applesmc.c

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/*
 * drivers/hwmon/applesmc.c - driver for Apple's SMC (accelerometer, temperature
 * sensors, fan control, keyboard backlight control) used in Intel-based Apple
 * computers.
 *
 * Copyright (C) 2007 Nicolas Boichat <[email protected]>
 * Copyright (C) 2010 Henrik Rydberg <[email protected]>
 *
 * Based on hdaps.c driver:
 * Copyright (C) 2005 Robert Love <[email protected]>
 * Copyright (C) 2005 Jesper Juhl <[email protected]>
 *
 * Fan control based on smcFanControl:
 * Copyright (C) 2006 Hendrik Holtmann <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License v2 as published by the
 * Free Software Foundation.
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/input-polldev.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/timer.h>
#include <linux/dmi.h>
#include <linux/mutex.h>
#include <linux/hwmon-sysfs.h>
#include <linux/io.h>
#include <linux/leds.h>
#include <linux/hwmon.h>
#include <linux/workqueue.h>
#include <linux/err.h>

/* data port used by Apple SMC */
#define APPLESMC_DATA_PORT  0x300
/* command/status port used by Apple SMC */
#define APPLESMC_CMD_PORT   0x304

#define APPLESMC_NR_PORTS   32 /* 0x300-0x31f */

#define APPLESMC_MAX_DATA_LENGTH 32

/* wait up to 128 ms for a status change. */
#define APPLESMC_MIN_WAIT   0x0010
#define APPLESMC_RETRY_WAIT 0x0100
#define APPLESMC_MAX_WAIT   0x20000

#define APPLESMC_READ_CMD   0x10
#define APPLESMC_WRITE_CMD  0x11
#define APPLESMC_GET_KEY_BY_INDEX_CMD   0x12
#define APPLESMC_GET_KEY_TYPE_CMD   0x13

#define KEY_COUNT_KEY       "#KEY" /* r-o ui32 */

#define LIGHT_SENSOR_LEFT_KEY   "ALV0" /* r-o {alv (6-10 bytes) */
#define LIGHT_SENSOR_RIGHT_KEY  "ALV1" /* r-o {alv (6-10 bytes) */
#define BACKLIGHT_KEY       "LKSB" /* w-o {lkb (2 bytes) */

#define CLAMSHELL_KEY       "MSLD" /* r-o ui8 (unused) */

#define MOTION_SENSOR_X_KEY "MO_X" /* r-o sp78 (2 bytes) */
#define MOTION_SENSOR_Y_KEY "MO_Y" /* r-o sp78 (2 bytes) */
#define MOTION_SENSOR_Z_KEY "MO_Z" /* r-o sp78 (2 bytes) */
#define MOTION_SENSOR_KEY   "MOCN" /* r/w ui16 */

#define FANS_COUNT      "FNum" /* r-o ui8 */
#define FANS_MANUAL     "FS! " /* r-w ui16 */
#define FAN_ID_FMT      "F%dID" /* r-o char[16] */

#define TEMP_SENSOR_TYPE    "sp78"

/* List of keys used to read/write fan speeds */
static const char *const fan_speed_fmt[] = {
    "F%dAc",        /* actual speed */
    "F%dMn",        /* minimum speed (rw) */
    "F%dMx",        /* maximum speed */
    "F%dSf",        /* safe speed - not all models */
    "F%dTg",        /* target speed (manual: rw) */
};

#define INIT_TIMEOUT_MSECS  5000    /* wait up to 5s for device init ... */
#define INIT_WAIT_MSECS     50  /* ... in 50ms increments */

#define APPLESMC_POLL_INTERVAL  50  /* msecs */
#define APPLESMC_INPUT_FUZZ 4   /* input event threshold */
#define APPLESMC_INPUT_FLAT 4

#define to_index(attr) (to_sensor_dev_attr(attr)->index & 0xffff)
#define to_option(attr) (to_sensor_dev_attr(attr)->index >> 16)

/* Dynamic device node attributes */
struct applesmc_dev_attr {
    struct sensor_device_attribute sda; /* hwmon attributes */
    char name[32];              /* room for node file name */
};

/* Dynamic device node group */
struct applesmc_node_group {
    char *format;               /* format string */
    void *show;             /* show function */
    void *store;                /* store function */
    int option;             /* function argument */
    struct applesmc_dev_attr *nodes;    /* dynamic node array */
};

/* AppleSMC entry - cached register information */
struct applesmc_entry {
    char key[5];        /* four-letter key code */
    u8 valid;       /* set when entry is successfully read once */
    u8 len;         /* bounded by APPLESMC_MAX_DATA_LENGTH */
    char type[5];       /* four-letter type code */
    u8 flags;       /* 0x10: func; 0x40: write; 0x80: read */
};

/* Register lookup and registers common to all SMCs */
static struct applesmc_registers {
    struct mutex mutex;     /* register read/write mutex */
    unsigned int key_count;     /* number of SMC registers */
    unsigned int fan_count;     /* number of fans */
    unsigned int temp_count;    /* number of temperature registers */
    unsigned int temp_begin;    /* temperature lower index bound */
    unsigned int temp_end;      /* temperature upper index bound */
    unsigned int index_count;   /* size of temperature index array */
    int num_light_sensors;      /* number of light sensors */
    bool has_accelerometer;     /* has motion sensor */
    bool has_key_backlight;     /* has keyboard backlight */
    bool init_complete;     /* true when fully initialized */
    struct applesmc_entry *cache;   /* cached key entries */
    const char **index;     /* temperature key index */
} smcreg = {
    .mutex = __MUTEX_INITIALIZER(smcreg.mutex),
};

static const int debug;
static struct platform_device *pdev;
static s16 rest_x;
static s16 rest_y;
static u8 backlight_state[2];

static struct device *hwmon_dev;
static struct input_polled_dev *applesmc_idev;

/*
 * Last index written to key_at_index sysfs file, and value to use for all other
 * key_at_index_* sysfs files.
 */
static unsigned int key_at_index;

static struct workqueue_struct *applesmc_led_wq;

/*
 * wait_read - Wait for a byte to appear on SMC port. Callers must
 * hold applesmc_lock.
 */
static int wait_read(void)
{
    u8 status;
    int us;
    for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
        udelay(us);
        status = inb(APPLESMC_CMD_PORT);
        /* read: wait for smc to settle */
        if (status & 0x01)
            return 0;
    }

    pr_warn("wait_read() fail: 0x%02x\n", status);
    return -EIO;
}

/*
 * send_byte - Write to SMC port, retrying when necessary. Callers
 * must hold applesmc_lock.
 */
static int send_byte(u8 cmd, u16 port)
{
    u8 status;
    int us;

    outb(cmd, port);
    for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
        udelay(us);
        status = inb(APPLESMC_CMD_PORT);
        /* write: wait for smc to settle */
        if (status & 0x02)
            continue;
        /* ready: cmd accepted, return */
        if (status & 0x04)
            return 0;
        /* timeout: give up */
        if (us << 1 == APPLESMC_MAX_WAIT)
            break;
        /* busy: long wait and resend */
        udelay(APPLESMC_RETRY_WAIT);
        outb(cmd, port);
    }

    pr_warn("send_byte(0x%02x, 0x%04x) fail: 0x%02x\n", cmd, port, status);
    return -EIO;
}

static int send_command(u8 cmd)
{
    return send_byte(cmd, APPLESMC_CMD_PORT);
}

static int send_argument(const char *key)
{
    int i;

    for (i = 0; i < 4; i++)
        if (send_byte(key[i], APPLESMC_DATA_PORT))
            return -EIO;
    return 0;
}

static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len)
{
    int i;

    if (send_command(cmd) || send_argument(key)) {
        pr_warn("%.4s: read arg fail\n", key);
        return -EIO;
    }

    if (send_byte(len, APPLESMC_DATA_PORT)) {
        pr_warn("%.4s: read len fail\n", key);
        return -EIO;
    }

    for (i = 0; i < len; i++) {
        if (wait_read()) {
            pr_warn("%.4s: read data[%d] fail\n", key, i);
            return -EIO;
        }
        buffer[i] = inb(APPLESMC_DATA_PORT);
    }

    return 0;
}

static int write_smc(u8 cmd, const char *key, const u8 *buffer, u8 len)
{
    int i;

    if (send_command(cmd) || send_argument(key)) {
        pr_warn("%s: write arg fail\n", key);
        return -EIO;
    }

    if (send_byte(len, APPLESMC_DATA_PORT)) {
        pr_warn("%.4s: write len fail\n", key);
        return -EIO;
    }

    for (i = 0; i < len; i++) {
        if (send_byte(buffer[i], APPLESMC_DATA_PORT)) {
            pr_warn("%s: write data fail\n", key);
            return -EIO;
        }
    }

    return 0;
}

static int read_register_count(unsigned int *count)
{
    __be32 be;
    int ret;

    ret = read_smc(APPLESMC_READ_CMD, KEY_COUNT_KEY, (u8 *)&be, 4);
    if (ret)
        return ret;

    *count = be32_to_cpu(be);
    return 0;
}

/*
 * Serialized I/O
 *
 * Returns zero on success or a negative error on failure.
 * All functions below are concurrency safe - callers should NOT hold lock.
 */

static int applesmc_read_entry(const struct applesmc_entry *entry,
                   u8 *buf, u8 len)
{
    int ret;

    if (entry->len != len)
        return -EINVAL;
    mutex_lock(&smcreg.mutex);
    ret = read_smc(APPLESMC_READ_CMD, entry->key, buf, len);
    mutex_unlock(&smcreg.mutex);

    return ret;
}

static int applesmc_write_entry(const struct applesmc_entry *entry,
                const u8 *buf, u8 len)
{
    int ret;

    if (entry->len != len)
        return -EINVAL;
    mutex_lock(&smcreg.mutex);
    ret = write_smc(APPLESMC_WRITE_CMD, entry->key, buf, len);
    mutex_unlock(&smcreg.mutex);
    return ret;
}

static const struct applesmc_entry *applesmc_get_entry_by_index(int index)
{
    struct applesmc_entry *cache = &smcreg.cache[index];
    u8 key[4], info[6];
    __be32 be;
    int ret = 0;

    if (cache->valid)
        return cache;

    mutex_lock(&smcreg.mutex);

    if (cache->valid)
        goto out;
    be = cpu_to_be32(index);
    ret = read_smc(APPLESMC_GET_KEY_BY_INDEX_CMD, (u8 *)&be, key, 4);
    if (ret)
        goto out;
    ret = read_smc(APPLESMC_GET_KEY_TYPE_CMD, key, info, 6);
    if (ret)
        goto out;

    memcpy(cache->key, key, 4);
    cache->len = info[0];
    memcpy(cache->type, &info[1], 4);
    cache->flags = info[5];
    cache->valid = 1;

out:
    mutex_unlock(&smcreg.mutex);
    if (ret)
        return ERR_PTR(ret);
    return cache;
}

static int applesmc_get_lower_bound(unsigned int *lo, const char *key)
{
    int begin = 0, end = smcreg.key_count;
    const struct applesmc_entry *entry;

    while (begin != end) {
        int middle = begin + (end - begin) / 2;
        entry = applesmc_get_entry_by_index(middle);
        if (IS_ERR(entry)) {
            *lo = 0;
            return PTR_ERR(entry);
        }
        if (strcmp(entry->key, key) < 0)
            begin = middle + 1;
        else
            end = middle;
    }

    *lo = begin;
    return 0;
}

static int applesmc_get_upper_bound(unsigned int *hi, const char *key)
{
    int begin = 0, end = smcreg.key_count;
    const struct applesmc_entry *entry;

    while (begin != end) {
        int middle = begin + (end - begin) / 2;
        entry = applesmc_get_entry_by_index(middle);
        if (IS_ERR(entry)) {
            *hi = smcreg.key_count;
            return PTR_ERR(entry);
        }
        if (strcmp(key, entry->key) < 0)
            end = middle;
        else
            begin = middle + 1;
    }

    *hi = begin;
    return 0;
}

static const struct applesmc_entry *applesmc_get_entry_by_key(const char *key)
{
    int begin, end;
    int ret;

    ret = applesmc_get_lower_bound(&begin, key);
    if (ret)
        return ERR_PTR(ret);
    ret = applesmc_get_upper_bound(&end, key);
    if (ret)
        return ERR_PTR(ret);
    if (end - begin != 1)
        return ERR_PTR(-EINVAL);

    return applesmc_get_entry_by_index(begin);
}

static int applesmc_read_key(const char *key, u8 *buffer, u8 len)
{
    const struct applesmc_entry *entry;

    entry = applesmc_get_entry_by_key(key);
    if (IS_ERR(entry))
        return PTR_ERR(entry);

    return applesmc_read_entry(entry, buffer, len);
}

static int applesmc_write_key(const char *key, const u8 *buffer, u8 len)
{
    const struct applesmc_entry *entry;

    entry = applesmc_get_entry_by_key(key);
    if (IS_ERR(entry))
        return PTR_ERR(entry);

    return applesmc_write_entry(entry, buffer, len);
}

static int applesmc_has_key(const char *key, bool *value)
{
    const struct applesmc_entry *entry;

    entry = applesmc_get_entry_by_key(key);
    if (IS_ERR(entry) && PTR_ERR(entry) != -EINVAL)
        return PTR_ERR(entry);

    *value = !IS_ERR(entry);
    return 0;
}

/*
 * applesmc_read_s16 - Read 16-bit signed big endian register
 */
static int applesmc_read_s16(const char *key, s16 *value)
{
    u8 buffer[2];
    int ret;

    ret = applesmc_read_key(key, buffer, 2);
    if (ret)
        return ret;

    *value = ((s16)buffer[0] << 8) | buffer[1];
    return 0;
}

/*
 * applesmc_device_init - initialize the accelerometer.  Can sleep.
 */
static void applesmc_device_init(void)
{
    int total;
    u8 buffer[2];

    if (!smcreg.has_accelerometer)
        return;

    for (total = INIT_TIMEOUT_MSECS; total > 0; total -= INIT_WAIT_MSECS) {
        if (!applesmc_read_key(MOTION_SENSOR_KEY, buffer, 2) &&
                (buffer[0] != 0x00 || buffer[1] != 0x00))
            return;
        buffer[0] = 0xe0;
        buffer[1] = 0x00;
        applesmc_write_key(MOTION_SENSOR_KEY, buffer, 2);
        msleep(INIT_WAIT_MSECS);
    }

    pr_warn("failed to init the device\n");
}

static int applesmc_init_index(struct applesmc_registers *s)
{
    const struct applesmc_entry *entry;
    unsigned int i;

    if (s->index)
        return 0;

    s->index = kcalloc(s->temp_count, sizeof(s->index[0]), GFP_KERNEL);
    if (!s->index)
        return -ENOMEM;

    for (i = s->temp_begin; i < s->temp_end; i++) {
        entry = applesmc_get_entry_by_index(i);
        if (IS_ERR(entry))
            continue;
        if (strcmp(entry->type, TEMP_SENSOR_TYPE))
            continue;
        s->index[s->index_count++] = entry->key;
    }

    return 0;
}

/*
 * applesmc_init_smcreg_try - Try to initialize register cache. Idempotent.
 */
static int applesmc_init_smcreg_try(void)
{
    struct applesmc_registers *s = &smcreg;
    bool left_light_sensor, right_light_sensor;
    u8 tmp[1];
    int ret;

    if (s->init_complete)
        return 0;

    ret = read_register_count(&s->key_count);
    if (ret)
        return ret;

    if (!s->cache)
        s->cache = kcalloc(s->key_count, sizeof(*s->cache), GFP_KERNEL);
    if (!s->cache)
        return -ENOMEM;

    ret = applesmc_read_key(FANS_COUNT, tmp, 1);
    if (ret)
        return ret;
    s->fan_count = tmp[0];

    ret = applesmc_get_lower_bound(&s->temp_begin, "T");
    if (ret)
        return ret;
    ret = applesmc_get_lower_bound(&s->temp_end, "U");
    if (ret)
        return ret;
    s->temp_count = s->temp_end - s->temp_begin;

    ret = applesmc_init_index(s);
    if (ret)
        return ret;

    ret = applesmc_has_key(LIGHT_SENSOR_LEFT_KEY, &left_light_sensor);
    if (ret)
        return ret;
    ret = applesmc_has_key(LIGHT_SENSOR_RIGHT_KEY, &right_light_sensor);
    if (ret)
        return ret;
    ret = applesmc_has_key(MOTION_SENSOR_KEY, &s->has_accelerometer);
    if (ret)
        return ret;
    ret = applesmc_has_key(BACKLIGHT_KEY, &s->has_key_backlight);
    if (ret)
        return ret;

    s->num_light_sensors = left_light_sensor + right_light_sensor;
    s->init_complete = true;

    pr_info("key=%d fan=%d temp=%d index=%d acc=%d lux=%d kbd=%d\n",
           s->key_count, s->fan_count, s->temp_count, s->index_count,
           s->has_accelerometer,
           s->num_light_sensors,
           s->has_key_backlight);

    return 0;
}

static void applesmc_destroy_smcreg(void)
{
    kfree(smcreg.index);
    smcreg.index = NULL;
    kfree(smcreg.cache);
    smcreg.cache = NULL;
    smcreg.init_complete = false;
}

/*
 * applesmc_init_smcreg - Initialize register cache.
 *
 * Retries until initialization is successful, or the operation times out.
 *
 */
static int applesmc_init_smcreg(void)
{
    int ms, ret;

    for (ms = 0; ms < INIT_TIMEOUT_MSECS; ms += INIT_WAIT_MSECS) {
        ret = applesmc_init_smcreg_try();
        if (!ret) {
            if (ms)
                pr_info("init_smcreg() took %d ms\n", ms);
            return 0;
        }
        msleep(INIT_WAIT_MSECS);
    }

    applesmc_destroy_smcreg();

    return ret;
}

/* Device model stuff */
static int applesmc_probe(struct platform_device *dev)
{
    int ret;

    ret = applesmc_init_smcreg();
    if (ret)
        return ret;

    applesmc_device_init();

    return 0;
}

/* Synchronize device with memorized backlight state */
static int applesmc_pm_resume(struct device *dev)
{
    if (smcreg.has_key_backlight)
        applesmc_write_key(BACKLIGHT_KEY, backlight_state, 2);
    return 0;
}

/* Reinitialize device on resume from hibernation */
static int applesmc_pm_restore(struct device *dev)
{
    applesmc_device_init();
    return applesmc_pm_resume(dev);
}

static const struct dev_pm_ops applesmc_pm_ops = {
    .resume = applesmc_pm_resume,
    .restore = applesmc_pm_restore,
};

static struct platform_driver applesmc_driver = {
    .probe = applesmc_probe,
    .driver = {
        .name = "applesmc",
        .owner = THIS_MODULE,
        .pm = &applesmc_pm_ops,
    },
};

/*
 * applesmc_calibrate - Set our "resting" values.  Callers must
 * hold applesmc_lock.
 */
static void applesmc_calibrate(void)
{
    applesmc_read_s16(MOTION_SENSOR_X_KEY, &rest_x);
    applesmc_read_s16(MOTION_SENSOR_Y_KEY, &rest_y);
    rest_x = -rest_x;
}

static void applesmc_idev_poll(struct input_polled_dev *dev)
{
    struct input_dev *idev = dev->input;
    s16 x, y;

    if (applesmc_read_s16(MOTION_SENSOR_X_KEY, &x))
        return;
    if (applesmc_read_s16(MOTION_SENSOR_Y_KEY, &y))
        return;

    x = -x;
    input_report_abs(idev, ABS_X, x - rest_x);
    input_report_abs(idev, ABS_Y, y - rest_y);
    input_sync(idev);
}

/* Sysfs Files */

static ssize_t applesmc_name_show(struct device *dev,
                   struct device_attribute *attr, char *buf)
{
    return snprintf(buf, PAGE_SIZE, "applesmc\n");
}

static ssize_t applesmc_position_show(struct device *dev,
                   struct device_attribute *attr, char *buf)
{
    int ret;
    s16 x, y, z;

    ret = applesmc_read_s16(MOTION_SENSOR_X_KEY, &x);
    if (ret)
        goto out;
    ret = applesmc_read_s16(MOTION_SENSOR_Y_KEY, &y);
    if (ret)
        goto out;
    ret = applesmc_read_s16(MOTION_SENSOR_Z_KEY, &z);
    if (ret)
        goto out;

out:
    if (ret)
        return ret;
    else
        return snprintf(buf, PAGE_SIZE, "(%d,%d,%d)\n", x, y, z);
}

static ssize_t applesmc_light_show(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    const struct applesmc_entry *entry;
    static int data_length;
    int ret;
    u8 left = 0, right = 0;
    u8 buffer[10];

    if (!data_length) {
        entry = applesmc_get_entry_by_key(LIGHT_SENSOR_LEFT_KEY);
        if (IS_ERR(entry))
            return PTR_ERR(entry);
        if (entry->len > 10)
            return -ENXIO;
        data_length = entry->len;
        pr_info("light sensor data length set to %d\n", data_length);
    }

    ret = applesmc_read_key(LIGHT_SENSOR_LEFT_KEY, buffer, data_length);
    /* newer macbooks report a single 10-bit bigendian value */
    if (data_length == 10) {
        left = be16_to_cpu(*(__be16 *)(buffer + 6)) >> 2;
        goto out;
    }
    left = buffer[2];
    if (ret)
        goto out;
    ret = applesmc_read_key(LIGHT_SENSOR_RIGHT_KEY, buffer, data_length);
    right = buffer[2];

out:
    if (ret)
        return ret;
    else
        return snprintf(sysfsbuf, PAGE_SIZE, "(%d,%d)\n", left, right);
}

/* Displays sensor key as label */
static ssize_t applesmc_show_sensor_label(struct device *dev,
            struct device_attribute *devattr, char *sysfsbuf)
{
    const char *key = smcreg.index[to_index(devattr)];

    return snprintf(sysfsbuf, PAGE_SIZE, "%s\n", key);
}

/* Displays degree Celsius * 1000 */
static ssize_t applesmc_show_temperature(struct device *dev,
            struct device_attribute *devattr, char *sysfsbuf)
{
    const char *key = smcreg.index[to_index(devattr)];
    int ret;
    s16 value;
    int temp;

    ret = applesmc_read_s16(key, &value);
    if (ret)
        return ret;

    temp = 250 * (value >> 6);

    return snprintf(sysfsbuf, PAGE_SIZE, "%d\n", temp);
}

static ssize_t applesmc_show_fan_speed(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    int ret;
    unsigned int speed = 0;
    char newkey[5];
    u8 buffer[2];

    sprintf(newkey, fan_speed_fmt[to_option(attr)], to_index(attr));

    ret = applesmc_read_key(newkey, buffer, 2);
    speed = ((buffer[0] << 8 | buffer[1]) >> 2);

    if (ret)
        return ret;
    else
        return snprintf(sysfsbuf, PAGE_SIZE, "%u\n", speed);
}

static ssize_t applesmc_store_fan_speed(struct device *dev,
                    struct device_attribute *attr,
                    const char *sysfsbuf, size_t count)
{
    int ret;
    unsigned long speed;
    char newkey[5];
    u8 buffer[2];

    if (kstrtoul(sysfsbuf, 10, &speed) < 0 || speed >= 0x4000)
        return -EINVAL;     /* Bigger than a 14-bit value */

    sprintf(newkey, fan_speed_fmt[to_option(attr)], to_index(attr));

    buffer[0] = (speed >> 6) & 0xff;
    buffer[1] = (speed << 2) & 0xff;
    ret = applesmc_write_key(newkey, buffer, 2);

    if (ret)
        return ret;
    else
        return count;
}

static ssize_t applesmc_show_fan_manual(struct device *dev,
            struct device_attribute *attr, char *sysfsbuf)
{
    int ret;
    u16 manual = 0;
    u8 buffer[2];

    ret = applesmc_read_key(FANS_MANUAL, buffer, 2);
    manual = ((buffer[0] << 8 | buffer[1]) >> to_index(attr)) & 0x01;

    if (ret)
        return ret;
    else
        return snprintf(sysfsbuf, PAGE_SIZE, "%d\n", manual);
}

static ssize_t applesmc_store_fan_manual(struct device *dev,
                     struct device_attribute *attr,
                     const char *sysfsbuf, size_t count)
{
    int ret;
    u8 buffer[2];
    unsigned long input;
    u16 val;

    if (kstrtoul(sysfsbuf, 10, &input) < 0)
        return -EINVAL;

    ret = applesmc_read_key(FANS_MANUAL, buffer, 2);
    val = (buffer[0] << 8 | buffer[1]);
    if (ret)
        goto out;

    if (input)
        val = val | (0x01 << to_index(attr));
    else
        val = val & ~(0x01 << to_index(attr));

    buffer[0] = (val >> 8) & 0xFF;
    buffer[1] = val & 0xFF;

    ret = applesmc_write_key(FANS_MANUAL, buffer, 2);

out:
    if (ret)
        return ret;
    else
        return count;
}

static ssize_t applesmc_show_fan_position(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    int ret;
    char newkey[5];
    u8 buffer[17];

    sprintf(newkey, FAN_ID_FMT, to_index(attr));

    ret = applesmc_read_key(newkey, buffer, 16);
    buffer[16] = 0;

    if (ret)
        return ret;
    else
        return snprintf(sysfsbuf, PAGE_SIZE, "%s\n", buffer+4);
}

static ssize_t applesmc_calibrate_show(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    return snprintf(sysfsbuf, PAGE_SIZE, "(%d,%d)\n", rest_x, rest_y);
}

static ssize_t applesmc_calibrate_store(struct device *dev,
    struct device_attribute *attr, const char *sysfsbuf, size_t count)
{
    applesmc_calibrate();

    return count;
}

static void applesmc_backlight_set(struct work_struct *work)
{
    applesmc_write_key(BACKLIGHT_KEY, backlight_state, 2);
}
static DECLARE_WORK(backlight_work, &applesmc_backlight_set);

static void applesmc_brightness_set(struct led_classdev *led_cdev,
                        enum led_brightness value)
{
    int ret;

    backlight_state[0] = value;
    ret = queue_work(applesmc_led_wq, &backlight_work);

    if (debug && (!ret))
        printk(KERN_DEBUG "applesmc: work was already on the queue.\n");
}

static ssize_t applesmc_key_count_show(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    int ret;
    u8 buffer[4];
    u32 count;

    ret = applesmc_read_key(KEY_COUNT_KEY, buffer, 4);
    count = ((u32)buffer[0]<<24) + ((u32)buffer[1]<<16) +
                        ((u32)buffer[2]<<8) + buffer[3];

    if (ret)
        return ret;
    else
        return snprintf(sysfsbuf, PAGE_SIZE, "%d\n", count);
}

static ssize_t applesmc_key_at_index_read_show(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    const struct applesmc_entry *entry;
    int ret;

    entry = applesmc_get_entry_by_index(key_at_index);
    if (IS_ERR(entry))
        return PTR_ERR(entry);
    ret = applesmc_read_entry(entry, sysfsbuf, entry->len);
    if (ret)
        return ret;

    return entry->len;
}

static ssize_t applesmc_key_at_index_data_length_show(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    const struct applesmc_entry *entry;

    entry = applesmc_get_entry_by_index(key_at_index);
    if (IS_ERR(entry))
        return PTR_ERR(entry);

    return snprintf(sysfsbuf, PAGE_SIZE, "%d\n", entry->len);
}

static ssize_t applesmc_key_at_index_type_show(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    const struct applesmc_entry *entry;

    entry = applesmc_get_entry_by_index(key_at_index);
    if (IS_ERR(entry))
        return PTR_ERR(entry);

    return snprintf(sysfsbuf, PAGE_SIZE, "%s\n", entry->type);
}

static ssize_t applesmc_key_at_index_name_show(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    const struct applesmc_entry *entry;

    entry = applesmc_get_entry_by_index(key_at_index);
    if (IS_ERR(entry))
        return PTR_ERR(entry);

    return snprintf(sysfsbuf, PAGE_SIZE, "%s\n", entry->key);
}

static ssize_t applesmc_key_at_index_show(struct device *dev,
                struct device_attribute *attr, char *sysfsbuf)
{
    return snprintf(sysfsbuf, PAGE_SIZE, "%d\n", key_at_index);
}

static ssize_t applesmc_key_at_index_store(struct device *dev,
    struct device_attribute *attr, const char *sysfsbuf, size_t count)
{
    unsigned long newkey;

    if (kstrtoul(sysfsbuf, 10, &newkey) < 0
        || newkey >= smcreg.key_count)
        return -EINVAL;

    key_at_index = newkey;
    return count;
}

static struct led_classdev applesmc_backlight = {
    .name           = "smc::kbd_backlight",
    .default_trigger    = "nand-disk",
    .brightness_set     = applesmc_brightness_set,
};

static struct applesmc_node_group info_group[] = {
    { "name", applesmc_name_show },
    { "key_count", applesmc_key_count_show },
    { "key_at_index", applesmc_key_at_index_show, applesmc_key_at_index_store },
    { "key_at_index_name", applesmc_key_at_index_name_show },
    { "key_at_index_type", applesmc_key_at_index_type_show },
    { "key_at_index_data_length", applesmc_key_at_index_data_length_show },
    { "key_at_index_data", applesmc_key_at_index_read_show },
    { }
};

static struct applesmc_node_group accelerometer_group[] = {
    { "position", applesmc_position_show },
    { "calibrate", applesmc_calibrate_show, applesmc_calibrate_store },
    { }
};

static struct applesmc_node_group light_sensor_group[] = {
    { "light", applesmc_light_show },
    { }
};

static struct applesmc_node_group fan_group[] = {
    { "fan%d_label", applesmc_show_fan_position },
    { "fan%d_input", applesmc_show_fan_speed, NULL, 0 },
    { "fan%d_min", applesmc_show_fan_speed, applesmc_store_fan_speed, 1 },
    { "fan%d_max", applesmc_show_fan_speed, NULL, 2 },
    { "fan%d_safe", applesmc_show_fan_speed, NULL, 3 },
    { "fan%d_output", applesmc_show_fan_speed, applesmc_store_fan_speed, 4 },
    { "fan%d_manual", applesmc_show_fan_manual, applesmc_store_fan_manual },
    { }
};

static struct applesmc_node_group temp_group[] = {
    { "temp%d_label", applesmc_show_sensor_label },
    { "temp%d_input", applesmc_show_temperature },
    { }
};

/* Module stuff */

/*
 * applesmc_destroy_nodes - remove files and free associated memory
 */
static void applesmc_destroy_nodes(struct applesmc_node_group *groups)
{
    struct applesmc_node_group *grp;
    struct applesmc_dev_attr *node;

    for (grp = groups; grp->nodes; grp++) {
        for (node = grp->nodes; node->sda.dev_attr.attr.name; node++)
            sysfs_remove_file(&pdev->dev.kobj,
                      &node->sda.dev_attr.attr);
        kfree(grp->nodes);
        grp->nodes = NULL;
    }
}

/*
 * applesmc_create_nodes - create a two-dimensional group of sysfs files
 */
static int applesmc_create_nodes(struct applesmc_node_group *groups, int num)
{
    struct applesmc_node_group *grp;
    struct applesmc_dev_attr *node;
    struct attribute *attr;
    int ret, i;

    for (grp = groups; grp->format; grp++) {
        grp->nodes = kcalloc(num + 1, sizeof(*node), GFP_KERNEL);
        if (!grp->nodes) {
            ret = -ENOMEM;
            goto out;
        }
        for (i = 0; i < num; i++) {
            node = &grp->nodes[i];
            sprintf(node->name, grp->format, i + 1);
            node->sda.index = (grp->option << 16) | (i & 0xffff);
            node->sda.dev_attr.show = grp->show;
            node->sda.dev_attr.store = grp->store;
            attr = &node->sda.dev_attr.attr;
            sysfs_attr_init(attr);
            attr->name = node->name;
            attr->mode = S_IRUGO | (grp->store ? S_IWUSR : 0);
            ret = sysfs_create_file(&pdev->dev.kobj, attr);
            if (ret) {
                attr->name = NULL;
                goto out;
            }
        }
    }

    return 0;
out:
    applesmc_destroy_nodes(groups);
    return ret;
}

/* Create accelerometer ressources */
static int applesmc_create_accelerometer(void)
{
    struct input_dev *idev;
    int ret;

    if (!smcreg.has_accelerometer)
        return 0;

    ret = applesmc_create_nodes(accelerometer_group, 1);
    if (ret)
        goto out;

    applesmc_idev = input_allocate_polled_device();
    if (!applesmc_idev) {
        ret = -ENOMEM;
        goto out_sysfs;
    }

    applesmc_idev->poll = applesmc_idev_poll;
    applesmc_idev->poll_interval = APPLESMC_POLL_INTERVAL;

    /* initial calibrate for the input device */
    applesmc_calibrate();

    /* initialize the input device */
    idev = applesmc_idev->input;
    idev->name = "applesmc";
    idev->id.bustype = BUS_HOST;
    idev->dev.parent = &pdev->dev;
    idev->evbit[0] = BIT_MASK(EV_ABS);
    input_set_abs_params(idev, ABS_X,
            -256, 256, APPLESMC_INPUT_FUZZ, APPLESMC_INPUT_FLAT);
    input_set_abs_params(idev, ABS_Y,
            -256, 256, APPLESMC_INPUT_FUZZ, APPLESMC_INPUT_FLAT);

    ret = input_register_polled_device(applesmc_idev);
    if (ret)
        goto out_idev;

    return 0;

out_idev:
    input_free_polled_device(applesmc_idev);

out_sysfs:
    applesmc_destroy_nodes(accelerometer_group);

out:
    pr_warn("driver init failed (ret=%d)!\n", ret);
    return ret;
}

/* Release all ressources used by the accelerometer */
static void applesmc_release_accelerometer(void)
{
    if (!smcreg.has_accelerometer)
        return;
    input_unregister_polled_device(applesmc_idev);
    input_free_polled_device(applesmc_idev);
    applesmc_destroy_nodes(accelerometer_group);
}

static int applesmc_create_light_sensor(void)
{
    if (!smcreg.num_light_sensors)
        return 0;
    return applesmc_create_nodes(light_sensor_group, 1);
}

static void applesmc_release_light_sensor(void)
{
    if (!smcreg.num_light_sensors)
        return;
    applesmc_destroy_nodes(light_sensor_group);
}

static int applesmc_create_key_backlight(void)
{
    if (!smcreg.has_key_backlight)
        return 0;
    applesmc_led_wq = create_singlethread_workqueue("applesmc-led");
    if (!applesmc_led_wq)
        return -ENOMEM;
    return led_classdev_register(&pdev->dev, &applesmc_backlight);
}

static void applesmc_release_key_backlight(void)
{
    if (!smcreg.has_key_backlight)
        return;
    led_classdev_unregister(&applesmc_backlight);
    destroy_workqueue(applesmc_led_wq);
}

static int applesmc_dmi_match(const struct dmi_system_id *id)
{
    return 1;
}

/*
 * Note that DMI_MATCH(...,"MacBook") will match "MacBookPro1,1".
 * So we need to put "Apple MacBook Pro" before "Apple MacBook".
 */
static __initdata struct dmi_system_id applesmc_whitelist[] = {
    { applesmc_dmi_match, "Apple MacBook Air", {
      DMI_MATCH(DMI_BOARD_VENDOR, "Apple"),
      DMI_MATCH(DMI_PRODUCT_NAME, "MacBookAir") },
    },
    { applesmc_dmi_match, "Apple MacBook Pro", {
      DMI_MATCH(DMI_BOARD_VENDOR, "Apple"),
      DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro") },
    },
    { applesmc_dmi_match, "Apple MacBook", {
      DMI_MATCH(DMI_BOARD_VENDOR, "Apple"),
      DMI_MATCH(DMI_PRODUCT_NAME, "MacBook") },
    },
    { applesmc_dmi_match, "Apple Macmini", {
      DMI_MATCH(DMI_BOARD_VENDOR, "Apple"),
      DMI_MATCH(DMI_PRODUCT_NAME, "Macmini") },
    },
    { applesmc_dmi_match, "Apple MacPro", {
      DMI_MATCH(DMI_BOARD_VENDOR, "Apple"),
      DMI_MATCH(DMI_PRODUCT_NAME, "MacPro") },
    },
    { applesmc_dmi_match, "Apple iMac", {
      DMI_MATCH(DMI_BOARD_VENDOR, "Apple"),
      DMI_MATCH(DMI_PRODUCT_NAME, "iMac") },
    },
    { .ident = NULL }
};

static int __init applesmc_init(void)
{
    int ret;

    if (!dmi_check_system(applesmc_whitelist)) {
        pr_warn("supported laptop not found!\n");
        ret = -ENODEV;
        goto out;
    }

    if (!request_region(APPLESMC_DATA_PORT, APPLESMC_NR_PORTS,
                                "applesmc")) {
        ret = -ENXIO;
        goto out;
    }

    ret = platform_driver_register(&applesmc_driver);
    if (ret)
        goto out_region;

    pdev = platform_device_register_simple("applesmc", APPLESMC_DATA_PORT,
                           NULL, 0);
    if (IS_ERR(pdev)) {
        ret = PTR_ERR(pdev);
        goto out_driver;
    }

    /* create register cache */
    ret = applesmc_init_smcreg();
    if (ret)
        goto out_device;

    ret = applesmc_create_nodes(info_group, 1);
    if (ret)
        goto out_smcreg;

    ret = applesmc_create_nodes(fan_group, smcreg.fan_count);
    if (ret)
        goto out_info;

    ret = applesmc_create_nodes(temp_group, smcreg.index_count);
    if (ret)
        goto out_fans;

    ret = applesmc_create_accelerometer();
    if (ret)
        goto out_temperature;

    ret = applesmc_create_light_sensor();
    if (ret)
        goto out_accelerometer;

    ret = applesmc_create_key_backlight();
    if (ret)
        goto out_light_sysfs;

    hwmon_dev = hwmon_device_register(&pdev->dev);
    if (IS_ERR(hwmon_dev)) {
        ret = PTR_ERR(hwmon_dev);
        goto out_light_ledclass;
    }

    return 0;

out_light_ledclass:
    applesmc_release_key_backlight();
out_light_sysfs:
    applesmc_release_light_sensor();
out_accelerometer:
    applesmc_release_accelerometer();
out_temperature:
    applesmc_destroy_nodes(temp_group);
out_fans:
    applesmc_destroy_nodes(fan_group);
out_info:
    applesmc_destroy_nodes(info_group);
out_smcreg:
    applesmc_destroy_smcreg();
out_device:
    platform_device_unregister(pdev);
out_driver:
    platform_driver_unregister(&applesmc_driver);
out_region:
    release_region(APPLESMC_DATA_PORT, APPLESMC_NR_PORTS);
out:
    pr_warn("driver init failed (ret=%d)!\n", ret);
    return ret;
}

static void __exit applesmc_exit(void)
{
    hwmon_device_unregister(hwmon_dev);
    applesmc_release_key_backlight();
    applesmc_release_light_sensor();
    applesmc_release_accelerometer();
    applesmc_destroy_nodes(temp_group);
    applesmc_destroy_nodes(fan_group);
    applesmc_destroy_nodes(info_group);
    applesmc_destroy_smcreg();
    platform_device_unregister(pdev);
    platform_driver_unregister(&applesmc_driver);
    release_region(APPLESMC_DATA_PORT, APPLESMC_NR_PORTS);
}

module_init(applesmc_init);
module_exit(applesmc_exit);

MODULE_AUTHOR("Nicolas Boichat");
MODULE_DESCRIPTION("Apple SMC");
MODULE_LICENSE("GPL v2");
MODULE_DEVICE_TABLE(dmi, applesmc_whitelist);