[PATCH 2/2] firmware: arm_scmi: Add compatibility checks for shmem node

[Etienne Carriere]

Hello Sudeep,


On Wed, 2 Jun 2021 at 00:51, Sudeep Holla <sudeep.holla at arm.com> wrote:
>
> The shared memory node used for communication between the firmware and
> the OS should be compatible with "arm,scmi-shmem". Add the check for the
> same while parsing the node before fetching the memory regions.
>
> Cc: Cristian Marussi <cristian.marussi at arm.com>
> Cc: Florian Fainelli <f.fainelli at gmail.com>
> Cc: Jim Quinlan <jim2101024 at gmail.com>
> Cc: Etienne Carriere <etienne.carriere at linaro.org>
> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
> ---
>  drivers/firmware/arm_scmi/mailbox.c | 3 +++
>  drivers/firmware/arm_scmi/smc.c     | 3 +++
>  2 files changed, 6 insertions(+)
>
> diff --git a/drivers/firmware/arm_scmi/mailbox.c b/drivers/firmware/arm_scmi/mailbox.c
> index 4626404be541..e3dcb58314ae 100644
> --- a/drivers/firmware/arm_scmi/mailbox.c
> +++ b/drivers/firmware/arm_scmi/mailbox.c
> @@ -69,6 +69,9 @@ static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
>                 return -ENOMEM;
>
>         shmem = of_parse_phandle(cdev->of_node, "shmem", idx);
> +       if (!of_device_is_compatible(shmem, "arm,scmi-shmem"))
> +               return -ENXIO;

Before this change, one could use another type of memory node, like "mmio-sram".
Is there a strong reason to enforce use of "arm,scmi-shmem" nodes?

Regards,
Etienne

> +
>         ret = of_address_to_resource(shmem, 0, &res);
>         of_node_put(shmem);
>         if (ret) {
> diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
> index fcbe2677f84b..78198ef94438 100644
> --- a/drivers/firmware/arm_scmi/smc.c
> +++ b/drivers/firmware/arm_scmi/smc.c
> @@ -76,6 +76,9 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
>                 return -ENOMEM;
>
>         np = of_parse_phandle(cdev->of_node, "shmem", 0);
> +       if (!of_device_is_compatible(shmem, "arm,scmi-shmem"))
> +               return -ENXIO;
> +
>         ret = of_address_to_resource(np, 0, &res);
>         of_node_put(np);
>         if (ret) {
> --
> 2.25.1
>