && ret) { /* ret should be 0 */
                /* safe version to select slave */
                if (!reset_select_slave(sl)) {

                        w1_write_8(dev_master, W1_RECALL_EEPROM);
                        ret = w1_poll_completion(dev_master, W1_POLL_RECALL_EEPROM);
                }

        }

        mutex_unlock(&dev_master->bus_mutex);

dec_refcnt:
        atomic_dec(THERM_REFCNT(sl->family_data));
error:
        return ret;
}

static int read_powermode(struct w1_slave *sl)
{
        struct w1_master *dev_master = sl->master;
        int max_trying = W1_THERM_MAX_TRY;
        int  ret = -ENODEV;

        if (!sl->family_data)
                goto error;

        /* prevent the slave from going away in sleep */
        atomic_inc(THERM_REFCNT(sl->family_data));

        if (!bus_mutex_lock(&dev_master->bus_mutex)) {
                ret = -EAGAIN;  /* Didn't acquire the mutex */
                goto dec_refcnt;
        }

        while ((max_trying--) && (ret < 0)) {
                /* safe version to select slave */
                if (!reset_select_slave(sl)) {
                        w1_write_8(dev_master, W1_READ_PSUPPLY);
                        /*
                         * Emit a read time slot and read only one bit,
                         * 1 is externally powered,
                         * 0 is parasite powered
                         */
                        ret = w1_touch_bit(dev_master, 1);
                        /* ret should be either 1 either 0 */
                }
        }
        mutex_unlock(&dev_master->bus_mutex);

dec_refcnt:
        atomic_dec(THERM_REFCNT(sl->family_data));
error:
        return ret;
}

static int trigger_bulk_read(struct w1_master *dev_master)
{
        struct w1_slave *sl = NULL; /* used to iterate through slaves */
        int max_trying = W1_THERM_MAX_TRY;
        int t_conv = 0;
        int ret = -ENODEV;
        bool strong_pullup = false;

        /*
         * Check whether there are parasite powered device on the bus,
         * and compute duration of conversion for these devices
         * so we can apply a strong pullup if required
         */
        list_for_each_entry(sl, &dev_master->slist, w1_slave_entry) {
                if (!sl->family_data)
                        goto error;
                if (bulk_read_support(sl)) {
                        int t_cur = conversion_time(sl);

                        t_conv = t_cur > t_conv ? t_cur : t_conv;
                        strong_pullup = strong_pullup ||
                                        (w1_strong_pullup == 2 ||
                                        (!SLAVE_POWERMODE(sl) &&
                                        w1_strong_pullup));
                }
        }

        /*
         * t_conv is the max conversion time required on the bus
         * If its 0, no device support the bulk read feature
         */
        if (!t_conv)
                goto error;

        if (!bus_mutex_lock(&dev_master->bus_mutex)) {
                ret = -EAGAIN;  /* Didn't acquire the mutex */
                goto error;
        }

        while ((max_trying--) && (ret < 0)) { /* ret should be either 0 */

                if (!w1_reset_bus(dev_master)) {        /* Just reset the bus */
                        unsigned long sleep_rem;

                        w1_write_8(dev_master, W1_SKIP_ROM);

                        if (strong_pullup)      /* Apply pullup if required */
                                w1_next_pullup(dev_master, t_conv);

                        w1_write_8(dev_master, W1_CONVERT_TEMP);

                        /* set a flag to instruct that converT pending */
                        list_for_each_entry(sl,
                                &dev_master->slist, w1_slave_entry) {
                                if (bulk_read_support(sl))
                                        SLAVE_CONVERT_TRIGGERED(sl) = -1;
                        }

                        if (strong_pullup) { /* some device need pullup */
                                sleep_rem = msleep_interruptible(t_conv);
                                if (sleep_rem != 0) {
                                        ret = -EINTR;
                                        goto mt_unlock;
                                }
                                mutex_unlock(&dev_master->bus_mutex);
                        } else {
                                mutex_unlock(&dev_master->bus_mutex);
                                sleep_rem = msleep_interruptible(t_conv);
                                if (sleep_rem != 0) {
                                        ret = -EINTR;
                                        goto set_flag;
                                }
                        }
                        ret = 0;
                        goto set_flag;
                }
        }

mt_unlock:
        mutex_unlock(&dev_master->bus_mutex);
set_flag:
        /* set a flag to register convsersion is done */
        list_for_each_entry(sl, &dev_master->slist, w1_slave_entry) {
                if (bulk_read_support(sl))
                        SLAVE_CONVERT_TRIGGERED(sl) = 1;
        }
error:
        return ret;
}

/* Sysfs Interface definition */

static ssize_t w1_slave_show(struct device *device,
                             struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        struct therm_info info;
        u8 *family_data = sl->family_data;
        int ret, i;
        ssize_t c = PAGE_SIZE;

        if (bulk_read_support(sl)) {
                if (SLAVE_CONVERT_TRIGGERED(sl) < 0) {
                        dev_dbg(device,
                                "%s: Conversion in progress, retry later\n",
                                __func__);
                        return 0;
                } else if (SLAVE_CONVERT_TRIGGERED(sl) > 0) {
                        /* A bulk read has been issued, read the device RAM */
                        ret = read_scratchpad(sl, &info);
                        SLAVE_CONVERT_TRIGGERED(sl) = 0;
                } else
                        ret = convert_t(sl, &info);
        } else
                ret = convert_t(sl, &info);

        if (ret < 0) {
                dev_dbg(device,
                        "%s: Temperature data may be corrupted. err=%d\n",
                        __func__, ret);
                return 0;
        }

        for (i = 0; i < 9; ++i)
                c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", info.rom[i]);
        c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
                      info.crc, (info.verdict) ? "YES" : "NO");

        if (info.verdict)
                memcpy(family_data, info.rom, sizeof(info.rom));
        else
                dev_warn(device, "%s:Read failed CRC check\n", __func__);

        for (i = 0; i < 9; ++i)
                c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ",
                              ((u8 *)family_data)[i]);

        c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
                        temperature_from_RAM(sl, info.rom));

        ret = PAGE_SIZE - c;
        return ret;
}

static ssize_t w1_slave_store(struct device *device,
                              struct device_attribute *attr, const char *buf,
                              size_t size)
{
        int val, ret = 0;
        struct w1_slave *sl = dev_to_w1_slave(device);

        ret = kstrtoint(buf, 10, &val); /* converting user entry to int */

        if (ret) {      /* conversion error */
                dev_info(device,
                        "%s: conversion error. err= %d\n", __func__, ret);
                return size;    /* return size to avoid call back again */
        }

        if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
                dev_info(device,
                        "%s: Device not supported by the driver\n", __func__);
                return size;  /* No device family */
        }

        if (val == 0)   /* val=0 : trigger a EEPROM save */
                ret = copy_scratchpad(sl);
        else {
                if (SLAVE_SPECIFIC_FUNC(sl)->set_resolution)
                        ret = SLAVE_SPECIFIC_FUNC(sl)->set_resolution(sl, val);
        }

        if (ret) {
                dev_warn(device, "%s: Set resolution - error %d\n", __func__, ret);
                /* Propagate error to userspace */
                return ret;
        }
        SLAVE_RESOLUTION(sl) = val;
        /* Reset the conversion time to default - it depends on resolution */
        SLAVE_CONV_TIME_OVERRIDE(sl) = CONV_TIME_DEFAULT;

        return size; /* always return size to avoid infinite calling */
}

static ssize_t temperature_show(struct device *device,
        struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        struct therm_info info;
        int ret = 0;

        if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
                dev_info(device,
                        "%s: Device not supported by the driver\n", __func__);
                return 0;  /* No device family */
        }

        if (bulk_read_support(sl)) {
                if (SLAVE_CONVERT_TRIGGERED(sl) < 0) {
                        dev_dbg(device,
                                "%s: Conversion in progress, retry later\n",
                                __func__);
                        return 0;
                } else if (SLAVE_CONVERT_TRIGGERED(sl) > 0) {
                        /* A bulk read has been issued, read the device RAM */
                        ret = read_scratchpad(sl, &info);
                        SLAVE_CONVERT_TRIGGERED(sl) = 0;
                } else
                        ret = convert_t(sl, &info);
        } else
                ret = convert_t(sl, &info);

        if (ret < 0) {
                dev_dbg(device,
                        "%s: Temperature data may be corrupted. err=%d\n",
                        __func__, ret);
                return 0;
        }

        return sprintf(buf, "%d\n", temperature_from_RAM(sl, info.rom));
}

static ssize_t ext_power_show(struct device *device,
        struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);

        if (!sl->family_data) {
                dev_info(device,
                        "%s: Device not supported by the driver\n", __func__);
                return 0;  /* No device family */
        }

        /* Getting the power mode of the device {external, parasite} */
        SLAVE_POWERMODE(sl) = read_powermode(sl);

        if (SLAVE_POWERMODE(sl) < 0) {
                dev_dbg(device,
                        "%s: Power_mode may be corrupted. err=%d\n",
                        __func__, SLAVE_POWERMODE(sl));
        }
        return sprintf(buf, "%d\n", SLAVE_POWERMODE(sl));
}

static ssize_t resolution_show(struct device *device,
        struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);

        if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
                dev_info(device,
                        "%s: Device not supported by the driver\n", __func__);
                return 0;  /* No device family */
        }

        /* get the correct function depending on the device */
        SLAVE_RESOLUTION(sl) = SLAVE_SPECIFIC_FUNC(sl)->get_resolution(sl);
        if (SLAVE_RESOLUTION(sl) < 0) {
                dev_dbg(device,
                        "%s: Resolution may be corrupted. err=%d\n",
                        __func__, SLAVE_RESOLUTION(sl));
        }

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

static ssize_t resolution_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        int val;
        int ret = 0;

        ret = kstrtoint(buf, 10, &val); /* converting user entry to int */

        if (ret) {      /* conversion error */
                dev_info(device,
                        "%s: conversion error. err= %d\n", __func__, ret);
                return size;    /* return size to avoid call back again */
        }

        if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
                dev_info(device,
                        "%s: Device not supported by the driver\n", __func__);
                return size;  /* No device family */
        }

        /*
         * Don't deal with the val enterd by user,
         * only device knows what is correct or not
         */

        /* get the correct function depending on the device */
        ret = SLAVE_SPECIFIC_FUNC(sl)->set_resolution(sl, val);

        if (ret)
                return ret;

        SLAVE_RESOLUTION(sl) = val;
        /* Reset the conversion time to default because it depends on resolution */
        SLAVE_CONV_TIME_OVERRIDE(sl) = CONV_TIME_DEFAULT;

        return size;
}

static ssize_t eeprom_cmd_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        int ret = -EINVAL; /* Invalid argument */

        if (size == sizeof(EEPROM_CMD_WRITE)) {
                if (!strncmp(buf, EEPROM_CMD_WRITE, sizeof(EEPROM_CMD_WRITE)-1))
                        ret = copy_scratchpad(sl);
        } else if (size == sizeof(EEPROM_CMD_READ)) {
                if (!strncmp(buf, EEPROM_CMD_READ, sizeof(EEPROM_CMD_READ)-1))
                        ret = recall_eeprom(sl);
        }

        if (ret)
                dev_info(device, "%s: error in process %d\n", __func__, ret);

        return size;
}

static ssize_t alarms_show(struct device *device,
        struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        int ret;
        s8 th = 0, tl = 0;
        struct therm_info scratchpad;

        ret = read_scratchpad(sl, &scratchpad);

        if (!ret)       {
                th = scratchpad.rom[2]; /* TH is byte 2 */
                tl = scratchpad.rom[3]; /* TL is byte 3 */
        } else {
                dev_info(device,
                        "%s: error reading alarms register %d\n",
                        __func__, ret);
        }

        return sprintf(buf, "%hd %hd\n", tl, th);
}

static ssize_t alarms_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        struct therm_info info;
        u8 new_config_register[3];      /* array of data to be written */
        int temp, ret;
        char *token = NULL;
        s8 tl, th, tt;  /* 1 byte per value + temp ring order */
        char *p_args, *orig;

        p_args = orig = kmalloc(size, GFP_KERNEL);
        /* Safe string copys as buf is const */
        if (!p_args) {
                dev_warn(device,
                        "%s: error unable to allocate memory %d\n",
                        __func__, -ENOMEM);
                return size;
        }
        strcpy(p_args, buf);

        /* Split string using space char */
        token = strsep(&p_args, " ");

        if (!token)     {
                dev_info(device,
                        "%s: error parsing args %d\n", __func__, -EINVAL);
                goto free_m;
        }

        /* Convert 1st entry to int */
        ret = kstrtoint (token, 10, &temp);
        if (ret) {
                dev_info(device,
                        "%s: error parsing args %d\n", __func__, ret);
                goto free_m;
        }

        tl = int_to_short(temp);

        /* Split string using space char */
        token = strsep(&p_args, " ");
        if (!token)     {
                dev_info(device,
                        "%s: error parsing args %d\n", __func__, -EINVAL);
                goto free_m;
        }
        /* Convert 2nd entry to int */
        ret = kstrtoint (token, 10, &temp);
        if (ret) {
                dev_info(device,
                        "%s: error parsing args %d\n", __func__, ret);
                goto free_m;
        }

        /* Prepare to cast to short by eliminating out of range values */
        th = int_to_short(temp);

        /* Reorder if required th and tl */
        if (tl > th) {
                tt = tl; tl = th; th = tt;
        }

        /*
         * Read the scratchpad to change only the required bits
         * (th : byte 2 - tl: byte 3)
         */
        ret = read_scratchpad(sl, &info);
        if (!ret) {
                new_config_register[0] = th;    /* Byte 2 */
                new_config_register[1] = tl;    /* Byte 3 */
                new_config_register[2] = info.rom[4];/* Byte 4 */
        } else {
                dev_info(device,
                        "%s: error reading from the slave device %d\n",
                        __func__, ret);
                goto free_m;
        }

        /* Write data in the device RAM */
        if (!SLAVE_SPECIFIC_FUNC(sl)) {
                dev_info(device,
                        "%s: Device not supported by the driver %d\n",
                        __func__, -ENODEV);
                goto free_m;
        }

        ret = SLAVE_SPECIFIC_FUNC(sl)->write_data(sl, new_config_register);
        if (ret)
                dev_info(device,
                        "%s: error writing to the slave device %d\n",
                        __func__, ret);

free_m:
        /* free allocated memory */
        kfree(orig);

        return size;
}

static ssize_t therm_bulk_read_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size)
{
        struct w1_master *dev_master = dev_to_w1_master(device);
        int ret = -EINVAL; /* Invalid argument */

        if (size == sizeof(BULK_TRIGGER_CMD))
                if (!strncmp(buf, BULK_TRIGGER_CMD,
                                sizeof(BULK_TRIGGER_CMD)-1))
                        ret = trigger_bulk_read(dev_master);

        if (ret)
                dev_info(device,
                        "%s: unable to trigger a bulk read on the bus. err=%d\n",
                        __func__, ret);

        return size;
}

static ssize_t therm_bulk_read_show(struct device *device,
        struct device_attribute *attr, char *buf)
{
        struct w1_master *dev_master = dev_to_w1_master(device);
        struct w1_slave *sl = NULL;
        int ret = 0;

        list_for_each_entry(sl, &dev_master->slist, w1_slave_entry) {
                if (sl->family_data) {
                        if (bulk_read_support(sl)) {
                                if (SLAVE_CONVERT_TRIGGERED(sl) == -1) {
                                        ret = -1;
                                        goto show_result;
                                }
                                if (SLAVE_CONVERT_TRIGGERED(sl) == 1)
                                        /* continue to check other slaves */
                                        ret = 1;
                        }
                }
        }
show_result:
        return sprintf(buf, "%d\n", ret);
}

static ssize_t conv_time_show(struct device *device,
        struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);

        if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
                dev_info(device,
                        "%s: Device is not supported by the driver\n", __func__);
                return 0;  /* No device family */
        }
        return sprintf(buf, "%d\n", conversion_time(sl));
}

static ssize_t conv_time_store(struct device *device,
        struct device_attribute *attr, const char *buf, size_t size)
{
        int val, ret = 0;
        struct w1_slave *sl = dev_to_w1_slave(device);

        if (kstrtoint(buf, 10, &val)) /* converting user entry to int */
                return -EINVAL;

        if (check_family_data(sl))
                return -ENODEV;

        if (val != CONV_TIME_MEASURE) {
                if (val >= CONV_TIME_DEFAULT)
                        SLAVE_CONV_TIME_OVERRIDE(sl) = val;
                else
                        return -EINVAL;

        } else {
                int conv_time;

                ret = conv_time_measure(sl, &conv_time);
                if (ret)
                        return -EIO;
                SLAVE_CONV_TIME_OVERRIDE(sl) = conv_time;
        }
        return size;
}

static ssize_t features_show(struct device *device,
                             struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);

        if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
                dev_info(device,
                         "%s: Device not supported by the driver\n", __func__);
                return 0;  /* No device family */
        }
        return sprintf(buf, "%u\n", SLAVE_FEATURES(sl));
}

static ssize_t features_store(struct device *device,
                              struct device_attribute *attr, const char *buf, size_t size)
{
        int val, ret = 0;
        bool strong_pullup;
        struct w1_slave *sl = dev_to_w1_slave(device);

        ret = kstrtouint(buf, 10, &val); /* converting user entry to int */
        if (ret)
                return -EINVAL;  /* invalid number */

        if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
                dev_info(device, "%s: Device not supported by the driver\n", __func__);
                return -ENODEV;
        }

        if ((val & W1_THERM_FEATURES_MASK) != val)
                return -EINVAL;

        SLAVE_FEATURES(sl) = val;

        strong_pullup = (w1_strong_pullup == 2 ||
                         (!SLAVE_POWERMODE(sl) &&

                          w1_strong_pullup));

        if (strong_pullup && SLAVE_FEATURES(sl) & W1_THERM_POLL_COMPLETION) {
                dev_warn(&sl->dev,
                         "%s: W1_THERM_POLL_COMPLETION disabled in parasite power mode.\n",
                         __func__);
                SLAVE_FEATURES(sl) &= ~W1_THERM_POLL_COMPLETION;
        }

        return size;
}

#if IS_REACHABLE(CONFIG_HWMON)
static int w1_read_temp(struct device *device, u32 attr, int channel,
                        long *val)
{
        struct w1_slave *sl = dev_get_drvdata(device);
        struct therm_info info;
        int ret;

        switch (attr) {
        case hwmon_temp_input:
                ret = convert_t(sl, &info);
                if (ret)
                        return ret;

                if (!info.verdict) {
                        ret = -EIO;
                        return ret;
                }

                *val = temperature_from_RAM(sl, info.rom);
                ret = 0;
                break;
        default:
                ret = -EOPNOTSUPP;
                break;
        }

        return ret;
}
#endif

#define W1_42_CHAIN     0x99
#define W1_42_CHAIN_OFF 0x3C
#define W1_42_CHAIN_OFF_INV     0xC3
#define W1_42_CHAIN_ON  0x5A
#define W1_42_CHAIN_ON_INV      0xA5
#define W1_42_CHAIN_DONE 0x96
#define W1_42_CHAIN_DONE_INV 0x69
#define W1_42_COND_READ 0x0F
#define W1_42_SUCCESS_CONFIRM_BYTE 0xAA
#define W1_42_FINISHED_BYTE 0xFF
static ssize_t w1_seq_show(struct device *device,
        struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        ssize_t c = PAGE_SIZE;
        int i;
        u8 ack;
        u64 rn;
        struct w1_reg_num *reg_num;
        int seq = 0;

        mutex_lock(&sl->master->bus_mutex);
        /* Place all devices in CHAIN state */
        if (w1_reset_bus(sl->master))
                goto error;
        w1_write_8(sl->master, W1_SKIP_ROM);
        w1_write_8(sl->master, W1_42_CHAIN);
        w1_write_8(sl->master, W1_42_CHAIN_ON);
        w1_write_8(sl->master, W1_42_CHAIN_ON_INV);
        msleep(sl->master->pullup_duration);

        /* check for acknowledgment */
        ack = w1_read_8(sl->master);
        if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
                goto error;

        /* In case the bus fails to send 0xFF, limit */
        for (i = 0; i <= 64; i++) {
                if (w1_reset_bus(sl->master))
                        goto error;

                w1_write_8(sl->master, W1_42_COND_READ);
                w1_read_block(sl->master, (u8 *)&rn, 8);
                reg_num = (struct w1_reg_num *) &rn;
                if (reg_num->family == W1_42_FINISHED_BYTE)
                        break;
                if (sl->reg_num.id == reg_num->id)
                        seq = i;

                w1_write_8(sl->master, W1_42_CHAIN);
                w1_write_8(sl->master, W1_42_CHAIN_DONE);
                w1_write_8(sl->master, W1_42_CHAIN_DONE_INV);
                w1_read_block(sl->master, &ack, sizeof(ack));

                /* check for acknowledgment */
                ack = w1_read_8(sl->master);
                if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
                        goto error;

        }

        /* Exit from CHAIN state */
        if (w1_reset_bus(sl->master))
                goto error;
        w1_write_8(sl->master, W1_SKIP_ROM);
        w1_write_8(sl->master, W1_42_CHAIN);
        w1_write_8(sl->master, W1_42_CHAIN_OFF);
        w1_write_8(sl->master, W1_42_CHAIN_OFF_INV);

        /* check for acknowledgment */
        ack = w1_read_8(sl->master);
        if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
                goto error;
        mutex_unlock(&sl->master->bus_mutex);

        c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", seq);
        return PAGE_SIZE - c;
error:
        mutex_unlock(&sl->master->bus_mutex);
        return -EIO;
}

static int __init w1_therm_init(void)
{
        int err, i;

        for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
                err = w1_register_family(w1_therm_families[i].f);
                if (err)
                        w1_therm_families[i].broken = 1;
        }

        return 0;
}

static void __exit w1_therm_fini(void)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
                if (!w1_therm_families[i].broken)
                        w1_unregister_family(w1_therm_families[i].f);
}

module_init(w1_therm_init);
module_exit(w1_therm_fini);

MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol, temperature family.");
MODULE_LICENSE("GPL");
MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS18S20));
MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS1822));
MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS18B20));
MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS1825));
MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS28EA00));