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