hwmon: (pmbus) Add documentation for new flags

Add documentation for the new pmbus flags PMBUS_WRITE_PROTECTED,
PMBUS_NO_CAPABILITY and PMBUS_READ_STATUS_AFTER_FAILED_CHECK

Signed-off-by: Erik Rosen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[groeck: Added newline at end of file]
Signed-off-by: Guenter Roeck <[email protected]>

Documentation/hwmon/pmbus-core.rst

@@ -289,21 +289,32 @@ PMBus driver platform data
 ==========================
 
 PMBus platform data is defined in include/linux/pmbus.h. Platform data
-currently only provides a flag field with a single bit used::
+currently provides a flags field with four bits used::
 
- #define PMBUS_SKIP_STATUS_CHECK (1 << 0)
+ #define PMBUS_SKIP_STATUS_CHECK BIT(0)
+
+ #define PMBUS_WRITE_PROTECTED BIT(1)
+
+ #define PMBUS_NO_CAPABILITY BIT(2)
+
+ #define PMBUS_READ_STATUS_AFTER_FAILED_CHECK BIT(3)
 
  struct pmbus_platform_data {
  u32 flags; /* Device specific flags */
+
+ /* regulator support */
+ int num_regulators;
+ struct regulator_init_data *reg_init_data;
  };
 
 
 Flags
 -----
 
 PMBUS_SKIP_STATUS_CHECK
- During register detection, skip checking the status register for
- communication or command errors.
+
+During register detection, skip checking the status register for
+communication or command errors.
 
 Some PMBus chips respond with valid data when trying to read an unsupported
 register. For such chips, checking the status register is mandatory when
@@ -315,3 +326,26 @@ status register must be disabled.
 Some i2c controllers do not support single-byte commands (write commands with
 no data, i2c_smbus_write_byte()). With such controllers, clearing the status
 register is impossible, and the PMBUS_SKIP_STATUS_CHECK flag must be set.
+
+PMBUS_WRITE_PROTECTED
+
+Set if the chip is write protected and write protection is not determined
+by the standard WRITE_PROTECT command.
+
+PMBUS_NO_CAPABILITY
+
+Some PMBus chips don't respond with valid data when reading the CAPABILITY
+register. For such chips, this flag should be set so that the PMBus core
+driver doesn't use CAPABILITY to determine it's behavior.
+
+PMBUS_READ_STATUS_AFTER_FAILED_CHECK
+
+Read the STATUS register after each failed register check.
+
+Some PMBus chips end up in an undefined state when trying to read an
+unsupported register. For such chips, it is necessary to reset the
+chip pmbus controller to a known state after a failed register check.
+This can be done by reading a known register. By setting this flag the
+driver will try to read the STATUS register after each failed
+register check. This read may fail, but it will put the chip into a
+known state.