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ds1620.c

/*
 * 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 <asm/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 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 spinlock_t gpio_lock;
extern unsigned int system_rev;

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

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

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

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

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

static inline void netwinder_lock(unsigned long *flags)
{
      spin_lock_irqsave(&gpio_lock, *flags);
}

static inline void netwinder_unlock(unsigned long *flags)
{
      spin_unlock_irqrestore(&gpio_lock, *flags);
}

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

      spin_lock_irqsave(&gpio_lock, flags);
      gpio_modify_op(GPIO_FAN, i ? GPIO_FAN : 0);
      spin_unlock_irqrestore(&gpio_lock, flags);
}

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

      return (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 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 inode *inode, 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;
}

#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       = nonseekable_open,
      .read       = ds1620_read,
      .ioctl            = ds1620_ioctl,
};

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");

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