lm75: add new-style driver

Teach the LM75 driver how to use new-style driver binding:

- Create a second driver struct, using new-style driver binding methods cribbed from the legacy code.

- Make the legacy probe logic delegate all its work to this new code.

- The old driver struct was renamed as "lm75_legacy".

- Sensor limits are chip-specific; record them, and use them in new routines to interconvert temperature and register values.

- More careful initialization. Chips are put into 9-bit mode so the current interconversion routines will never fail.

- Save the original chip configuration, and restore it on exit.

A later patch updates those interconversion routines to support higher resolution measurements on chips which support them.

Signed-off-by David Brownell <[email protected]>

---
 drivers/hwmon/Kconfig |    9 +-
 drivers/hwmon/lm75.c  |  191 +++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 149 insertions(+), 51 deletions(-)

(...)

drivers/hwmon/lm75.c +4 -3

@@ -54,18 +54,19 @@ static const u8 LM75_REG_TEMP[3] = {
 
 /* Each client has this additional data */
 struct lm75_data {
-	struct i2c_client	client;
+	struct i2c_client	*client;
 	struct device		*hwmon_dev;
 	struct mutex		update_lock;
+	long			min, max;
+	u8			orig_conf;
 	char			valid;		/* !=0 if registers are valid */
 	unsigned long		last_updated;	/* In jiffies */
-	u16			temp[3];	/* Register values,
+	s16			temp[3];	/* Register values,
 						   0 = input
 						   1 = max
 						   2 = hyst */
 };
 
-static void lm75_init_client(struct i2c_client *client);
 static int lm75_read_value(struct i2c_client *client, u8 reg);
 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
 static struct lm75_data *lm75_update_device(struct device *dev);

@@ -75,13 +76,28 @@ static struct lm75_data *lm75_update_dev
 

drivers/hwmon/lm75.c +9 -2

+}
+
+static inline int reg_to_temp(s16 reg)
+{
+	return LM75_TEMP_FROM_REG(reg);
+}
+
 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
 			 char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct lm75_data *data = lm75_update_device(dev);
-	return sprintf(buf, "%d\n",
-		       LM75_TEMP_FROM_REG(data->temp[attr->index]));
+
+	return sprintf(buf, "%d\n", reg_to_temp(data->temp[attr->index]));
 }
 
 static ssize_t set_temp(struct device *dev, struct device_attribute *da,

Hi David,

Quoted 24 lines · David Brownell

Teach the LM75 driver how to use new-style driver binding:

- Create a second driver struct, using new-style driver binding methods cribbed from the legacy code.

- Make the legacy probe logic delegate all its work to this new code.

- The old driver struct was renamed as "lm75_legacy".

- Sensor limits are chip-specific; record them, and use them in new routines to interconvert temperature and register values.

- More careful initialization. Chips are put into 9-bit mode so the current interconversion routines will never fail.

- Save the original chip configuration, and restore it on exit.

A later patch updates those interconversion routines to support higher resolution measurements on chips which support them.

Signed-off-by David Brownell <[email protected]>

---
 drivers/hwmon/Kconfig |    9 +-
 drivers/hwmon/lm75.c  |  191 

Quoted 2 lines

 2 files changed, 149 insertions(+), 51 deletions(-)

Out of the various comments I made back in September 2007, there's really only one which I have to repeat here. Let's say that the other ones were only nitpicking on my side.

Quoted 22 lines

(...)

drivers/hwmon/lm75.c +4 -2

@@ -54,18 +54,19 @@ static const u8 LM75_REG_TEMP[3] = {
 
 /* Each client has this additional data */
 struct lm75_data {
-	struct i2c_client	client;
+	struct i2c_client	*client;
 	struct device		*hwmon_dev;
 	struct mutex		update_lock;
+	long			min, max;
+	u8			orig_conf;
 	char			valid;		/* !=0 if registers are valid */
 	unsigned long		last_updated;	/* In jiffies */
-	u16			temp[3];	/* Register values,
+	s16			temp[3];	/* Register values,
 						   0 = input
 						   1 = max
 						   2 = hyst */
 };
 

drivers/hwmon/lm75.c static const u8 LM75_REG_TEMP[3] = {

Quoted 3 lines

drivers/hwmon/lm75.c +0 -1

-static void lm75_init_client(struct i2c_client *client);
 static int lm75_read_value(struct i2c_client *client, u8 reg);
 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 

drivers/hwmon/lm75.c static struct lm75_data *lm75_update_dev · line 86

Quoted 13 lines

drivers/hwmon/lm75.c +8 -0

 static struct lm75_data *lm75_update_device(struct device *dev);

@@ -75,13 +76,28 @@ static struct lm75_data *lm75_update_dev
 
 /* sysfs attributes for hwmon */
 
+static inline s16 temp_to_reg(struct lm75_data *lm75, long temp)
+{
+	if (temp < lm75->min)
+		temp = lm75->min;
+	else if (temp > lm75->max)
+		temp = lm75->max;
+
+	return LM75_TEMP_TO_REG(temp);

This is inefficient. Your have already done half of what LM75_TEMP_TO_REG() does, so you're better copying the rest in your function.

Alternatively, you could just move the addition of the min and max settings the next patch in the series, as I can't really see how they are related to converting the driver to new-style i2c. This would be in line with your own comment that my complaint is "addressed in the third patch".

Quoted 22 lines

drivers/hwmon/lm75.c +9 -2

+}
+
+static inline int reg_to_temp(s16 reg)
+{
+	return LM75_TEMP_FROM_REG(reg);
+}
+
 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
 			 char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct lm75_data *data = lm75_update_device(dev);
-	return sprintf(buf, "%d\n",
-		       LM75_TEMP_FROM_REG(data->temp[attr->index]));
+
+	return sprintf(buf, "%d\n", reg_to_temp(data->temp[attr->index]));
 }
 
 static ssize_t set_temp(struct device *dev, struct device_attribute *da,

@@ -94,7 +110,7 @@ static ssize_t set_temp(struct device *d
 	long temp = simple_strtol(buf, NULL, 10);
 

drivers/hwmon/lm75.c static ssize_t set_temp(struct device *d · line 116

Quoted 6 lines

drivers/hwmon/lm75.c +1 -1

 	mutex_lock(&data->update_lock);
-	data->temp[nr] = LM75_TEMP_TO_REG(temp);
+	data->temp[nr] = temp_to_reg(data, temp);
 	lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
 	mutex_unlock(&data->update_lock);
 	return count;