/* Send 8 bits. */
static void
out_byte(unsigned char x)
{
int i;
TK_SDA_DIR(1);
for (i = 8; i--;) {
/* The chip latches incoming bits on the rising edge of SCL. */
TK_SCL_OUT(0);
TK_SDA_OUT(x & 1);
tempudelay(1);
TK_SCL_OUT(1);
tempudelay(1);
x >>= 1;
}
TK_SDA_DIR(0);
}
static int
ds1302_probe(void)
{
int retval, res;
TK_RST_DIR(1);
TK_SCL_DIR(1);
TK_SDA_DIR(0);
/* Try to talk to timekeeper. */
ds1302_wenable();
start();
out_byte(0xc0); /* write RAM byte 0 */
out_byte(MAGIC_PATTERN); /* write something magic */
start();
out_byte(0xc1); /* read RAM byte 0 */
if((res = in_byte()) == MAGIC_PATTERN) {
char buf[100];
stop();
ds1302_wdisable();
printk("%s: RTC found.\n", ds1302_name);
printk("%s: SDA, SCL, RST on PB%i, PB%i, %s%i\n",
ds1302_name,
CONFIG_ETRAX_DS1302_SDABIT,
CONFIG_ETRAX_DS1302_SCLBIT,
#ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
"GENIO",
#else
"PB",
#endif
CONFIG_ETRAX_DS1302_RSTBIT);
get_rtc_status(buf);
printk(buf);
retval = 1;
} else {
stop();
printk("%s: RTC not found.\n", ds1302_name);
retval = 0;
}
return retval;
}
static unsigned char
in_byte(void)
{
unsigned char x = 0;
int i;
/* Read byte. Bits come LSB first, on the falling edge of SCL.
* Assume SDA is in input direction already.
*/
TK_SDA_DIR(0);
for (i = 8; i--;) {
TK_SCL_OUT(0);
tempudelay(1);
x >>= 1;
x |= (TK_SDA_IN() << 7);
TK_SCL_OUT(1);
tempudelay(1);
}
return x;
}
