hwmon: (lm90) Support ADT7461 in extended mode

Support ADT7461 in extended temperature range mode, which will change
the range of readings from 0..127 to -64..191 degC.  Adjust the
register conversion functions accordingly.

Signed-off-by: Nate Case <ncase@xes-inc.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Tested-by: Martyn Welch <martyn.welch@gefanuc.com>

2 files changed, 95 insertions, 32 deletions

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index ebacc0af40fe..96701e099e81 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -510,11 +510,8 @@ config SENSORS_LM90
 	depends on I2C
 	help
 	  If you say yes here you get support for National Semiconductor LM90,
-	  LM86, LM89 and LM99, Analog Devices ADM1032 and Maxim MAX6657,
-	  MAX6658, MAX6659, MAX6680 and MAX6681 sensor chips.
-
-	  The Analog Devices ADT7461 sensor chip is also supported, but only
-	  if found in ADM1032 compatibility mode.
+	  LM86, LM89 and LM99, Analog Devices ADM1032 and ADT7461, and Maxim
+	  MAX6657, MAX6658, MAX6659, MAX6680 and MAX6681 sensor chips.
 
 	  This driver can also be built as a module.  If so, the module
 	  will be called lm90.
diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index b2d9b3f0946d..fe5d860fc838 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -37,11 +37,10 @@
  * chips. The MAX6680 and MAX6681 only differ in the pinout so they can
  * be treated identically.
  *
- * This driver also supports the ADT7461 chip from Analog Devices but
- * only in its "compatability mode". If an ADT7461 chip is found but
- * is configured in non-compatible mode (where its temperature
- * register values are decoded differently) it is ignored by this
- * driver.
+ * This driver also supports the ADT7461 chip from Analog Devices.
+ * It's supported in both compatibility and extended mode. It is mostly
+ * compatible with LM90 except for a data format difference for the
+ * temperature value registers.
  *
  * Since the LM90 was the first chipset supported by this driver, most
  * comments will refer to this chipset, but are actually general and
@@ -138,6 +137,11 @@ I2C_CLIENT_INSMOD_7(lm90, adm1032, lm99, lm86, max6657, adt7461, max6680);
 #define MAX6657_REG_R_LOCAL_TEMPL	0x11
 
 /*
+ * Device flags
+ */
+#define LM90_FLAG_ADT7461_EXT		0x01	/* ADT7461 extended mode */
+
+/*
  * Functions declaration
  */
 
@@ -191,6 +195,7 @@ struct lm90_data {
 	char valid; /* zero until following fields are valid */
 	unsigned long last_updated; /* in jiffies */
 	int kind;
+	int flags;
 
 	/* registers values */
 	s8 temp8[4];	/* 0: local low limit
@@ -256,26 +261,61 @@ static u8 hyst_to_reg(long val)
 }
 
 /*
- * ADT7461 is almost identical to LM90 except that attempts to write
- * values that are outside the range 0 < temp < 127 are treated as
- * the boundary value.
+ * ADT7461 in compatibility mode is almost identical to LM90 except that
+ * attempts to write values that are outside the range 0 < temp < 127 are
+ * treated as the boundary value.
+ *
+ * ADT7461 in "extended mode" operation uses unsigned integers offset by
+ * 64 (e.g., 0 -> -64 degC).  The range is restricted to -64..191 degC.
  */
-static u8 temp1_to_reg_adt7461(long val)
+static inline int temp1_from_reg_adt7461(struct lm90_data *data, u8 val)
 {
-	if (val <= 0)
-		return 0;
-	if (val >= 127000)
-		return 127;
-	return (val + 500) / 1000;
+	if (data->flags & LM90_FLAG_ADT7461_EXT)
+		return (val - 64) * 1000;
+	else
+		return temp1_from_reg(val);
 }
 
-static u16 temp2_to_reg_adt7461(long val)
+static inline int temp2_from_reg_adt7461(struct lm90_data *data, u16 val)
 {
-	if (val <= 0)
-		return 0;
-	if (val >= 127750)
-		return 0x7FC0;
-	return (val + 125) / 250 * 64;
+	if (data->flags & LM90_FLAG_ADT7461_EXT)
+		return (val - 0x4000) / 64 * 250;
+	else
+		return temp2_from_reg(val);
+}
+
+static u8 temp1_to_reg_adt7461(struct lm90_data *data, long val)
+{
+	if (data->flags & LM90_FLAG_ADT7461_EXT) {
+		if (val <= -64000)
+			return 0;
+		if (val >= 191000)
+			return 0xFF;
+		return (val + 500 + 64000) / 1000;
+	} else {
+		if (val <= 0)
+			return 0;
+		if (val >= 127000)
+			return 127;
+		return (val + 500) / 1000;
+	}
+}
+
+static u16 temp2_to_reg_adt7461(struct lm90_data *data, long val)
+{
+	if (data->flags & LM90_FLAG_ADT7461_EXT) {
+		if (val <= -64000)
+			return 0;
+		if (val >= 191750)
+			return 0xFFC0;
+		return (val + 64000 + 125) / 250 * 64;
+	} else {
+		if (val <= 0)
+			return 0;
+		if (val >= 127750)
+			return 0x7FC0;
+		return (val + 125) / 250 * 64;
+	}
 }
 
 /*
@@ -287,7 +327,14 @@ static ssize_t show_temp8(struct device *dev, struct device_attribute *devattr,
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 	struct lm90_data *data = lm90_update_device(dev);
-	return sprintf(buf, "%d\n", temp1_from_reg(data->temp8[attr->index]));
+	int temp;
+
+	if (data->kind == adt7461)
+		temp = temp1_from_reg_adt7461(data, data->temp8[attr->index]);
+	else
+		temp = temp1_from_reg(data->temp8[attr->index]);
+
+	return sprintf(buf, "%d\n", temp);
 }
 
 static ssize_t set_temp8(struct device *dev, struct device_attribute *devattr,
@@ -308,7 +355,7 @@ static ssize_t set_temp8(struct device *dev, struct device_attribute *devattr,
 
 	mutex_lock(&data->update_lock);
 	if (data->kind == adt7461)
-		data->temp8[nr] = temp1_to_reg_adt7461(val);
+		data->temp8[nr] = temp1_to_reg_adt7461(data, val);
 	else
 		data->temp8[nr] = temp1_to_reg(val);
 	i2c_smbus_write_byte_data(client, reg[nr], data->temp8[nr]);
@@ -321,7 +368,14 @@ static ssize_t show_temp11(struct device *dev, struct device_attribute *devattr,
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 	struct lm90_data *data = lm90_update_device(dev);
-	return sprintf(buf, "%d\n", temp2_from_reg(data->temp11[attr->index]));
+	int temp;
+
+	if (data->kind == adt7461)
+		temp = temp2_from_reg_adt7461(data, data->temp11[attr->index]);
+	else
+		temp = temp2_from_reg(data->temp11[attr->index]);
+
+	return sprintf(buf, "%d\n", temp);
 }
 
 static ssize_t set_temp11(struct device *dev, struct device_attribute *devattr,
@@ -344,7 +398,7 @@ static ssize_t set_temp11(struct device *dev, struct device_attribute *devattr,
 
 	mutex_lock(&data->update_lock);
 	if (data->kind == adt7461)
-		data->temp11[nr] = temp2_to_reg_adt7461(val);
+		data->temp11[nr] = temp2_to_reg_adt7461(data, val);
 	else if (data->kind == max6657 || data->kind == max6680)
 		data->temp11[nr] = temp1_to_reg(val) << 8;
 	else
@@ -364,8 +418,14 @@ static ssize_t show_temphyst(struct device *dev, struct device_attribute *devatt
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 	struct lm90_data *data = lm90_update_device(dev);
-	return sprintf(buf, "%d\n", temp1_from_reg(data->temp8[attr->index])
-		       - temp1_from_reg(data->temp_hyst));
+	int temp;
+
+	if (data->kind == adt7461)
+		temp = temp1_from_reg_adt7461(data, data->temp8[attr->index]);
+	else
+		temp = temp1_from_reg(data->temp8[attr->index]);
+
+	return sprintf(buf, "%d\n", temp - temp1_from_reg(data->temp_hyst));
 }
 
 static ssize_t set_temphyst(struct device *dev, struct device_attribute *dummy,
@@ -598,7 +658,7 @@ static int lm90_detect(struct i2c_client *new_client, int kind,
 				kind = adm1032;
 			} else
 			if (chip_id == 0x51 /* ADT7461 */
-			 && (reg_config1 & 0x1F) == 0x00 /* check compat mode */
+			 && (reg_config1 & 0x1B) == 0x00
 			 && reg_convrate <= 0x0A) {
 				kind = adt7461;
 			}
@@ -737,6 +797,12 @@ static void lm90_init_client(struct i2c_client *client)
 	}
 	config_orig = config;
 
+	/* Check Temperature Range Select */
+	if (data->kind == adt7461) {
+		if (config & 0x04)
+			data->flags |= LM90_FLAG_ADT7461_EXT;
+	}
+
 	/*
 	 * Put MAX6680/MAX8881 into extended resolution (bit 0x10,
 	 * 0.125 degree resolution) and range (0x08, extend range