[PATCH 2/4] driver core: platform: allow platform drivers to bind to any device

[Kim Phillips <kim.phillips@linaro.org>]

Platform drivers such as the vfio-platform "meta-" driver [1]
should be allowed to specify that they can bind to any device,
much like PCI drivers can with PCI_ANY_ID.

Currently, binding platform drivers to devices depends on:

- a string match in the device node's compatible entry (OF)
- a string match in the ACPI id list (ACPI)
- a string match in the id_table (platform data)
- a string match on the driver name (fall-back)

none of which allow for the notion of "match any."

This patch adds the notion by adding a "match any device" boolean to
struct platform_driver, for drivers to be able to set and thus not cause
platform_match() to fail when a bind is requested.

[1] http://www.spinics.net/lists/kvm/msg96701.html

Signed-off-by: Kim Phillips <kim.phillips@linaro.org>
---
 drivers/base/platform.c         | 4 ++++
 include/linux/platform_device.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 4f8bef3..0ca20d4 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -727,6 +727,10 @@ static int platform_match(struct device *dev, struct device_driver *drv)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct platform_driver *pdrv = to_platform_driver(drv);
 
+	/* the driver matches any device */
+	if (pdrv->match_any_dev)
+		return 1;
+
 	/* Attempt an OF style match first */
 	if (of_driver_match_device(dev, drv))
 		return 1;
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index ce8e4ff..2d25d50 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -178,6 +178,7 @@ struct platform_driver {
 	int (*resume)(struct platform_device *);
 	struct device_driver driver;
 	const struct platform_device_id *id_table;
+	bool match_any_dev;
 };
 
 #define to_platform_driver(drv)	(container_of((drv), struct platform_driver, \
-- 
1.8.4