summaryrefslogtreecommitdiffstats
path: root/dtt/ds1775.c
diff options
context:
space:
mode:
Diffstat (limited to 'dtt/ds1775.c')
-rw-r--r--dtt/ds1775.c156
1 files changed, 156 insertions, 0 deletions
diff --git a/dtt/ds1775.c b/dtt/ds1775.c
new file mode 100644
index 0000000000..e44cee3279
--- /dev/null
+++ b/dtt/ds1775.c
@@ -0,0 +1,156 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * Dallas Semiconductor's DS1775 Digital Thermometer and Thermostat
+ */
+
+#include <common.h>
+
+#ifdef CONFIG_DTT_DS1775
+#include <i2c.h>
+#include <dtt.h>
+
+#define DTT_I2C_DEV_CODE 0x49 /* Dallas Semi's DS1775 device code */
+
+int dtt_read(int sensor, int reg)
+{
+ int dlen;
+ uchar data[2];
+
+ /*
+ * Calculate sensor address and command
+ */
+ sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1775 */
+
+ /*
+ * Prepare to handle 2 byte result
+ */
+ if ((reg == DTT_READ_TEMP) ||
+ (reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST))
+ dlen = 2;
+ else
+ dlen = 1;
+
+ /*
+ * Now try to read the register
+ */
+ if (i2c_read(sensor, reg, 1, data, dlen) != 0)
+ return 1;
+
+ /*
+ * Handle 2 byte result
+ */
+ if (dlen == 2)
+ return ((int)((short)data[1] + (((short)data[0]) << 8)));
+
+ return (int) data[0];
+}
+
+
+int dtt_write(int sensor, int reg, int val)
+{
+ int dlen;
+ uchar data[2];
+
+ /*
+ * Calculate sensor address and register
+ */
+ sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
+
+ /*
+ * Handle various data sizes
+ */
+ if ((reg == DTT_READ_TEMP) ||
+ (reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST)) {
+ dlen = 2;
+ data[0] = (char)((val >> 8) & 0xff); /* MSB first */
+ data[1] = (char)(val & 0xff);
+ } else {
+ dlen = 1;
+ data[0] = (char)(val & 0xff);
+ }
+
+ /*
+ * Write value to device
+ */
+ if (i2c_write(sensor, reg, 1, data, dlen) != 0)
+ return 1;
+
+ return 0;
+}
+
+
+static int _dtt_init(int sensor)
+{
+ int val;
+
+ /*
+ * Setup High Temp
+ */
+ val = ((CFG_DTT_MAX_TEMP * 2) << 7) & 0xff80;
+ if (dtt_write(sensor, DTT_TEMP_OS, val) != 0)
+ return 1;
+ udelay(50000); /* Max 50ms */
+
+ /*
+ * Setup Low Temp - hysteresis
+ */
+ val = (((CFG_DTT_MAX_TEMP - CFG_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
+ if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
+ return 1;
+ udelay(50000); /* Max 50ms */
+
+ /*
+ * Setup configuraton register
+ *
+ * Fault Tolerance limits 4, Thermometer resolution bits is 9,
+ * Polarity = Active Low,continuous conversion mode, Thermostat
+ * mode is interrupt mode
+ */
+ val = 0xa;
+ if (dtt_write(sensor, DTT_CONFIG, val) != 0)
+ return 1;
+ udelay(50000); /* Max 50ms */
+
+ return 0;
+}
+
+
+int dtt_init (void)
+{
+ int i;
+ unsigned char sensors[] = CONFIG_DTT_SENSORS;
+
+ for (i = 0; i < sizeof(sensors); i++) {
+ if (_dtt_init(sensors[i]) != 0)
+ printf("DTT%d: FAILED\n", i+1);
+ else
+ printf("DTT%d: %i C\n", i+1, dtt_get_temp(sensors[i]));
+ }
+
+ return (0);
+}
+
+
+int dtt_get_temp(int sensor)
+{
+ return (dtt_read(sensor, DTT_READ_TEMP) / 256);
+}
+
+
+#endif /* CONFIG_DTT_DS1775 */
OpenPOWER on IntegriCloud