w1_therm.c

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/*
 *  w1_therm.c
 *
 * Copyright (c) 2004 Evgeniy Polyakov <[email protected]>
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the therms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#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/delay.h>

#include "../w1.h"
#include "../w1_int.h"
#include "../w1_family.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <[email protected]>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol, temperature family.");

/* 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.
 */
static int w1_strong_pullup = 1;
module_param_named(strong_pullup, w1_strong_pullup, int, 0);

static u8 bad_roms[][9] = {
                {0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87},
                {}
            };

static ssize_t w1_therm_read(struct device *device,
    struct device_attribute *attr, char *buf);

static struct device_attribute w1_therm_attr =
    __ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL);

static int w1_therm_add_slave(struct w1_slave *sl)
{
    return device_create_file(&sl->dev, &w1_therm_attr);
}

static void w1_therm_remove_slave(struct w1_slave *sl)
{
    device_remove_file(&sl->dev, &w1_therm_attr);
}

static struct w1_family_ops w1_therm_fops = {
    .add_slave  = w1_therm_add_slave,
    .remove_slave   = w1_therm_remove_slave,
};

static struct w1_family w1_therm_family_DS18S20 = {
    .fid = W1_THERM_DS18S20,
    .fops = &w1_therm_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_therm_fops,
};

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

struct w1_therm_family_converter
{
    u8          broken;
    u16         reserved;
    struct w1_family    *f;
    int         (*convert)(u8 rom[9]);
};

/* The return value is millidegrees Centigrade. */
static inline int w1_DS18B20_convert_temp(u8 rom[9]);
static inline int w1_DS18S20_convert_temp(u8 rom[9]);

static struct w1_therm_family_converter w1_therm_families[] = {
    {
        .f      = &w1_therm_family_DS18S20,
        .convert    = w1_DS18S20_convert_temp
    },
    {
        .f      = &w1_therm_family_DS1822,
        .convert    = w1_DS18B20_convert_temp
    },
    {
        .f      = &w1_therm_family_DS18B20,
        .convert    = w1_DS18B20_convert_temp
    },
    {
        .f      = &w1_therm_family_DS28EA00,
        .convert    = w1_DS18B20_convert_temp
    },
    {
        .f      = &w1_therm_family_DS1825,
        .convert    = w1_DS18B20_convert_temp
    }
};

static inline int w1_DS18B20_convert_temp(u8 rom[9])
{
    s16 t = le16_to_cpup((__le16 *)rom);
    return t*1000/16;
}

static inline int w1_DS18S20_convert_temp(u8 rom[9])
{
    int t, h;

    if (!rom[7])
        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;
}

static inline int w1_convert_temp(u8 rom[9], u8 fid)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
        if (w1_therm_families[i].f->fid == fid)
            return w1_therm_families[i].convert(rom);

    return 0;
}

static int w1_therm_check_rom(u8 rom[9])
{
    int i;

    for (i=0; i<sizeof(bad_roms)/9; ++i)
        if (!memcmp(bad_roms[i], rom, 9))
            return 1;

    return 0;
}

static ssize_t w1_therm_read(struct device *device,
    struct device_attribute *attr, char *buf)
{
    struct w1_slave *sl = dev_to_w1_slave(device);
    struct w1_master *dev = sl->master;
    u8 rom[9], crc, verdict, external_power;
    int i, max_trying = 10;
    ssize_t c = PAGE_SIZE;

    i = mutex_lock_interruptible(&dev->bus_mutex);
    if (i != 0)
        return i;

    memset(rom, 0, sizeof(rom));

    verdict = 0;
    crc = 0;

    while (max_trying--) {
        if (!w1_reset_select_slave(sl)) {
            int count = 0;
            unsigned int tm = 750;
            unsigned long sleep_rem;

            w1_write_8(dev, W1_READ_PSUPPLY);
            external_power = w1_read_8(dev);

            if (w1_reset_select_slave(sl))
                continue;

            /* 750ms strong pullup (or delay) after the convert */
            if (!external_power && w1_strong_pullup)
                w1_next_pullup(dev, tm);

            w1_write_8(dev, W1_CONVERT_TEMP);

            if (external_power) {
                mutex_unlock(&dev->bus_mutex);

                sleep_rem = msleep_interruptible(tm);
                if (sleep_rem != 0)
                    return -EINTR;

                i = mutex_lock_interruptible(&dev->bus_mutex);
                if (i != 0)
                    return i;
            } else if (!w1_strong_pullup) {
                sleep_rem = msleep_interruptible(tm);
                if (sleep_rem != 0) {
                    mutex_unlock(&dev->bus_mutex);
                    return -EINTR;
                }
            }

            if (!w1_reset_select_slave(sl)) {

                w1_write_8(dev, W1_READ_SCRATCHPAD);
                if ((count = w1_read_block(dev, rom, 9)) != 9) {
                    dev_warn(device, "w1_read_block() "
                        "returned %u instead of 9.\n",
                        count);
                }

                crc = w1_calc_crc8(rom, 8);

                if (rom[8] == crc)
                    verdict = 1;
            }
        }

        if (!w1_therm_check_rom(rom))
            break;
    }

    for (i = 0; i < 9; ++i)
        c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
    c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
               crc, (verdict) ? "YES" : "NO");
    if (verdict)
        memcpy(sl->rom, rom, sizeof(sl->rom));
    else
        dev_warn(device, "18S20 doesn't respond to CONVERT_TEMP.\n");

    for (i = 0; i < 9; ++i)
        c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]);

    c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
        w1_convert_temp(rom, sl->family->fid));
    mutex_unlock(&dev->bus_mutex);

    return PAGE_SIZE - c;
}

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);