coresight: cti: Allow cti to be built as a module

Allow to build coresight-cti as a module, for ease of development.

- Kconfig becomes a tristate, to allow =m
- append -core to source file name to allow module to
  be called coresight-cti by the Makefile
- add an cti_remove function, for module unload
- add a MODULE_DEVICE_TABLE for autoloading on boot
- move cti_remove_conn_xrefs to cti_remove since all sysfs links
  have gone when system calls device_release.

Reviewed-by Mike Leach <mike.leach@linaro.org>

Tested-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200928163513.70169-22-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/Kconfig

@@ -136,7 +136,7 @@ config CORESIGHT_CPU_DEBUG
 	  module will be called coresight-cpu-debug.
 
 config CORESIGHT_CTI
-	bool "CoreSight Cross Trigger Interface (CTI) driver"
+	tristate "CoreSight Cross Trigger Interface (CTI) driver"
 	depends on ARM || ARM64
 	help
 	  This driver provides support for CoreSight CTI and CTM components.
@@ -147,6 +147,9 @@ config CORESIGHT_CTI
 	  halt compared to disabling sources and sinks normally in driver
 	  software.
 
+	  To compile this driver as a module, choose M here: the
+	  module will be called coresight-cti.
+
 config CORESIGHT_CTI_INTEGRATION_REGS
 	bool "Access CTI CoreSight Integration Registers"
 	depends on CORESIGHT_CTI

drivers/hwtracing/coresight/Makefile

@@ -19,6 +19,6 @@ coresight-etm4x-y := coresight-etm4x-core.o coresight-etm4x-sysfs.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
+obj-$(CONFIG_CORESIGHT_CTI) += coresight-cti.o
+coresight-cti-y := coresight-cti-core.o	coresight-cti-platform.o \
+		   coresight-cti-sysfs.o

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

@@ -822,7 +822,6 @@ static void cti_device_release(struct device *dev)
 	struct cti_drvdata *ect_item, *ect_tmp;
 
 	mutex_lock(&ect_mutex);
-	cti_remove_conn_xrefs(drvdata);
 	cti_pm_release(drvdata);
 
 	/* remove from the list */
@@ -837,6 +836,18 @@ static void cti_device_release(struct device *dev)
 	if (drvdata->csdev_release)
 		drvdata->csdev_release(dev);
 }
+static int __exit cti_remove(struct amba_device *adev)
+{
+	struct cti_drvdata *drvdata = dev_get_drvdata(&adev->dev);
+
+	mutex_lock(&ect_mutex);
+	cti_remove_conn_xrefs(drvdata);
+	mutex_unlock(&ect_mutex);
+
+	coresight_unregister(drvdata->csdev);
+
+	return 0;
+}
 
 static int cti_probe(struct amba_device *adev, const struct amba_id *id)
 {
@@ -957,6 +968,8 @@ static const struct amba_id cti_ids[] = {
 	{ 0, 0},
 };
 
+MODULE_DEVICE_TABLE(amba, cti_ids);
+
 static struct amba_driver cti_driver = {
 	.drv = {
 		.name	= "coresight-cti",
@@ -964,6 +977,7 @@ static struct amba_driver cti_driver = {
 		.suppress_bind_attrs = true,
 	},
 	.probe		= cti_probe,
+	.remove		= cti_remove,
 	.id_table	= cti_ids,
 };
 
@@ -986,3 +1000,7 @@ static void __exit cti_exit(void)
 
 module_init(cti_init);
 module_exit(cti_exit);
+
+MODULE_AUTHOR("Mike Leach <mike.leach@linaro.org>");
+MODULE_DESCRIPTION("Arm CoreSight CTI Driver");
+MODULE_LICENSE("GPL v2");

drivers/hwtracing/coresight/coresight-platform.c

@@ -75,6 +75,7 @@ coresight_find_csdev_by_fwnode(struct fwnode_handle *r_fwnode)
 	}
 	return csdev;
 }
+EXPORT_SYMBOL_GPL(coresight_find_csdev_by_fwnode);
 
 #ifdef CONFIG_OF
 static inline bool of_coresight_legacy_ep_is_input(struct device_node *ep)

drivers/hwtracing/coresight/coresight.c

@@ -288,6 +288,7 @@ void coresight_set_assoc_ectdev_mutex(struct coresight_device *csdev,
 	csdev->ect_dev = ect_csdev;
 	mutex_unlock(&coresight_mutex);
 }
+EXPORT_SYMBOL_GPL(coresight_set_assoc_ectdev_mutex);
 
 static int coresight_enable_sink(struct coresight_device *csdev,
 				 u32 mode, void *data)