/*
   * 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)
  {

  	spin_lock_irqsave(&nw_gpio_lock, *flags);

  }
  
  static inline void netwinder_unlock(unsigned long *flags)
  {

  	spin_unlock_irqrestore(&nw_gpio_lock, *flags);

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

  	spin_lock_irqsave(&nw_gpio_lock, flags);
  	nw_gpio_modify_op(GPIO_FAN, i ? GPIO_FAN : 0);
  	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
  ",
  		      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
  ");
  #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.
  ",
  	       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");