Re: [PATCH v2 11/18] firmware: qcom_scm-32: Use SMC arch wrappers

Stephen Boyd
2019-11-16T00:41:37Z

Quoting Elliot Berman (2019-11-12 13:22:47)
> Use SMC arch wrappers instead of inline assembly.
>
> Signed-off-by: Elliot Berman <eberman@codeaurora.org>
> ---

Nice. Can this come earlier in the series?

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

> diff --git a/drivers/firmware/qcom_scm-32.c b/drivers/firmware/qcom_scm-32.c
> index e06d59b..c3aeccf 100644
> --- a/drivers/firmware/qcom_scm-32.c
> +++ b/drivers/firmware/qcom_scm-32.c
> @@ -10,6 +10,7 @@
> #include <linux/errno.h>
> #include <linux/err.h>
> #include <linux/qcom_scm.h>
> +#include <linux/arm-smccc.h>
> #include <linux/dma-mapping.h>
>
> #include "qcom_scm.h"
> @@ -124,25 +125,13 @@ static inline void *legacy_get_response_buffer(
> static u32 __qcom_scm_call_do(u32 cmd_addr)
> {
> int context_id;
> - register u32 r0 asm("r0") = 1;
> - register u32 r1 asm("r1") = (u32)&context_id;
> - register u32 r2 asm("r2") = cmd_addr;
> + struct arm_smccc_res res;
> do {
> - asm volatile(
> - __asmeq("%0", "r0")
> - __asmeq("%1", "r0")
> - __asmeq("%2", "r1")
> - __asmeq("%3", "r2")
> -#ifdef REQUIRES_SEC
> - ".arch_extension sec\n"
> -#endif
> - "smc #0 @ switch to secure world\n"
> - : "=r" (r0)
> - : "r" (r0), "r" (r1), "r" (r2)
> - : "r3", "r12");

I assume that the clobber list is not a problem? i.e. r12 is going to
get clobbered and that's not a problem.

> - } while (r0 == QCOM_SCM_INTERRUPTED);
> -
> - return r0;
> + arm_smccc_smc(1, (unsigned long)&context_id, cmd_addr,
> + 0, 0, 0, 0, 0, &res);