[PATCH v3 1/2] ASoC: atmel-i2s: add DT bindings for I2S controller

[Cyrille Pitchen]

This patch adds DT bindings for the new Atmel I2S controller embedded
inside sama5d2x SoCs.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
---
 .../devicetree/bindings/sound/atmel-i2s.txt        | 87 ++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/sound/atmel-i2s.txt

diff --git a/Documentation/devicetree/bindings/sound/atmel-i2s.txt b/Documentation/devicetree/bindings/sound/atmel-i2s.txt
new file mode 100644
index 000000000000..25dcb32314bf
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/atmel-i2s.txt
@@ -0,0 +1,87 @@
+* Atmel I2S controller
+
+Required properties:
+- compatible:     Should be "atmel,sama5d2-i2s".
+- reg:            Should be the physical base address of the controller and the
+                  length of memory mapped region.
+- interrupts:     Should contain the interrupt for the controller.
+- dmas:           Should be a list of pairs of DMA controller phandle and flags.
+- dma-names:      Should be a list of DMA channel name among "rx", "tx" or
+                  "rx-tx".
+- clocks:         Should be a list of phandles of clocks used by the controller
+                  (1).
+- clock-names:    Should be a list matching the clocks phandles list:
+                  - "pclk" (peripheral clock) Required.
+                  - "gclk" (generated clock) Optional (1).
+                  - "aclk" (Audio PLL clock) Optional (1).
+
+Optional properties:
+- pinctrl-0:      Should specify pin control groups used for this controller.
+- princtrl-names: Should contain only one value - "default".
+
+
+(1) : Only the peripheral clock is required. The generated clock and the Audio
+      PLL clock are optional and should only be set together.
+
+Example:
+
+	i2s@f8050000 {
+		compatible = "atmel,sama5d2-i2s";
+		reg = <0xf8050000 0x300>;
+		interrupts = <54 IRQ_TYPE_LEVEL_HIGH 7>;
+		dmas = <&dma0
+			(AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1) |
+			 AT91_XDMAC_DT_PERID(31))>,
+		       <&dma0
+			(AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1) |
+			 AT91_XDMAC_DT_PERID(32))>;
+		dma-names = "tx", "rx";
+		clocks = <&i2s0_clk>, <&i2s0_gclk>, <&audio_pll_pmc>;
+		clock-names = "pclk", "gclk", "aclk";
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_i2s0_default>;
+	};
+
+
+sama5d2 SoCs only:
+
+When the I2S controller is configured as a master, it generates the master,
+bitrate and frame clocks from a PMC input clock. This PMC input clock can be
+either the I2S peripheral clock or the I2S generated clock.
+The generated clock can reach higher frequencies and is more suited for audio
+applications hence should be preferred to the peripheral clock.
+The I2SCLKSEL register of the Special Function Register (SFR) is used to select
+the relevant PMC input clock: bit0 selects the input clock for I2S controller 0
+whereas bit1 selects the input clock for I2S controller 1.
+
+Aliases are used in the device-tree to retrieve the index of each I2S controller
+so the right bit can be updated in the I2SCLKSEL register.
+
+Finally, the SFR itself is handled by the generic syscon driver.
+Its "compatible" DT property must contain the "atmel,sama5d2-sfr" string so the
+I2S controller driver (and likely other drivers) can find the SFR node when
+needed.
+
+aliases {
+	i2s0 = &i2s0;
+	i2s1 = &i2s1;
+};
+
+...
+
+ahb {
+	apb {
+		sfr@f8030000 {
+			compatible = "atmel,sama5d2-sfr", "syscon";
+			reg = <0xf8030000 0x98>;
+		};
+
+		i2s0: i2s@f8050000 {
+			...
+		};
+
+		i2s1: i2s@fc04c000 {
+			...
+		};
+	};
+};
-- 
1.8.2.2