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[PATCH v2 1/9] dmaengine: st_fdma: Add STMicroelectronics FDMA DT binding documentation

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  [PATCH v2 1/9] dmaengine: st_fdma: Add STMicroelectronics FDMA DT binding documentation Peter Griffin <peter.griffin@linaro.org> - 2015-09-11 16:20 +0200
    Re: [PATCH v2 1/9] dmaengine: st_fdma: Add STMicroelectronics FDMA DT binding documentation Arnd Bergmann <arnd@arndb.de> - 2015-09-11 22:40 +0200
      Re: [PATCH v2 1/9] dmaengine: st_fdma: Add STMicroelectronics FDMA  DT binding documentation Peter Griffin <peter.griffin@linaro.org> - 2015-09-12 14:10 +0200
        Re: [PATCH v2 1/9] dmaengine: st_fdma: Add STMicroelectronics FDMA  DT binding documentation Lee Jones <lee.jones@linaro.org> - 2015-09-14 10:20 +0200

#1222872 — [PATCH v2 1/9] dmaengine: st_fdma: Add STMicroelectronics FDMA DT binding documentation

This patch adds the DT binding documentation for the FDMA constroller
found on STi based chipsets from STMicroelectronics.

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
---
 Documentation/devicetree/bindings/dma/st_fdma.txt | 78 +++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/st_fdma.txt

diff --git a/Documentation/devicetree/bindings/dma/st_fdma.txt b/Documentation/devicetree/bindings/dma/st_fdma.txt
new file mode 100644
index 0000000..c24b8d7
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/st_fdma.txt
@@ -0,0 +1,78 @@
+* STMicroelectronics Flexible Direct Memory Access Device Tree bindings
+
+The FDMA is a general-purpose direct memory access controller capable of
+supporting 16 independent DMA channels. It accepts up to 32 DMA requests.
+The FDMA is based on a Slim processor which require a firmware.
+
+* FDMA Controller
+
+Required properties:
+- compatible	: Should be "st,stih407-fdma-mpe31"
+- reg		: Should contain DMA registers location and length
+- interrupts	: Should contain one interrupt shared by all channels
+- dma-channels	: Number of channels supported by the controller
+- #dma-cells	: Must be <3>. See DMA client section below
+- st,fdma-id	: Must contain fdma controller number
+- clocks	: Must contain an entry for each name in clock-names
+- clock-names	: Must contain "fdma_slim, fdma_hi, fdma_low, fdma_ic" entries
+See: Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+
+Example:
+
+	fdma1: fdma-app@8e40000 {
+		compatible = "st,stih407-fdma-mpe31";
+		reg = <0x8e40000 0x20000>;
+		interrupts = <GIC_SPI 7 IRQ_TYPE_NONE>;
+		dma-channels = <16>;
+		#dma-cells = <3>;
+		st,fdma-id = <0>;
+		clocks = <&CLK_S_C0_FLEXGEN CLK_FDMA>,
+			 <&CLK_S_C0_FLEXGEN CLK_TX_ICN_DMU>,
+			 <&CLK_S_C0_FLEXGEN CLK_TX_ICN_DMU>,
+			 <&CLK_S_C0_FLEXGEN CLK_EXT2F_A9>;
+		clock-names = "fdma_slim",
+			      "fdma_hi",
+			      "fdma_low",
+			      "fdma_ic";
+		};
+
+* DMA client
+
+Required properties:
+- dmas: Comma separated list of dma channel requests
+- dma-names: Names of the aforementioned requested channels
+
+Each dmas request consists of 4 cells:
+1. A phandle pointing to the FDMA controller
+2. The request line number
+3. A 32bit mask specifying (see include/linux/platform_data/dma-st-fdma.h)
+ -bit 2-0: Holdoff value, dreq will be masked for
+	0x0: 0-0.5us
+	0x1: 0.5-1us
+	0x2: 1-1.5us
+ -bit 17: data swap
+	0x0: disabled
+	0x1: enabled
+ -bit 21: Increment Address
+	0x0: no address increment between transfers
+	0x1: increment address between transfers
+ -bit 22: 2 STBus Initiator Coprocessor interface
+	0x0: high priority port
+	0x1: low priority port
+4. transfers type
+ 0 free running
+ 1 paced
+
+Example:
+
+	snd_uni_player2: snd-uni-player@2 {
+		compatible = "st,snd_uni_player";
+		status = "okay";
+		reg = <0x8D82000  0x158>;
+		interrupts = <GIC_SPI 86 IRQ_TYPE_NONE>;
+		version = <5>;
+		dmas = <&fdma0 4 0 1>;
+		dma-names = "tx";
+		description = "Uni Player #2 (DAC)";
+	};
-- 
1.9.1

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#1223092

On Friday 11 September 2015 15:14:23 Peter Griffin wrote:
> +- st,fdma-id	: Must contain fdma controller number

What for?
> +Example:
> +
> +	fdma1: fdma-app@8e40000 {

The name should be "dma-controller", not "fdma-app".

> +Example:
> +
> +	snd_uni_player2: snd-uni-player@2 {
> +		compatible = "st,snd_uni_player";

Maybe change the compatible string to "st,snd-uni-player"?

The string you use here would not be acceptable for a binding.

	Arnd
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#1223393 — Re: [PATCH v2 1/9] dmaengine: st_fdma: Add STMicroelectronics FDMA DT binding documentation

Hi Arnd,

On Fri, 11 Sep 2015, Arnd Bergmann wrote:

> On Friday 11 September 2015 15:14:23 Peter Griffin wrote:
> > +- st,fdma-id	: Must contain fdma controller number
> 
> What for?

It is used by the driver to generate a unique firmware name.
Basically we need to know which controller instance we
are as each controller has a different firmware which needs
to be loaded.

Rob did say that having a index type property is undesirable
over here, see my reply at the bottom
http://www.spinics.net/lists/devicetree/msg92529.html.

However I can't think of any other useful properties we could add
to derive this information.

> > +Example:
> > +
> > +	fdma1: fdma-app@8e40000 {
> 
> The name should be "dma-controller", not "fdma-app".

Ok will fix in v3

> 
> > +Example:
> > +
> > +	snd_uni_player2: snd-uni-player@2 {
> > +		compatible = "st,snd_uni_player";
> 
> Maybe change the compatible string to "st,snd-uni-player"?

Just checking the upstream driver which got merged for v4.3
and the compatible has changed to "st,sti-uni-player" so I
can update the DT doc example to use this in v3.

> 
> The string you use here would not be acceptable for a binding.

Presumably it is the use of "underscores" in the compatible which
is not allowed? Is that correct?

regards,

Peter.


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#1223913 — Re: [PATCH v2 1/9] dmaengine: st_fdma: Add STMicroelectronics FDMA DT binding documentation

On Sat, 12 Sep 2015, Peter Griffin wrote:

> Hi Arnd,
> 
> On Fri, 11 Sep 2015, Arnd Bergmann wrote:
> 
> > On Friday 11 September 2015 15:14:23 Peter Griffin wrote:
> > > +- st,fdma-id	: Must contain fdma controller number
> > 
> > What for?
> 
> It is used by the driver to generate a unique firmware name.
> Basically we need to know which controller instance we
> are as each controller has a different firmware which needs
> to be loaded.
> 
> Rob did say that having a index type property is undesirable
> over here, see my reply at the bottom
> http://www.spinics.net/lists/devicetree/msg92529.html.
> 
> However I can't think of any other useful properties we could add
> to derive this information.

I wouldn't use a property at all.  Why not use the compatible string?

Who chooses the naming scheme of the firmware binary?

Is there any reason they can't be:

  fdma_STiH407_audio.elf
  fdma_STiH407_app.elf
  fdma_STiH407_free_running.elf

Then you can have a different compatible for each:

  compatible = "st,stih407-fdma-mpe31-audio";
  compatible = "st,stih407-fdma-mpe31-app";
  compatible = "st,stih407-fdma-mpe31-free-running";

[...]

> > > +Example:
> > > +
> > > +	snd_uni_player2: snd-uni-player@2 {
> > > +		compatible = "st,snd_uni_player";
> > 
> > Maybe change the compatible string to "st,snd-uni-player"?
> 
> Just checking the upstream driver which got merged for v4.3
> and the compatible has changed to "st,sti-uni-player" so I
> can update the DT doc example to use this in v3.
> 
> > 
> > The string you use here would not be acceptable for a binding.
> 
> Presumably it is the use of "underscores" in the compatible which
> is not allowed? Is that correct?

Yes.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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