Re: [PATCH V3 03/14] coresight: etm4x: Add support for PE OS lock

Mike Leach
2021-02-15T14:10:25Z

Reviewed-by: mike.leach <mike.leach@linaro.org>

On Wed, 27 Jan 2021 at 08:55, Anshuman Khandual
<anshuman.khandual@arm.com> wrote:
>
> From: Suzuki K Poulose <suzuki.poulose@arm.com>
>
> ETE may not implement the OS lock and instead could rely on
> the PE OS Lock for the trace unit access. This is indicated
> by the TRCOLSR.OSM == 0b100. Add support for handling the
> PE OS lock
>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Mike Leach <mike.leach@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> drivers/hwtracing/coresight/coresight-etm4x-core.c | 50 ++++++++++++++++++----
> drivers/hwtracing/coresight/coresight-etm4x.h | 15 +++++++
> 2 files changed, 56 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 473ab74..9edf8be 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -114,30 +114,59 @@ void etm4x_sysreg_write(u64 val, u32 offset, bool _relaxed, bool _64bit)
> }
> }
>
> -static void etm4_os_unlock_csa(struct etmv4_drvdata *drvdata, struct csdev_access *csa)
> +static void etm_detect_os_lock(struct etmv4_drvdata *drvdata,
> + struct csdev_access *csa)
> {
> - /* Writing 0 to TRCOSLAR unlocks the trace registers */
> - etm4x_relaxed_write32(csa, 0x0, TRCOSLAR);
> - drvdata->os_unlock = true;
> + u32 oslsr = etm4x_relaxed_read32(csa, TRCOSLSR);
> +
> + drvdata->os_lock_model = ETM_OSLSR_OSLM(oslsr);
> +}
> +
> +static void etm_write_os_lock(struct etmv4_drvdata *drvdata,
> + struct csdev_access *csa, u32 val)
> +{
> + val = !!val;
> +
> + switch (drvdata->os_lock_model) {
> + case ETM_OSLOCK_PRESENT:
> + etm4x_relaxed_write32(csa, val, TRCOSLAR);
> + break;
> + case ETM_OSLOCK_PE:
> + write_sysreg_s(val, SYS_OSLAR_EL1);
> + break;
> + default:
> + pr_warn_once("CPU%d: Unsupported Trace OSLock model: %x\n",
> + smp_processor_id(), drvdata->os_lock_model);
> + fallthrough;
> + case ETM_OSLOCK_NI:
> + return;
> + }
> isb();
> }
>
> +static inline void etm4_os_unlock_csa(struct etmv4_drvdata *drvdata,
> + struct csdev_access *csa)
> +{
> + WARN_ON(drvdata->cpu != smp_processor_id());
> +
> + /* Writing 0 to OS Lock unlocks the trace unit registers */
> + etm_write_os_lock(drvdata, csa, 0x0);
> + drvdata->os_unlock = true;
> +}
> +
> static void etm4_os_unlock(struct etmv4_drvdata *drvdata)
> {
> if (!WARN_ON(!drvdata->csdev))
> etm4_os_unlock_csa(drvdata, &drvdata->csdev->access);
> -
> }
>
> static void etm4_os_lock(struct etmv4_drvdata *drvdata)
> {
> if (WARN_ON(!drvdata->csdev))
> return;
> -
> - /* Writing 0x1 to TRCOSLAR locks the trace registers */
> - etm4x_relaxed_write32(&drvdata->csdev->access, 0x1, TRCOSLAR);
> + /* Writing 0x1 to OS Lock locks the trace registers */
> + etm_write_os_lock(drvdata, &drvdata->csdev->access, 0x1);
> drvdata->os_unlock = false;
> - isb();
> }
>
> static void etm4_cs_lock(struct etmv4_drvdata *drvdata,
> @@ -906,6 +935,9 @@ static void etm4_init_arch_data(void *info)
> if (!etm4_init_csdev_access(drvdata, csa))
> return;
>
> + /* Detect the support for OS Lock before we actuall use it */
> + etm_detect_os_lock(drvdata, csa);
> +
> /* Make sure all registers are accessible */
> etm4_os_unlock_csa(drvdata, csa);
> etm4_cs_unlock(drvdata, csa);
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index 0af6057..0e86eba 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -506,6 +506,20 @@
> ETM_MODE_EXCL_USER)
>
> /*
> + * TRCOSLSR.OSLM advertises the OS Lock model.
> + * OSLM[2:0] = TRCOSLSR[4:3,0]
> + *
> + * 0b000 - Trace OS Lock is not implemented.
> + * 0b010 - Trace OS Lock is implemented.
> + * 0b100 - Trace OS Lock is not implemented, unit is controlled by PE OS Lock.
> + */
> +#define ETM_OSLOCK_NI 0b000
> +#define ETM_OSLOCK_PRESENT 0b010
> +#define ETM_OSLOCK_PE 0b100
> +
> +#define ETM_OSLSR_OSLM(oslsr) ((((oslsr) & GENMASK(4, 3)) >> 2) | (oslsr & 0x1))
> +
> +/*
> * TRCDEVARCH Bit field definitions
> * Bits[31:21] - ARCHITECT = Always Arm Ltd.
> * * Bits[31:28] = 0x4
> @@ -897,6 +911,7 @@ struct etmv4_drvdata {
> u8 s_ex_level;
> u8 ns_ex_level;
> u8 q_support;
> + u8 os_lock_model;
> bool sticky_enable;
> bool boot_enable;
> bool os_unlock;
> --
> 2.7.4
>

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