1 files changed, 156 insertions, 0 deletions
diff --git a/dtt/ds1775.c b/dtt/ds1775.c
new file mode 100644
index 0000000..e44cee3
--- /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 */