Add binding document for the Pulse Density Modulator (PDM) DAC present on the Pistachio SOC.
Signed-off-by: Naidu Tellapati <[email protected]> Signed-off-by: Arul Ramasamy <[email protected]> --- Documentation/devicetree/bindings/misc/img-pdm.txt | 54 ++++++++++++++++++++ 1 files changed, 54 insertions(+), 0 deletions(-) create mode 100644 Documentation/devicetree/bindings/misc/img-pdm.txt diff --git a/Documentation/devicetree/bindings/misc/img-pdm.txt b/Documentation/devicetree/bindings/misc/img-pdm.txt new file mode 100644 index 0000000..730d38a --- /dev/null +++ b/Documentation/devicetree/bindings/misc/img-pdm.txt @@ -0,0 +1,54 @@ +*Imagination Technologies Pulse Density Modulator (PDM) DAC. + +Required properties: + - compatible: Must be "img,pistachio-pdm" + - clocks: Must contain an entry for each entry in clock-names. + - clock-names: Must include the following entry: + Required elements: "pdm" + - img,cr-periph: Must contain a phandle to the peripheral control + syscon node which contains PDM control registers. + - #pdm-cells: Must be 2. + - The first cell is the PDM channel number (valid values: 0, 1, 2, 3) + - The second cell is 12-bit pulse-in value + +Specifying PDM information for devices +====================================== + +1. PDM User nodes + +PDM properties should be named "pdms". The exact meaning of each pdms property +is described above. + + pdm-specifier : array of #pdm-cells specifying the given PDM + (controller specific) + +The following example could be used to describe a PDM-based backlight device: + + pdm: pdm { + #pdm-cells = <2>; + }; + + [...] + + bl: backlight { + pdms = <&pdm 2 0>; + }; + +pdm-specifier typically encodes the chip-relative PDM channel number and the +12-bit pulse-in value. + +2. PDM Controller nodes + +PDM controller nodes must specify the number of cells used for the specifier +using the '#pdm-cells' property. + +An example PDM controller might look like this: + +Example: + pdm: pdm@18148000 { + compatible = "img,pistachio-pdm"; + clocks = <&pdm_clk>; + clk-names = "pdm"; + img,cr-periph = <&cr_periph>; + #pdm-cells = <2>; + }; -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-pwm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
