[RFC PATCH 20/57] platform: Add a helper to find device by driver

[Suzuki K Poulose]

There are a couple of places where we reuse platform specific
match to find a device. Instead of spilling the global varilable
everywhere, let us provide a helper to do the same.

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Inki Dae <inki.dae@xxxxxxxxxxx>
Cc: Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx>
Cc: Sandy Huang <hjc@xxxxxxxxxxxxxx>
Cc: "Heiko StÃbner" <heiko@xxxxxxxxx>
Cc: Eric Anholt <eric@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
 drivers/base/platform.c                     | 14 ++++++++++++++
 drivers/gpu/drm/exynos/exynos_drm_drv.c     |  9 +++------
 drivers/gpu/drm/rockchip/rockchip_drm_drv.c |  3 +--
 drivers/gpu/drm/vc4/vc4_drv.c               |  3 +--
 include/linux/platform_device.h             |  3 +++
 5 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 4d17298..daca44f 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -1197,6 +1197,20 @@ struct bus_type platform_bus_type = {
 };
 EXPORT_SYMBOL_GPL(platform_bus_type);
 
+/**
+ * platform_find_device_by_driver - Find a platform device with a given
+ * driver.
+ * @start: The device to start the search from.
+ * @drv: The device driver to look for.
+ */
+struct device *platform_find_device_by_driver(struct device *start,
+					      const struct device_driver *drv)
+{
+	return bus_find_device(&platform_bus_type, start, (void *)drv,
+			       (int (*)(struct device *, void *))platform_match);
+}
+EXPORT_SYMBOL_GPL(platform_find_device_by_driver);
+
 int __init platform_bus_init(void)
 {
 	int error;
diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c b/drivers/gpu/drm/exynos/exynos_drm_drv.c
index ba8932a..b357e0d 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
@@ -244,9 +244,7 @@ static struct component_match *exynos_drm_match_add(struct device *dev)
 		if (!info->driver || !(info->flags & DRM_COMPONENT_DRIVER))
 			continue;
 
-		while ((d = bus_find_device(&platform_bus_type, p,
-					    &info->driver->driver,
-					    (void *)platform_bus_type.match))) {
+		while ((d = platform_find_device_by_driver(p, &info->driver->driver))) {
 			put_device(p);
 
 			if (!(info->flags & DRM_FIMC_DEVICE) ||
@@ -414,9 +412,8 @@ static void exynos_drm_unregister_devices(void)
 		if (!info->driver || !(info->flags & DRM_VIRTUAL_DEVICE))
 			continue;
 
-		while ((dev = bus_find_device(&platform_bus_type, NULL,
-					    &info->driver->driver,
-					    (void *)platform_bus_type.match))) {
+		while ((dev = platform_find_device_by_driver(NULL,
+						&info->driver->driver))) {
 			put_device(dev);
 			platform_device_unregister(to_platform_device(dev));
 		}
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index cb938d3..4eb4fb8 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -338,8 +338,7 @@ static struct component_match *rockchip_drm_match_add(struct device *dev)
 		struct device *p = NULL, *d;
 
 		do {
-			d = bus_find_device(&platform_bus_type, p, &drv->driver,
-					    (void *)platform_bus_type.match);
+			d = platform_find_device_by_driver(p, &drv->driver);
 			put_device(p);
 			p = d;
 
diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
index 6d9be20..d159eb5 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.c
+++ b/drivers/gpu/drm/vc4/vc4_drv.c
@@ -236,8 +236,7 @@ static void vc4_match_add_drivers(struct device *dev,
 		struct device_driver *drv = &drivers[i]->driver;
 		struct device *p = NULL, *d;
 
-		while ((d = bus_find_device(&platform_bus_type, p, drv,
-					    (void *)platform_bus_type.match))) {
+		while ((d = platform_find_device_by_driver(p, drv))) {
 			put_device(p);
 			component_match_add(dev, match, compare_dev, d);
 			p = d;
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index cc46485..a82b3ec 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -52,6 +52,9 @@ extern struct device platform_bus;
 extern void arch_setup_pdev_archdata(struct platform_device *);
 extern struct resource *platform_get_resource(struct platform_device *,
 					      unsigned int, unsigned int);
+extern struct device *
+platform_find_device_by_driver(struct device dev*,
+			       const struct device_driver *drv);
 extern void __iomem *
 devm_platform_ioremap_resource(struct platform_device *pdev,
 			       unsigned int index);
-- 
2.7.4