ds1620.c

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/*
 * linux/drivers/char/ds1620.c: Dallas Semiconductors DS1620
 *   thermometer driver (as used in the Rebel.com NetWinder)
 */
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/delay.h>
#include <linux/proc_fs.h>
#include <linux/capability.h>
#include <linux/init.h>
#include <linux/mutex.h>

#include <mach/hardware.h>
#include <asm/mach-types.h>
#include <asm/uaccess.h>
#include <asm/therm.h>

#ifdef CONFIG_PROC_FS
/* define for /proc interface */
#define THERM_USE_PROC
#endif

/* Definitions for DS1620 chip */
#define THERM_START_CONVERT 0xee
#define THERM_RESET     0xaf
#define THERM_READ_CONFIG   0xac
#define THERM_READ_TEMP     0xaa
#define THERM_READ_TL       0xa2
#define THERM_READ_TH       0xa1
#define THERM_WRITE_CONFIG  0x0c
#define THERM_WRITE_TL      0x02
#define THERM_WRITE_TH      0x01

#define CFG_CPU         2
#define CFG_1SHOT       1

static DEFINE_MUTEX(ds1620_mutex);
static const char *fan_state[] = { "off", "on", "on (hardwired)" };

/*
 * Start of NetWinder specifics
 *  Note!  We have to hold the gpio lock with IRQs disabled over the
 *  whole of our transaction to the Dallas chip, since there is a
 *  chance that the WaveArtist driver could touch these bits to
 *  enable or disable the speaker.
 */
extern unsigned int system_rev;

static inline void netwinder_ds1620_set_clk(int clk)
{
    nw_gpio_modify_op(GPIO_DSCLK, clk ? GPIO_DSCLK : 0);
}

static inline void netwinder_ds1620_set_data(int dat)
{
    nw_gpio_modify_op(GPIO_DATA, dat ? GPIO_DATA : 0);
}

static inline int netwinder_ds1620_get_data(void)
{
    return nw_gpio_read() & GPIO_DATA;
}

static inline void netwinder_ds1620_set_data_dir(int dir)
{
    nw_gpio_modify_io(GPIO_DATA, dir ? GPIO_DATA : 0);
}

static inline void netwinder_ds1620_reset(void)
{
    nw_cpld_modify(CPLD_DS_ENABLE, 0);
    nw_cpld_modify(CPLD_DS_ENABLE, CPLD_DS_ENABLE);
}

static inline void netwinder_lock(unsigned long *flags)
{
    raw_spin_lock_irqsave(&nw_gpio_lock, *flags);
}

static inline void netwinder_unlock(unsigned long *flags)
{
    raw_spin_unlock_irqrestore(&nw_gpio_lock, *flags);
}

static inline void netwinder_set_fan(int i)
{
    unsigned long flags;

    raw_spin_lock_irqsave(&nw_gpio_lock, flags);
    nw_gpio_modify_op(GPIO_FAN, i ? GPIO_FAN : 0);
    raw_spin_unlock_irqrestore(&nw_gpio_lock, flags);
}

static inline int netwinder_get_fan(void)
{
    if ((system_rev & 0xf000) == 0x4000)
        return FAN_ALWAYS_ON;

    return (nw_gpio_read() & GPIO_FAN) ? FAN_ON : FAN_OFF;
}

/*
 * End of NetWinder specifics
 */

static void ds1620_send_bits(int nr, int value)
{
    int i;

    for (i = 0; i < nr; i++) {
        netwinder_ds1620_set_data(value & 1);
        netwinder_ds1620_set_clk(0);
        udelay(1);
        netwinder_ds1620_set_clk(1);
        udelay(1);

        value >>= 1;
    }
}

static unsigned int ds1620_recv_bits(int nr)
{
    unsigned int value = 0, mask = 1;
    int i;

    netwinder_ds1620_set_data(0);

    for (i = 0; i < nr; i++) {
        netwinder_ds1620_set_clk(0);
        udelay(1);

        if (netwinder_ds1620_get_data())
            value |= mask;

        mask <<= 1;

        netwinder_ds1620_set_clk(1);
        udelay(1);
    }

    return value;
}

static void ds1620_out(int cmd, int bits, int value)
{
    unsigned long flags;

    netwinder_lock(&flags);
    netwinder_ds1620_set_clk(1);
    netwinder_ds1620_set_data_dir(0);
    netwinder_ds1620_reset();

    udelay(1);

    ds1620_send_bits(8, cmd);
    if (bits)
        ds1620_send_bits(bits, value);

    udelay(1);

    netwinder_ds1620_reset();
    netwinder_unlock(&flags);

    msleep(20);
}

static unsigned int ds1620_in(int cmd, int bits)
{
    unsigned long flags;
    unsigned int value;

    netwinder_lock(&flags);
    netwinder_ds1620_set_clk(1);
    netwinder_ds1620_set_data_dir(0);
    netwinder_ds1620_reset();

    udelay(1);

    ds1620_send_bits(8, cmd);

    netwinder_ds1620_set_data_dir(1);
    value = ds1620_recv_bits(bits);

    netwinder_ds1620_reset();
    netwinder_unlock(&flags);

    return value;
}

static int cvt_9_to_int(unsigned int val)
{
    if (val & 0x100)
        val |= 0xfffffe00;

    return val;
}

static void ds1620_write_state(struct therm *therm)
{
    ds1620_out(THERM_WRITE_CONFIG, 8, CFG_CPU);
    ds1620_out(THERM_WRITE_TL, 9, therm->lo);
    ds1620_out(THERM_WRITE_TH, 9, therm->hi);
    ds1620_out(THERM_START_CONVERT, 0, 0);
}

static void ds1620_read_state(struct therm *therm)
{
    therm->lo = cvt_9_to_int(ds1620_in(THERM_READ_TL, 9));
    therm->hi = cvt_9_to_int(ds1620_in(THERM_READ_TH, 9));
}

static int ds1620_open(struct inode *inode, struct file *file)
{
    return nonseekable_open(inode, file);
}

static ssize_t
ds1620_read(struct file *file, char __user *buf, size_t count, loff_t *ptr)
{
    signed int cur_temp;
    signed char cur_temp_degF;

    cur_temp = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9)) >> 1;

    /* convert to Fahrenheit, as per wdt.c */
    cur_temp_degF = (cur_temp * 9) / 5 + 32;

    if (copy_to_user(buf, &cur_temp_degF, 1))
        return -EFAULT;

    return 1;
}

static int
ds1620_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    struct therm therm;
    union {
        struct therm __user *therm;
        int __user *i;
    } uarg;
    int i;

    uarg.i = (int __user *)arg;

    switch(cmd) {
    case CMD_SET_THERMOSTATE:
    case CMD_SET_THERMOSTATE2:
        if (!capable(CAP_SYS_ADMIN))
            return -EPERM;

        if (cmd == CMD_SET_THERMOSTATE) {
            if (get_user(therm.hi, uarg.i))
                return -EFAULT;
            therm.lo = therm.hi - 3;
        } else {
            if (copy_from_user(&therm, uarg.therm, sizeof(therm)))
                return -EFAULT;
        }

        therm.lo <<= 1;
        therm.hi <<= 1;

        ds1620_write_state(&therm);
        break;

    case CMD_GET_THERMOSTATE:
    case CMD_GET_THERMOSTATE2:
        ds1620_read_state(&therm);

        therm.lo >>= 1;
        therm.hi >>= 1;

        if (cmd == CMD_GET_THERMOSTATE) {
            if (put_user(therm.hi, uarg.i))
                return -EFAULT;
        } else {
            if (copy_to_user(uarg.therm, &therm, sizeof(therm)))
                return -EFAULT;
        }
        break;

    case CMD_GET_TEMPERATURE:
    case CMD_GET_TEMPERATURE2:
        i = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9));

        if (cmd == CMD_GET_TEMPERATURE)
            i >>= 1;

        return put_user(i, uarg.i) ? -EFAULT : 0;

    case CMD_GET_STATUS:
        i = ds1620_in(THERM_READ_CONFIG, 8) & 0xe3;

        return put_user(i, uarg.i) ? -EFAULT : 0;

    case CMD_GET_FAN:
        i = netwinder_get_fan();

        return put_user(i, uarg.i) ? -EFAULT : 0;

    case CMD_SET_FAN:
        if (!capable(CAP_SYS_ADMIN))
            return -EPERM;

        if (get_user(i, uarg.i))
            return -EFAULT;

        netwinder_set_fan(i);
        break;
        
    default:
        return -ENOIOCTLCMD;
    }

    return 0;
}

static long
ds1620_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    int ret;

    mutex_lock(&ds1620_mutex);
    ret = ds1620_ioctl(file, cmd, arg);
    mutex_unlock(&ds1620_mutex);

    return ret;
}

#ifdef THERM_USE_PROC
static int
proc_therm_ds1620_read(char *buf, char **start, off_t offset,
               int len, int *eof, void *unused)
{
    struct therm th;
    int temp;

    ds1620_read_state(&th);
    temp =  cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9));

    len = sprintf(buf, "Thermostat: HI %i.%i, LOW %i.%i; "
              "temperature: %i.%i C, fan %s\n",
              th.hi >> 1, th.hi & 1 ? 5 : 0,
              th.lo >> 1, th.lo & 1 ? 5 : 0,
              temp  >> 1, temp  & 1 ? 5 : 0,
              fan_state[netwinder_get_fan()]);

    return len;
}

static struct proc_dir_entry *proc_therm_ds1620;
#endif

static const struct file_operations ds1620_fops = {
    .owner      = THIS_MODULE,
    .open       = ds1620_open,
    .read       = ds1620_read,
    .unlocked_ioctl = ds1620_unlocked_ioctl,
    .llseek     = no_llseek,
};

static struct miscdevice ds1620_miscdev = {
    TEMP_MINOR,
    "temp",
    &ds1620_fops
};

static int __init ds1620_init(void)
{
    int ret;
    struct therm th, th_start;

    if (!machine_is_netwinder())
        return -ENODEV;

    ds1620_out(THERM_RESET, 0, 0);
    ds1620_out(THERM_WRITE_CONFIG, 8, CFG_CPU);
    ds1620_out(THERM_START_CONVERT, 0, 0);

    /*
     * Trigger the fan to start by setting
     * temperature high point low.  This kicks
     * the fan into action.
     */
    ds1620_read_state(&th);
    th_start.lo = 0;
    th_start.hi = 1;
    ds1620_write_state(&th_start);

    msleep(2000);

    ds1620_write_state(&th);

    ret = misc_register(&ds1620_miscdev);
    if (ret < 0)
        return ret;

#ifdef THERM_USE_PROC
    proc_therm_ds1620 = create_proc_entry("therm", 0, NULL);
    if (proc_therm_ds1620)
        proc_therm_ds1620->read_proc = proc_therm_ds1620_read;
    else
        printk(KERN_ERR "therm: unable to register /proc/therm\n");
#endif

    ds1620_read_state(&th);
    ret = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9));

    printk(KERN_INFO "Thermostat: high %i.%i, low %i.%i, "
           "current %i.%i C, fan %s.\n",
           th.hi >> 1, th.hi & 1 ? 5 : 0,
           th.lo >> 1, th.lo & 1 ? 5 : 0,
           ret   >> 1, ret   & 1 ? 5 : 0,
           fan_state[netwinder_get_fan()]);

    return 0;
}

static void __exit ds1620_exit(void)
{
#ifdef THERM_USE_PROC
    remove_proc_entry("therm", NULL);
#endif
    misc_deregister(&ds1620_miscdev);
}

module_init(ds1620_init);
module_exit(ds1620_exit);

MODULE_LICENSE("GPL");