Re: [PATCH v2 2/2] dt-bindings: Document the Synopsys GPIO via CREG bindings
From: Rob Herring <robh@kernel.org>
Date: 2018-08-29 01:02:34
Also in:
linux-gpio, lkml
On Tue, Aug 28, 2018 at 02:27:21PM +0300, Eugeniy Paltsev wrote:
quoted hunk ↗ jump to hunk
This patch adds documentation of device tree bindings for the Synopsys GPIO via CREG driver. Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> --- .../devicetree/bindings/gpio/snps,creg-gpio.txt | 49 ++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/snps,creg-gpio.txtdiff --git a/Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt b/Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt new file mode 100644 index 000000000000..eb022d44ccda --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt@@ -0,0 +1,49 @@ +GPIO via CREG (Control REGisers) driver
REGisters? Bindings don't describe drivers.
+ +This is is single-register MMIO GPIO driver to control such strangely mapped +outputs: + +31 11 8 7 5 0 < bit number +| | | | | | +[ not used | gpio-1 | shift-1 | gpio-0 | shift-0 ] < 32 bit MMIO register + ^ ^ + | | + | write 0x2 == set output to "1" (on) + | write 0x3 == set output to "0" (off) + | + write 0x1 == set output to "1" (on) + write 0x4 == set output to "0" (off)
What kind of crazy h/w designer designed this?
+Required properties: +- compatible : "snps,creg-gpio" +- reg : Exactly one register range with length 0x4. +- #gpio-cells : Should be one - the pin number. +- gpio-controller : Marks the device node as a GPIO controller. +- snps,ngpios: Number of GPIO pins. +- snps,bit-per-line: Number of bits per each gpio line (see picture). + Array the size of "snps,ngpios" +- snps,shift: Shift (in bits) of the each GPIO field from the previous one in + register (see picture). Array the size of "snps,ngpios" +- snps,on-val: Value should be set in corresponding field to set + output to "1" (see picture). Array the size of "snps,ngpios" +- snps,off-val: Value should be set in corresponding field to set + output to "0" (see picture). Array the size of "snps,ngpios"
Convince me we need to parameterize all this. We try to avoid describing h/w like this.
+
+Optional properties:
+- snps,default-val: default output field values. Array the size of "snps,ngpios"
+
+Example (see picture):
+
+gpio: gpio@f00014b0 {
+ compatible = "snps,creg-gpio";
+ reg = <0xf00014b0 0x4>;
+ gpio-controller;
+ #gpio-cells = <1>;
+ snps,ngpios = <2>;
+ snps,shift = <5 1>;
+ snps,bit-per-line = <2 3>;
+ snps,on-val = <2 1>;
+ snps,off-val = <3 4>;
+ snps,default-val = <2 1>;
+};
--
2.14.4