Initial revision
diff --git a/dtt/ds1621.c b/dtt/ds1621.c
new file mode 100644
index 0000000..5c25f64
--- /dev/null
+++ b/dtt/ds1621.c
@@ -0,0 +1,191 @@
+/*
+ * (C) Copyright 2001
+ * Erik Theisen, Wave 7 Optics, etheisen@mindspring.com.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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 DS1621 Digital Thermometer and Thermostat.
+ */
+
+#include <common.h>
+
+#ifdef CONFIG_DTT_DS1621
+#if !defined(CFG_EEPROM_PAGE_WRITE_ENABLE) || \
+ (CFG_EEPROM_PAGE_WRITE_BITS < 1)
+# error "CFG_EEPROM_PAGE_WRITE_ENABLE must be defined and CFG_EEPROM_PAGE_WRITE_BITS must be greater than 1 to use CONFIG_DTT_DS1621"
+#endif
+#include <i2c.h>
+#include <dtt.h>
+
+/*
+ * Device code
+ */
+#define DTT_I2C_DEV_CODE 0x48 /* Dallas Semi's DS1621 */
+
+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 ds1621*/
+
+ /*
+ * Prepare to handle 2 byte result.
+ */
+ if ((reg == DTT_READ_TEMP) ||
+ (reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW))
+ 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];
+} /* dtt_read() */
+
+
+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 & sensor);
+
+ /*
+ * Handle various data sizes.
+ */
+ if ((reg == DTT_READ_TEMP) ||
+ (reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW)) {
+ dlen = 2;
+ data[0] = (char)((val >> 8) & 0xff); /* MSB first */
+ data[1] = (char)(val & 0xff);
+ }
+ else if ((reg == DTT_WRITE_START_CONV) || (reg == DTT_WRITE_STOP_CONV)) {
+ dlen = 0;
+ data[0] = (char)0;
+ data[1] = (char)0;
+ }
+ 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;
+} /* dtt_write() */
+
+
+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_HIGH, 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_LOW, val) != 0)
+ return 1;
+ udelay(50000); /* Max 50ms */
+
+ /*
+ * Setup configuraton register
+ *
+ * Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
+ *
+ * We run in polled mode, since there isn't any way to know if this
+ * lousy device is ready to provide temperature readings on power up.
+ */
+ val = 0x9;
+ if (dtt_write(sensor, DTT_CONFIG, val) != 0)
+ return 1;
+ udelay(50000); /* Max 50ms */
+
+ return 0;
+} /* _dtt_init() */
+
+
+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);
+} /* dtt_init() */
+
+
+int dtt_get_temp(int sensor)
+{
+ int i;
+
+ /*
+ * Start a conversion, may take up to 1 second.
+ */
+ dtt_write(sensor, DTT_WRITE_START_CONV, 0);
+ for (i = 0; i <= 10; i++) {
+ udelay(100000);
+ if (dtt_read(sensor, DTT_CONFIG) & 0x80)
+ break;
+ }
+
+ return (dtt_read(sensor, DTT_READ_TEMP) / 256);
+} /* dtt_get_temp() */
+
+
+#endif /* CONFIG_DTT_DS1621 */
+