Re: [PATCH v2 01/15] coresight: Make ETM4x TRCIDR0 register accesses consistent with sysreg.h

[Mike Leach]

Hi James,

On Thu, 3 Feb 2022 at 12:06, James Clark <james.clark@xxxxxxx> wrote:
>
> This is a no-op change for style and consistency and has no effect on the
> binary produced by gcc-11.
>
> Signed-off-by: James Clark <james.clark@xxxxxxx>
> ---
>  .../coresight/coresight-etm4x-core.c          | 36 +++++--------------
>  drivers/hwtracing/coresight/coresight-etm4x.h | 17 +++++++++
>  drivers/hwtracing/coresight/coresight-priv.h  |  5 +++
>  3 files changed, 30 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index e2eebd865241..107e81948f76 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -1091,41 +1091,21 @@ static void etm4_init_arch_data(void *info)
>         etmidr0 = etm4x_relaxed_read32(csa, TRCIDR0);
>
>         /* INSTP0, bits[2:1] P0 tracing support field */
> -       if (BMVAL(etmidr0, 1, 2) == 0b11)
> -               drvdata->instrp0 = true;
> -       else
> -               drvdata->instrp0 = false;
> -
> +       drvdata->instrp0 = !!(REG_VAL(etmidr0, TRCIDR0_INSTP0) == 0b11);
>         /* TRCBB, bit[5] Branch broadcast tracing support bit */
> -       if (BMVAL(etmidr0, 5, 5))
> -               drvdata->trcbb = true;
> -       else
> -               drvdata->trcbb = false;
> -
> +       drvdata->trcbb = !!(etmidr0 & TRCIDR0_TRCBB);
>         /* TRCCOND, bit[6] Conditional instruction tracing support bit */
> -       if (BMVAL(etmidr0, 6, 6))
> -               drvdata->trccond = true;
> -       else
> -               drvdata->trccond = false;
> -
> +       drvdata->trccond = !!(etmidr0 & TRCIDR0_TRCCOND);
>         /* TRCCCI, bit[7] Cycle counting instruction bit */
> -       if (BMVAL(etmidr0, 7, 7))
> -               drvdata->trccci = true;
> -       else
> -               drvdata->trccci = false;
> -
> +       drvdata->trccci = !!(etmidr0 & TRCIDR0_TRCCCI);
>         /* RETSTACK, bit[9] Return stack bit */
> -       if (BMVAL(etmidr0, 9, 9))
> -               drvdata->retstack = true;
> -       else
> -               drvdata->retstack = false;
> -
> +       drvdata->retstack = !!(etmidr0 & TRCIDR0_RETSTACK);
>         /* NUMEVENT, bits[11:10] Number of events field */
> -       drvdata->nr_event = BMVAL(etmidr0, 10, 11);
> +       drvdata->nr_event = REG_VAL(etmidr0, TRCIDR0_NUMEVENT);
>         /* QSUPP, bits[16:15] Q element support field */
> -       drvdata->q_support = BMVAL(etmidr0, 15, 16);
> +       drvdata->q_support = REG_VAL(etmidr0, TRCIDR0_QSUPP);
>         /* TSSIZE, bits[28:24] Global timestamp size field */
> -       drvdata->ts_size = BMVAL(etmidr0, 24, 28);
> +       drvdata->ts_size = REG_VAL(etmidr0, TRCIDR0_TSSIZE);
>
>         /* maximum size of resources */
>         etmidr2 = etm4x_relaxed_read32(csa, TRCIDR2);
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index 3c4d69b096ca..2bd8ad953b8e 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -130,6 +130,23 @@
>
>  #define TRCRSR_TA                      BIT(12)
>
> +/*
> + * Bit positions of registers that are defined above, in the sysreg.h style
> + * of _MASK, _SHIFT and BIT().
> + */
> +#define TRCIDR0_INSTP0_SHIFT                   1
> +#define TRCIDR0_INSTP0_MASK                    GENMASK(1, 0)
> +#define TRCIDR0_TRCBB                          BIT(5)
> +#define TRCIDR0_TRCCOND                                BIT(6)
> +#define TRCIDR0_TRCCCI                         BIT(7)
> +#define TRCIDR0_RETSTACK                       BIT(9)
> +#define TRCIDR0_NUMEVENT_SHIFT                 10
> +#define TRCIDR0_NUMEVENT_MASK                  GENMASK(1, 0)
> +#define TRCIDR0_QSUPP_SHIFT                    15
> +#define TRCIDR0_QSUPP_MASK                     GENMASK(1, 0)
> +#define TRCIDR0_TSSIZE_SHIFT                   24
> +#define TRCIDR0_TSSIZE_MASK                    GENMASK(4, 0)
> +
>  /*
>   * System instructions to access ETM registers.
>   * See ETMv4.4 spec ARM IHI0064F section 4.3.6 System instructions
> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> index ff1dd2092ac5..1452c6038421 100644
> --- a/drivers/hwtracing/coresight/coresight-priv.h
> +++ b/drivers/hwtracing/coresight/coresight-priv.h
> @@ -36,6 +36,11 @@
>
>  #define TIMEOUT_US             100
>  #define BMVAL(val, lsb, msb)   ((val & GENMASK(msb, lsb)) >> lsb)
> +/*
> + * Extract a field from a register where field is #defined in the form
> + * <register_name>_<field_name>_MASK and <register_name>_<field_name>_SHIFT
> + */
> +#define REG_VAL(val, field)    ((val & (field##_MASK << field##_SHIFT)) >> field##_SHIFT)
>

The only v minor comment I would have is that this macro could be
REG_FIELD() or REG_FIELD_VAL(), which in my view would make more
natural and obvious reading in the source files where it appears.

e.g.

drvdata->nr_event = REG_FIELD(etmidr0, TRCIDR0_NUMEVENT);

However it ends up, it certainly needs to stay in a common header for
possible use in other drivers (not just ETMv3).

Regards

Mike

>  #define ETM_MODE_EXCL_KERN     BIT(30)
>  #define ETM_MODE_EXCL_USER     BIT(31)
> --
> 2.28.0
>


-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK