coresight-tpdm: Add integration test support

Integration test for tpdm can help to generate the data for
verification of the topology during TPDM software bring up.

Sample:
echo 1 > /sys/bus/coresight/devices/tmc_etf0/enable_sink
echo 1 > /sys/bus/coresight/devices/tpdm0/enable_source
echo 1 > /sys/bus/coresight/devices/tpdm0/integration_test
echo 2 > /sys/bus/coresight/devices/tpdm0/integration_test
cat /dev/tmc_etf0 > /data/etf-tpdm0.bin

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230117145708.16739-6-quic_jinlmao@quicinc.com

Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm

@@ -0,0 +1,13 @@
+What:		/sys/bus/coresight/devices/<tpdm-name>/integration_test
+Date:		January 2023
+KernelVersion	6.2
+Contact:	Jinlong Mao (QUIC) <quic_jinlmao@quicinc.com>, Tao Zhang (QUIC) <quic_taozha@quicinc.com>
+Description:
+		(Write) Run integration test for tpdm. Integration test
+		will generate test data for tpdm. It can help to make
+		sure that the trace path is enabled and the link configurations
+		are fine.
+
+		Accepts only one of the 2 values -  1 or 2.
+		1 : Generate 64 bits data
+		2 : Generate 32 bits data

drivers/hwtracing/coresight/coresight-tpdm.c

@@ -121,6 +121,59 @@ static void tpdm_init_default_data(struct tpdm_drvdata *drvdata)
 	CS_LOCK(drvdata->base);
 }
 
+/*
+ * value 1: 64 bits test data
+ * value 2: 32 bits test data
+ */
+static ssize_t integration_test_store(struct device *dev,
+					  struct device_attribute *attr,
+					  const char *buf,
+					  size_t size)
+{
+	int i, ret = 0;
+	unsigned long val;
+	struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	ret = kstrtoul(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	if (val != 1 && val != 2)
+		return -EINVAL;
+
+	if (!drvdata->enable)
+		return -EINVAL;
+
+	if (val == 1)
+		val = ATBCNTRL_VAL_64;
+	else
+		val = ATBCNTRL_VAL_32;
+	CS_UNLOCK(drvdata->base);
+	writel_relaxed(0x1, drvdata->base + TPDM_ITCNTRL);
+
+	for (i = 0; i < INTEGRATION_TEST_CYCLE; i++)
+		writel_relaxed(val, drvdata->base + TPDM_ITATBCNTRL);
+
+	writel_relaxed(0, drvdata->base + TPDM_ITCNTRL);
+	CS_LOCK(drvdata->base);
+	return size;
+}
+static DEVICE_ATTR_WO(integration_test);
+
+static struct attribute *tpdm_attrs[] = {
+	&dev_attr_integration_test.attr,
+	NULL,
+};
+
+static struct attribute_group tpdm_attr_grp = {
+	.attrs = tpdm_attrs,
+};
+
+static const struct attribute_group *tpdm_attr_grps[] = {
+	&tpdm_attr_grp,
+	NULL,
+};
+
 static int tpdm_probe(struct amba_device *adev, const struct amba_id *id)
 {
 	void __iomem *base;
@@ -157,6 +210,7 @@ static int tpdm_probe(struct amba_device *adev, const struct amba_id *id)
 	desc.pdata = adev->dev.platform_data;
 	desc.dev = &adev->dev;
 	desc.access = CSDEV_ACCESS_IOMEM(base);
+	desc.groups = tpdm_attr_grps;
 	drvdata->csdev = coresight_register(&desc);
 	if (IS_ERR(drvdata->csdev))
 		return PTR_ERR(drvdata->csdev);

drivers/hwtracing/coresight/coresight-tpdm.h

@@ -14,6 +14,20 @@
 /* Enable bit for DSB subunit */
 #define TPDM_DSB_CR_ENA		BIT(0)
 
+/* TPDM integration test registers */
+#define TPDM_ITATBCNTRL		(0xEF0)
+#define TPDM_ITCNTRL		(0xF00)
+
+/* Register value for integration test */
+#define ATBCNTRL_VAL_32		0xC00F1409
+#define ATBCNTRL_VAL_64		0xC01F1409
+
+/*
+ * Number of cycles to write value when
+ * integration test.
+ */
+#define INTEGRATION_TEST_CYCLE	10
+
 /**
  * The bits of PERIPHIDR0 register.
  * The fields [6:0] of PERIPHIDR0 are used to determine what