// SPDX-License-Identifier: GPL-2.0
/*
 * Hwmon client for disk and solid state drives with temperature sensors
 * Copyright (C) 2019 Zodiac Inflight Innovations
 *
 * With input from:
 *    Hwmon client for S.M.A.R.T. hard disk drives with temperature sensors.
 *    (C) 2018 Linus Walleij
 *
 *    hwmon: Driver for SCSI/ATA temperature sensors
 *    by Constantin Baranov <const@mimas.ru>, submitted September 2009
 *
 * This drive supports reporting the temperature of SATA drives. It can be
 * easily extended to report the temperature of SCSI drives.
 *
 * The primary means to read drive temperatures and temperature limits
 * for ATA drives is the SCT Command Transport feature set as specified in
 * ATA8-ACS.
 * It can be used to read the current drive temperature, temperature limits,
 * and historic minimum and maximum temperatures. The SCT Command Transport
 * feature set is documented in "AT Attachment 8 - ATA/ATAPI Command Set
 * (ATA8-ACS)".
 *
 * If the SCT Command Transport feature set is not available, drive temperatures
 * may be readable through SMART attributes. Since SMART attributes are not well
 * defined, this method is only used as fallback mechanism.
 *
 * There are three SMART attributes which may report drive temperatures.
 * Those are defined as follows (from
 * http://www.cropel.com/library/smart-attribute-list.aspx).
 *
 * 190  Temperature     Temperature, monitored by a sensor somewhere inside
 *                      the drive. Raw value typicaly holds the actual
 *                      temperature (hexadecimal) in its rightmost two digits.
 *
 * 194  Temperature     Temperature, monitored by a sensor somewhere inside
 *                      the drive. Raw value typicaly holds the actual
 *                      temperature (hexadecimal) in its rightmost two digits.
 *
 * 231  Temperature     Temperature, monitored by a sensor somewhere inside
 *                      the drive. Raw value typicaly holds the actual
 *                      temperature (hexadecimal) in its rightmost two digits.
 *
 * Wikipedia defines attributes a bit differently.
 *
 * 190  Temperature     Value is equal to (100-temp. °C), allowing manufacturer
 *      Difference or   to set a minimum threshold which corresponds to a
 *      Airflow         maximum temperature. This also follows the convention of
 *      Temperature     100 being a best-case value and lower values being
 *                      undesirable. However, some older drives may instead
 *                      report raw Temperature (identical to 0xC2) or
 *                      Temperature minus 50 here.
 * 194  Temperature or  Indicates the device temperature, if the appropriate
 *      Temperature     sensor is fitted. Lowest byte of the raw value contains
 *      Celsius         the exact temperature value (Celsius degrees).
 * 231  Life Left       Indicates the approximate SSD life left, in terms of
 *      (SSDs) or       program/erase cycles or available reserved blocks.
 *      Temperature     A normalized value of 100 represents a new drive, with
 *                      a threshold value at 10 indicating a need for
 *                      replacement. A value of 0 may mean that the drive is
 *                      operating in read-only mode to allow data recovery.
 *                      Previously (pre-2010) occasionally used for Drive
 *                      Temperature (more typically reported at 0xC2).
 *
 * Common denominator is that the first raw byte reports the temperature
 * in degrees C on almost all drives. Some drives may report a fractional
 * temperature in the second raw byte.
 *
 * Known exceptions (from libatasmart):
 * - SAMSUNG SV0412H and SAMSUNG SV1204H) report the temperature in 10th
 *   degrees C in the first two raw bytes.
 * - A few Maxtor drives report an unknown or bad value in attribute 194.
 * - Certain Apple SSD drives report an unknown value in attribute 190.
 *   Only certain firmware versions are affected.
 *
 * Those exceptions affect older ATA drives and are currently ignored.
 * Also, the second raw byte (possibly reporting the fractional temperature)
 * is currently ignored.
 *
 * Many drives also report temperature limits in additional SMART data raw
 * bytes. The format of those is not well defined and varies widely.
 * The driver does not currently attempt to report those limits.
 *
 * According to data in smartmontools, attribute 231 is rarely used to report
 * drive temperatures. At the same time, several drives report SSD life left
 * in attribute 231, but do not support temperature sensors. For this reason,
 * attribute 231 is currently ignored.
 *
 * Following above definitions, temperatures are reported as follows.
 *   If SCT Command Transport is supported, it is used to read the
 *   temperature and, if available, temperature limits.
 * - Otherwise, if SMART attribute 194 is supported, it is used to read
 *   the temperature.
 * - Otherwise, if SMART attribute 190 is supported, it is used to read
 *   the temperature.
 */

#include <linux/ata.h>
#include <linux/bits.h>
#include <linux/device.h>
#include <linux/hwmon.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_proto.h>

struct drivetemp_data {
        struct list_head list;          /* list of instantiated devices */
        struct scsi_device *sdev;       /* SCSI device */
        struct device *dev;             /* instantiating device */
        struct device *hwdev;           /* hardware monitoring device */
        u8 smartdata[ATA_SECT_SIZE];    /* local buffer */
        int (*get_temp)(struct drivetemp_data *st, u32 attr, long *val);
        bool have_temp_lowest;          /* lowest temp in SCT status */
        bool have_temp_highest;         /* highest temp in SCT status */
        bool have_temp_min;             /* have min temp */
        bool have_temp_max;             /* have max temp */
        bool have_temp_lcrit;           /* have lower critical limit */
        bool have_temp_crit;            /* have critical limit */
        int temp_min;                   /* min temp */
        int temp_max;                   /* max temp */
        int temp_lcrit;                 /* lower critical limit */
        int temp_crit;                  /* critical limit */
};

static LIST_HEAD(drivetemp_devlist);

#define ATA_MAX_SMART_ATTRS     30
#define SMART_TEMP_PROP_190     190
#define SMART_TEMP_PROP_194     194

#define SCT_STATUS_REQ_ADDR     0xe0
#define  SCT_STATUS_VERSION_LOW         0       /* log byte offsets */
#define  SCT_STATUS_VERSION_HIGH        1
#define  SCT_STATUS_TEMP                200
#define  SCT_STATUS_TEMP_LOWEST         201
#define  SCT_STATUS_TEMP_HIGHEST        202
#define SCT_READ_LOG_ADDR       0xe1
#define  SMART_READ_LOG                 0xd5
#define  SMART_WRITE_LOG                0xd6

#define INVALID_TEMP            0x80

#define temp_is_valid(temp)     ((temp) != INVALID_TEMP)
#define temp_from_sct(temp)     (((s8)(temp)) * 1000)

static inline bool ata_id_smart_supported(u16 *id)
{
        return id[ATA_ID_COMMAND_SET_1] & BIT(0);
}

static inline bool ata_id_smart_enabled(u16 *id)
{
        return id[ATA_ID_CFS_ENABLE_1] & BIT(0);
}

static int drivetemp_scsi_command(struct drivetemp_data *st,
                                 u8 ata_command, u8 feature,
                                 u8 lba_low, u8 lba_mid, u8 lba_high)
{
        u8 scsi_cmd[MAX_COMMAND_SIZE];
        enum req_op op;
        int err;

        memset(scsi_cmd, 0, sizeof(scsi_cmd));
        scsi_cmd[0] = ATA_16;
        if (ata_command == ATA_CMD_SMART && feature == SMART_WRITE_LOG) {
                scsi_cmd[1] = (5 << 1); /* PIO Data-out */
                /*
                 * No off.line or cc, write to dev, block count in sector count
                 * field.
                 */
                scsi_cmd[2] = 0x06;
                op = REQ_OP_DRV_OUT;
        } else {
                scsi_cmd[1] = (4 << 1); /* PIO Data-in */
                /*
                 * No off.line or cc, read from dev, block count in sector count
                 * field.
                 */
                scsi_cmd[2] = 0x0e;
                op = REQ_OP_DRV_IN;
        }
        scsi_cmd[4] = feature;
        scsi_cmd[6] = 1;        /* 1 sector */
        scsi_cmd[8] = lba_low;
        scsi_cmd[10] = lba_mid;
        scsi_cmd[12] = lba_high;
        scsi_cmd[14] = ata_command;

        err = scsi_execute_cmd(st->sdev, scsi_cmd, op, st->smartdata,
                               ATA_SECT_SIZE, 10 * HZ, 5, NULL);
        if (err > 0)
                err = -EIO;
        return err;
}

static int drivetemp_ata_command(struct drivetemp_data *st, u8 feature,
                                 u8 select)
{
        return drivetemp_scsi_command(st, ATA_CMD_SMART, feature, select,
                                     ATA_SMART_LBAM_PASS, ATA_SMART_LBAH_PASS);
}

static int drivetemp_get_smarttemp(struct drivetemp_data *st, u32 attr,
                                  long *temp)
{
        u8 *buf = st->smartdata;
        bool have_temp = false;
        u8 temp_raw;
        u8 csum;
        int err;
        int i;

        err = drivetemp_ata_command(st, ATA_SMART_READ_VALUES, 0);
        if (err)
                return err;

        /* Checksum the read value table */
        csum = 0;
        for (i = 0; i < ATA_SECT_SIZE; i++)
                csum += buf[i];
        if (csum) {
                dev_dbg(&st->sdev->sdev_gendev,
                        "checksum error reading SMART values\n");
                return -EIO;
        }

        for (i = 0; i < ATA_MAX_SMART_ATTRS; i++) {
                u8 *attr = buf + i * 12;
                int id = attr[2];

                if (!id)
                        continue;

                if (id == SMART_TEMP_PROP_190) {
                        temp_raw = attr[7];
                        have_temp = true;
                }
                if (id == SMART_TEMP_PROP_194) {
                        temp_raw = attr[7];
                        have_temp = true;
                        break;
                }
        }

        if (have_temp) {
                *temp = temp_raw * 1000;
                return 0;
        }

        return -ENXIO;
}

static int drivetemp_get_scttemp(struct drivetemp_data *st, u32 attr, long *val)
{
        u8 *buf = st->smartdata;
        int err;

        err = drivetemp_ata_command(st, SMART_READ_LOG, SCT_STATUS_REQ_ADDR);
        if (err)
                return err;
        switch (attr) {
        case hwmon_temp_input:
                if (!temp_is_valid(buf[SCT_STATUS_TEMP]))
                        return -ENODATA;
                *val = temp_from_sct(buf[SCT_STATUS_TEMP]);
                break;
        case hwmon_temp_lowest:
                if (!temp_is_valid(buf[SCT_STATUS_TEMP_LOWEST]))
                        return -ENODATA;
                *val = temp_from_sct(buf[SCT_STATUS_TEMP_LOWEST]);
                break;
        case hwmon_temp_highest:
                if (!temp_is_valid(buf[SCT_STATUS_TEMP_HIGHEST]))
                        return -ENODATA;
                *val = temp_from_sct(buf[SCT_STATUS_TEMP_HIGHEST]);
                break;
        default:
                err = -EINVAL;
                break;
        }
        return err;
}

static const char * const sct_avoid_models[] = {
/*
 * These drives will have WRITE FPDMA QUEUED command timeouts and sometimes just
 * freeze until power-cycled under heavy write loads when their temperature is
 * getting polled in SCT mode. The SMART mode seems to be fine, though.
 *
 * While only the 3 TB model (DT01ACA3) was actually caught exhibiting the
 * problem let's play safe here to avoid data corruption and ban the whole
 * DT01ACAx family.

 * The models from this array are prefix-matched.
 */
        "TOSHIBA DT01ACA",
};

static bool drivetemp_sct_avoid(struct drivetemp_data *st)
{
        struct scsi_device *sdev = st->sdev;
        unsigned int ctr;

        if (!sdev->model)
                return false;

        /*
         * The "model" field contains just the raw SCSI INQUIRY response
         * "product identification" field, which has a width of 16 bytes.
         * This field is space-filled, but is NOT NULL-terminated.
         */
        for (ctr = 0; ctr < ARRAY_SIZE(sct_avoid_models); ctr++)
                if (!strncmp(sdev->model, sct_avoid_models[ctr],
                             strlen(sct_avoid_models[ctr])))
                        return true;

        return false;
}

static int drivetemp_identify_sata(struct drivetemp_data *st)
{
        struct scsi_device *sdev = st->sdev;
        u8 *buf = st->smartdata;
        struct scsi_vpd *vpd;
        bool is_ata, is_sata;
        bool have_sct_data_table;
        bool have_sct_temp;
        bool have_smart;
        bool have_sct;
        u16 *ata_id;
        u16 version;
        long temp;
        int err;

        /* SCSI-ATA Translation present? */
        rcu_read_lock();
        vpd = rcu_dereference(sdev->vpd_pg89);

        /*
         * Verify that ATA IDENTIFY DEVICE data is included in ATA Information
         * VPD and that the drive implements the SATA protocol.
         */
        if (!vpd || vpd->len < 572 || vpd->data[56] != ATA_CMD_ID_ATA ||
            vpd->data[36] != 0x34) {
                rcu_read_unlock();
                return -ENODEV;
        }
        ata_id = (u16 *)&vpd->data[60];
        is_ata = ata_id_is_ata(ata_id);
        is_sata = ata_id_is_sata(ata_id);
        have_sct = ata_id_sct_supported(ata_id);
        have_sct_data_table = ata_id_sct_data_tables(ata_id);
        have_smart = ata_id_smart_supported(ata_id) &&
                                ata_id_smart_enabled(ata_id);

        rcu_read_unlock();

        /* bail out if this is not a SATA device */
        if (!is_ata || !is_sata)
                return -ENODEV;

        if (have_sct && drivetemp_sct_avoid(st)) {
                dev_notice(&sdev->sdev_gendev,
                           "will avoid using SCT for temperature monitoring\n");
                have_sct = false;
        }

        if (!have_sct)
                goto skip_sct;

        err = drivetemp_ata_command(st, SMART_READ_LOG, SCT_STATUS_REQ_ADDR);
        if (err)
                goto skip_sct;

        version = (buf[SCT_STATUS_VERSION_HIGH] << 8) |
                  buf[SCT_STATUS_VERSION_LOW];
        if (version != 2 && version != 3)
                goto skip_sct;

        have_sct_temp = temp_is_valid(buf[SCT_STATUS_TEMP]);
        if (!have_sct_temp)
                goto skip_sct;

        st->have_temp_lowest = temp_is_valid(buf[SCT_STATUS_TEMP_LOWEST]);
        st->have_temp_highest = temp_is_valid(buf[SCT_STATUS_TEMP_HIGHEST]);

        if (!have_sct_data_table)
                goto skip_sct_data;

        /* Request and read temperature history table */
        memset(buf, '\0', sizeof(st->smartdata));
        buf[0] = 5;     /* data table command */
        buf[2] = 1;     /* read table */
        buf[4] = 2;     /* temperature history table */

        err = drivetemp_ata_command(st, SMART_WRITE_LOG, SCT_STATUS_REQ_ADDR);
        if (err)
                goto skip_sct_data;

        err = drivetemp_ata_command(st, SMART_READ_LOG, SCT_READ_LOG_ADDR);
        if (err)
                goto skip_sct_data;

        /*
         * Temperature limits per AT Attachment 8 -
         * ATA/ATAPI Command Set (ATA8-ACS)
         */
        st->have_temp_max = temp_is_valid(buf[6]);
        st->have_temp_crit = temp_is_valid(buf[7]);
        st->have_temp_min = temp_is_valid(buf[8]);
        st->have_temp_lcrit = temp_is_valid(buf[9]);

        st->temp_max = temp_from_sct(buf[6]);
        st->temp_crit = temp_from_sct(buf[7]);
        st->temp_min = temp_from_sct(buf[8]);
        st->temp_lcrit = temp_from_sct(buf[9]);

skip_sct_data:
        if (have_sct_temp) {
                st->get_temp = drivetemp_get_scttemp;
                return 0;
        }
skip_sct:
        if (!have_smart)
                return -ENODEV;
        st->get_temp = drivetemp_get_smarttemp;
        return drivetemp_get_smarttemp(st, hwmon_temp_input, &temp);
}

static int drivetemp_identify(struct drivetemp_data *st)
{
        struct scsi_device *sdev = st->sdev;

        /* Bail out immediately if there is no inquiry data */
        if (!sdev->inquiry || sdev->inquiry_len < 16)
                return -ENODEV;

        /* Disk device? */
        if (sdev->type != TYPE_DISK && sdev->type != TYPE_ZBC)
                return -ENODEV;

        return drivetemp_identify_sata(st);
}

static int drivetemp_read(struct device *dev, enum hwmon_sensor_types type,
                         u32 attr, int channel, long *val)
{
        struct drivetemp_data *st = dev_get_drvdata(dev);
        int err = 0;

        if (type != hwmon_temp)
                return -EINVAL;

        switch (attr) {
        case hwmon_temp_input:
        case hwmon_temp_lowest:
        case hwmon_temp_highest:
                err = st->get_temp(st, attr, val);
                break;
        case hwmon_temp_lcrit:
                *val = st->temp_lcrit;
                break;
        case hwmon_temp_min:
                *val = st->temp_min;
                break;
        case hwmon_temp_max:
                *val = st->temp_max;
                break;
        case hwmon_temp_crit:
                *val = st->temp_crit;
                break;
        default:
                err = -EINVAL;
                break;
        }
        return err;
}

static umode_t drivetemp_is_visible(const void *data,
                                   enum hwmon_sensor_types type,
                                   u32 attr, int channel)
{
        const struct drivetemp_data *st = data;

        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_input:
                        return 0444;
                case hwmon_temp_lowest:
                        if (st->have_temp_lowest)
                                return 0444;
                        break;
                case hwmon_temp_highest:
                        if (st->have_temp_highest)
                                return 0444;
                        break;
                case hwmon_temp_min:
                        if (st->have_temp_min)
                                return 0444;
                        break;
                case hwmon_temp_max:
                        if (st->have_temp_max)
                                return 0444;
                        break;
                case hwmon_temp_lcrit:
                        if (st->have_temp_lcrit)
                                return 0444;
                        break;
                case hwmon_temp_crit:
                        if (st->have_temp_crit)
                                return 0444;
                        break;
                default:
                        break;
                }
                break;
        default:
                break;
        }
        return 0;
}

static const struct hwmon_channel_info * const drivetemp_info[] = {
        HWMON_CHANNEL_INFO(chip,
                           HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT |
                           HWMON_T_LOWEST | HWMON_T_HIGHEST |
                           HWMON_T_MIN | HWMON_T_MAX |
                           HWMON_T_LCRIT | HWMON_T_CRIT),
        NULL
};

static const struct hwmon_ops drivetemp_ops = {
        .is_visible = drivetemp_is_visible,
        .read = drivetemp_read,
};

static const struct hwmon_chip_info drivetemp_chip_info = {
        .ops = &drivetemp_ops,
        .info = drivetemp_info,
};

/*
 * The device argument points to sdev->sdev_dev. Its parent is
 * sdev->sdev_gendev, which we can use to get the scsi_device pointer.
 */
static int drivetemp_add(struct device *dev)
{
        struct scsi_device *sdev = to_scsi_device(dev->parent);
        struct drivetemp_data *st;
        int err;

        st = kzalloc_obj(*st);
        if (!st)
                return -ENOMEM;

        st->sdev = sdev;
        st->dev = dev;

        if (drivetemp_identify(st)) {
                err = -ENODEV;
                goto abort;
        }

        st->hwdev = hwmon_device_register_with_info(dev->parent, "drivetemp",
                                                    st, &drivetemp_chip_info,
                                                    NULL);
        if (IS_ERR(st->hwdev)) {
                err = PTR_ERR(st->hwdev);
                goto abort;
        }

        list_add(&st->list, &drivetemp_devlist);
        return 0;

abort:
        kfree(st);
        return err;
}

static void drivetemp_remove(struct device *dev)
{
        struct drivetemp_data *st, *tmp;

        list_for_each_entry_safe(st, tmp, &drivetemp_devlist, list) {
                if (st->dev == dev) {
                        list_del(&st->list);
                        hwmon_device_unregister(st->hwdev);
                        kfree(st);
                        break;
                }
        }
}

static struct class_interface drivetemp_interface = {
        .add_dev = drivetemp_add,
        .remove_dev = drivetemp_remove,
};

static int __init drivetemp_init(void)
{
        return scsi_register_interface(&drivetemp_interface);
}

static void __exit drivetemp_exit(void)
{
        scsi_unregister_interface(&drivetemp_interface);
}

module_init(drivetemp_init);
module_exit(drivetemp_exit);

MODULE_AUTHOR("Guenter Roeck <linus@roeck-us.net>");
MODULE_DESCRIPTION("Hard drive temperature monitor");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:drivetemp");