[PATCH 3/7] coresight: Only check bottom two claim bits

[James Clark]

The use of the whole register and == could break the claim mechanism if
any of the other bits are used in the future. The referenced doc "PSCI -
ARM DEN 0022D" also says to only read and clear the bottom two bits.

Use FIELD_GET() to extract only the relevant part.

Signed-off-by: James Clark <james.clark at linaro.org>
---
 drivers/hwtracing/coresight/coresight-core.c | 3 ++-
 drivers/hwtracing/coresight/coresight-priv.h | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index a669872b4118..7b53165c93af 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -129,7 +129,8 @@ coresight_find_out_connection(struct coresight_device *csdev,
 
 static inline u32 coresight_read_claim_tags(struct csdev_access *csa)
 {
-	return csdev_access_relaxed_read32(csa, CORESIGHT_CLAIMCLR);
+	return FIELD_GET(CORESIGHT_CLAIM_MASK,
+			 csdev_access_relaxed_read32(csa, CORESIGHT_CLAIMCLR));
 }
 
 static inline bool coresight_is_claimed_self_hosted(struct csdev_access *csa)
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index 05f891ca6b5c..cc7ff1e36ef4 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -35,6 +35,7 @@ extern const struct device_type coresight_dev_type[];
  * Coresight device CLAIM protocol.
  * 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 TIMEOUT_US		100
-- 
2.34.1