On Thu, 31 Jan 2013 21:51:36 +0100, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > On Thu, Jan 31, 2013 at 4:58 PM, Lars Poeschel <larsi@xxxxxxxxxxxxxxxxx> wrote: > > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt > > @@ -0,0 +1,27 @@ > > +Microchip MCP2308/MCP23S08/MCP23017/MCP23S17 driver for > > +8-/16-bit I/O expander with serial interface (I2C/SPI) > > + > > +Required properties: > > +- compatible : Should be "mcp,mcp23s08-gpio", "mcp,mcp23s17-gpio", > > + "mcp,mcp23008-gpio" or "mcp,mcp23017-gpio" > > +- base : The first gpio number that should be assigned by this chip. > > No. We do not tie the global GPIO numbers into the device tree. > > In the DT GPIOs are referenced by ampersand <&gpio0 1 2> > notation referring to the instance, so as you realize DT itself > has no need for that number. > > Further it is not OS-neutral. > > You have to find another way to handle this in the driver code. > In worst case: use AUXDATA. Hi Lars, The trick is to declare the io expander to be a "gpio-controller" and use the #gpio-cells property to declare how many cells (32-bit numbers) are need to specify a single gpio line. Most gpio controllers use "gpio-cells=<2>"; The first cell is the *controller local* gpio number, and the second cell is used for flags. That way your gpio controller can be referenced by other nodes in the tree with a "gpios" property. You can find lots of examples of this in the tree. g. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
