[PATCH v3 2/7] driver: Add rescan hook to struct device

[Sascha Hauer]

When devices are enabled with a device tree overlay the newly enabled
devices can be probed by doing a of_probe(). This works fine for the
regular platform devices, but doesn't work for devices which are not
probed by the core, but by the subsystem. Prominent examples are I2C or
SPI devices.

This patch adds a struct device::rescan hook that subsystems can
implement to trigger rescanning the device nodes.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/of/platform.c | 12 +++++-------
 include/driver.h      |  6 ++++++
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index edb082b106..23b8fa7934 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -153,8 +153,10 @@ struct device *of_platform_device_create(struct device_node *np,
 	 * Linux uses the OF_POPULATED flag to skip already populated/created
 	 * devices.
 	 */
-	if (np->dev)
+	if (np->dev) {
+		device_rescan(np->dev);
 		return np->dev;
+	}
 
 	/* count the io resources */
 	if (of_can_translate_address(np))
@@ -414,17 +416,13 @@ static struct device *of_device_create_on_demand(struct device_node *np)
 {
 	struct device_node *parent;
 	struct device *parent_dev, *dev;
-	int ret;
 
 	parent = of_get_parent(np);
 	if (!parent)
 		return NULL;
 
-	if (!np->dev && parent->dev) {
-		ret = device_detect(parent->dev);
-		if (ret && ret != -ENOSYS)
-			return ERR_PTR(ret);
-	}
+	if (!np->dev && parent->dev)
+		device_rescan(parent->dev);
 
 	if (!np->dev)
 		pr_debug("Creating device for %s\n", np->full_name);
diff --git a/include/driver.h b/include/driver.h
index f53668711b..2cf0190699 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -91,6 +91,7 @@ struct device {
 	 * when the driver should actually detect client devices
 	 */
 	int     (*detect) (struct device *);
+	void	(*rescan) (struct device *);
 
 	/*
 	 * if a driver probe is deferred, this stores the last error
@@ -158,6 +159,11 @@ static inline void put_device(struct device *dev) {}
 void free_device_res(struct device *dev);
 void free_device(struct device *dev);
 
+static inline void device_rescan(struct device *dev)
+{
+	if (dev->rescan)
+		dev->rescan(dev);
+}
 
 /* Iterate over a devices children
  */
-- 
2.30.2