hwmon: (tmp102) Convert to use regmap, and drop local cache

By converting the driver to regmap, we can use regmap to cache non-volatile
registers. Stop caching the temperature register; while potentially reading
it more often can result in reading it more often than necessary, this is
offset by the gain due to not re-reading the limit registers.

A positive side effect of this change is that limit registers can now be
read and updated before the first temperature conversion is complete.

Acked-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

2 files changed, 71 insertions, 78 deletions

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index f271353b4b55..e72cd3d33d4e 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1561,6 +1561,7 @@ config SENSORS_TMP102
         tristate "Texas Instruments TMP102"
         depends on I2C
         depends on THERMAL || !THERMAL_OF
+        select REGMAP_I2C
         help
           If you say yes here you get support for Texas Instruments TMP102
           sensor chips.
diff --git a/drivers/hwmon/tmp102.c b/drivers/hwmon/tmp102.c
index 82a8a29af2e4..a942a2574a4d 100644
--- a/drivers/hwmon/tmp102.c
+++ b/drivers/hwmon/tmp102.c
@@ -24,6 +24,7 @@
 #include <linux/mutex.h>
 #include <linux/device.h>
 #include <linux/jiffies.h>
+#include <linux/regmap.h>
 #include <linux/thermal.h>
 #include <linux/of.h>
 
@@ -61,13 +62,9 @@
 #define CONVERSION_TIME_MS              35      /* in milli-seconds */
 
 struct tmp102 {
-        struct i2c_client *client;
-        struct mutex lock;
+        struct regmap *regmap;
         u16 config_orig;
-        unsigned long last_update;
         unsigned long ready_time;
-        bool valid;
-        int temp[3];
 };
 
 /* convert left adjusted 13-bit TMP102 register value to milliCelsius */
@@ -82,45 +79,22 @@ static inline u16 tmp102_mC_to_reg(int val)
         return (val * 128) / 1000;
 }
 
-static const u8 tmp102_reg[] = {
-        TMP102_TEMP_REG,
-        TMP102_TLOW_REG,
-        TMP102_THIGH_REG,
-};
-
-static void tmp102_update_device(struct device *dev)
-{
-        struct tmp102 *tmp102 = dev_get_drvdata(dev);
-        struct i2c_client *client = tmp102->client;
-
-        mutex_lock(&tmp102->lock);
-        if (!tmp102->valid ||
-            time_after(jiffies, tmp102->last_update + HZ / 3)) {
-                int i;
-                for (i = 0; i < ARRAY_SIZE(tmp102->temp); ++i) {
-                        int status = i2c_smbus_read_word_swapped(client,
-                                                                 tmp102_reg[i]);
-                        if (status > -1)
-                                tmp102->temp[i] = tmp102_reg_to_mC(status);
-                }
-                tmp102->last_update = jiffies;
-                tmp102->valid = true;
-        }
-        mutex_unlock(&tmp102->lock);
-}
-
 static int tmp102_read_temp(void *dev, int *temp)
 {
         struct tmp102 *tmp102 = dev_get_drvdata(dev);
+        unsigned int reg;
+        int ret;
 
         if (time_before(jiffies, tmp102->ready_time)) {
                 dev_dbg(dev, "%s: Conversion not ready yet..\n", __func__);
                 return -EAGAIN;
         }
 
-        tmp102_update_device(dev);
+        ret = regmap_read(tmp102->regmap, TMP102_TEMP_REG, &reg);
+        if (ret < 0)
+                return ret;
 
-        *temp = tmp102->temp[0];
+        *temp = tmp102_reg_to_mC(reg);
 
         return 0;
 }
@@ -131,13 +105,19 @@ static ssize_t tmp102_show_temp(struct device *dev,
 {
         struct sensor_device_attribute *sda = to_sensor_dev_attr(attr);
         struct tmp102 *tmp102 = dev_get_drvdata(dev);
+        int regaddr = sda->index;
+        unsigned int reg;
+        int err;
 
-        if (time_before(jiffies, tmp102->ready_time))
+        if (regaddr == TMP102_TEMP_REG &&
+            time_before(jiffies, tmp102->ready_time))
                 return -EAGAIN;
 
-        tmp102_update_device(dev);
+        err = regmap_read(tmp102->regmap, regaddr, &reg);
+        if (err < 0)
+                return err;
 
-        return sprintf(buf, "%d\n", tmp102->temp[sda->index]);
+        return sprintf(buf, "%d\n", tmp102_reg_to_mC(reg));
 }
 
 static ssize_t tmp102_set_temp(struct device *dev,
@@ -146,29 +126,26 @@ static ssize_t tmp102_set_temp(struct device *dev,
 {
         struct sensor_device_attribute *sda = to_sensor_dev_attr(attr);
         struct tmp102 *tmp102 = dev_get_drvdata(dev);
-        struct i2c_client *client = tmp102->client;
+        int reg = sda->index;
         long val;
-        int status;
+        int err;
 
         if (kstrtol(buf, 10, &val) < 0)
                 return -EINVAL;
         val = clamp_val(val, -256000, 255000);
 
-        mutex_lock(&tmp102->lock);
-        tmp102->temp[sda->index] = val;
-        status = i2c_smbus_write_word_swapped(client, tmp102_reg[sda->index],
-                                              tmp102_mC_to_reg(val));
-        mutex_unlock(&tmp102->lock);
-        return status ? : count;
+        err = regmap_write(tmp102->regmap, reg, tmp102_mC_to_reg(val));
+        return err ? : count;
 }
 
-static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, tmp102_show_temp, NULL , 0);
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, tmp102_show_temp, NULL,
+                          TMP102_TEMP_REG);
 
 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO, tmp102_show_temp,
-                          tmp102_set_temp, 1);
+                          tmp102_set_temp, TMP102_TLOW_REG);
 
 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, tmp102_show_temp,
-                          tmp102_set_temp, 2);
+                          tmp102_set_temp, TMP102_THIGH_REG);
 
 static struct attribute *tmp102_attrs[] = {
         &sensor_dev_attr_temp1_input.dev_attr.attr,
@@ -185,19 +162,39 @@ static const struct thermal_zone_of_device_ops tmp102_of_thermal_ops = {
 static void tmp102_restore_config(void *data)
 {
         struct tmp102 *tmp102 = data;
-        struct i2c_client *client = tmp102->client;
 
-        i2c_smbus_write_word_swapped(client, TMP102_CONF_REG,
-                                     tmp102->config_orig);
+        regmap_write(tmp102->regmap, TMP102_CONF_REG, tmp102->config_orig);
+}
+
+static bool tmp102_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+        return reg != TMP102_TEMP_REG;
 }
 
+static bool tmp102_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+        return reg == TMP102_TEMP_REG;
+}
+
+static const struct regmap_config tmp102_regmap_config = {
+        .reg_bits = 8,
+        .val_bits = 16,
+        .max_register = TMP102_THIGH_REG,
+        .writeable_reg = tmp102_is_writeable_reg,
+        .volatile_reg = tmp102_is_volatile_reg,
+        .val_format_endian = REGMAP_ENDIAN_BIG,
+        .cache_type = REGCACHE_RBTREE,
+        .use_single_rw = true,
+};
+
 static int tmp102_probe(struct i2c_client *client,
                                   const struct i2c_device_id *id)
 {
         struct device *dev = &client->dev;
         struct device *hwmon_dev;
         struct tmp102 *tmp102;
-        int status;
+        unsigned int regval;
+        int err;
 
         if (!i2c_check_functionality(client->adapter,
                                      I2C_FUNC_SMBUS_WORD_DATA)) {
@@ -211,35 +208,36 @@ static int tmp102_probe(struct i2c_client *client,
                 return -ENOMEM;
 
         i2c_set_clientdata(client, tmp102);
-        tmp102->client = client;
 
-        status = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
-        if (status < 0) {
+        tmp102->regmap = devm_regmap_init_i2c(client, &tmp102_regmap_config);
+        if (IS_ERR(tmp102->regmap))
+                return PTR_ERR(tmp102->regmap);
+
+        err = regmap_read(tmp102->regmap, TMP102_CONF_REG, &regval);
+        if (err < 0) {
                 dev_err(dev, "error reading config register\n");
-                return status;
+                return err;
         }
 
-        if ((status & ~TMP102_CONFREG_MASK) !=
+        if ((regval & ~TMP102_CONFREG_MASK) !=
             (TMP102_CONF_R0 | TMP102_CONF_R1)) {
                 dev_err(dev, "unexpected config register value\n");
                 return -ENODEV;
         }
 
-        tmp102->config_orig = status;
+        tmp102->config_orig = regval;
 
         devm_add_action(dev, tmp102_restore_config, tmp102);
 
-        status &= ~TMP102_CONFIG_CLEAR;
-        status |= TMP102_CONFIG_SET;
+        regval &= ~TMP102_CONFIG_CLEAR;
+        regval |= TMP102_CONFIG_SET;
 
-        status = i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, status);
-        if (status < 0) {
+        err = regmap_write(tmp102->regmap, TMP102_CONF_REG, regval);
+        if (err < 0) {
                 dev_err(dev, "error writing config register\n");
-                return status;
+                return err;
         }
 
-        mutex_init(&tmp102->lock);
-
         tmp102->ready_time = jiffies;
         if (tmp102->config_orig & TMP102_CONF_SD) {
                 /*
@@ -268,30 +266,24 @@ static int tmp102_probe(struct i2c_client *client,
 static int tmp102_suspend(struct device *dev)
 {
         struct i2c_client *client = to_i2c_client(dev);
-        int config;
-
-        config = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
-        if (config < 0)
-                return config;
+        struct tmp102 *tmp102 = i2c_get_clientdata(client);
 
-        config |= TMP102_CONF_SD;
-        return i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, config);
+        return regmap_update_bits(tmp102->regmap, TMP102_CONF_REG,
+                                  TMP102_CONF_SD, TMP102_CONF_SD);
 }
 
 static int tmp102_resume(struct device *dev)
 {
         struct i2c_client *client = to_i2c_client(dev);
         struct tmp102 *tmp102 = i2c_get_clientdata(client);
-        int config;
+        int err;
 
-        config = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
-        if (config < 0)
-                return config;
+        err = regmap_update_bits(tmp102->regmap, TMP102_CONF_REG,
+                                 TMP102_CONF_SD, 0);
 
         tmp102->ready_time = jiffies + msecs_to_jiffies(CONVERSION_TIME_MS);
 
-        config &= ~TMP102_CONF_SD;
-        return i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, config);
+        return err;
 }
 #endif /* CONFIG_PM */