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coresight: Add claim tag warnings and debug messages

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Add a dev_dbg() message so that external debugger conflicts are more
visible. There are multiple reasons for -EBUSY so a message for this
particular one could be helpful. Add errors for and enumerate all the
other cases that are impossible.

Reviewed-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250325-james-coresight-claim-tags-v4-3-dfbd3822b2e5@linaro.org
This commit is contained in:
James Clark 2025-03-25 11:58:48 +00:00 committed by Suzuki K Poulose
parent a4e65842e1
commit a244a18c15
2 changed files with 36 additions and 20 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

51
drivers/hwtracing/coresight/coresight-core.c
View file

@ -135,16 +135,6 @@ static inline u32 coresight_read_claim_tags_unlocked(struct coresight_device *cs
csdev_access_relaxed_read32(&csdev->access, CORESIGHT_CLAIMCLR));
}
static inline bool coresight_is_claimed_self_hosted(struct coresight_device *csdev)
{
return coresight_read_claim_tags_unlocked(csdev) == CORESIGHT_CLAIM_SELF_HOSTED;
}
static inline bool coresight_is_claimed_any(struct coresight_device *csdev)
{
return coresight_read_claim_tags_unlocked(csdev) != 0;
}
static inline void coresight_set_self_claim_tag_unlocked(struct coresight_device *csdev)
{
csdev_access_relaxed_write32(&csdev->access, CORESIGHT_CLAIM_SELF_HOSTED,
@ -182,18 +172,41 @@ EXPORT_SYMBOL_GPL(coresight_clear_self_claim_tag_unlocked);
*/
int coresight_claim_device_unlocked(struct coresight_device *csdev)
{
int tag;
struct csdev_access *csa;
if (WARN_ON(!csdev))
return -EINVAL;
if (coresight_is_claimed_any(csdev))
csa = &csdev->access;
tag = coresight_read_claim_tags_unlocked(csdev);
switch (tag) {
case CORESIGHT_CLAIM_FREE:
coresight_set_self_claim_tag_unlocked(csdev);
if (coresight_read_claim_tags_unlocked(csdev) == CORESIGHT_CLAIM_SELF_HOSTED)
return 0;
/* There was a race setting the tag, clean up and fail */
coresight_clear_self_claim_tag_unlocked(csa);
dev_dbg(&csdev->dev, "Busy: Couldn't set self claim tag");
return -EBUSY;
coresight_set_self_claim_tag_unlocked(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_unlocked(&csdev->access);
return -EBUSY;
case CORESIGHT_CLAIM_EXTERNAL:
/* External debug is an expected state, so log and report BUSY */
dev_dbg(&csdev->dev, "Busy: Claimed by external debugger");
return -EBUSY;
default:
case CORESIGHT_CLAIM_SELF_HOSTED:
case CORESIGHT_CLAIM_INVALID:
/*
* Warn here because we clear a lingering self hosted tag
* on probe, so other tag combinations are impossible.
*/
dev_err_once(&csdev->dev, "Invalid claim tag state: %x", tag);
return -EBUSY;
}
}
EXPORT_SYMBOL_GPL(coresight_claim_device_unlocked);
@ -222,7 +235,7 @@ void coresight_disclaim_device_unlocked(struct coresight_device *csdev)
if (WARN_ON(!csdev))
return;
if (coresight_is_claimed_self_hosted(csdev))
if (coresight_read_claim_tags_unlocked(csdev) == CORESIGHT_CLAIM_SELF_HOSTED)
coresight_clear_self_claim_tag_unlocked(&csdev->access);
else
/*
@ -230,7 +243,7 @@ void coresight_disclaim_device_unlocked(struct coresight_device *csdev)
* and has manipulated it. Or something else has seriously
* gone wrong in our driver.
*/
WARN_ON_ONCE(1);
dev_WARN_ONCE(&csdev->dev, 1, "External agent took claim tag");
}
EXPORT_SYMBOL_GPL(coresight_disclaim_device_unlocked);

5
drivers/hwtracing/coresight/coresight-priv.h
View file

@ -36,7 +36,10 @@ extern const struct device_type coresight_dev_type[];
* See PSCI - ARM DEN 0022D, Section: 6.8.1 Debug and Trace save and restore.
*/
#define CORESIGHT_CLAIM_MASK GENMASK(1, 0)
#define CORESIGHT_CLAIM_SELF_HOSTED BIT(1)
#define CORESIGHT_CLAIM_FREE 0
#define CORESIGHT_CLAIM_EXTERNAL 1
#define CORESIGHT_CLAIM_SELF_HOSTED 2
#define CORESIGHT_CLAIM_INVALID 3
#define TIMEOUT_US 100
#define BMVAL(val, lsb, msb) ((val & GENMASK(msb, lsb)) >> lsb)