coresight: etm4x: Detect access early on the target CPU

In preparation to detect the support for system instruction
support, move the detection of the device access to the target
CPU.

Link: https://lore.kernel.org/r/20210110224850.1880240-19-suzuki.poulose@arm.com
Cc: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210201181351.1475223-21-mathieu.poirier@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -59,6 +59,11 @@ static u64 etm4_get_access_type(struct etmv4_config *config);
 
 static enum cpuhp_state hp_online;
 
+struct etm4_init_arg {
+	struct etmv4_drvdata	*drvdata;
+	struct csdev_access	*csa;
+};
+
 /*
  * Check if TRCSSPCICRn(i) is implemented for a given instance.
  *
@@ -776,6 +781,22 @@ static const struct coresight_ops etm4_cs_ops = {
 	.source_ops	= &etm4_source_ops,
 };
 
+static bool etm4_init_iomem_access(struct etmv4_drvdata *drvdata,
+				   struct csdev_access *csa)
+{
+	*csa = CSDEV_ACCESS_IOMEM(drvdata->base);
+	return true;
+}
+
+static bool etm4_init_csdev_access(struct etmv4_drvdata *drvdata,
+				   struct csdev_access *csa)
+{
+	if (drvdata->base)
+		return etm4_init_iomem_access(drvdata, csa);
+
+	return false;
+}
+
 static void etm4_init_arch_data(void *info)
 {
 	u32 etmidr0;
@@ -784,11 +805,22 @@ static void etm4_init_arch_data(void *info)
 	u32 etmidr3;
 	u32 etmidr4;
 	u32 etmidr5;
-	struct etmv4_drvdata *drvdata = info;
-	struct csdev_access tmp_csa = CSDEV_ACCESS_IOMEM(drvdata->base);
-	struct csdev_access *csa = &tmp_csa;
+	struct etm4_init_arg *init_arg = info;
+	struct etmv4_drvdata *drvdata;
+	struct csdev_access *csa;
 	int i;
 
+	drvdata = init_arg->drvdata;
+	csa = init_arg->csa;
+
+	/*
+	 * If we are unable to detect the access mechanism,
+	 * or unable to detect the trace unit type, fail
+	 * early.
+	 */
+	if (!etm4_init_csdev_access(drvdata, csa))
+		return;
+
 	/* Make sure all registers are accessible */
 	etm4_os_unlock_csa(drvdata, csa);
 	etm4_cs_unlock(drvdata, csa);
@@ -1634,6 +1666,7 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
 	struct etmv4_drvdata *drvdata;
 	struct resource *res = &adev->res;
 	struct coresight_desc desc = { 0 };
+	struct etm4_init_arg init_arg = { 0 };
 
 	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
 	if (!drvdata)
@@ -1661,7 +1694,6 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
 		return PTR_ERR(base);
 
 	drvdata->base = base;
-	desc.access = CSDEV_ACCESS_IOMEM(base);
 
 	spin_lock_init(&drvdata->spinlock);
 
@@ -1673,8 +1705,11 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
 	if (!desc.name)
 		return -ENOMEM;
 
+	init_arg.drvdata = drvdata;
+	init_arg.csa = &desc.access;
+
 	if (smp_call_function_single(drvdata->cpu,
-				etm4_init_arch_data,  drvdata, 1))
+				etm4_init_arch_data,  &init_arg, 1))
 		dev_err(dev, "ETM arch init failed\n");
 
 	if (etm4_arch_supported(drvdata->arch) == false)