coresight: cti: Initial CoreSight CTI Driver

This introduces a baseline CTI driver and associated configuration files.

Uses the platform agnostic naming standard for CoreSight devices, along
with a generic platform probing method that currently supports device
tree descriptions, but allows for the ACPI bindings to be added once these
have been defined for the CTI devices.

Driver will probe for the device on the AMBA bus, and load the CTI driver
on CoreSight ID match to CTI IDs in tables.

Initial sysfs support for enable / disable provided.

Default CTI interconnection data is generated based on hardware
register signal counts, with no additional connection information.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200320165303.13681-2-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/Kconfig

@@ -110,4 +110,16 @@ config CORESIGHT_CPU_DEBUG
 	  properly, please refer Documentation/trace/coresight-cpu-debug.rst
 	  for detailed description and the example for usage.
 
+config CORESIGHT_CTI
+	bool "CoreSight Cross Trigger Interface (CTI) driver"
+	depends on ARM || ARM64
+	help
+	  This driver provides support for CoreSight CTI and CTM components.
+	  These provide hardware triggering events between CoreSight trace
+	  source and sink components. These can be used to halt trace or
+	  inject events into the trace stream. CTI also provides a software
+	  control to trigger the same halt events. This can provide fast trace
+	  halt compared to disabling sources and sinks normally in driver
+	  software.
+
 endif

drivers/hwtracing/coresight/Makefile

@@ -17,3 +17,6 @@ obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
 obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
 obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
 obj-$(CONFIG_CORESIGHT_CATU) += coresight-catu.o
+obj-$(CONFIG_CORESIGHT_CTI) += coresight-cti.o \
+				coresight-cti-platform.o \
+				coresight-cti-sysfs.o

drivers/hwtracing/coresight/coresight-cti-platform.c

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, The Linaro Limited. All rights reserved.
+ */
+
+#include <linux/of.h>
+
+#include "coresight-cti.h"
+
+/* get the hardware configuration & connection data. */
+int cti_plat_get_hw_data(struct device *dev,
+			 struct cti_drvdata *drvdata)
+{
+	int rc = 0;
+	struct cti_device *cti_dev = &drvdata->ctidev;
+
+	/* if no connections, just add a single default based on max IN-OUT */
+	if (cti_dev->nr_trig_con == 0)
+		rc = cti_add_default_connection(dev, drvdata);
+	return rc;
+}
+
+struct coresight_platform_data *
+coresight_cti_get_platform_data(struct device *dev)
+{
+	int ret = -ENOENT;
+	struct coresight_platform_data *pdata = NULL;
+	struct fwnode_handle *fwnode = dev_fwnode(dev);
+	struct cti_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (IS_ERR_OR_NULL(fwnode))
+		goto error;
+
+	/*
+	 * Alloc platform data but leave it zero init. CTI does not use the
+	 * same connection infrastructuree as trace path components but an
+	 * empty struct enables us to use the standard coresight component
+	 * registration code.
+	 */
+	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata) {
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	/* get some CTI specifics */
+	ret = cti_plat_get_hw_data(dev, drvdata);
+
+	if (!ret)
+		return pdata;
+error:
+	return ERR_PTR(ret);
+}

drivers/hwtracing/coresight/coresight-cti-sysfs.c

@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Linaro Limited, All rights reserved.
+ * Author: Mike Leach <mike.leach@linaro.org>
+ */
+
+#include <linux/coresight.h>
+
+#include "coresight-cti.h"
+
+/* basic attributes */
+static ssize_t enable_show(struct device *dev,
+			   struct device_attribute *attr,
+			   char *buf)
+{
+	int enable_req;
+	bool enabled, powered;
+	struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	enable_req = atomic_read(&drvdata->config.enable_req_count);
+	spin_lock(&drvdata->spinlock);
+	powered = drvdata->config.hw_powered;
+	enabled = drvdata->config.hw_enabled;
+	spin_unlock(&drvdata->spinlock);
+
+	if (powered)
+		return sprintf(buf, "%d\n", enabled);
+	else
+		return sprintf(buf, "%d\n", !!enable_req);
+}
+
+static ssize_t enable_store(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t size)
+{
+	int ret = 0;
+	unsigned long val;
+	struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	ret = kstrtoul(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	if (val)
+		ret = cti_enable(drvdata->csdev);
+	else
+		ret = cti_disable(drvdata->csdev);
+	if (ret)
+		return ret;
+	return size;
+}
+static DEVICE_ATTR_RW(enable);
+
+static ssize_t powered_show(struct device *dev,
+			    struct device_attribute *attr,
+			    char *buf)
+{
+	bool powered;
+	struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	spin_lock(&drvdata->spinlock);
+	powered = drvdata->config.hw_powered;
+	spin_unlock(&drvdata->spinlock);
+
+	return sprintf(buf, "%d\n", powered);
+}
+static DEVICE_ATTR_RO(powered);
+
+/* attribute and group sysfs tables. */
+static struct attribute *coresight_cti_attrs[] = {
+	&dev_attr_enable.attr,
+	&dev_attr_powered.attr,
+	NULL,
+};
+
+static const struct attribute_group coresight_cti_group = {
+	.attrs = coresight_cti_attrs,
+};
+
+const struct attribute_group *coresight_cti_groups[] = {
+	&coresight_cti_group,
+	NULL,
+};