[PATCH 3/6] hwmon: (lm92) Replace chip IDs with limit register resolution

[Guenter Roeck <linux@roeck-us.net>]

The chip IDs are not used by the driver. Drop them. Use driver data to
store the limit register resolution instead, and use this information
when writing temperature limits to improve chip specific rounding and
to avoid writing into unused register bits.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/lm92.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/hwmon/lm92.c b/drivers/hwmon/lm92.c
index b0179d72b779..5ff45a0033f1 100644
--- a/drivers/hwmon/lm92.c
+++ b/drivers/hwmon/lm92.c
@@ -43,8 +43,6 @@
  */
 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
 						I2C_CLIENT_END };
-enum chips { lm92, max6635 };
-
 /* The LM92 registers */
 #define LM92_REG_CONFIG			0x01 /* 8-bit, RW */
 #define LM92_REG_TEMP			0x00 /* 16-bit, RO */
@@ -66,10 +64,10 @@ static inline int TEMP_FROM_REG(s16 reg)
 	return reg / 8 * 625 / 10;
 }
 
-static inline s16 TEMP_TO_REG(long val)
+static inline s16 TEMP_TO_REG(long val, int resolution)
 {
 	val = clamp_val(val, -60000, 160000);
-	return val * 10 / 625 * 8;
+	return DIV_ROUND_CLOSEST(val << (resolution - 9), 1000) << (16 - resolution);
 }
 
 /* Alarm flags are stored in the 3 LSB of the temperature register */
@@ -99,6 +97,7 @@ static const u8 regs[t_num_regs] = {
 struct lm92_data {
 	struct i2c_client *client;
 	struct mutex update_lock;
+	int resolution;
 	bool valid; /* false until following fields are valid */
 	unsigned long last_updated; /* in jiffies */
 
@@ -159,7 +158,7 @@ static ssize_t temp_store(struct device *dev,
 		return err;
 
 	mutex_lock(&data->update_lock);
-	data->temp[nr] = TEMP_TO_REG(val);
+	data->temp[nr] = TEMP_TO_REG(val, data->resolution);
 	i2c_smbus_write_word_swapped(client, regs[nr], data->temp[nr]);
 	mutex_unlock(&data->update_lock);
 	return count;
@@ -201,7 +200,8 @@ static ssize_t temp_hyst_store(struct device *dev,
 	val = clamp_val(val, -120000, 220000);
 	mutex_lock(&data->update_lock);
 	data->temp[t_hyst] =
-		TEMP_TO_REG(TEMP_FROM_REG(data->temp[attr->index]) - val);
+		TEMP_TO_REG(TEMP_FROM_REG(data->temp[attr->index]) - val,
+			    data->resolution);
 	i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
 				     data->temp[t_hyst]);
 	mutex_unlock(&data->update_lock);
@@ -311,6 +311,7 @@ static int lm92_probe(struct i2c_client *new_client)
 		return -ENOMEM;
 
 	data->client = new_client;
+	data->resolution = (unsigned long)i2c_get_match_data(new_client);
 	mutex_init(&data->update_lock);
 
 	/* Initialize the chipset */
@@ -326,9 +327,10 @@ static int lm92_probe(struct i2c_client *new_client)
  * Module and driver stuff
  */
 
+/* .driver_data is limit register resolution */ 
 static const struct i2c_device_id lm92_id[] = {
-	{ "lm92", lm92 },
-	{ "max6635", max6635 },
+	{ "lm92", 13 },
+	{ "max6635", 9 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, lm92_id);
-- 
2.39.2