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path: root/drivers/ds1722.c
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Diffstat (limited to 'drivers/ds1722.c')
-rw-r--r--drivers/ds1722.c142
1 files changed, 142 insertions, 0 deletions
diff --git a/drivers/ds1722.c b/drivers/ds1722.c
new file mode 100644
index 0000000..34eb80c
--- /dev/null
+++ b/drivers/ds1722.c
@@ -0,0 +1,142 @@
+
+#include <common.h>
+
+#include <ssi.h>
+
+#ifdef CONFIG_DS1722
+
+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;
+}
+
+#endif