linux-kernel - [PATCH] coresight-etm4x: Conditionally access register TRCEXTINSELR

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Message-Id: <20250811-trcextinselr_issue-v1-1-ed78f3215502@oss.qualcomm.com>
Date: Mon, 11 Aug 2025 02:57:20 -0700
From: Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>
To: Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        James Clark <james.clark@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: kernel@....qualcomm.com, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>
Subject: [PATCH] coresight-etm4x: Conditionally access register
 TRCEXTINSELR

The TRCEXTINSELR is only implemented if TRCIDR5.NUMEXTINSEL > 0.
To avoid invalid accesses, introduce a check on numextinsel
(derived from TRCIDR5[11:9]) before reading or writing to this register.

Signed-off-by: Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>
---
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 11 ++++++++---
 drivers/hwtracing/coresight/coresight-etm4x.h      |  2 ++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 42e5d37403addc6ec81f2e3184522d67d1677c04..8a9c4caceff0165e4fce7ac4250f3e16ccc1d34e 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -528,7 +528,8 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 		etm4x_relaxed_write32(csa, config->seq_rst, TRCSEQRSTEVR);
 		etm4x_relaxed_write32(csa, config->seq_state, TRCSEQSTR);
 	}
-	etm4x_relaxed_write32(csa, config->ext_inp, TRCEXTINSELR);
+	if (drvdata->numextinsel)
+		etm4x_relaxed_write32(csa, config->ext_inp, TRCEXTINSELR);
 	for (i = 0; i < drvdata->nr_cntr; i++) {
 		etm4x_relaxed_write32(csa, config->cntrldvr[i], TRCCNTRLDVRn(i));
 		etm4x_relaxed_write32(csa, config->cntr_ctrl[i], TRCCNTCTLRn(i));
@@ -1423,6 +1424,7 @@ static void etm4_init_arch_data(void *info)
 	etmidr5 = etm4x_relaxed_read32(csa, TRCIDR5);
 	/* NUMEXTIN, bits[8:0] number of external inputs implemented */
 	drvdata->nr_ext_inp = FIELD_GET(TRCIDR5_NUMEXTIN_MASK, etmidr5);
+	drvdata->numextinsel = FIELD_GET(TRCIDR5_NUMEXTINSEL_MASK, etmidr5);
 	/* TRACEIDSIZE, bits[21:16] indicates the trace ID width */
 	drvdata->trcid_size = FIELD_GET(TRCIDR5_TRACEIDSIZE_MASK, etmidr5);
 	/* ATBTRIG, bit[22] implementation can support ATB triggers? */
@@ -1852,7 +1854,9 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
 		state->trcseqrstevr = etm4x_read32(csa, TRCSEQRSTEVR);
 		state->trcseqstr = etm4x_read32(csa, TRCSEQSTR);
 	}
-	state->trcextinselr = etm4x_read32(csa, TRCEXTINSELR);
+
+	if (drvdata->nrseqstate)
+		state->trcextinselr = etm4x_read32(csa, TRCEXTINSELR);
 
 	for (i = 0; i < drvdata->nr_cntr; i++) {
 		state->trccntrldvr[i] = etm4x_read32(csa, TRCCNTRLDVRn(i));
@@ -1984,7 +1988,8 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
 		etm4x_relaxed_write32(csa, state->trcseqrstevr, TRCSEQRSTEVR);
 		etm4x_relaxed_write32(csa, state->trcseqstr, TRCSEQSTR);
 	}
-	etm4x_relaxed_write32(csa, state->trcextinselr, TRCEXTINSELR);
+	if (drvdata->numextinsel)
+		etm4x_relaxed_write32(csa, state->trcextinselr, TRCEXTINSELR);
 
 	for (i = 0; i < drvdata->nr_cntr; i++) {
 		etm4x_relaxed_write32(csa, state->trccntrldvr[i], TRCCNTRLDVRn(i));
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index ac649515054d905fa365203bd35f1d839b03292f..823914fefa90a36a328b652b0dc3828b9bddd990 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -162,6 +162,7 @@
 #define TRCIDR4_NUMVMIDC_MASK			GENMASK(31, 28)
 
 #define TRCIDR5_NUMEXTIN_MASK			GENMASK(8, 0)
+#define TRCIDR5_NUMEXTINSEL_MASK               GENMASK(11, 9)
 #define TRCIDR5_TRACEIDSIZE_MASK		GENMASK(21, 16)
 #define TRCIDR5_ATBTRIG				BIT(22)
 #define TRCIDR5_LPOVERRIDE			BIT(23)
@@ -999,6 +1000,7 @@ struct etmv4_drvdata {
 	u8				nr_cntr;
 	u8				nr_ext_inp;
 	u8				numcidc;
+	u8				numextinsel;
 	u8				numvmidc;
 	u8				nrseqstate;
 	u8				nr_event;

---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250811-trcextinselr_issue-f267afa0e5ed

Best regards,
-- 
Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>