> -----Original Message-----
> From: Radu Sabau <radu.sabau@xxxxxxxxxx>
> Sent: Thursday, May 30, 2024 2:25 PM
> To: Jean Delvare <jdelvare@xxxxxxxx>; Guenter Roeck <linux@xxxxxxxxxxxx>; Jonathan Corbet <corbet@xxxxxxx>; linux-
> hwmon@xxxxxxxxxxxxxxx; linux-doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: Sabau, Radu bogdan <Radu.Sabau@xxxxxxxxxx>
> Subject: [PATCH v5] drivers: hwmon: max31827: Add PEC support
>
> Add support for PEC by configuring chip accordingly to the hwmon core
> PEC attribute handling.
> Add chip_write function to be used by max31827_write when setting
> the attribute.
>
> Signed-off-by: Radu Sabau <radu.sabau@xxxxxxxxxx>
> ---
> Change log:
> v2:
> *Rebase on top of v6.9
> *Attach pec attribute only to i2c device
> *Fix bug to attach pec attribute to i2c device if the device supports it.
> v3:
> *Use only one variable to write PEC_EN bit in configuration register
> *Use regmap_set_bits to set PEC_EN bit when requested instead of
> regmap_update_bits.
> *Fix typo in commit message.
> v4:
> *Use regmap_clear_bits to clear PEC_EN bit when requested instead of
> regmap_update_bits.
> v5:
> *Adapt driver to the new hwmon PEC attribute handling from the hwmon core.
> ---
> Documentation/hwmon/max31827.rst | 13 ++++++++++---
> drivers/hwmon/max31827.c | 17 ++++++++++++++++-
> 2 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
> index 44ab9dc064cb..9c11a9518c67 100644
> --- a/Documentation/hwmon/max31827.rst
> +++ b/Documentation/hwmon/max31827.rst
> @@ -131,7 +131,14 @@ The Fault Queue bits select how many consecutive temperature faults must occur
> before overtemperature or undertemperature faults are indicated in the
> corresponding status bits.
>
> -Notes
> ------
> +PEC Support
> +-----------
> +
> +When reading a register value, the PEC byte is computed and sent by the chip.
> +
> +PEC on word data transaction respresents a signifcant increase in bandwitdh
> +usage (+33% for both write and reads) in normal conditions.
>
> -PEC is not implemented.
> +Since this operation implies there will be an extra delay to each
> +transaction, PEC can be disabled or enabled through sysfs.
> +Just write 1 to the "pec" file for enabling PEC and 0 for disabling it.
> diff --git a/drivers/hwmon/max31827.c b/drivers/hwmon/max31827.c
> index f8a13b30f100..4a5f86afd84e 100644
> --- a/drivers/hwmon/max31827.c
> +++ b/drivers/hwmon/max31827.c
> @@ -24,6 +24,7 @@
>
> #define MAX31827_CONFIGURATION_1SHOT_MASK BIT(0)
> #define MAX31827_CONFIGURATION_CNV_RATE_MASK GENMASK(3, 1)
> +#define MAX31827_CONFIGURATION_PEC_EN_MASK BIT(4)
> #define MAX31827_CONFIGURATION_TIMEOUT_MASK BIT(5)
> #define MAX31827_CONFIGURATION_RESOLUTION_MASK GENMASK(7, 6)
> #define MAX31827_CONFIGURATION_ALRM_POL_MASK BIT(8)
> @@ -332,6 +333,18 @@ static int max31827_read(struct device *dev, enum hwmon_sensor_types type,
> return ret;
> }
>
> +static int max31827_chip_write(struct *regmap, u32 attr, long val)
regmap parameter is declared wrong here, will send fix in next patch.
> +{
> + switch (attr) {
> + case hwmon_chip_pec:
> + return regmap_update_bits(regmap, MAX31827_CONFIGURATION_REG,
> + MAX38127_CONFIGURATION_PEC_EN_MASK,
typo, MAX38127 -> MAX31827
> + val ? MAX38127_CONFIGURATION_PEC_EN_MASK : 0);
typo, MAX38127 -> MAX31827
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> static int max31827_write(struct device *dev, enum hwmon_sensor_types type,
> u32 attr, int channel, long val)
> {
> @@ -340,6 +353,8 @@ static int max31827_write(struct device *dev, enum hwmon_sensor_types type,
> int ret;
>
> switch (type) {
> + case hwmon_chip:
> + return max31827_chip_write(st->regmap, attr, val);
> case hwmon_temp:
> switch (attr) {
> case hwmon_temp_enable:
> @@ -583,7 +598,7 @@ static const struct hwmon_channel_info *max31827_info[] = {
> HWMON_T_MIN_HYST | HWMON_T_MIN_ALARM |
> HWMON_T_MAX | HWMON_T_MAX_HYST |
> HWMON_T_MAX_ALARM),
> - HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
> + HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL | HWMON_C_PEC),
> NULL,
> };
This patch is wrong due to the fact that hwmon_chip case is duplicated inside the switch, and therefore
I will send another patch fixing this and also modifying max31827_chip_write.
>
> --
> 2.34.1
