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[PATCH V3 3/6] dt/bindings: Add bindings for Tegra GMI controller

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  [PATCH V3 3/6] dt/bindings: Add bindings for Tegra GMI controller Mirza Krak <mirza.krak@gmail.com> - 2016-10-27 16:20 +0200
    Re: [PATCH V3 3/6] dt/bindings: Add bindings for Tegra GMI controller Rob Herring <robh@kernel.org> - 2016-10-31 06:40 +0100

#1510247 — [PATCH V3 3/6] dt/bindings: Add bindings for Tegra GMI controller

From: Mirza Krak <mirza.krak@gmail.com>

Document the devicetree bindings for the Generic Memory Interface (GMI)
bus driver found on Tegra SOCs.

Signed-off-by: Mirza Krak <mirza.krak@gmail.com>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-on: Colibri T20/T30 on EvalBoard V3.x and GMI-Memory Board
---

Changes in v2:
- Updated examples and some information based on comments from Jon Hunter.

Changes in v3:
- Updates ranges description based on comments from Rob Herring

 .../devicetree/bindings/bus/nvidia,tegra20-gmi.txt | 132 +++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt

diff --git a/Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt b/Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt
new file mode 100644
index 0000000..49bda2f
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt
@@ -0,0 +1,132 @@
+Device tree bindings for NVIDIA Tegra Generic Memory Interface bus
+
+The Generic Memory Interface bus enables memory transfers between internal and
+external memory. Can be used to attach various high speed devices such as
+synchronous/asynchronous NOR, FPGA, UARTS and more.
+
+The actual devices are instantiated from the child nodes of a GMI node.
+
+Required properties:
+ - compatible : Should contain one of the following:
+        For Tegra20 must contain "nvidia,tegra20-gmi".
+        For Tegra30 must contain "nvidia,tegra30-gmi".
+ - reg: Should contain GMI controller registers location and length.
+ - clocks: Must contain an entry for each entry in clock-names.
+ - clock-names: Must include the following entries: "gmi"
+ - resets : Must contain an entry for each entry in reset-names.
+ - reset-names : Must include the following entries: "gmi"
+ - #address-cells: The number of cells used to represent physical base
+   addresses in the GMI address space. Should be 2.
+ - #size-cells: The number of cells used to represent the size of an address
+   range in the GMI address space. Should be 1.
+ - ranges: Must be set up to reflect the memory layout with three integer values
+   for each chip-select line in use (only one entry is supported, see below
+   comments):
+   <cs-number> <offset> <physical address of mapping> <size>
+
+Note that the GMI controller does not have any internal chip-select address
+decoding, because of that chip-selects either need to be managed via software
+or by employing external chip-select decoding logic.
+
+If external chip-select logic is used to support multiple devices it is assumed
+that the devices use the same timing and so are probably the same type. It also
+assumes that they can fit in the 256MB address range. In this case only one
+child device is supported which represents the active chip-select line, see
+examples for more insight.
+
+The chip-select number is decoded from the child nodes second address cell of
+'ranges' property, if 'ranges' property is not present or empty chip-select will
+then be decoded from the first cell of the 'reg' property.
+
+Optional child cs node properties:
+
+ - nvidia,snor-data-width-32bit: Use 32bit data-bus, default is 16bit.
+ - nvidia,snor-mux-mode: Enable address/data MUX mode.
+ - nvidia,snor-rdy-active-before-data: Assert RDY signal one cycle before data.
+   If omitted it will be asserted with data.
+ - nvidia,snor-rdy-inv: RDY signal is active high
+ - nvidia,snor-adv-inv: ADV signal is active high
+ - nvidia,snor-oe-inv: WE/OE signal is active high
+ - nvidia,snor-cs-inv: CS signal is active high
+
+  Note that there is some special handling for the timing values.
+  From Tegra TRM:
+  Programming 0 means 1 clock cycle: actual cycle = programmed cycle + 1
+
+ - nvidia,snor-muxed-width: Number of cycles MUX address/data asserted on the
+   bus. Valid values are 0-15, default is 1
+ - nvidia,snor-hold-width: Number of cycles CE stays asserted after the
+   de-assertion of WR_N (in case of SLAVE/MASTER Request) or OE_N
+   (in case of MASTER Request). Valid values are 0-15, default is 1
+ - nvidia,snor-adv-width: Number of cycles during which ADV stays asserted.
+   Valid values are 0-15, default is 1.
+ - nvidia,snor-ce-width: Number of cycles before CE is asserted.
+   Valid values are 0-15, default is 4
+ - nvidia,snor-we-width: Number of cycles during which WE stays asserted.
+   Valid values are 0-15, default is 1
+ - nvidia,snor-oe-width: Number of cycles during which OE stays asserted.
+   Valid values are 0-255, default is 1
+ - nvidia,snor-wait-width: Number of cycles before READY is asserted.
+   Valid values are 0-255, default is 3
+
+Example with two SJA1000 CAN controllers connected to the GMI bus. We wrap the
+controllers with a simple-bus node since they are all connected to the same
+chip-select (CS4), in this example external address decoding is provided:
+
+gmi@70090000 {
+	compatible = "nvidia,tegra20-gmi";
+	reg = <0x70009000 0x1000>;
+	#address-cells = <2>;
+	#size-cells = <1>;
+	clocks = <&tegra_car TEGRA20_CLK_NOR>;
+	clock-names = "gmi";
+	resets = <&tegra_car 42>;
+	reset-names = "gmi";
+	ranges = <4 0 0xd0000000 0xfffffff>;
+
+	status = "okay";
+
+	bus@4,0 {
+		compatible = "simple-bus";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 4 0 0x40100>;
+
+		nvidia,snor-mux-mode;
+		nvidia,snor-adv-inv;
+
+		can@0 {
+			reg = <0 0x100>;
+			...
+		};
+
+		can@40000 {
+			reg = <0x40000 0x100>;
+			...
+		};
+	};
+};
+
+Example with one SJA1000 CAN controller connected to the GMI bus
+on CS4:
+
+gmi@70090000 {
+	compatible = "nvidia,tegra20-gmi";
+	reg = <0x70009000 0x1000>;
+	#address-cells = <2>;
+	#size-cells = <1>;
+	clocks = <&tegra_car TEGRA20_CLK_NOR>;
+	clock-names = "gmi";
+	resets = <&tegra_car 42>;
+	reset-names = "gmi";
+	ranges = <4 0 0xd0000000 0xfffffff>;
+
+	status = "okay";
+
+	can@4,0 {
+		reg = <4 0 0x100>;
+		nvidia,snor-mux-mode;
+		nvidia,snor-adv-inv;
+		...
+	};
+};
--
2.1.4

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#1512331

On Thu, Oct 27, 2016 at 04:01:09PM +0200, Mirza Krak wrote:
> From: Mirza Krak <mirza.krak@gmail.com>
> 
> Document the devicetree bindings for the Generic Memory Interface (GMI)
> bus driver found on Tegra SOCs.
> 
> Signed-off-by: Mirza Krak <mirza.krak@gmail.com>
> Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
> Tested-on: Colibri T20/T30 on EvalBoard V3.x and GMI-Memory Board
> ---
> 
> Changes in v2:
> - Updated examples and some information based on comments from Jon Hunter.
> 
> Changes in v3:
> - Updates ranges description based on comments from Rob Herring
> 
>  .../devicetree/bindings/bus/nvidia,tegra20-gmi.txt | 132 +++++++++++++++++++++
>  1 file changed, 132 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt
> 
> diff --git a/Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt b/Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt
> new file mode 100644
> index 0000000..49bda2f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt
> @@ -0,0 +1,132 @@
> +Device tree bindings for NVIDIA Tegra Generic Memory Interface bus
> +
> +The Generic Memory Interface bus enables memory transfers between internal and
> +external memory. Can be used to attach various high speed devices such as
> +synchronous/asynchronous NOR, FPGA, UARTS and more.
> +
> +The actual devices are instantiated from the child nodes of a GMI node.
> +
> +Required properties:
> + - compatible : Should contain one of the following:
> +        For Tegra20 must contain "nvidia,tegra20-gmi".
> +        For Tegra30 must contain "nvidia,tegra30-gmi".
> + - reg: Should contain GMI controller registers location and length.
> + - clocks: Must contain an entry for each entry in clock-names.
> + - clock-names: Must include the following entries: "gmi"
> + - resets : Must contain an entry for each entry in reset-names.
> + - reset-names : Must include the following entries: "gmi"
> + - #address-cells: The number of cells used to represent physical base
> +   addresses in the GMI address space. Should be 2.
> + - #size-cells: The number of cells used to represent the size of an address
> +   range in the GMI address space. Should be 1.
> + - ranges: Must be set up to reflect the memory layout with three integer values
> +   for each chip-select line in use (only one entry is supported, see below
> +   comments):
> +   <cs-number> <offset> <physical address of mapping> <size>
> +
> +Note that the GMI controller does not have any internal chip-select address
> +decoding, because of that chip-selects either need to be managed via software
> +or by employing external chip-select decoding logic.
> +
> +If external chip-select logic is used to support multiple devices it is assumed
> +that the devices use the same timing and so are probably the same type. It also
> +assumes that they can fit in the 256MB address range. In this case only one
> +child device is supported which represents the active chip-select line, see
> +examples for more insight.
> +
> +The chip-select number is decoded from the child nodes second address cell of
> +'ranges' property, if 'ranges' property is not present or empty chip-select will
> +then be decoded from the first cell of the 'reg' property.
> +
> +Optional child cs node properties:
> +
> + - nvidia,snor-data-width-32bit: Use 32bit data-bus, default is 16bit.
> + - nvidia,snor-mux-mode: Enable address/data MUX mode.
> + - nvidia,snor-rdy-active-before-data: Assert RDY signal one cycle before data.
> +   If omitted it will be asserted with data.
> + - nvidia,snor-rdy-inv: RDY signal is active high
> + - nvidia,snor-adv-inv: ADV signal is active high
> + - nvidia,snor-oe-inv: WE/OE signal is active high
> + - nvidia,snor-cs-inv: CS signal is active high

Inverted is meaningless unless I know what not inverted state is. Name 
the properties using "active high".

With that,

Acked-by: Rob Herring <robh@kernel.org>

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