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authorSuzuki K Poulose <suzuki.poulose@arm.com>2018-09-20 13:18:11 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-09-25 20:09:19 +0200
commit2478a6ae4a6a4c8e3f7e9f6f849dffe92e5238e1 (patch)
treec1250692bc7cf6a36e6ecd3da9c5b141d9050e0f /drivers/hwtracing
parent30af4fb619e5126cb3152072e687b377fc9398d6 (diff)
downloadlinux-stericsson-2478a6ae4a6a4c8e3f7e9f6f849dffe92e5238e1.tar.gz
coresight: Add support for CLAIM tag protocol
Coresight architecture defines CLAIM tags for a device to negotiate control of the components (external agent vs self-hosted). Each device has a pair of registers (CLAIMSET & CLAIMCLR) for managing the CLAIM tags. However, the protocol for the CLAIM tags is IMPLEMENTATION DEFINED. PSCI has recommendations for the use of the CLAIM tags to negotiate controls for external agent vs self-hosted use. This patch implements the recommended protocol by PSCI. The claim/disclaim operations are performed from the device specific drivers. The disadvantage is that the calls are sprinkled in each driver, but this makes the operation much simpler. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hwtracing')
-rw-r--r--drivers/hwtracing/coresight/coresight-priv.h7
-rw-r--r--drivers/hwtracing/coresight/coresight.c86
2 files changed, 93 insertions, 0 deletions
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index c11da5564a67..579f34943bf1 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -25,6 +25,13 @@
#define CORESIGHT_DEVID 0xfc8
#define CORESIGHT_DEVTYPE 0xfcc
+
+/*
+ * Coresight device CLAIM protocol.
+ * See PSCI - ARM DEN 0022D, Section: 6.8.1 Debug and Trace save and restore.
+ */
+#define CORESIGHT_CLAIM_SELF_HOSTED BIT(1)
+
#define TIMEOUT_US 100
#define BMVAL(val, lsb, msb) ((val & GENMASK(msb, lsb)) >> lsb)
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index f4f50753cf75..2b0df1a0a8df 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -128,6 +128,92 @@ static int coresight_find_link_outport(struct coresight_device *csdev,
return -ENODEV;
}
+static inline u32 coresight_read_claim_tags(void __iomem *base)
+{
+ return readl_relaxed(base + CORESIGHT_CLAIMCLR);
+}
+
+static inline bool coresight_is_claimed_self_hosted(void __iomem *base)
+{
+ return coresight_read_claim_tags(base) == CORESIGHT_CLAIM_SELF_HOSTED;
+}
+
+static inline bool coresight_is_claimed_any(void __iomem *base)
+{
+ return coresight_read_claim_tags(base) != 0;
+}
+
+static inline void coresight_set_claim_tags(void __iomem *base)
+{
+ writel_relaxed(CORESIGHT_CLAIM_SELF_HOSTED, base + CORESIGHT_CLAIMSET);
+ isb();
+}
+
+static inline void coresight_clear_claim_tags(void __iomem *base)
+{
+ writel_relaxed(CORESIGHT_CLAIM_SELF_HOSTED, base + CORESIGHT_CLAIMCLR);
+ isb();
+}
+
+/*
+ * coresight_claim_device_unlocked : Claim the device for self-hosted usage
+ * to prevent an external tool from touching this device. As per PSCI
+ * standards, section "Preserving the execution context" => "Debug and Trace
+ * save and Restore", DBGCLAIM[1] is reserved for Self-hosted debug/trace and
+ * DBGCLAIM[0] is reserved for external tools.
+ *
+ * Called with CS_UNLOCKed for the component.
+ * Returns : 0 on success
+ */
+int coresight_claim_device_unlocked(void __iomem *base)
+{
+ if (coresight_is_claimed_any(base))
+ return -EBUSY;
+
+ coresight_set_claim_tags(base);
+ if (coresight_is_claimed_self_hosted(base))
+ return 0;
+ /* There was a race setting the tags, clean up and fail */
+ coresight_clear_claim_tags(base);
+ return -EBUSY;
+}
+
+int coresight_claim_device(void __iomem *base)
+{
+ int rc;
+
+ CS_UNLOCK(base);
+ rc = coresight_claim_device_unlocked(base);
+ CS_LOCK(base);
+
+ return rc;
+}
+
+/*
+ * coresight_disclaim_device_unlocked : Clear the claim tags for the device.
+ * Called with CS_UNLOCKed for the component.
+ */
+void coresight_disclaim_device_unlocked(void __iomem *base)
+{
+
+ if (coresight_is_claimed_self_hosted(base))
+ coresight_clear_claim_tags(base);
+ else
+ /*
+ * The external agent may have not honoured our claim
+ * and has manipulated it. Or something else has seriously
+ * gone wrong in our driver.
+ */
+ WARN_ON_ONCE(1);
+}
+
+void coresight_disclaim_device(void __iomem *base)
+{
+ CS_UNLOCK(base);
+ coresight_disclaim_device_unlocked(base);
+ CS_LOCK(base);
+}
+
static int coresight_enable_sink(struct coresight_device *csdev,
u32 mode, void *data)
{