ds1722.c
1.81 KB
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#include <common.h>
#include <asm/ic/ssi.h>
#include <ds1722.h>
static void ds1722_select(int dev)
{
ssi_set_interface(4096, 0, 0, 0);
ssi_chip_select(0);
udelay(1);
ssi_chip_select(dev);
udelay(1);
}
u8 ds1722_read(int dev, int addr)
{
u8 res;
ds1722_select(dev);
ssi_tx_byte(addr);
res = ssi_rx_byte();
ssi_chip_select(0);
return res;
}
void ds1722_write(int dev, int addr, u8 data)
{
ds1722_select(dev);
ssi_tx_byte(0x80|addr);
ssi_tx_byte(data);
ssi_chip_select(0);
}
u16 ds1722_temp(int dev, int resolution)
{
static int useconds[] = {
75000, 150000, 300000, 600000, 1200000
};
char temp;
u16 res;
/* set up the desired resulotion ... */
ds1722_write(dev, 0, 0xe0 | (resolution << 1));
/* wait while the chip measures the tremperature */
udelay(useconds[resolution]);
res = (temp = ds1722_read(dev, 2)) << 8;
if (temp < 0) {
temp = (16 - (ds1722_read(dev, 1) >> 4)) & 0x0f;
} else {
temp = (ds1722_read(dev, 1) >> 4);
}
switch (temp) {
case 0:
/* .0000 */
break;
case 1:
/* .0625 */
res |=1;
break;
case 2:
/* .1250 */
res |=1;
break;
case 3:
/* .1875 */
res |=2;
break;
case 4:
/* .2500 */
res |=3;
break;
case 5:
/* .3125 */
res |=3;
break;
case 6:
/* .3750 */
res |=4;
break;
case 7:
/* .4375 */
res |=4;
break;
case 8:
/* .5000 */
res |=5;
break;
case 9:
/* .5625 */
res |=6;
break;
case 10:
/* .6250 */
res |=6;
break;
case 11:
/* .6875 */
res |=7;
break;
case 12:
/* .7500 */
res |=8;
break;
case 13:
/* .8125 */
res |=8;
break;
case 14:
/* .8750 */
res |=9;
break;
case 15:
/* .9375 */
res |=9;
break;
}
return res;
}
int ds1722_probe(int dev)
{
u16 temp = ds1722_temp(dev, DS1722_RESOLUTION_12BIT);
printf("%d.%d deg C\n\n", (char)(temp >> 8), temp & 0xff);
return 0;
}