[PATCH 3/4] hwmon: (lm75) Add support for writing conversion time for TMP112

[Guenter Roeck]

TMP112 uses an uncommon method to write the conversion time: its
configuration register is 16 bit wide, and the conversion time is
configured in its second byte.

Signed-off-by: Guenter Roeck <li...@roeck-us.net>
---
 drivers/hwmon/lm75.c | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index 644da2620a26..ce0f6c671b8f 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -242,6 +242,8 @@ static const struct lm75_params device_params[] = {
                .clr_mask = 1 << 7,     /* no one-shot mode*/
                .default_resolution = 12,
                .default_sample_time = MSEC_PER_SEC / 4,
+               .num_sample_times = 4,
+               .sample_times = (unsigned int []){ 125, 250, 1000, 4000 },
        },
        [tmp175] = {
                .set_mask = 3 << 5,     /* 12-bit mode */
@@ -391,21 +393,36 @@ static int lm75_write_temp(struct device *dev, u32 attr, 
long temp)
 static int lm75_update_interval(struct device *dev, long val)
 {
        struct lm75_data *data = dev_get_drvdata(dev);
+       unsigned int reg;
        u8 index;
        s32 err;
 
        index = find_closest(val, data->params->sample_times,
                             (int)data->params->num_sample_times);
 
-       err = lm75_write_config(data, lm75_sample_set_masks[index],
-                               LM75_SAMPLE_CLEAR_MASK);
-       if (err)
-               return err;
-
-       data->sample_time = data->params->sample_times[index];
-       if (data->params->resolutions)
-               data->resolution = data->params->resolutions[index];
+       switch (data->kind) {
+       default:
+               err = lm75_write_config(data, lm75_sample_set_masks[index],
+                                       LM75_SAMPLE_CLEAR_MASK);
+               if (err)
+                       return err;
 
+               data->sample_time = data->params->sample_times[index];
+               if (data->params->resolutions)
+                       data->resolution = data->params->resolutions[index];
+               break;
+       case tmp112:
+               err = regmap_read(data->regmap, LM75_REG_CONF, &reg);
+               if (err < 0)
+                       return err;
+               reg &= ~0x00c0;
+               reg |= (3 - index) << 6;
+               err = regmap_write(data->regmap, LM75_REG_CONF, reg);
+               if (err < 0)
+                       return err;
+               data->sample_time = data->params->sample_times[index];
+               break;
+       }
        return 0;
 }
 
@@ -489,7 +506,7 @@ static bool lm75_is_writeable_reg(struct device *dev, 
unsigned int reg)
 
 static bool lm75_is_volatile_reg(struct device *dev, unsigned int reg)
 {
-       return reg == LM75_REG_TEMP;
+       return reg == LM75_REG_TEMP || reg == LM75_REG_CONF;
 }
 
 static const struct regmap_config lm75_regmap_config = {
-- 
2.7.4