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.

Fixes: f5bd523 ("coresight: etm4x: Convert all register accesses")
Signed-off-by: Yuanfang Zhang <yuanfang.zhang@oss.qualcomm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250812-trcextinselr_issue-v2-1-e6eb121dfcf4@oss.qualcomm.com

Author: Yuanfang Zhang

drivers/hwtracing/coresight/coresight-etm4x-core.c

@@ -529,7 +529,8 @@ 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));
@@ -1424,6 +1425,7 @@ 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? */
@@ -1853,7 +1855,9 @@ 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->numextinsel)
+		state->trcextinselr = etm4x_read32(csa, TRCEXTINSELR);
 
 	for (i = 0; i < drvdata->nr_cntr; i++) {
 		state->trccntrldvr[i] = etm4x_read32(csa, TRCCNTRLDVRn(i));
@@ -1985,7 +1989,8 @@ 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));

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;