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 --- drivers/hwtracing/coresight/coresight-core.c | 51 +++++++++++++++++----------- drivers/hwtracing/coresight/coresight-priv.h | 5 ++- 2 files changed, 36 insertions(+), 20 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index e0638e5de0e0..33824f4a631d 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -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);
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index 38bb4e8b50ef..6e8cf55aee0a 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -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)