linux-kernel - [PATCH 11/25] coresight: etb: Allow etb to be built as a module

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Message-Id: <20200928163513.70169-12-mathieu.poirier@linaro.org>
Date:   Mon, 28 Sep 2020 10:34:59 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 11/25] coresight: etb: Allow etb to be built as a module

From: Kim Phillips <kim.phillips@....com>

Allow to build coresight-etb10 as a module, for ease of development.

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

Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Leo Yan <leo.yan@...aro.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Randy Dunlap <rdunlap@...radead.org>
Cc: Suzuki K Poulose <Suzuki.Poulose@....com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Russell King <linux@...linux.org.uk>
Signed-off-by: Kim Phillips <kim.phillips@....com>
Signed-off-by: Tingwei Zhang <tingwei@...eaurora.org>
Tested-by: Mike Leach <mike.leach@...aro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
---
 drivers/hwtracing/coresight/Kconfig           |  5 +++-
 drivers/hwtracing/coresight/coresight-etb10.c | 26 ++++++++++++++++++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index d6e107bbd30b..996d84a1edb8 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -57,13 +57,16 @@ config CORESIGHT_SINK_TPIU
 	  the on-board coresight memory can handle.
 
 config CORESIGHT_SINK_ETBV10
-	bool "Coresight ETBv1.0 driver"
+	tristate "Coresight ETBv1.0 driver"
 	depends on CORESIGHT_LINKS_AND_SINKS
 	help
 	  This enables support for the Embedded Trace Buffer version 1.0 driver
 	  that complies with the generic implementation of the component without
 	  special enhancement or added features.
 
+	  To compile this driver as a module, choose M here: the
+	  module will be called coresight-etb10.
+
 config CORESIGHT_SOURCE_ETM3X
 	tristate "CoreSight Embedded Trace Macrocell 3.x driver"
 	depends on !ARM64
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index 04ee9cda988d..248cc82c838e 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -801,6 +801,21 @@ static int etb_probe(struct amba_device *adev, const struct amba_id *id)
 	return ret;
 }
 
+static int __exit etb_remove(struct amba_device *adev)
+{
+	struct etb_drvdata *drvdata = dev_get_drvdata(&adev->dev);
+
+	/*
+	 * Since misc_open() holds a refcount on the f_ops, which is
+	 * etb fops in this case, device is there until last file
+	 * handler to this device is closed.
+	 */
+	misc_deregister(&drvdata->miscdev);
+	coresight_unregister(drvdata->csdev);
+
+	return 0;
+}
+
 #ifdef CONFIG_PM
 static int etb_runtime_suspend(struct device *dev)
 {
@@ -835,6 +850,8 @@ static const struct amba_id etb_ids[] = {
 	{ 0, 0},
 };
 
+MODULE_DEVICE_TABLE(amba, etb_ids);
+
 static struct amba_driver etb_driver = {
 	.drv = {
 		.name	= "coresight-etb10",
@@ -844,6 +861,13 @@ static struct amba_driver etb_driver = {
 
 	},
 	.probe		= etb_probe,
+	.remove		= etb_remove,
 	.id_table	= etb_ids,
 };
-builtin_amba_driver(etb_driver);
+
+module_amba_driver(etb_driver);
+
+MODULE_AUTHOR("Pratik Patel <pratikp@...eaurora.org>");
+MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@...aro.org>");
+MODULE_DESCRIPTION("Arm CoreSight Embedded Trace Buffer driver");
+MODULE_LICENSE("GPL v2");
-- 
2.25.1