hwmon: (lm70) Add TI TMP121 support

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.  The TMP123 differs in pin assign-
ment.

Signed-off-by: Manuel Lauss <mano@roarinelk.homelinux.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

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
+    Information: http://focus.ti.com/docs/prod/folders/print/tmp121.html
 
 Author:
         Kaiwan N Billimoria <kaiwan@designergraphix.com>
@@ -29,6 +31,10 @@ As a real (in-tree) example of this "SPI protocol driver" interfacing
 with a "SPI master controller driver", see drivers/spi/spi_lm70llp.c
 and its associated documentation.
 
+The TMP121/TMP123 are very similar; main differences are 4 wire SPI inter-
+face (read only) and 13-bit temperature data (0.0625 degrees celsius reso-
+lution).
+
 Thanks to
 ---------
 Jean Delvare <khali@linux-fr.org> for mentoring the hwmon-side driver

drivers/hwmon/Kconfig

@@ -428,11 +428,12 @@ 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.

drivers/hwmon/lm70.c

@@ -37,17 +37,21 @@
 
 #define DRVNAME		"lm70"
 
+#define LM70_CHIP_LM70		0	/* original NS LM70 */
+#define LM70_CHIP_TMP121	1	/* TI TMP121/TMP123 */
+
 struct lm70 {
 	struct device *hwmon_dev;
 	struct mutex lock;
+	unsigned int chip;
 };
 
 /* sysfs hook function */
 static ssize_t lm70_sense_temp(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct spi_device *spi = to_spi_device(dev);
-	int status, val;
+	int status, val = 0;
 	u8 rxbuf[2];
 	s16 raw=0;
 	struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
@@ -70,6 +74,7 @@ static ssize_t lm70_sense_temp(struct device *dev,
 		rxbuf[0], rxbuf[1], 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.
@@ -79,8 +84,21 @@ 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/TMP123:
+	 * 13 bits of 2's complement data, discard LSB 3 bits,
+	 * resolution 0.0625 degrees celsius.
 	 */
-	val = ((int)raw/32) * 250;
+	switch (p_lm70->chip) {
+	case LM70_CHIP_LM70:
+		val = ((int)raw / 32) * 250;
+		break;
+
+	case LM70_CHIP_TMP121:
+		val = ((int)raw / 8) * 625 / 10;
+		break;
+	}
+
 	status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
 out:
 	mutex_unlock(&p_lm70->lock);
@@ -92,29 +110,39 @@ 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 lm70 *p_lm70 = dev_get_drvdata(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);
 
 /*----------------------------------------------------------------------*/
 
-static int __devinit lm70_probe(struct spi_device *spi)
+static int __devinit common_probe(struct spi_device *spi, int chip)
 {
 	struct lm70 *p_lm70;
 	int status;
 
-	/* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */
-	if ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE))
-		return -EINVAL;
-
 	/* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
 
 	p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
 	if (!p_lm70)
 		return -ENOMEM;
 
 	mutex_init(&p_lm70->lock);
+	p_lm70->chip = chip;
 
 	/* sysfs hook */
 	p_lm70->hwmon_dev = hwmon_device_register(&spi->dev);
@@ -142,6 +170,24 @@ static int __devinit lm70_probe(struct spi_device *spi)
 	return status;
 }
 
+static int __devinit lm70_probe(struct spi_device *spi)
+{
+	/* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */
+	if ((spi->mode & (SPI_CPOL | SPI_CPHA)) || !(spi->mode & SPI_3WIRE))
+		return -EINVAL;
+
+	return common_probe(spi, LM70_CHIP_LM70);
+}
+
+static int __devinit tmp121_probe(struct spi_device *spi)
+{
+	/* signaling is SPI_MODE_0 with only MISO connected */
+	if (spi->mode & (SPI_CPOL | SPI_CPHA))
+		return -EINVAL;
+
+	return common_probe(spi, LM70_CHIP_TMP121);
+}
+
 static int __devexit lm70_remove(struct spi_device *spi)
 {
 	struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
@@ -155,6 +201,15 @@ static int __devexit lm70_remove(struct spi_device *spi)
 	return 0;
 }
 
+static struct spi_driver tmp121_driver = {
+	.driver = {
+		.name	= "tmp121",
+		.owner	= THIS_MODULE,
+	},
+	.probe	= tmp121_probe,
+	.remove	= __devexit_p(lm70_remove),
+};
+
 static struct spi_driver lm70_driver = {
 	.driver = {
 		.name	= "lm70",
@@ -166,17 +221,26 @@ static struct spi_driver lm70_driver = {
 
 static int __init init_lm70(void)
 {
-	return spi_register_driver(&lm70_driver);
+	int ret = spi_register_driver(&lm70_driver);
+	if (ret)
+		return ret;
+
+	ret = spi_register_driver(&tmp121_driver);
+	if (ret)
+		spi_unregister_driver(&lm70_driver);
+
+	return ret;
 }
 
 static void __exit cleanup_lm70(void)
 {
 	spi_unregister_driver(&lm70_driver);
+	spi_unregister_driver(&tmp121_driver);
 }
 
 module_init(init_lm70);
 module_exit(cleanup_lm70);
 
 MODULE_AUTHOR("Kaiwan N Billimoria");
-MODULE_DESCRIPTION("National Semiconductor LM70 Linux driver");
+MODULE_DESCRIPTION("NS LM70 / TI TMP121/TMP123 Linux driver");
 MODULE_LICENSE("GPL");