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gpio: dt-bindings: add ibm,ppc4xx-gpio binding

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This patch adds binding information for IBM/AMCC/APM GPIO
Controllers of the PowerPC 4XX series and compatible SoCs.

The "PowerPC 405EP Embedded Processor Data Sheet" has the
following to say about the GPIO controllers: "

 - Controller functions and GPIO registers are programmed
   and accessed via memory-mapped OPB bus master accesses

 - All GPIOs are pin-shared with other functions. DCRs control
   whether a particular pin that has GPIO capabilities acts
   as a GPIO or is used for another purpose.

 - Each GPIO outputs is separately programmable to emulate
   an open-drain driver (i.e. drives to zero, threestated if
   output bit is 1)

"
The ppc4xx_gpio.c driver is part of the platform/sysdev drivers
in arch/powerpc/sysdev.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
This commit is contained in:
Christian Lamparter 2016-05-12 00:07:48 +02:00 committed by Rob Herring
parent 27f4ec1443
commit 9a0d440427
1 changed files with 24 additions and 0 deletions
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24
Documentation/devicetree/bindings/gpio/ibm,ppc4xx-gpio.txt Normal file
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* IBM/AMCC/APM GPIO Controller for PowerPC 4XX series and compatible SoCs
All GPIOs are pin-shared with other functions. DCRs control whether a
particular pin that has GPIO capabilities acts as a GPIO or is used for
another purpose. GPIO outputs are separately programmable to emulate
an open-drain driver.
Required properties:
- compatible: must be "ibm,ppc4xx-gpio"
- reg: address and length of the register set for the device
- #gpio-cells: must be set to 2. The first cell is the pin number
and the second cell is used to specify the gpio polarity:
0 = active high
1 = active low
- gpio-controller: marks the device node as a gpio controller.
Example:
GPIO0: gpio@ef600b00 {
compatible = "ibm,ppc4xx-gpio";
reg = <0xef600b00 0x00000048>;
#gpio-cells = <2>;
gpio-controller;
};