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List:       linux-arm-kernel
Subject:    Re: [PATCH v4 16/25] coresight: etm4x: Detect access early on the target CPU
From:       Mathieu Poirier <mathieu.poirier () linaro ! org>
Date:       2020-11-30 21:53:11
Message-ID: 20201130215311.GK1092947 () xps15
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On Thu, Nov 19, 2020 at 04:45:38PM +0000, Suzuki K Poulose wrote:
> In preparation to detect the support for system instruction
> support, move the detection of the device access to the target
> CPU.
> 
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Mike Leach <mike.leach@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> Changes since v3
> - Name constructs etm4_xx instead of etm_** (Mathieu)
> ---
> .../coresight/coresight-etm4x-core.c          | 45 ++++++++++++++++---
> 1 file changed, 40 insertions(+), 5 deletions(-)
> 

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>

> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c \
> b/drivers/hwtracing/coresight/coresight-etm4x-core.c index \
>                 a91e7de77ab9..d3b009c3724e 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -56,6 +56,11 @@ static u64 etm4_get_access_type(struct etmv4_config *config);
> 
> static enum cpuhp_state hp_online;
> 
> +struct etm4_init_arg {
> +	struct etmv4_drvdata	*drvdata;
> +	struct csdev_access	*csa;
> +};
> +
> /*
> * Check if TRCSSPCICRn(i) is implemented for a given instance.
> *
> @@ -678,6 +683,22 @@ static const struct coresight_ops etm4_cs_ops = {
> 	.source_ops	= &etm4_source_ops,
> };
> 
> +static bool etm4_init_iomem_access(struct etmv4_drvdata *drvdata,
> +				   struct csdev_access *csa)
> +{
> +	*csa = CSDEV_ACCESS_IOMEM(drvdata->base);
> +	return true;
> +}
> +
> +static bool etm4_init_csdev_access(struct etmv4_drvdata *drvdata,
> +				   struct csdev_access *csa)
> +{
> +	if (drvdata->base)
> +		return etm4_init_iomem_access(drvdata, csa);
> +
> +	return false;
> +}
> +
> static void etm4_init_arch_data(void *info)
> {
> 	u32 etmidr0;
> @@ -686,11 +707,22 @@ static void etm4_init_arch_data(void *info)
> 	u32 etmidr3;
> 	u32 etmidr4;
> 	u32 etmidr5;
> -	struct etmv4_drvdata *drvdata = info;
> -	struct csdev_access tmp_csa = CSDEV_ACCESS_IOMEM(drvdata->base);
> -	struct csdev_access *csa = &tmp_csa;
> +	struct etm4_init_arg *init_arg = info;
> +	struct etmv4_drvdata *drvdata;
> +	struct csdev_access *csa;
> 	int i;
> 
> +	drvdata = init_arg->drvdata;
> +	csa = init_arg->csa;
> +
> +	/*
> +	 * If we are unable to detect the access mechanism,
> +	 * or unable to detect the trace unit type, fail
> +	 * early.
> +	 */
> +	if (!etm4_init_csdev_access(drvdata, csa))
> +		return;
> +
> 	/* Make sure all registers are accessible */
> 	etm4_os_unlock_csa(drvdata, csa);
> 	etm4_cs_unlock(drvdata, csa);
> @@ -1536,6 +1568,7 @@ static int etm4_probe(struct amba_device *adev, const struct \
> amba_id *id)  struct etmv4_drvdata *drvdata;
> 	struct resource *res = &adev->res;
> 	struct coresight_desc desc = { 0 };
> +	struct etm4_init_arg init_arg = { 0 };
> 
> 	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> 	if (!drvdata)
> @@ -1563,7 +1596,6 @@ static int etm4_probe(struct amba_device *adev, const struct \
> amba_id *id)  return PTR_ERR(base);
> 
> 	drvdata->base = base;
> -	desc.access = CSDEV_ACCESS_IOMEM(base);
> 
> 	spin_lock_init(&drvdata->spinlock);
> 
> @@ -1575,8 +1607,11 @@ static int etm4_probe(struct amba_device *adev, const struct \
> amba_id *id)  if (!desc.name)
> 		return -ENOMEM;
> 
> +	init_arg.drvdata = drvdata;
> +	init_arg.csa = &desc.access;
> +
> 	if (smp_call_function_single(drvdata->cpu,
> -				etm4_init_arch_data,  drvdata, 1))
> +				etm4_init_arch_data,  &init_arg, 1))
> 		dev_err(dev, "ETM arch init failed\n");
> 
> 	if (etm4_arch_supported(drvdata->arch) == false)
> -- 
> 2.24.1
> 

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