[PATCH v4 2/2] firmware: arm_scmi: Augment SMC/HVC to allow optional parameters

[Nikunj Kela]

Reminder: Please review this patch! Thanks

On 4/18/2023 11:56 AM, Nikunj Kela wrote:
> This patch add support for passing shmem channel address as parameters
> in smc/hvc call. The address is split into 4KB-page and offset.
> This patch is useful when multiple scmi instances are using same smc-id
> and firmware needs to distinguish among the instances.
>
> Signed-off-by: Nikunj Kela <quic_nkela at quicinc.com>
> ---
>   drivers/firmware/arm_scmi/driver.c |  1 +
>   drivers/firmware/arm_scmi/smc.c    | 14 +++++++++++++-
>   2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index e7d97b59963b..b5957cc12fee 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -2914,6 +2914,7 @@ static const struct of_device_id scmi_of_match[] = {
>   #endif
>   #ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC
>   	{ .compatible = "arm,scmi-smc", .data = &scmi_smc_desc},
> +	{ .compatible = "arm,scmi-smc-param", .data = &scmi_smc_desc},
>   #endif
>   #ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
>   	{ .compatible = "arm,scmi-virtio", .data = &scmi_virtio_desc},
> diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
> index 93272e4bbd12..71e080b70df5 100644
> --- a/drivers/firmware/arm_scmi/smc.c
> +++ b/drivers/firmware/arm_scmi/smc.c
> @@ -20,6 +20,11 @@
>   
>   #include "common.h"
>   
> +#define SHMEM_SHIFT 12
> +#define SHMEM_SIZE (_AC(1, UL) << SHMEM_SHIFT)
> +#define SHMEM_PAGE(x) ((unsigned long)((x) >> SHMEM_SHIFT))
> +#define SHMEM_OFFSET(x) ((x) & (SHMEM_SIZE - 1))
> +
>   /**
>    * struct scmi_smc - Structure representing a SCMI smc transport
>    *
> @@ -30,6 +35,7 @@
>    * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
>    *	      Used when operating in atomic mode.
>    * @func_id: smc/hvc call function id
> + * @param: physical address of the shmem channel
>    */
>   
>   struct scmi_smc {
> @@ -40,6 +46,7 @@ struct scmi_smc {
>   #define INFLIGHT_NONE	MSG_TOKEN_MAX
>   	atomic_t inflight;
>   	u32 func_id;
> +	phys_addr_t param;
>   };
>   
>   static irqreturn_t smc_msg_done_isr(int irq, void *data)
> @@ -137,6 +144,8 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
>   	if (ret < 0)
>   		return ret;
>   
> +	if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param"))
> +		scmi_info->param = res.start;
>   	/*
>   	 * If there is an interrupt named "a2p", then the service and
>   	 * completion of a message is signaled by an interrupt rather than by
> @@ -179,6 +188,8 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
>   {
>   	struct scmi_smc *scmi_info = cinfo->transport_info;
>   	struct arm_smccc_res res;
> +	unsigned long page = SHMEM_PAGE(scmi_info->param);
> +	unsigned long offset = SHMEM_OFFSET(scmi_info->param);
>   
>   	/*
>   	 * Channel will be released only once response has been
> @@ -188,7 +199,8 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
>   
>   	shmem_tx_prepare(scmi_info->shmem, xfer, cinfo);
>   
> -	arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
> +	arm_smccc_1_1_invoke(scmi_info->func_id, page, offset, 0, 0, 0, 0, 0,
> +			     &res);
>   
>   	/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
>   	if (res.a0) {