This patch adds documentation clarifying the reset GPIO bindings most
commonly in use (reset-gpios and <name>-reset-gpios properties).
Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
---
Documentation/devicetree/bindings/reset/reset.txt | 26 +++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/reset/reset.txt b/Documentation/devicetree/bindings/reset/reset.txt
index 31db6ff..51f9e35 100644
--- a/Documentation/devicetree/bindings/reset/reset.txt
+++ b/Documentation/devicetree/bindings/reset/reset.txt
@@ -2,8 +2,8 @@
This binding is intended to represent the hardware reset signals present
internally in most IC (SoC, FPGA, ...) designs. Reset signals for whole
-standalone chips are most likely better represented as GPIOs, although there
-are likely to be exceptions to this rule.
+standalone chips are most likely better represented as GPIOs, ideally using a
+common scheme as described below.
Hardware blocks typically receive a reset signal. This signal is generated by
a reset provider (e.g. power management or clock module) and received by a
@@ -56,6 +56,20 @@ reset-names: List of reset signal name strings sorted in the same order as
the resets property. Consumers drivers will use reset-names to
match reset signal names with reset specifiers.
+= GPIO Reset consumers =
+
+For the common case of reset lines controlled by GPIOs, the GPIO binding
+documented in devicetree/bindings/gpio/gpio.txt should be used:
+
+Required properties:
+reset-gpios or Reset GPIO using standard GPIO bindings,
+<name>-reset-gpios: optionally named to specify the reset line
+
+Optional properties:
+reset-boot-asserted or Boolean. If set, the corresponding reset is
+<name>-reset-boot-asserted: initially asserted and should be kept that way
+ until released by the driver.
+
For example:
device {
@@ -65,6 +79,14 @@ For example:
This represents a device with a single reset signal named "reset".
+ device2 {
+ reset-gpios = <&gpio3 15 GPIO_ACTIVE_LOW>;
+ reset-boot-asserted;
+ };
+
+This represents a device with a single reset signal, controlled
+by an active-low GPIO, which is initally kept in reset.
+
bus {
resets = <&rst 10> <&rst 11> <&rst 12> <&rst 11>;
reset-names = "i2s1", "i2s2", "dma", "mixer";
--
1.9.1
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