[PATCH v4 3/5] lib: sbi_pmu: add override for counter data

[Atish Patra]

On Mon, Sep 26, 2022 at 3:18 AM Heiko Stuebner <heiko at sntech.de> wrote:
>
> In general counter-data is auto-detected but some platforms
> may implement counters in a way that breaks this detection.
>
> Implement an abstraction that those platforms can hook into
> and override the counter-data.
>
> Signed-off-by: Heiko Stuebner <heiko at sntech.de>
> ---
>  include/sbi/sbi_pmu.h | 8 ++++++++
>  lib/sbi/sbi_hart.c    | 7 +++++++
>  lib/sbi/sbi_pmu.c     | 7 +++++++
>  3 files changed, 22 insertions(+)
>
> diff --git a/include/sbi/sbi_pmu.h b/include/sbi/sbi_pmu.h
> index c365243..d257b14 100644
> --- a/include/sbi/sbi_pmu.h
> +++ b/include/sbi/sbi_pmu.h
> @@ -78,6 +78,11 @@ struct sbi_pmu_device {
>          * Custom function returning the machine-specific irq-bit.
>          */
>         int (*hw_counter_irq_bit)(void);
> +
> +       /**
> +        * Override autodetected counter data.
> +        */
> +       void (*hw_counter_data)(unsigned int *count, unsigned int *bits);
>  };
>
>  /** Get the PMU platform device */
> @@ -95,6 +100,9 @@ void sbi_pmu_exit(struct sbi_scratch *scratch);
>  /** Return the pmu irq bit depending on extension existence */
>  int sbi_pmu_irq_bit(void);
>
> +/** Allow non-standard platforms to override probed counter information */
> +void sbi_pmu_override_counter_data(unsigned int *count, unsigned int *bits);
> +
>  /**
>   * Add the hardware event to counter mapping information. This should be called
>   * from the platform code to update the mapping table.
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
> index 45fbcde..6506a19 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -632,6 +632,13 @@ __mhpm_skip:
>  #undef __check_csr_2
>  #undef __check_csr
>
> +       /**
> +        * Allow non-standard implementations to override the detected
> +        * values for number of counters and bits.
> +        */
> +       sbi_pmu_override_counter_data(&hfeatures->mhpm_count,
> +                                     &hfeatures->mhpm_bits);
> +
>         /* Detect if hart supports Priv v1.10 */
>         val = csr_read_allowed(CSR_MCOUNTEREN, (unsigned long)&trap);
>         if (!trap.cause)
> diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
> index 91d9ccc..c8becf3 100644
> --- a/lib/sbi/sbi_pmu.c
> +++ b/lib/sbi/sbi_pmu.c
> @@ -852,3 +852,10 @@ int sbi_pmu_init(struct sbi_scratch *scratch, bool cold_boot)
>
>         return 0;
>  }
> +
> +void sbi_pmu_override_counter_data(unsigned int *count,
> +                                  unsigned int *bits)
> +{
> +       if (pmu_dev && pmu_dev->hw_counter_data)
> +               pmu_dev->hw_counter_data(count, bits);
> +}
> --
> 2.35.1
>
>
> --
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We may need similar functionality in the future as well where the
platform may override the hart feature details.
Should we pass the hfeatures in the extension_init callback so that a
specific platform override can access it ?

-- 
Regards,
Atish