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

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