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charset=us-ascii Content-Disposition: inline In-Reply-To: <20240523121057.5689-1-radu.sabau@analog.com> On Thu, May 23, 2024 at 03:10:56PM +0300, Radu Sabau wrote: > Add support for PEC by attaching PEC attribute to the i2c device. > Add pec_store and pec_show function for accesing the "pec" file. > > Signed-off-by: Radu Sabau > --- Change log missing. > Documentation/hwmon/max31827.rst | 13 +++++-- > drivers/hwmon/max31827.c | 64 ++++++++++++++++++++++++++++++++ > 2 files changed, 74 insertions(+), 3 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..e86f8890ee72 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) > @@ -475,6 +476,54 @@ static ssize_t temp1_resolution_store(struct device *dev, > > static DEVICE_ATTR_RW(temp1_resolution); > > +static ssize_t pec_show(struct device *dev, struct device_attribute *devattr, > + char *buf) > +{ > + struct i2c_client *client = to_i2c_client(dev); > + > + return scnprintf(buf, PAGE_SIZE, "%d\n", !!(client->flags & I2C_CLIENT_PEC)); > +} > + > +static ssize_t pec_store(struct device *dev, struct device_attribute *devattr, > + const char *buf, size_t count) > +{ > + struct max31827_state *st = dev_get_drvdata(dev); > + struct i2c_client *client = to_i2c_client(dev); > + unsigned int val; > + int err; > + > + err = kstrtouint(buf, 10, &val); > + if (err < 0) > + return err; > + > + switch (val) { > + case 0: > + err = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG, > + MAX31827_CONFIGURATION_PEC_EN_MASK, > + val); While correct, this is misleading. Should write 0. > + if (err) > + return err; > + > + client->flags &= ~I2C_CLIENT_PEC; > + break; > + case 1: > + err = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG, > + MAX31827_CONFIGURATION_PEC_EN_MASK, > + val); This is wrong. s/val/MAX31827_CONFIGURATION_PEC_EN_MASK/ Guenter