Re: [PATCH v4 1/2] hwmon: (jc42) Convert register access and caching to regmap/regcache

From: Guenter Roeck
Date: Wed Oct 26 2022 - 11:06:12 EST

On Sun, Oct 23, 2022 at 11:31:56PM +0200, Martin Blumenstingl wrote:
> 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>

Applied to hwmon-next.

Thanks,
Guenter

> ---
> drivers/hwmon/Kconfig | 1 +
> drivers/hwmon/jc42.c | 233 ++++++++++++++++++++++++------------------
> 2 files changed, 132 insertions(+), 102 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..355639d208d0 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 +200,14 @@ 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)
> @@ -248,85 +232,102 @@ 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;
> + struct jc42_data *data = dev_get_drvdata(dev);
> + unsigned int regval;
> + int ret, temp, hyst;
>
> - if (IS_ERR(data))
> - return PTR_ERR(data);
> + mutex_lock(&data->update_lock);
>
> switch (attr) {
> case hwmon_temp_input:
> - *val = jc42_temp_from_reg(data->temp[t_input]);
> - return 0;
> + ret = regmap_read(data->regmap, JC42_REG_TEMP, &regval);
> + if (ret)
> + break;
> +
> + *val = jc42_temp_from_reg(regval);
> + break;
> case hwmon_temp_min:
> - *val = jc42_temp_from_reg(data->temp[t_min]);
> - return 0;
> + ret = regmap_read(data->regmap, JC42_REG_TEMP_LOWER, &regval);
> + if (ret)
> + break;
> +
> + *val = jc42_temp_from_reg(regval);
> + break;
> case hwmon_temp_max:
> - *val = jc42_temp_from_reg(data->temp[t_max]);
> - return 0;
> + ret = regmap_read(data->regmap, JC42_REG_TEMP_UPPER, &regval);
> + if (ret)
> + break;
> +
> + *val = jc42_temp_from_reg(regval);
> + break;
> case hwmon_temp_crit:
> - *val = jc42_temp_from_reg(data->temp[t_crit]);
> - return 0;
> + ret = regmap_read(data->regmap, JC42_REG_TEMP_CRITICAL,
> + &regval);
> + if (ret)
> + break;
> +
> + *val = jc42_temp_from_reg(regval);
> + break;
> 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)
> + break;
> +
> + temp = jc42_temp_from_reg(regval);
> hyst = jc42_hysteresis[(data->config & JC42_CFG_HYST_MASK)
> >> JC42_CFG_HYST_SHIFT];
> *val = temp - hyst;
> - return 0;
> + break;
> 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)
> + break;
> +
> + temp = jc42_temp_from_reg(regval);
> hyst = jc42_hysteresis[(data->config & JC42_CFG_HYST_MASK)
> >> JC42_CFG_HYST_SHIFT];
> *val = temp - hyst;
> - return 0;
> + break;
> case hwmon_temp_min_alarm:
> - *val = (data->temp[t_input] >> JC42_ALARM_MIN_BIT) & 1;
> - return 0;
> + ret = regmap_read(data->regmap, JC42_REG_TEMP, &regval);
> + if (ret)
> + break;
> +
> + *val = (regval >> JC42_ALARM_MIN_BIT) & 1;
> + break;
> case hwmon_temp_max_alarm:
> - *val = (data->temp[t_input] >> JC42_ALARM_MAX_BIT) & 1;
> - return 0;
> + ret = regmap_read(data->regmap, JC42_REG_TEMP, &regval);
> + if (ret)
> + break;
> +
> + *val = (regval >> JC42_ALARM_MAX_BIT) & 1;
> + break;
> case hwmon_temp_crit_alarm:
> - *val = (data->temp[t_input] >> JC42_ALARM_CRIT_BIT) & 1;
> - return 0;
> + ret = regmap_read(data->regmap, JC42_REG_TEMP, &regval);
> + if (ret)
> + break;
> +
> + *val = (regval >> JC42_ALARM_CRIT_BIT) & 1;
> + break;
> default:
> - return -EOPNOTSUPP;
> + ret = -EOPNOTSUPP;
> + break;
> }
> +
> + mutex_unlock(&data->update_lock);
> +
> + return ret;
> }
>
> 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;
>
> @@ -334,21 +335,23 @@ static int jc42_write(struct device *dev, enum hwmon_sensor_types type,
>
> 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 +359,7 @@ 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)
> @@ -368,9 +371,8 @@ 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;
> @@ -470,51 +472,80 @@ 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 +566,7 @@ 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 +577,7 @@ 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 +586,7 @@ 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;
> }
>