[PATCH] sbi/sbi_pmu.c: Align the event type offset as per SBI specification

[Andrew Jones]

On Thu, Mar 30, 2023 at 04:41:14PM +0800, Yu Chien Peter Lin wrote:
> The bits encoded in event_idx[19:16] indicate the event type, with an
> offset of 16 instead of 20.
> 
> Signed-off-by: Yu Chien Peter Lin <peterlin at andestech.com>
> ---
>  include/sbi/sbi_ecall_interface.h | 4 ++--
>  lib/sbi/sbi_pmu.c                 | 7 ++++---
>  2 files changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
> index 4597358..54d1951 100644
> --- a/include/sbi/sbi_ecall_interface.h
> +++ b/include/sbi/sbi_ecall_interface.h
> @@ -214,10 +214,10 @@ enum sbi_pmu_ctr_type {
>  };
>  
>  /* Helper macros to decode event idx */
> -#define SBI_PMU_EVENT_IDX_OFFSET 20
>  #define SBI_PMU_EVENT_IDX_MASK 0xFFFFF
> +#define SBI_PMU_EVENT_IDX_TYPE_OFFSET 16
> +#define SBI_PMU_EVENT_IDX_TYPE_MASK (0xF << SBI_PMU_EVENT_IDX_TYPE_OFFSET)
>  #define SBI_PMU_EVENT_IDX_CODE_MASK 0xFFFF
> -#define SBI_PMU_EVENT_IDX_TYPE_MASK 0xF0000
>  #define SBI_PMU_EVENT_RAW_IDX 0x20000
>  
>  #define SBI_PMU_EVENT_IDX_INVALID 0xFFFFFFFF
> diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
> index 74d6912..ef1eab0 100644
> --- a/lib/sbi/sbi_pmu.c
> +++ b/lib/sbi/sbi_pmu.c
> @@ -81,7 +81,8 @@ static uint32_t num_hw_ctrs;
>  static uint32_t total_ctrs;
>  
>  /* Helper macros to retrieve event idx and code type */
> -#define get_cidx_type(x) ((x & SBI_PMU_EVENT_IDX_TYPE_MASK) >> 16)
> +#define get_cidx_type(x) \
> +  ((x & SBI_PMU_EVENT_IDX_TYPE_MASK) >> SBI_PMU_EVENT_IDX_TYPE_OFFSET)
>  #define get_cidx_code(x) (x & SBI_PMU_EVENT_IDX_CODE_MASK)
>  
>  /**
> @@ -903,10 +904,10 @@ int sbi_pmu_init(struct sbi_scratch *scratch, bool cold_boot)
>  	pmu_reset_event_map(hartid);
>  
>  	/* First three counters are fixed by the priv spec and we enable it by default */
> -	active_events[hartid][0] = SBI_PMU_EVENT_TYPE_HW << SBI_PMU_EVENT_IDX_OFFSET |
> +	active_events[hartid][0] = SBI_PMU_EVENT_TYPE_HW << SBI_PMU_EVENT_IDX_TYPE_OFFSET |
>  				   SBI_PMU_HW_CPU_CYCLES;
>  	active_events[hartid][1] = SBI_PMU_EVENT_IDX_INVALID;
> -	active_events[hartid][2] = SBI_PMU_EVENT_TYPE_HW << SBI_PMU_EVENT_IDX_OFFSET |
> +	active_events[hartid][2] = SBI_PMU_EVENT_TYPE_HW << SBI_PMU_EVENT_IDX_TYPE_OFFSET |
>  				   SBI_PMU_HW_INSTRUCTIONS;
>  
>  	return 0;
> -- 
> 2.34.1
>

I guess this was found by inspection, since SBI_PMU_EVENT_TYPE_HW is zero,
so the patch doesn't change anything. And, even though nothing is changed,
it is still a fix, so probably worth adding

Fixes: 13d40f21d588 ("lib: sbi: Add PMU support")

Either way,

Reviewed-by: Andrew Jones <ajones at ventanamicro.com>

Thanks,
drew