linux-kernel - Re: [PATCH v3 16/26] coresight: etm4x: Check for Software Lock

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Message-ID: <20201105215000.GB3047244@xps15>
Date:   Thu, 5 Nov 2020 14:50:00 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, mike.leach@...aro.org,
        coresight@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 16/26] coresight: etm4x: Check for Software Lock

On Wed, Oct 28, 2020 at 10:09:35PM +0000, Suzuki K Poulose wrote:
> The Software lock is not implemented for system instructions
> based accesses. So, skip the lock register access in such
> cases.
> 
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
>  .../coresight/coresight-etm4x-core.c          | 40 ++++++++++++-------
>  1 file changed, 25 insertions(+), 15 deletions(-)
>

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
 
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index a5c914b16e59..a12d58a04c5d 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -121,6 +121,21 @@ static void etm4_os_lock(struct etmv4_drvdata *drvdata)
>  	isb();
>  }
>  
> +static void etm4_cs_lock(struct etmv4_drvdata *drvdata,
> +			 struct csdev_access *csa)
> +{
> +	/* Software Lock is only accessible via memory mapped interface */
> +	if (csa->io_mem)
> +		CS_LOCK(csa->base);
> +}
> +
> +static void etm4_cs_unlock(struct etmv4_drvdata *drvdata,
> +			 struct csdev_access *csa)
> +{
> +	if (csa->io_mem)
> +		CS_UNLOCK(csa->base);
> +}
> +
>  static bool etm4_arch_supported(u8 arch)
>  {
>  	/* Mask out the minor version number */
> @@ -160,8 +175,7 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
>  	struct device *etm_dev = &csdev->dev;
>  	struct csdev_access *csa = &csdev->access;
>  
> -	CS_UNLOCK(drvdata->base);
> -
> +	etm4_cs_unlock(drvdata, csa);
>  	etm4_os_unlock(drvdata);
>  
>  	rc = coresight_claim_device_unlocked(csdev);
> @@ -262,7 +276,7 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
>  	isb();
>  
>  done:
> -	CS_LOCK(drvdata->base);
> +	etm4_cs_lock(drvdata, csa);
>  
>  	dev_dbg(etm_dev, "cpu: %d enable smp call done: %d\n",
>  		drvdata->cpu, rc);
> @@ -519,7 +533,7 @@ static void etm4_disable_hw(void *info)
>  	struct csdev_access *csa = &csdev->access;
>  	int i;
>  
> -	CS_UNLOCK(drvdata->base);
> +	etm4_cs_unlock(drvdata, csa);
>  
>  	if (!drvdata->skip_power_up) {
>  		/* power can be removed from the trace unit now */
> @@ -560,8 +574,7 @@ static void etm4_disable_hw(void *info)
>  	}
>  
>  	coresight_disclaim_device_unlocked(csdev);
> -
> -	CS_LOCK(drvdata->base);
> +	etm4_cs_lock(drvdata, csa);
>  
>  	dev_dbg(&drvdata->csdev->dev,
>  		"cpu: %d disable smp call done\n", drvdata->cpu);
> @@ -671,8 +684,7 @@ static void etm4_init_arch_data(void *info)
>  
>  	/* Make sure all registers are accessible */
>  	etm4_os_unlock_csa(drvdata, csa);
> -
> -	CS_UNLOCK(drvdata->base);
> +	etm4_cs_unlock(drvdata, csa);
>  
>  	/* find all capabilities of the tracing unit */
>  	etmidr0 = etm4x_relaxed_read32(csa, TRCIDR0);
> @@ -837,7 +849,7 @@ static void etm4_init_arch_data(void *info)
>  	drvdata->nrseqstate = BMVAL(etmidr5, 25, 27);
>  	/* NUMCNTR, bits[30:28] number of counters available for tracing */
>  	drvdata->nr_cntr = BMVAL(etmidr5, 28, 30);
> -	CS_LOCK(drvdata->base);
> +	etm4_cs_lock(drvdata, csa);
>  }
>  
>  /* Set ELx trace filter access in the TRCVICTLR register */
> @@ -1218,8 +1230,7 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
>  	dsb(sy);
>  	isb();
>  
> -	CS_UNLOCK(drvdata->base);
> -
> +	etm4_cs_unlock(drvdata, csa);
>  	/* Lock the OS lock to disable trace and external debugger access */
>  	etm4_os_lock(drvdata);
>  
> @@ -1330,7 +1341,7 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
>  	etm4x_relaxed_write32(csa, (state->trcpdcr & ~TRCPDCR_PU), TRCPDCR);
>  
>  out:
> -	CS_LOCK(drvdata->base);
> +	etm4_cs_lock(drvdata, csa);
>  	return ret;
>  }
>  
> @@ -1341,8 +1352,7 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
>  	struct csdev_access tmp_csa = CSDEV_ACCESS_IOMEM(drvdata->base);
>  	struct csdev_access *csa = &tmp_csa;
>  
> -	CS_UNLOCK(drvdata->base);
> -
> +	etm4_cs_unlock(drvdata, csa);
>  	etm4x_relaxed_write32(csa, state->trcclaimset, TRCCLAIMSET);
>  
>  	etm4x_relaxed_write32(csa, state->trcprgctlr, TRCPRGCTLR);
> @@ -1426,7 +1436,7 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
>  
>  	/* Unlock the OS lock to re-enable trace and external debug access */
>  	etm4_os_unlock(drvdata);
> -	CS_LOCK(drvdata->base);
> +	etm4_cs_lock(drvdata, csa);
>  }
>  
>  static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
> -- 
> 2.24.1
>