of: Keep track of populated platform devices

In "Device Tree powered" systems, platform devices are usually massively
populated with of_platform_populate() call, executed at some level of
initcalls, either by generic architecture or by platform-specific code.

There are situations though where certain devices must be created (and
bound with drivers) before all the others. This presents a challenge,
as devices created explicitly would be created again by
of_platform_populate().

This patch tries to solve that issue in a generic way, adding a
"populated" flag for a DT node description. Subsequent
of_platform_populate() will skip such nodes (and its children) in
a similar way to the non-available ones.

This patch also adds of_platform_depopulate() as an operation
complementary to the _populate() one. It removes a platform or an amba
device populated from the Device Tree, together with its all children
(leaving, however, devices without associated of_node untouched)
clearing the "populated" flag on the way.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Grant Likely <grant.likely@linaro.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/of.h b/include/linux/of.h
index 3bad8d106e0..4c50d0b78b8 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -130,6 +130,12 @@ static inline int of_node_check_flag(struct device_node *n, unsigned long flag)
 	return test_bit(flag, &n->_flags);
 }
 
+static inline int of_node_test_and_set_flag(struct device_node *n,
+					    unsigned long flag)
+{
+	return test_and_set_bit(flag, &n->_flags);
+}
+
 static inline void of_node_set_flag(struct device_node *n, unsigned long flag)
 {
 	set_bit(flag, &n->_flags);
@@ -197,6 +203,7 @@ static inline unsigned long of_read_ulong(const __be32 *cell, int size)
 /* flag descriptions */
 #define OF_DYNAMIC	1 /* node and properties were allocated via kmalloc */
 #define OF_DETACHED	2 /* node has been detached from the device tree */
+#define OF_POPULATED	3 /* device already created for the node */
 
 #define OF_IS_DYNAMIC(x) test_bit(OF_DYNAMIC, &x->_flags)
 #define OF_MARK_DYNAMIC(x) set_bit(OF_DYNAMIC, &x->_flags)