Enabling and disabling PEC for PMBus devices is currently only supported
with a debugfs attribute, which requires debugfs to be enabled and is
thus less than perfect. Take the lm90 driver as example and add a 'pec'
attribute to the I2C device if both the I2C adapter and the PMBus device
support it. Remove the now obsolete 'pec' attribute from debugfs.
Cc: Andrew Jeffery <andrew@xxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-class-hwmon | 9 +++
Documentation/hwmon/pmbus-core.rst | 9 +++
drivers/hwmon/pmbus/pmbus_core.c | 89 ++++++++++++---------
3 files changed, 68 insertions(+), 39 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-class-hwmon b/Documentation/ABI/testing/sysfs-class-hwmon
index 653d4c75eddb..7271781a23b2 100644
--- a/Documentation/ABI/testing/sysfs-class-hwmon
+++ b/Documentation/ABI/testing/sysfs-class-hwmon
@@ -938,3 +938,12 @@ Description:
- 1: enable
RW
+
+What: /sys/class/hwmon/hwmonX/device/pec
+Description:
+ PEC support on I2C devices
+
+ - 0, off, n: disable
+ - 1, on, y: enable
+
+ RW
diff --git a/Documentation/hwmon/pmbus-core.rst b/Documentation/hwmon/pmbus-core.rst
index e7e0c9ef10be..84c5a4e40c40 100644
--- a/Documentation/hwmon/pmbus-core.rst
+++ b/Documentation/hwmon/pmbus-core.rst
@@ -121,6 +121,15 @@ Specifically, it provides the following information.
non-standard PMBus commands to standard commands, or to augment standard
command return values with device specific information.
+PEC Support
+===========
+
+Many PMBus devices support SMBus PEC (Packet Error Checking). If supported
+by both the I2C adapter and by the PMBus chip, it is by default enabled.
+If PEC is supported, the PMBus core driver adds an attribute named 'pec' to
+the I2C device. This attribute can be used to control PEC support in the
+communication with the PMBus chip.
+
API functions
=============
diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 84b05dbd7de8..bb21f1e79289 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -2522,6 +2522,42 @@ static int pmbus_read_status_word(struct i2c_client *client, int page)
return _pmbus_read_word_data(client, page, 0xff, PMBUS_STATUS_WORD);
}
+/* PEC attribute support */
+
+static ssize_t pec_show(struct device *dev, struct device_attribute *dummy,
+ char *buf)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+
+ return sysfs_emit(buf, "%d\n", !!(client->flags & I2C_CLIENT_PEC));
+}
+
+static ssize_t pec_store(struct device *dev, struct device_attribute *dummy,
+ const char *buf, size_t count)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ bool enable;
+ int err;
+
+ err = kstrtobool(buf, &enable);
+ if (err < 0)
+ return err;
+
+ if (enable)
+ client->flags |= I2C_CLIENT_PEC;
+ else
+ client->flags &= ~I2C_CLIENT_PEC;
+
+ return count;
+}
+
+static DEVICE_ATTR_RW(pec);
+
+static void pmbus_remove_pec(void *dev)
+{
+ device_remove_file(dev, &dev_attr_pec);
+}
+
static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
struct pmbus_driver_info *info)
{
@@ -2608,6 +2644,20 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
return ret;
}
+ if (client->flags & I2C_CLIENT_PEC) {
+ /*
+ * If I2C_CLIENT_PEC is set here, both the I2C adapter and the
+ * chip support PEC. Add 'pec' attribute to client device to let
+ * the user control it.
+ */
+ ret = device_create_file(dev, &dev_attr_pec);
+ if (ret)
+ return ret;
+ ret = devm_add_action_or_reset(dev, pmbus_remove_pec, dev);
+ if (ret)
+ return ret;
+ }
+
return 0;
}
@@ -2916,42 +2966,6 @@ static int pmbus_debugfs_get_status(void *data, u64 *val)
DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops_status, pmbus_debugfs_get_status,
NULL, "0x%04llx\n");
-static int pmbus_debugfs_get_pec(void *data, u64 *val)
-{
- struct i2c_client *client = data;
-
- *val = !!(client->flags & I2C_CLIENT_PEC);
-
- return 0;
-}
-
-static int pmbus_debugfs_set_pec(void *data, u64 val)
-{
- int rc;
- struct i2c_client *client = data;
-
- if (!val) {
- client->flags &= ~I2C_CLIENT_PEC;
- return 0;
- }
-
- if (val != 1)
- return -EINVAL;
-
- rc = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);
- if (rc < 0)
- return rc;
-
- if (!(rc & PB_CAPABILITY_ERROR_CHECK))
- return -EOPNOTSUPP;
-
- client->flags |= I2C_CLIENT_PEC;
-
- return 0;
-}
-DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops_pec, pmbus_debugfs_get_pec,
- pmbus_debugfs_set_pec, "%llu\n");
-
static void pmbus_remove_debugfs(void *data)
{
struct dentry *entry = data;
@@ -2987,9 +3001,6 @@ static int pmbus_init_debugfs(struct i2c_client *client,
if (!entries)
return -ENOMEM;
- debugfs_create_file("pec", 0664, data->debugfs, client,
- &pmbus_debugfs_ops_pec);
-
for (i = 0; i < data->info->pages; ++i) {
/* Check accessibility of status register if it's not page 0 */
if (!i || pmbus_check_status_register(client, i)) {
--
2.35.1
