coresight: etm4x: Fix accesses to TRCSEQRSTEVR and TRCSEQSTR

The TRCSEQRSTEVR and TRCSEQSTR registers are not implemented if the
TRCIDR5.NUMSEQSTATE == 0. Skip accessing the registers in such cases.

Fixes: 2e1cdfe ("coresight-etm4x: Adding CoreSight ETM4x driver")
Signed-off-by: Junhao He <hejunhao3@huawei.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230114091632.60095-1-hejunhao3@huawei.com

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

@@ -427,8 +427,10 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 		etm4x_relaxed_write32(csa, config->vipcssctlr, TRCVIPCSSCTLR);
 	for (i = 0; i < drvdata->nrseqstate - 1; i++)
 		etm4x_relaxed_write32(csa, config->seq_ctrl[i], TRCSEQEVRn(i));
-	etm4x_relaxed_write32(csa, config->seq_rst, TRCSEQRSTEVR);
-	etm4x_relaxed_write32(csa, config->seq_state, TRCSEQSTR);
+	if (drvdata->nrseqstate) {
+		etm4x_relaxed_write32(csa, config->seq_rst, TRCSEQRSTEVR);
+		etm4x_relaxed_write32(csa, config->seq_state, TRCSEQSTR);
+	}
 	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));
@@ -1634,8 +1636,10 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
 	for (i = 0; i < drvdata->nrseqstate - 1; i++)
 		state->trcseqevr[i] = etm4x_read32(csa, TRCSEQEVRn(i));
 
-	state->trcseqrstevr = etm4x_read32(csa, TRCSEQRSTEVR);
-	state->trcseqstr = etm4x_read32(csa, TRCSEQSTR);
+	if (drvdata->nrseqstate) {
+		state->trcseqrstevr = etm4x_read32(csa, TRCSEQRSTEVR);
+		state->trcseqstr = etm4x_read32(csa, TRCSEQSTR);
+	}
 	state->trcextinselr = etm4x_read32(csa, TRCEXTINSELR);
 
 	for (i = 0; i < drvdata->nr_cntr; i++) {
@@ -1763,8 +1767,10 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
 	for (i = 0; i < drvdata->nrseqstate - 1; i++)
 		etm4x_relaxed_write32(csa, state->trcseqevr[i], TRCSEQEVRn(i));
 
-	etm4x_relaxed_write32(csa, state->trcseqrstevr, TRCSEQRSTEVR);
-	etm4x_relaxed_write32(csa, state->trcseqstr, TRCSEQSTR);
+	if (drvdata->nrseqstate) {
+		etm4x_relaxed_write32(csa, state->trcseqrstevr, TRCSEQRSTEVR);
+		etm4x_relaxed_write32(csa, state->trcseqstr, TRCSEQSTR);
+	}
 	etm4x_relaxed_write32(csa, state->trcextinselr, TRCEXTINSELR);
 
 	for (i = 0; i < drvdata->nr_cntr; i++) {