On Thu, Oct 24, 2024 at 08:10:37PM +0200, Jerome Brunet wrote:
> Add a module parameter to force the write protection mode of pmbus chips.
>
> 2 protections modes are provided to start with:
> * 0: Remove the write protection if possible
> * 1: Enable full write protection if possible
>
> 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/admin-guide/kernel-parameters.txt | 4 ++
> drivers/hwmon/pmbus/pmbus_core.c | 74 ++++++++++++++++++-------
> 2 files changed, 59 insertions(+), 19 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 1518343bbe2237f1d577df5656339d6224b769be..aa79242fe0a9238f618182289f18563ed63cba1c 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4733,6 +4733,10 @@
> Format: { parport<nr> | timid | 0 }
> See also Documentation/admin-guide/parport.rst.
>
> + pmbus.wp= [HW] PMBus Chips write protection forced mode
> + Format: { 0 | 1 }
> + See drivers/hwmon/pmbus/pmbus_core.c
> +
I have always seen that file as applicable for core kernel parameters,
not for driver kernel parameters. I can not accept a global change like
this without guidance. Please explain why it is desirable to have this
parameter documented here and not in driver documentation.
> pmtmr= [X86] Manual setup of pmtmr I/O Port.
> Override pmtimer IOPort with a hex value.
> e.g. pmtmr=0x508
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index 7bdd8f2ffcabc51500437182f411e9826cd7a55d..ce697ca03de01c0e5a352f8f6b72671137721868 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -31,6 +31,20 @@
> #define PMBUS_ATTR_ALLOC_SIZE 32
> #define PMBUS_NAME_SIZE 24
>
> +/*
> + * PMBus write protect forced mode:
> + * PMBus may come up with a variety of write protection configuration.
> + * 'pmbus_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: write protection fully enabled, including OPERATION and VOUT_COMMAND
> + * registers. Chips essentially become read-only with this.
Would it be desirable to also suppport the ability to set the output voltage
but not limits (PB_WP_VOUT) ?
Guenter
