linux-kernel - [RFC PATCH v2 4/4] hwmon: (jc42) Don't cache the temperature register

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Message-Id: <20221020210320.1624617-5-martin.blumenstingl@googlemail.com>
Date:   Thu, 20 Oct 2022 23:03:20 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     linux@...ck-us.net, linux-hwmon@...r.kernel.org
Cc:     jdelvare@...e.com, linux-kernel@...r.kernel.org,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: [RFC PATCH v2 4/4] hwmon: (jc42) Don't cache the temperature register

Now that we're utilizing regmap and it's regcache for the
minimum/maximum/critical temperature registers the only cached register
that's left is the actual temperature register. Drop the custom cache
implementation as it just complicates things.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
---
 drivers/hwmon/jc42.c | 59 ++++++++++++++++----------------------------
 1 file changed, 21 insertions(+), 38 deletions(-)

diff --git a/drivers/hwmon/jc42.c b/drivers/hwmon/jc42.c
index 61311483a5c6..52a60eb0791b 100644
--- a/drivers/hwmon/jc42.c
+++ b/drivers/hwmon/jc42.c
@@ -203,13 +203,10 @@ static struct jc42_chips jc42_chips[] = {
 /* Each client has this additional data */
 struct jc42_data {
 	struct regmap	*regmap;
-	struct mutex	update_lock;	/* protect register access */
 	bool		extended;	/* true if extended range supported */
 	bool		valid;
-	unsigned long	last_updated;	/* In jiffies */
 	u16		orig_config;	/* original configuration */
 	u16		config;		/* current configuration */
-	u16		temp;		/* Cached temperature register value */
 };
 
 #define JC42_TEMP_MIN_EXTENDED	(-40000)
@@ -234,41 +231,20 @@ static int jc42_temp_from_reg(s16 reg)
 	return reg * 125 / 2;
 }
 
-static struct jc42_data *jc42_update_device(struct device *dev)
-{
-	struct jc42_data *data = dev_get_drvdata(dev);
-	unsigned int val;
-	int ret;
-
-	mutex_lock(&data->update_lock);
-
-	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
-		ret = regmap_read(data->regmap, JC42_REG_TEMP, &val);
-		if (ret)
-			goto abort;
-
-		data->temp = val;
-		data->last_updated = jiffies;
-		data->valid = true;
-	}
-abort:
-	mutex_unlock(&data->update_lock);
-	return ret ? ERR_PTR(ret) : data;
-}
-
 static int jc42_read(struct device *dev, enum hwmon_sensor_types type,
 		     u32 attr, int channel, long *val)
 {
-	struct jc42_data *data = jc42_update_device(dev);
+	struct jc42_data *data = dev_get_drvdata(dev);
 	unsigned int regval;
 	int ret, temp, hyst;
 
-	if (IS_ERR(data))
-		return PTR_ERR(data);
-
 	switch (attr) {
 	case hwmon_temp_input:
-		*val = jc42_temp_from_reg(data->temp);
+		ret = regmap_read(data->regmap, JC42_REG_TEMP, &regval);
+		if (ret)
+			return ret;
+
+		*val = jc42_temp_from_reg(regval);
 		return 0;
 	case hwmon_temp_min:
 		ret = regmap_read(data->regmap, JC42_REG_TEMP_LOWER, &regval);
@@ -314,13 +290,25 @@ static int jc42_read(struct device *dev, enum hwmon_sensor_types type,
 		*val = temp - hyst;
 		return 0;
 	case hwmon_temp_min_alarm:
-		*val = (data->temp >> JC42_ALARM_MIN_BIT) & 1;
+		ret = regmap_read(data->regmap, JC42_REG_TEMP, &regval);
+		if (ret)
+			return ret;
+
+		*val = (regval >> JC42_ALARM_MIN_BIT) & 1;
 		return 0;
 	case hwmon_temp_max_alarm:
-		*val = (data->temp >> JC42_ALARM_MAX_BIT) & 1;
+		ret = regmap_read(data->regmap, JC42_REG_TEMP, &regval);
+		if (ret)
+			return ret;
+
+		*val = (regval >> JC42_ALARM_MAX_BIT) & 1;
 		return 0;
 	case hwmon_temp_crit_alarm:
-		*val = (data->temp >> JC42_ALARM_CRIT_BIT) & 1;
+		ret = regmap_read(data->regmap, JC42_REG_TEMP, &regval);
+		if (ret)
+			return ret;
+
+		*val = (regval >> JC42_ALARM_CRIT_BIT) & 1;
 		return 0;
 	default:
 		return -EOPNOTSUPP;
@@ -335,8 +323,6 @@ static int jc42_write(struct device *dev, enum hwmon_sensor_types type,
 	int diff, hyst;
 	int ret;
 
-	mutex_lock(&data->update_lock);
-
 	switch (attr) {
 	case hwmon_temp_min:
 		ret = regmap_write(data->regmap, JC42_REG_TEMP_LOWER,
@@ -383,8 +369,6 @@ static int jc42_write(struct device *dev, enum hwmon_sensor_types type,
 		break;
 	}
 
-	mutex_unlock(&data->update_lock);
-
 	return ret;
 }
 
@@ -521,7 +505,6 @@ static int jc42_probe(struct i2c_client *client)
 		return PTR_ERR(data->regmap);
 
 	i2c_set_clientdata(client, data);
-	mutex_init(&data->update_lock);
 
 	ret = regmap_read(data->regmap, JC42_REG_CAP, &cap);
 	if (ret)
-- 
2.38.1