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Subject[PATCH v2 1/6] dt-bindings: hwlock: add support of shared locks
Date
Use #hwlock-cells value to define whether the locks can be shared
by several users.

Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
.../devicetree/bindings/hwlock/hwlock.txt | 27 ++++++++++++++++------
1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/Documentation/devicetree/bindings/hwlock/hwlock.txt b/Documentation/devicetree/bindings/hwlock/hwlock.txt
index 085d1f5..e98088a 100644
--- a/Documentation/devicetree/bindings/hwlock/hwlock.txt
+++ b/Documentation/devicetree/bindings/hwlock/hwlock.txt
@@ -13,7 +13,7 @@ hwlock providers:

Required properties:
- #hwlock-cells: Specifies the number of cells needed to represent a
- specific lock.
+ specific lock. Shall be 1 or 2 (see hwlocks below).

hwlock users:
=============
@@ -27,6 +27,11 @@ Required properties:
#hwlock-cells. The list can have just a single hwlock
or multiple hwlocks, with each hwlock represented by
a phandle and a corresponding args specifier.
+ If #hwlock-cells is 1, all of the locks are exclusive
+ (cannot be used by several users).
+ If #hwlock-cells is 2, the value of the second cell
+ defines whether the lock is for exclusive usage (0) or
+ shared (1) i.e. can be used by several users.

Optional properties:
- hwlock-names: List of hwlock name strings defined in the same order
@@ -46,14 +51,22 @@ of length 1.
...
};

-2. Example of a node using multiple specific hwlocks:
+2. Example of nodes using multiple and shared specific hwlocks:

-The following example has a node requesting two hwlocks, a hwlock within
-the hwlock device node 'hwlock1' with #hwlock-cells value of 1, and another
-hwlock within the hwlock device node 'hwlock2' with #hwlock-cells value of 2.
+The following example has a nodeA requesting two hwlocks:
+- an exclusive one (#hwlock-cells = 1) within the hwlock device node 'hwlock1'
+- a shared one (#hwlock-cells = 2, second cell = 1) within the hwlock device
+ node 'hwlock2'.
+The shared lock is also be used by nodeB.

- node {
+ nodeA {
...
- hwlocks = <&hwlock1 2>, <&hwlock2 0 3>;
+ hwlocks = <&hwlock1 2>, <&hwlock2 0 1>;
...
};
+
+ nodeB {
+ ...
+ hwlocks = <&hwlock2 0 1>;
+ ...
+ };
\ No newline at end of file
--
2.7.4
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