Re: [PATCH v2 09/18] firmware: qcom_scm-64: Move SMC register filling to qcom_scm_call_smccc

Stephen Boyd
2019-11-15T23:57:10Z

Quoting Elliot Berman (2019-11-12 13:22:45)
> diff --git a/drivers/firmware/qcom_scm-64.c b/drivers/firmware/qcom_scm-64.c
> index 4131093..977654bb 100644
> --- a/drivers/firmware/qcom_scm-64.c
> +++ b/drivers/firmware/qcom_scm-64.c
> @@ -54,6 +54,10 @@ struct qcom_scm_desc {
> u32 owner;
> };
>
> +struct arm_smccc_args {
> + unsigned long a[8];

Please call it 'args', not just 'a'.

> +};
> +
> static u64 qcom_smccc_convention = -1;
> static DEFINE_MUTEX(qcom_scm_lock);
>
> @@ -95,12 +95,22 @@ static int ___qcom_scm_call_smccc(struct device *dev,
> {
> int arglen = desc->arginfo & 0xf;
> int i;
> - u64 x5 = desc->args[SMCCC_FIRST_EXT_IDX];
> dma_addr_t args_phys = 0;
> void *args_virt = NULL;
> size_t alloc_len;
> gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;
> + u32 smccc_call_type = atomic ? ARM_SMCCC_FAST_CALL : ARM_SMCCC_STD_CALL;
> struct arm_smccc_res res;
> + struct arm_smccc_args smc = {0};
> +
> + smc.a[0] = ARM_SMCCC_CALL_VAL(
> + smccc_call_type,
> + qcom_smccc_convention,
> + desc->owner,
> + SMCCC_FUNCNUM(desc->svc, desc->cmd));
> + smc.a[1] = desc->arginfo;
> + for (i = 0; i < SMCCC_N_REG_ARGS; i++)
> + smc.a[i + SMCCC_FIRST_REG_IDX] = desc->args[i];
>
> if (unlikely(arglen > SMCCC_N_REG_ARGS)) {
> alloc_len = SMCCC_N_EXT_ARGS * sizeof(u64);
> @@ -131,19 +141,18 @@ static int ___qcom_scm_call_smccc(struct device *dev,
> return -ENOMEM;
> }
>
> - x5 = args_phys;
> + smc.a[SMCCC_LAST_REG_IDX] = args_phys;
> }
>
> if (atomic) {
> - __qcom_scm_call_do_quirk(desc, &res, x5, ARM_SMCCC_FAST_CALL);
> + __qcom_scm_call_do_quirk(&smc, &res);
> } else {
> int retry_count = 0;
>
> do {
> mutex_lock(&qcom_scm_lock);
>
> - __qcom_scm_call_do_quirk(desc, &res, x5,
> - ARM_SMCCC_STD_CALL);
> + __qcom_scm_call_do_quirk(&smc, &res);
>
> mutex_unlock(&qcom_scm_lock);
>

Maybe we need to restructure this whole function to be a few steps

setup_and_map_args()
do_call()
unmap_args()
remap_error()

And pass some set of args to those functions. That would probably
provide clarity to this monstrously large function.