linux-kernel - Re: [PATCH v2 2/8] coresight: Convert tag clear function to take a struct cs

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Message-ID: <20250319082423.GC2860028@e132581.arm.com>
Date: Wed, 19 Mar 2025 08:24:23 +0000
From: Leo Yan <leo.yan@....com>
To: James Clark <james.clark@...aro.org>
Cc: Suzuki K Poulose <suzuki.poulose@....com>,
	Mike Leach <mike.leach@...aro.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH v2 2/8] coresight: Convert tag clear function to take a
 struct cs_access

On Tue, Mar 18, 2025 at 04:21:56PM +0000, James Clark wrote:
> The self hosted claim tag will be reset on device probe in a later
> commit. We'll want to do this before coresight_register() is called so
> won't have a coresight_device and have to use cs_access instead.
> 
> Also make them public and create locked and unlocked versions for
> later use.
> 
> Signed-off-by: James Clark <james.clark@...aro.org>

Reviewed-by: Leo Yan <leo.yan@....com>

> ---
>  drivers/hwtracing/coresight/coresight-core.c | 17 +++++++++++++----
>  include/linux/coresight.h                    |  3 ++-
>  2 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index 3f1c996d668a..9ff601e2415a 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -151,12 +151,21 @@ static inline void coresight_set_self_claim_tag(struct coresight_device *csdev)
>  	isb();
>  }
>  
> -static inline void coresight_clear_self_claim_tag(struct coresight_device *csdev)
> +void coresight_clear_self_claim_tag(struct csdev_access *csa)
>  {
> -	csdev_access_relaxed_write32(&csdev->access, CORESIGHT_CLAIM_SELF_HOSTED,
> +	CS_UNLOCK(csa->base);
> +	coresight_clear_self_claim_tag_unlocked(csa);
> +	CS_LOCK(csa->base);
> +}
> +EXPORT_SYMBOL_GPL(coresight_clear_self_claim_tag);
> +
> +void coresight_clear_self_claim_tag_unlocked(struct csdev_access *csa)
> +{
> +	csdev_access_relaxed_write32(csa, CORESIGHT_CLAIM_SELF_HOSTED,
>  				     CORESIGHT_CLAIMCLR);
>  	isb();
>  }
> +EXPORT_SYMBOL_GPL(coresight_clear_self_claim_tag_unlocked);
>  
>  /*
>   * coresight_claim_device_unlocked : Claim the device for self-hosted usage
> @@ -180,7 +189,7 @@ int coresight_claim_device_unlocked(struct coresight_device *csdev)
>  	if (coresight_is_claimed_self_hosted(csdev))
>  		return 0;
>  	/* There was a race setting the tag, clean up and fail */
> -	coresight_clear_self_claim_tag(csdev);
> +	coresight_clear_self_claim_tag_unlocked(&csdev->access);
>  	return -EBUSY;
>  }
>  EXPORT_SYMBOL_GPL(coresight_claim_device_unlocked);
> @@ -211,7 +220,7 @@ void coresight_disclaim_device_unlocked(struct coresight_device *csdev)
>  		return;
>  
>  	if (coresight_is_claimed_self_hosted(csdev))
> -		coresight_clear_self_claim_tag(csdev);
> +		coresight_clear_self_claim_tag_unlocked(&csdev->access);
>  	else
>  		/*
>  		 * The external agent may have not honoured our claim
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index d79a242b271d..00134a80d358 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -685,7 +685,8 @@ extern int coresight_timeout_action(struct csdev_access *csa, u32 offset,
>  
>  extern int coresight_claim_device(struct coresight_device *csdev);
>  extern int coresight_claim_device_unlocked(struct coresight_device *csdev);
> -
> +void coresight_clear_self_claim_tag(struct csdev_access *csa);
> +void coresight_clear_self_claim_tag_unlocked(struct csdev_access *csa);
>  extern void coresight_disclaim_device(struct coresight_device *csdev);
>  extern void coresight_disclaim_device_unlocked(struct coresight_device *csdev);
>  extern char *coresight_alloc_device_name(struct coresight_dev_list *devs,
> 
> -- 
> 2.34.1
>