ds1603.c
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/*
* Dallas Semiconductors 1603 RTC driver
*
* Brian Murphy <brian@murphy.dk>
*
*/
#include <linux/kernel.h>
#include <asm/lasat/lasat.h>
#include <linux/delay.h>
#include <asm/lasat/ds1603.h>
#include <asm/time.h>
#include "ds1603.h"
#define READ_TIME_CMD 0x81
#define SET_TIME_CMD 0x80
#define TRIMMER_SET_CMD 0xC0
#define TRIMMER_VALUE_MASK 0x38
#define TRIMMER_SHIFT 3
struct ds_defs *ds1603;
/* HW specific register functions */
static void rtc_reg_write(unsigned long val)
{
*ds1603->reg = val;
}
static unsigned long rtc_reg_read(void)
{
unsigned long tmp = *ds1603->reg;
return tmp;
}
static unsigned long rtc_datareg_read(void)
{
unsigned long tmp = *ds1603->data_reg;
return tmp;
}
static void rtc_nrst_high(void)
{
rtc_reg_write(rtc_reg_read() | ds1603->rst);
}
static void rtc_nrst_low(void)
{
rtc_reg_write(rtc_reg_read() & ~ds1603->rst);
}
static void rtc_cycle_clock(unsigned long data)
{
data |= ds1603->clk;
rtc_reg_write(data);
lasat_ndelay(250);
if (ds1603->data_reversed)
data &= ~ds1603->data;
else
data |= ds1603->data;
data &= ~ds1603->clk;
rtc_reg_write(data);
lasat_ndelay(250 + ds1603->huge_delay);
}
static void rtc_write_databit(unsigned int bit)
{
unsigned long data = rtc_reg_read();
if (ds1603->data_reversed)
bit = !bit;
if (bit)
data |= ds1603->data;
else
data &= ~ds1603->data;
rtc_reg_write(data);
lasat_ndelay(50 + ds1603->huge_delay);
rtc_cycle_clock(data);
}
static unsigned int rtc_read_databit(void)
{
unsigned int data;
data = (rtc_datareg_read() & (1 << ds1603->data_read_shift))
>> ds1603->data_read_shift;
rtc_cycle_clock(rtc_reg_read());
return data;
}
static void rtc_write_byte(unsigned int byte)
{
int i;
for (i = 0; i <= 7; i++) {
rtc_write_databit(byte & 1L);
byte >>= 1;
}
}
static void rtc_write_word(unsigned long word)
{
int i;
for (i = 0; i <= 31; i++) {
rtc_write_databit(word & 1L);
word >>= 1;
}
}
static unsigned long rtc_read_word(void)
{
int i;
unsigned long word = 0;
unsigned long shift = 0;
for (i = 0; i <= 31; i++) {
word |= rtc_read_databit() << shift;
shift++;
}
return word;
}
static void rtc_init_op(void)
{
rtc_nrst_high();
rtc_reg_write(rtc_reg_read() & ~ds1603->clk);
lasat_ndelay(50);
}
static void rtc_end_op(void)
{
rtc_nrst_low();
lasat_ndelay(1000);
}
void read_persistent_clock(struct timespec *ts)
{
unsigned long word;
unsigned long flags;
spin_lock_irqsave(&rtc_lock, flags);
rtc_init_op();
rtc_write_byte(READ_TIME_CMD);
word = rtc_read_word();
rtc_end_op();
spin_unlock_irqrestore(&rtc_lock, flags);
ts->tv_sec = word;
ts->tv_nsec = 0;
}
int rtc_mips_set_mmss(unsigned long time)
{
unsigned long flags;
spin_lock_irqsave(&rtc_lock, flags);
rtc_init_op();
rtc_write_byte(SET_TIME_CMD);
rtc_write_word(time);
rtc_end_op();
spin_unlock_irqrestore(&rtc_lock, flags);
return 0;
}
void ds1603_set_trimmer(unsigned int trimval)
{
rtc_init_op();
rtc_write_byte(((trimval << TRIMMER_SHIFT) & TRIMMER_VALUE_MASK)
| (TRIMMER_SET_CMD));
rtc_end_op();
}
void ds1603_disable(void)
{
ds1603_set_trimmer(TRIMMER_DISABLE_RTC);
}
void ds1603_enable(void)
{
ds1603_set_trimmer(TRIMMER_DEFAULT);
}