[lm-sensors] [PATCH] hwmon: support TI TMP121/TMP123 with LM70 driver.

Manuel Lauss mano at roarinelk.homelinux.net
Tue Sep 16 19:53:45 CEST 2008


The Texas Instruments TMP121 is a SPI temperature sensor very similar
to the LM70, with slightly higher resolution.  This patch extends the
LM70 driver to support the TMP121.  Chip type is determined by
platform data.

Signed-off-by: Manuel Lauss <mano at roarinelk.homelinux.net>
---
 Documentation/hwmon/lm70 |    7 +++++-
 drivers/hwmon/Kconfig    |    5 ++-
 drivers/hwmon/lm70.c     |   56 ++++++++++++++++++++++++++++++++++++++++-----
 include/linux/spi/lm70.h |   15 ++++++++++++
 4 files changed, 73 insertions(+), 10 deletions(-)
 create mode 100644 include/linux/spi/lm70.h

diff --git a/Documentation/hwmon/lm70 b/Documentation/hwmon/lm70
index 2bdd3fe..88f4322 100644
--- a/Documentation/hwmon/lm70
+++ b/Documentation/hwmon/lm70
@@ -1,9 +1,11 @@
 Kernel driver lm70
 ==================
 
-Supported chip:
+Supported chips:
   * National Semiconductor LM70
     Datasheet: http://www.national.com/pf/LM/LM70.html
+  * Texas Instruments TMP121/TMP123
+    Datasheet: http://www.ti.com/lit/gpn/tmp121
 
 Author:
         Kaiwan N Billimoria <kaiwan at designergraphix.com>
@@ -25,6 +27,9 @@ complement digital temperature (sent via the SIO line), is available in the
 driver for interpretation. This driver makes use of the kernel's in-core
 SPI support.
 
+The TMP121 is very similar; main differences are 4 wire SPI interface,
+and 13bit temperature data (0.0625 celsius resolution).
+
 Thanks to
 ---------
 Jean Delvare <khali at linux-fr.org> for mentoring the hwmon-side driver
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index d402e8d..56a84e0 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -407,11 +407,12 @@ config SENSORS_LM63
 	  will be called lm63.
 
 config SENSORS_LM70
-	tristate "National Semiconductor LM70"
+	tristate "National Semiconductor LM70 / Texas Instruments TMP121"
 	depends on SPI_MASTER && EXPERIMENTAL
 	help
 	  If you say yes here you get support for the National Semiconductor
-	  LM70 digital temperature sensor chip.
+	  LM70 and Texas Instruments TMP121/TMP123 digital temperature
+	  sensor chips.
 
 	  This driver can also be built as a module.  If so, the module
 	  will be called lm70.
diff --git a/drivers/hwmon/lm70.c b/drivers/hwmon/lm70.c
index d435f00..9ab0479 100644
--- a/drivers/hwmon/lm70.c
+++ b/drivers/hwmon/lm70.c
@@ -33,13 +33,14 @@
 #include <linux/hwmon.h>
 #include <linux/mutex.h>
 #include <linux/spi/spi.h>
-
+#include <linux/spi/lm70.h>
 
 #define DRVNAME		"lm70"
 
 struct lm70 {
 	struct device *hwmon_dev;
 	struct mutex lock;
+	unsigned int chip;
 };
 
 /* sysfs hook function */
@@ -67,10 +68,8 @@ static ssize_t lm70_sense_temp(struct device *dev,
 	}
 	dev_dbg(dev, "rxbuf[1] : 0x%x rxbuf[0] : 0x%x\n", rxbuf[1], rxbuf[0]);
 
-	raw = (rxbuf[1] << 8) + rxbuf[0];
-	dev_dbg(dev, "raw=0x%x\n", raw);
-
 	/*
+	 * LM70:
 	 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
 	 * complement value. Only the MSB 11 bits (1 sign + 10 temperature
 	 * bits) are meaningful; the LSB 5 bits are to be discarded.
@@ -80,8 +79,27 @@ static ssize_t lm70_sense_temp(struct device *dev,
 	 * by 0.25. Also multiply by 1000 to represent in millidegrees
 	 * Celsius.
 	 * So it's equivalent to multiplying by 0.25 * 1000 = 250.
+	 *
+	 * TMP121:
+	 * 13bits of 2's complement data, discard lower 3 bits.  Chip
+	 * transmits high byte first.  Resolution 0.0625 celsius.
 	 */
-	val = ((int)raw/32) * 250;
+	switch (p_lm70->chip) {
+	case LM70_CHIP_LM70:
+		raw = (rxbuf[1] << 8) + rxbuf[0];
+		dev_dbg(dev, "raw=0x%x\n", raw);
+		val = ((int)raw/32) * 250;
+		break;
+
+	case LM70_CHIP_TMP121:
+		raw = (rxbuf[0] << 8) + rxbuf[1];
+		dev_dbg(dev, "raw=0x%x\n", raw);
+		val = (raw / 8) * 625 / 10;
+		break;
+
+	default:
+		raw = 0;
+	}
 	status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
 out:
 	mutex_unlock(&p_lm70->lock);
@@ -93,7 +111,21 @@ static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
 static ssize_t lm70_show_name(struct device *dev, struct device_attribute
 			      *devattr, char *buf)
 {
-	return sprintf(buf, "lm70\n");
+	struct spi_device *spi = to_spi_device(dev);
+	struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
+	int ret;
+
+	switch (p_lm70->chip) {
+	case LM70_CHIP_LM70:
+		ret = sprintf(buf, "lm70\n");
+		break;
+	case LM70_CHIP_TMP121:
+		ret = sprintf(buf, "tmp121\n");
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	return ret;
 }
 
 static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL);
@@ -102,11 +134,20 @@ static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL);
 
 static int __devinit lm70_probe(struct spi_device *spi)
 {
+	struct lm70_platform_data *pdata;
 	struct lm70 *p_lm70;
 	int status;
+	unsigned int chip;
+
+	pdata = spi->dev.platform_data;
+	if (pdata)
+		chip = pdata->chip;
+	else
+		chip = LM70_CHIP_LM70;
 
 	/* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */
-	if ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE))
+	if ((chip == LM70_CHIP_LM70) &&
+	    ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE)))
 		return -EINVAL;
 
 	p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
@@ -114,6 +155,7 @@ static int __devinit lm70_probe(struct spi_device *spi)
 		return -ENOMEM;
 
 	mutex_init(&p_lm70->lock);
+	p_lm70->chip = chip;
 
 	/* sysfs hook */
 	p_lm70->hwmon_dev = hwmon_device_register(&spi->dev);
diff --git a/include/linux/spi/lm70.h b/include/linux/spi/lm70.h
new file mode 100644
index 0000000..986c35a
--- /dev/null
+++ b/include/linux/spi/lm70.h
@@ -0,0 +1,15 @@
+/*
+ * LM70 platform data
+ */
+
+#ifndef _LM70_H_
+#define _LM70_H_
+
+#define LM70_CHIP_LM70		0
+#define LM70_CHIP_TMP121	1
+
+struct lm70_platform_data {
+	unsigned int chip;
+};
+
+#endif
-- 
1.6.0.1





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