Add a module parameter to force the write protection mode of pmbus chips.
4 protections modes are provided to start with:
* 0: Remove the write protection
* 1: Disable all writes except to the WRITE_PROTECT, OPERATION,
PAGE, ON_OFF_CONFIG and VOUT_COMMAND commands
* 2: Disable all writes except to the WRITE_PROTECT, OPERATION and
PAGE commands
* 3: Disable all writes except to the WRITE_PROTECT command
Of course, if the parameter is not provided, the default write protection
status of the pmbus chips is left untouched.
Suggested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
---
Documentation/hwmon/pmbus-core.rst | 21 +++++++++++++++++++++
drivers/hwmon/pmbus/pmbus_core.c | 29 +++++++++++++++++++++++++++++
2 files changed, 50 insertions(+)
diff --git a/Documentation/hwmon/pmbus-core.rst b/Documentation/hwmon/pmbus-core.rst
index 0a251960f8910ffb121d82b45e729d06f98424ef..fdfb237731486ce9977b337586333d28f7419d1d 100644
--- a/Documentation/hwmon/pmbus-core.rst
+++ b/Documentation/hwmon/pmbus-core.rst
@@ -387,3 +387,24 @@ PMBUS_VOUT_PROTECTED
Set if the chip VOUT_COMMAND command is protected and protection is not
determined by the standard WRITE_PROTECT command.
+
+Module parameter
+----------------
+
+pmbus_core.wp: PMBus write protect forced mode
+
+PMBus may come up with a variety of write protection configuration.
+'pmbus_core.wp' may be used if a particular write protection is necessary.
+The ability to actually alter the protection may also depend on the chip
+so the actual runtime write protection configuration may differ from
+the requested one. pmbus_core currently support the following value:
+
+* 0: write protection removed.
+* 1: Disable all writes except to the WRITE_PROTECT, OPERATION,
+ PAGE, ON_OFF_CONFIG and VOUT_COMMAND commands.
+* 2: Disable all writes except to the WRITE_PROTECT, OPERATION and
+ PAGE commands.
+* 3: Disable all writes except to the WRITE_PROTECT command. Note that
+ protection should include the PAGE register. This may be problematic
+ for multi-page chips, if the chips strictly follows the PMBus
+ specification, preventing the chip from changing the active page.
diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 94252e420ad79fd3e932c0f1df9e1c9a5d8a13d0..f6753004e40af3c258a2d85e3aea3e412ae4029e 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -31,6 +31,9 @@
#define PMBUS_ATTR_ALLOC_SIZE 32
#define PMBUS_NAME_SIZE 24
+static int wp = -1;
+module_param(wp, int, 0444);
+
struct pmbus_sensor {
struct pmbus_sensor *next;
char name[PMBUS_NAME_SIZE]; /* sysfs sensor name */
@@ -2669,6 +2672,32 @@ static void pmbus_init_wp(struct i2c_client *client, struct pmbus_data *data)
{
int ret;
+ switch (wp) {
+ case 0:
+ _pmbus_write_byte_data(client, -1,
+ PMBUS_WRITE_PROTECT, 0);
+ break;
+
+ case 1:
+ _pmbus_write_byte_data(client, -1,
+ PMBUS_WRITE_PROTECT, PB_WP_VOUT);
+ break;
+
+ case 2:
+ _pmbus_write_byte_data(client, -1,
+ PMBUS_WRITE_PROTECT, PB_WP_OP);
+ break;
+
+ case 3:
+ _pmbus_write_byte_data(client, -1,
+ PMBUS_WRITE_PROTECT, PB_WP_ALL);
+ break;
+
+ default:
+ /* Ignore the other values */
+ break;
+ }
+
ret = _pmbus_read_byte_data(client, -1, PMBUS_WRITE_PROTECT);
if (ret < 0)
return;
--
2.45.2
