coresight: stm: Allow to build coresight-stm as a module

- Kconfig becomes a tristate, to allow =m
- add a stm_remove function, for module unload
- add a MODULE_DEVICE_TABLE for autoloading on boot

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@armlinux.org.uk>
Tested-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Kim Phillips <kim.phillips@arm.com>
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200928163513.70169-8-mathieu.poirier@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/Kconfig

@@ -86,7 +86,7 @@ config CORESIGHT_SOURCE_ETM4X
 	  data tracing may also be available.
 
 config CORESIGHT_STM
-	bool "CoreSight System Trace Macrocell driver"
+	tristate "CoreSight System Trace Macrocell driver"
 	depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) || ARM64
 	select CORESIGHT_LINKS_AND_SINKS
 	select STM
@@ -96,6 +96,9 @@ config CORESIGHT_STM
 	  logging useful software events or data coming from various entities
 	  in the system, possibly running different OSs
 
+	  To compile this driver as a module, choose M here: the
+	  module will be called coresight-stm.
+
 config CORESIGHT_CPU_DEBUG
 	tristate "CoreSight CPU Debug driver"
 	depends on ARM || ARM64

drivers/hwtracing/coresight/coresight-stm.c

@@ -951,6 +951,17 @@ static int stm_probe(struct amba_device *adev, const struct amba_id *id)
 	return ret;
 }
 
+static int __exit stm_remove(struct amba_device *adev)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(&adev->dev);
+
+	coresight_unregister(drvdata->csdev);
+
+	stm_unregister_device(&drvdata->stm);
+
+	return 0;
+}
+
 #ifdef CONFIG_PM
 static int stm_runtime_suspend(struct device *dev)
 {
@@ -983,6 +994,8 @@ static const struct amba_id stm_ids[] = {
 	{ 0, 0},
 };
 
+MODULE_DEVICE_TABLE(amba, stm_ids);
+
 static struct amba_driver stm_driver = {
 	.drv = {
 		.name   = "coresight-stm",
@@ -991,7 +1004,12 @@ static struct amba_driver stm_driver = {
 		.suppress_bind_attrs = true,
 	},
 	.probe          = stm_probe,
+	.remove         = stm_remove,
 	.id_table	= stm_ids,
 };
 
-builtin_amba_driver(stm_driver);
+module_amba_driver(stm_driver);
+
+MODULE_AUTHOR("Pratik Patel <pratikp@codeaurora.org>");
+MODULE_DESCRIPTION("Arm CoreSight System Trace Macrocell driver");
+MODULE_LICENSE("GPL v2");