Add documentation for the new pmbus flags PMBUS_WRITE_PROTECTED and
PMBUS_READ_STATUS_AFTER_FAILED_CHECK
Signed-off-by: Erik Rosen <erik.rosen@xxxxxxxxxxxxx>
---
Documentation/hwmon/pmbus-core.rst | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/Documentation/hwmon/pmbus-core.rst b/Documentation/hwmon/pmbus-core.rst
index 73e23ab42cc3..001c64f0f8c0 100644
--- a/Documentation/hwmon/pmbus-core.rst
+++ b/Documentation/hwmon/pmbus-core.rst
@@ -289,9 +289,13 @@ 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 only provides a flag field with three bits used::
- #define PMBUS_SKIP_STATUS_CHECK (1 << 0)
+ #define PMBUS_SKIP_STATUS_CHECK BIT(0)
+
+ #define PMBUS_WRITE_PROTECTED BIT(1)
+
+ #define PMBUS_READ_STATUS_AFTER_FAILED_CHECK BIT(2)
struct pmbus_platform_data {
u32 flags; /* Device specific flags */
@@ -315,3 +319,19 @@ 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_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.
\ No newline at end of file
--
2.20.1
