[PATCH v3 1/2] hwmon: (jc42) Convert register access and caching to regmap/regcache

From: Martin Blumenstingl
Date: Fri Oct 21 2022 - 12:50:44 EST

Switch the jc42 driver to use an I2C regmap to access the registers.
Also move over to regmap's built-in caching instead of adding a
custom caching implementation. This works for JC42_REG_TEMP_UPPER,
JC42_REG_TEMP_LOWER and JC42_REG_TEMP_CRITICAL as these values never
change except when explicitly written. The cache For JC42_REG_TEMP is
dropped (regmap can't cache it because it's volatile, meaning it can
change at any time) as well for simplicity and consistency with other
drivers.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
---
drivers/hwmon/Kconfig | 1 +
drivers/hwmon/jc42.c | 214 +++++++++++++++++++++++-------------------
2 files changed, 116 insertions(+), 99 deletions(-)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 7ac3daaf59ce..d3bccc8176c5 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -799,6 +799,7 @@ config SENSORS_IT87
config SENSORS_JC42
tristate "JEDEC JC42.4 compliant memory module temperature sensors"
depends on I2C
+ select REGMAP_I2C
help
If you say yes here, you get support for JEDEC JC42.4 compliant
temperature sensors, which are used on many DDR3 memory modules for
diff --git a/drivers/hwmon/jc42.c b/drivers/hwmon/jc42.c
index 30888feaf589..8d70960d5444 100644
--- a/drivers/hwmon/jc42.c
+++ b/drivers/hwmon/jc42.c
@@ -19,6 +19,7 @@
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/of.h>
+#include <linux/regmap.h>

/* Addresses to scan */
static const unsigned short normal_i2c[] = {
@@ -199,31 +200,13 @@ static struct jc42_chips jc42_chips[] = {
{ STM_MANID, STTS3000_DEVID, STTS3000_DEVID_MASK },
};

-enum temp_index {
- t_input = 0,
- t_crit,
- t_min,
- t_max,
- t_num_temp
-};
-
-static const u8 temp_regs[t_num_temp] = {
- [t_input] = JC42_REG_TEMP,
- [t_crit] = JC42_REG_TEMP_CRITICAL,
- [t_min] = JC42_REG_TEMP_LOWER,
- [t_max] = JC42_REG_TEMP_UPPER,
-};
-
/* Each client has this additional data */
struct jc42_data {
- struct i2c_client *client;
- struct mutex update_lock; /* protect register access */
+ struct regmap *regmap;
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[t_num_temp];/* Temperatures */
};

#define JC42_TEMP_MIN_EXTENDED (-40000)
@@ -248,74 +231,84 @@ 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);
- struct i2c_client *client = data->client;
- struct jc42_data *ret = data;
- int i, val;
-
- mutex_lock(&data->update_lock);
-
- if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
- for (i = 0; i < t_num_temp; i++) {
- val = i2c_smbus_read_word_swapped(client, temp_regs[i]);
- if (val < 0) {
- ret = ERR_PTR(val);
- goto abort;
- }
- data->temp[i] = val;
- }
- data->last_updated = jiffies;
- data->valid = true;
- }
-abort:
- mutex_unlock(&data->update_lock);
- return ret;
-}
-
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);
- int temp, hyst;
-
- if (IS_ERR(data))
- return PTR_ERR(data);
+ struct jc42_data *data = dev_get_drvdata(dev);
+ unsigned int regval;
+ int ret, temp, hyst;

switch (attr) {
case hwmon_temp_input:
- *val = jc42_temp_from_reg(data->temp[t_input]);
+ 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:
- *val = jc42_temp_from_reg(data->temp[t_min]);
+ ret = regmap_read(data->regmap, JC42_REG_TEMP_LOWER, &regval);
+ if (ret)
+ return ret;
+
+ *val = jc42_temp_from_reg(regval);
return 0;
case hwmon_temp_max:
- *val = jc42_temp_from_reg(data->temp[t_max]);
+ ret = regmap_read(data->regmap, JC42_REG_TEMP_UPPER, &regval);
+ if (ret)
+ return ret;
+
+ *val = jc42_temp_from_reg(regval);
return 0;
case hwmon_temp_crit:
- *val = jc42_temp_from_reg(data->temp[t_crit]);
+ ret = regmap_read(data->regmap, JC42_REG_TEMP_CRITICAL,
+ &regval);
+ if (ret)
+ return ret;
+
+ *val = jc42_temp_from_reg(regval);
return 0;
case hwmon_temp_max_hyst:
- temp = jc42_temp_from_reg(data->temp[t_max]);
+ ret = regmap_read(data->regmap, JC42_REG_TEMP_UPPER, &regval);
+ if (ret)
+ return ret;
+
+ temp = jc42_temp_from_reg(regval);
hyst = jc42_hysteresis[(data->config & JC42_CFG_HYST_MASK)
>> JC42_CFG_HYST_SHIFT];
*val = temp - hyst;
return 0;
case hwmon_temp_crit_hyst:
- temp = jc42_temp_from_reg(data->temp[t_crit]);
+ ret = regmap_read(data->regmap, JC42_REG_TEMP_CRITICAL,
+ &regval);
+ if (ret)
+ return ret;
+
+ temp = jc42_temp_from_reg(regval);
hyst = jc42_hysteresis[(data->config & JC42_CFG_HYST_MASK)
>> JC42_CFG_HYST_SHIFT];
*val = temp - hyst;
return 0;
case hwmon_temp_min_alarm:
- *val = (data->temp[t_input] >> 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[t_input] >> 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[t_input] >> 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;
@@ -326,29 +319,29 @@ static int jc42_write(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long val)
{
struct jc42_data *data = dev_get_drvdata(dev);
- struct i2c_client *client = data->client;
+ unsigned int regval;
int diff, hyst;
int ret;

- mutex_lock(&data->update_lock);
-
switch (attr) {
case hwmon_temp_min:
- data->temp[t_min] = jc42_temp_to_reg(val, data->extended);
- ret = i2c_smbus_write_word_swapped(client, temp_regs[t_min],
- data->temp[t_min]);
+ ret = regmap_write(data->regmap, JC42_REG_TEMP_LOWER,
+ jc42_temp_to_reg(val, data->extended));
break;
case hwmon_temp_max:
- data->temp[t_max] = jc42_temp_to_reg(val, data->extended);
- ret = i2c_smbus_write_word_swapped(client, temp_regs[t_max],
- data->temp[t_max]);
+ ret = regmap_write(data->regmap, JC42_REG_TEMP_UPPER,
+ jc42_temp_to_reg(val, data->extended));
break;
case hwmon_temp_crit:
- data->temp[t_crit] = jc42_temp_to_reg(val, data->extended);
- ret = i2c_smbus_write_word_swapped(client, temp_regs[t_crit],
- data->temp[t_crit]);
+ ret = regmap_write(data->regmap, JC42_REG_TEMP_CRITICAL,
+ jc42_temp_to_reg(val, data->extended));
break;
case hwmon_temp_crit_hyst:
+ ret = regmap_read(data->regmap, JC42_REG_TEMP_CRITICAL,
+ &regval);
+ if (ret)
+ return ret;
+
/*
* JC42.4 compliant chips only support four hysteresis values.
* Pick best choice and go from there.
@@ -356,7 +349,7 @@ static int jc42_write(struct device *dev, enum hwmon_sensor_types type,
val = clamp_val(val, (data->extended ? JC42_TEMP_MIN_EXTENDED
: JC42_TEMP_MIN) - 6000,
JC42_TEMP_MAX);
- diff = jc42_temp_from_reg(data->temp[t_crit]) - val;
+ diff = jc42_temp_from_reg(regval) - val;
hyst = 0;
if (diff > 0) {
if (diff < 2250)
@@ -368,17 +361,14 @@ static int jc42_write(struct device *dev, enum hwmon_sensor_types type,
}
data->config = (data->config & ~JC42_CFG_HYST_MASK) |
(hyst << JC42_CFG_HYST_SHIFT);
- ret = i2c_smbus_write_word_swapped(data->client,
- JC42_REG_CONFIG,
- data->config);
+ ret = regmap_write(data->regmap, JC42_REG_CONFIG,
+ data->config);
break;
default:
ret = -EOPNOTSUPP;
break;
}

- mutex_unlock(&data->update_lock);
-
return ret;
}

@@ -470,51 +460,79 @@ static const struct hwmon_chip_info jc42_chip_info = {
.info = jc42_info,
};

+static bool jc42_readable_reg(struct device *dev, unsigned int reg)
+{
+ return (reg >= JC42_REG_CAP && reg <= JC42_REG_DEVICEID) ||
+ reg == JC42_REG_SMBUS;
+}
+
+static bool jc42_writable_reg(struct device *dev, unsigned int reg)
+{
+ return (reg >= JC42_REG_CONFIG && reg <= JC42_REG_TEMP_CRITICAL) ||
+ reg == JC42_REG_SMBUS;
+}
+
+static bool jc42_volatile_reg(struct device *dev, unsigned int reg)
+{
+ return reg == JC42_REG_CONFIG || reg == JC42_REG_TEMP;
+}
+
+static const struct regmap_config jc42_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 16,
+ .val_format_endian = REGMAP_ENDIAN_BIG,
+ .max_register = JC42_REG_SMBUS,
+ .writeable_reg = jc42_writable_reg,
+ .readable_reg = jc42_readable_reg,
+ .volatile_reg = jc42_volatile_reg,
+ .cache_type = REGCACHE_RBTREE,
+};
+
static int jc42_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct device *hwmon_dev;
+ unsigned int config, cap;
struct jc42_data *data;
- int config, cap;
+ int ret;

data = devm_kzalloc(dev, sizeof(struct jc42_data), GFP_KERNEL);
if (!data)
return -ENOMEM;

- data->client = client;
+ data->regmap = devm_regmap_init_i2c(client, &jc42_regmap_config);
+ if (IS_ERR(data->regmap))
+ return PTR_ERR(data->regmap);
+
i2c_set_clientdata(client, data);
- mutex_init(&data->update_lock);

- cap = i2c_smbus_read_word_swapped(client, JC42_REG_CAP);
- if (cap < 0)
- return cap;
+ ret = regmap_read(data->regmap, JC42_REG_CAP, &cap);
+ if (ret)
+ return ret;

data->extended = !!(cap & JC42_CAP_RANGE);

if (device_property_read_bool(dev, "smbus-timeout-disable")) {
- int smbus;
-
/*
* Not all chips support this register, but from a
* quick read of various datasheets no chip appears
* incompatible with the below attempt to disable
* the timeout. And the whole thing is opt-in...
*/
- smbus = i2c_smbus_read_word_swapped(client, JC42_REG_SMBUS);
- if (smbus < 0)
- return smbus;
- i2c_smbus_write_word_swapped(client, JC42_REG_SMBUS,
- smbus | SMBUS_STMOUT);
+ ret = regmap_set_bits(data->regmap, JC42_REG_SMBUS,
+ SMBUS_STMOUT);
+ if (ret)
+ return ret;
}

- config = i2c_smbus_read_word_swapped(client, JC42_REG_CONFIG);
- if (config < 0)
- return config;
+ ret = regmap_read(data->regmap, JC42_REG_CONFIG, &config);
+ if (ret)
+ return ret;

data->orig_config = config;
if (config & JC42_CFG_SHUTDOWN) {
config &= ~JC42_CFG_SHUTDOWN;
- i2c_smbus_write_word_swapped(client, JC42_REG_CONFIG, config);
+ regmap_write(data->regmap, JC42_REG_CONFIG, config);
}
data->config = config;

@@ -535,7 +553,7 @@ static void jc42_remove(struct i2c_client *client)

config = (data->orig_config & ~JC42_CFG_HYST_MASK)
| (data->config & JC42_CFG_HYST_MASK);
- i2c_smbus_write_word_swapped(client, JC42_REG_CONFIG, config);
+ regmap_write(data->regmap, JC42_REG_CONFIG, config);
}
}

@@ -546,8 +564,7 @@ static int jc42_suspend(struct device *dev)
struct jc42_data *data = dev_get_drvdata(dev);

data->config |= JC42_CFG_SHUTDOWN;
- i2c_smbus_write_word_swapped(data->client, JC42_REG_CONFIG,
- data->config);
+ regmap_write(data->regmap, JC42_REG_CONFIG, data->config);
return 0;
}

@@ -556,8 +573,7 @@ static int jc42_resume(struct device *dev)
struct jc42_data *data = dev_get_drvdata(dev);

data->config &= ~JC42_CFG_SHUTDOWN;
- i2c_smbus_write_word_swapped(data->client, JC42_REG_CONFIG,
- data->config);
+ regmap_write(data->regmap, JC42_REG_CONFIG, data->config);
return 0;
}

--
2.38.1