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hwmon: (pmbus/core) improve handling of write protected regulators

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Writing PMBus protected registers does succeed from the smbus perspective,
even if the write is ignored by the device and a communication fault is
raised. This fault will silently be caught and cleared by pmbus irq if one
has been registered.

This means that the regulator call may return succeed although the
operation was ignored.

With this change, the operation which are not supported will be properly
flagged as such and the regulator framework won't even try to execute them.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
[groeck: Adjust to EXPORT_SYMBOL_NS_GPL API change]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Jerome Brunet 2024-12-02 11:28:00 +01:00 committed by Guenter Roeck
parent c26eef8957
commit f404525775
4 changed files with 78 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
Documentation/hwmon/pmbus-core.rst
View File

@ -312,6 +312,10 @@ currently provides a flags field with four bits used::
#define PMBUS_USE_COEFFICIENTS_CMD BIT(5)
#define PMBUS_OP_PROTECTED BIT(6)
#define PMBUS_VOUT_PROTECTED BIT(7)
struct pmbus_platform_data {
u32 flags; /* Device specific flags */
@ -373,3 +377,13 @@ PMBUS_USE_COEFFICIENTS_CMD
When this flag is set the PMBus core driver will use the COEFFICIENTS
register to initialize the coefficients for the direct mode format.
PMBUS_OP_PROTECTED
Set if the chip OPERATION command is protected and protection is not
determined by the standard WRITE_PROTECT command.
PMBUS_VOUT_PROTECTED
Set if the chip VOUT_COMMAND command is protected and protection is not
determined by the standard WRITE_PROTECT command.

4
drivers/hwmon/pmbus/pmbus.h
View File

@ -487,6 +487,8 @@ struct pmbus_driver_info {
/* Regulator ops */
extern const struct regulator_ops pmbus_regulator_ops;
int pmbus_regulator_init_cb(struct regulator_dev *rdev,
struct regulator_config *config);
/* Macros for filling in array of struct regulator_desc */
#define PMBUS_REGULATOR_STEP(_name, _id, _voltages, _step, _min_uV) \
@ -501,6 +503,7 @@ extern const struct regulator_ops pmbus_regulator_ops;
.n_voltages = _voltages, \
.uV_step = _step, \
.min_uV = _min_uV, \
.init_cb = pmbus_regulator_init_cb, \
}
#define PMBUS_REGULATOR(_name, _id) PMBUS_REGULATOR_STEP(_name, _id, 0, 0, 0)
@ -516,6 +519,7 @@ extern const struct regulator_ops pmbus_regulator_ops;
.n_voltages = _voltages, \
.uV_step = _step, \
.min_uV = _min_uV, \
.init_cb = pmbus_regulator_init_cb, \
}
#define PMBUS_REGULATOR_ONE(_name) PMBUS_REGULATOR_STEP_ONE(_name, 0, 0, 0)

52
drivers/hwmon/pmbus/pmbus_core.c
View File

@ -2665,6 +2665,30 @@ static void pmbus_remove_pec(void *dev)
device_remove_file(dev, &dev_attr_pec);
}
static void pmbus_init_wp(struct i2c_client *client, struct pmbus_data *data)
{
int ret;
ret = _pmbus_read_byte_data(client, -1, PMBUS_WRITE_PROTECT);
if (ret < 0)
return;
switch (ret & PB_WP_ANY) {
case PB_WP_ALL:
data->flags |= PMBUS_OP_PROTECTED;
fallthrough;
case PB_WP_OP:
data->flags |= PMBUS_VOUT_PROTECTED;
fallthrough;
case PB_WP_VOUT:
data->flags |= PMBUS_WRITE_PROTECTED | PMBUS_SKIP_STATUS_CHECK;
break;
default:
break;
}
}
static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
struct pmbus_driver_info *info)
{
@ -2718,12 +2742,8 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
* faults, and we should not try it. Also, in that case, writes into
* limit registers need to be disabled.
*/
if (!(data->flags & PMBUS_NO_WRITE_PROTECT)) {
ret = _pmbus_read_byte_data(client, -1, PMBUS_WRITE_PROTECT);
if (ret > 0 && (ret & PB_WP_ANY))
data->flags |= PMBUS_WRITE_PROTECTED | PMBUS_SKIP_STATUS_CHECK;
}
if (!(data->flags & PMBUS_NO_WRITE_PROTECT))
pmbus_init_wp(client, data);
ret = i2c_smbus_read_byte_data(client, PMBUS_REVISION);
if (ret >= 0)
@ -3183,8 +3203,12 @@ static int pmbus_regulator_list_voltage(struct regulator_dev *rdev,
{
struct device *dev = rdev_get_dev(rdev);
struct i2c_client *client = to_i2c_client(dev->parent);
struct pmbus_data *data = i2c_get_clientdata(client);
int val, low, high;
if (data->flags & PMBUS_VOUT_PROTECTED)
return 0;
if (selector >= rdev->desc->n_voltages ||
selector < rdev->desc->linear_min_sel)
return -EINVAL;
@ -3219,6 +3243,22 @@ const struct regulator_ops pmbus_regulator_ops = {
};
EXPORT_SYMBOL_NS_GPL(pmbus_regulator_ops, "PMBUS");
int pmbus_regulator_init_cb(struct regulator_dev *rdev,
struct regulator_config *config)
{
struct pmbus_data *data = config->driver_data;
struct regulation_constraints *constraints = rdev->constraints;
if (data->flags & PMBUS_OP_PROTECTED)
constraints->valid_ops_mask &= ~REGULATOR_CHANGE_STATUS;
if (data->flags & PMBUS_VOUT_PROTECTED)
constraints->valid_ops_mask &= ~REGULATOR_CHANGE_VOLTAGE;
return 0;
}
EXPORT_SYMBOL_NS_GPL(pmbus_regulator_init_cb, "PMBUS");
static int pmbus_regulator_register(struct pmbus_data *data)
{
struct device *dev = data->dev;

14
include/linux/pmbus.h
View File

@ -73,6 +73,20 @@
*/
#define PMBUS_USE_COEFFICIENTS_CMD BIT(5)
/*
* PMBUS_OP_PROTECTED
* Set if the chip OPERATION command is protected and protection is not
* determined by the standard WRITE_PROTECT command.
*/
#define PMBUS_OP_PROTECTED BIT(6)
/*
* PMBUS_VOUT_PROTECTED
* Set if the chip VOUT_COMMAND command is protected and protection is not
* determined by the standard WRITE_PROTECT command.
*/
#define PMBUS_VOUT_PROTECTED BIT(7)
struct pmbus_platform_data {
u32 flags; /* Device specific flags */