On Wed, 2016-08-24 at 15:37 +0200, Mirza Krak wrote:
> From: Mirza Krak <mirza.krak@xxxxxxxxx>
>
> Document the devicetree bindings for the Generic Memory Interface
> (GMI)
> bus driver found on Tegra SOCs.
>
> Signed-off-by: Mirza Krak <mirza.krak@xxxxxxxxx>
> ---
> Changes in v2:
> - Updated examples and some information based on comments from Jon
> Hunter.
>
> .../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..8c1e15f
> --- /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 1.
> + - #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> <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.
> +
> +Required child cs node properties:
> + - reg: First entry should contain the active chip-select number
> +
> +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 {
It's actually 70009000.
> + compatible = "nvidia,tegra20-gmi";
> + reg = <0x70009000 0x1000>;
> + #address-cells = <1>;
> + #size-cells = <1>;
> + clocks = <&tegra_car TEGRA20_CLK_NOR>;
> + clock-names = "gmi";
> + resets = <&tegra_car 42>;
> + reset-names = "gmi";
> + ranges = <4 0x48000000 0x7ffffff>;
> +
> + status = "disabled";
I guess in an example one could even set this to okay.
> +
> + bus@4 {
> + compatible = "simple-bus";
> + reg = <4>;
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges = <0 4 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 {
Same here.
> + compatible = "nvidia,tegra20-gmi";
> + reg = <0x70009000 0x1000>;
> + #address-cells = <1>;
> + #size-cells = <1>;
> + clocks = <&tegra_car TEGRA20_CLK_NOR>;
> + clock-names = "gmi";
> + resets = <&tegra_car 42>;
> + reset-names = "gmi";
> + ranges = <4 0x48000000 0x7ffffff>;
> +
> + status = "disabled";
Same here.
> +
> + can@4 {
> + reg = <4 0x100>;
> + ...
> + nvidia,snor-mux-mode;
> + nvidia,snor-adv-inv;
> + };
> +};
> --
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