Add support for PEC by attaching PEC attribute to the i2c device.
Add pec_store and pec_show function for accessing the "pec" file.
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.
---
Documentation/hwmon/max31827.rst | 13 +++++--
drivers/hwmon/max31827.c | 62 ++++++++++++++++++++++++++++++++
2 files changed, 72 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..c120032582ac 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 +476,52 @@ 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_clear_bits(st->regmap, MAX31827_CONFIGURATION_REG,
+ MAX31827_CONFIGURATION_PEC_EN_MASK);
+ if (err)
+ return err;
+
+ client->flags &= ~I2C_CLIENT_PEC;
+ break;
+ case 1:
+ err = regmap_set_bits(st->regmap, MAX31827_CONFIGURATION_REG,
+ MAX31827_CONFIGURATION_PEC_EN_MASK);
+ if (err)
+ return err;
+
+ client->flags |= I2C_CLIENT_PEC;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return count;
+}
+
+static DEVICE_ATTR_RW(pec);
+
static struct attribute *max31827_attrs[] = {
&dev_attr_temp1_resolution.attr,
NULL
@@ -578,6 +625,11 @@ static int max31827_init_client(struct max31827_state *st,
return regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, res);
}
+static void max31827_remove_pec(void *dev)
+{
+ device_remove_file(dev, &dev_attr_pec);
+}
+
static const struct hwmon_channel_info *max31827_info[] = {
HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT | HWMON_T_MIN |
HWMON_T_MIN_HYST | HWMON_T_MIN_ALARM |
@@ -627,6 +679,16 @@ static int max31827_probe(struct i2c_client *client)
if (err)
return err;
+ if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_PEC)) {
+ err = device_create_file(dev, &dev_attr_pec);
+ if (err)
+ return err;
+
+ err = devm_add_action_or_reset(dev, max31827_remove_pec, dev);
+ if (err)
+ return err;
+ }
+
hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, st,
&max31827_chip_info,
max31827_groups);
--
2.34.1
