/**
* Issues a reset bus sequence.
*
* @param dev The bus master pointer
* @return 0=Device present, 1=No device present or error
*/
static u8 w1_gpio_reset_bus(void *data)
{
int result=1, i;
struct w1_gpio_msm_platform_data *pdata = data;
void (*write_bit)(void *, u8);
unsigned long irq_flags;
int temp_read[MAX_SAMPLE]={'1',};
int loop_cnt = 3;
if (pdata->is_open_drain) {
write_bit = w1_gpio_write_bit_val;
} else {
write_bit = w1_gpio_write_bit_dir;
}
spin_lock_irqsave(&w1_gpio_msm_lock, irq_flags);
while (loop_cnt > 0) {
write_bit(data, 0);
/* minimum 48, max 80 us(In DS Documnet)
* be nice and sleep, except 18b20 spec lists 960us maximum,
* so until we can sleep with microsecond accuracy, spin.
* Feel free to come up with some other way to give up the
* cpu for such a short amount of time AND get it back in
* the maximum amount of time.
*/
(pdata->slave_speed == 0)? __const_udelay(500*UDELAY_MULT) : __const_udelay(50*UDELAY_MULT);
write_bit(data, 1);
(pdata->slave_speed == 0)? __const_udelay(60*UDELAY_MULT) : __const_udelay(1*UDELAY_MULT);
for(i=0;i<MAX_SAMPLE;i++)
temp_read[i] = gpio_get_value_msm(pdata->pin);
for(i=0;i<MAX_SAMPLE;i++)
result &= temp_read[i];
/* minmum 70 (above) + 410 = 480 us
* There aren't any timing requirements between a reset and
* the following transactions. Sleeping is safe here.
*/
/* w1_delay(410); min required time */
(pdata->slave_speed == 0)? msleep(1) : __const_udelay(40*UDELAY_MULT);
if (result)
loop_cnt--;
else
break;
}
spin_unlock_irqrestore(&w1_gpio_msm_lock, irq_flags);
return result;
}
void __ndelay(unsigned long nsecs)
{
__const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */
}
void __udelay(unsigned long usecs)
{
__const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */
}
void __udelay(unsigned long usecs)
{
__const_udelay(usecs * 0x000010c6); /* 2**32 / 1000000 */
}
void __ndelay(unsigned long nsecs)
{
__const_udelay(nsecs * 0x00000005);
}
void __ndelay(unsigned long n)
{
__const_udelay(n * 0x5UL);
}
void __udelay(unsigned long n)
{
__const_udelay(n * 0x10c7UL);
}