doc: dt: add documentation for pl172 memory bindings

Add documentation for configuration and timing setup of
static memory devices on the ARM PL172 controller.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

diff --git a/Documentation/devicetree/bindings/memory-controllers/arm,pl172.txt b/Documentation/devicetree/bindings/memory-controllers/arm,pl172.txt
new file mode 100644 (file)
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+++ b/Documentation/devicetree/bindings/memory-controllers/arm,pl172.txt
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+* Device tree bindings for ARM PL172 MultiPort Memory Controller
+
+Required properties:
+
+- compatible:          "arm,pl172", "arm,primecell"
+
+- reg:                 Must contains offset/length value for controller.
+
+- #address-cells:      Must be 2. The partition number has to be encoded in the
+                       first address cell and it may accept values 0..N-1
+                       (N - total number of partitions). The second cell is the
+                       offset into the partition.
+
+- #size-cells:         Must be set to 1.
+
+- ranges:              Must contain one or more chip select memory regions.
+
+- clocks:              Must contain references to controller clocks.
+
+- clock-names:         Must contain "mpmcclk" and "apb_pclk".
+
+- clock-ranges:                Empty property indicating that child nodes can inherit
+                       named clocks. Required only if clock tree data present
+                       in device tree.
+                       See clock-bindings.txt
+
+Child chip-select (cs) nodes contain the memory devices nodes connected to
+such as NOR (e.g. cfi-flash) and NAND.
+
+Required child cs node properties:
+
+- #address-cells:      Must be 2.
+
+- #size-cells:         Must be 1.
+
+- ranges:              Empty property indicating that child nodes can inherit
+                       memory layout.
+
+- clock-ranges:                Empty property indicating that child nodes can inherit
+                       named clocks. Required only if clock tree data present
+                       in device tree.
+
+- mpmc,cs:             Chip select number. Indicates to the pl0172 driver
+                       which chipselect is used for accessing the memory.
+
+- mpmc,memory-width:   Width of the chip select memory. Must be equal to
+                       either 8, 16 or 32.
+
+Optional child cs node config properties:
+
+- mpmc,async-page-mode:        Enable asynchronous page mode.
+
+- mpmc,cs-active-high: Set chip select polarity to active high.
+
+- mpmc,byte-lane-low:  Set byte lane state to low.
+
+- mpmc,extended-wait:  Enable extended wait.
+
+- mpmc,buffer-enable:  Enable write buffer.
+
+- mpmc,write-protect:  Enable write protect.
+
+Optional child cs node timing properties:
+
+- mpmc,write-enable-delay:     Delay from chip select assertion to write
+                               enable (WE signal) in nano seconds.
+
+- mpmc,output-enable-delay:    Delay from chip select assertion to output
+                               enable (OE signal) in nano seconds.
+
+- mpmc,write-access-delay:     Delay from chip select assertion to write
+                               access in nano seconds.
+
+- mpmc,read-access-delay:      Delay from chip select assertion to read
+                               access in nano seconds.
+
+- mpmc,page-mode-read-delay:   Delay for asynchronous page mode sequential
+                               accesses in nano seconds.
+
+- mpmc,turn-round-delay:       Delay between access to memory banks in nano
+                               seconds.
+
+If any of the above timing parameters are absent, current parameter value will
+be taken from the corresponding HW reg.
+
+Example for pl172 with nor flash on chip select 0 shown below.
+
+emc: memory-controller@40005000 {
+       compatible = "arm,pl172", "arm,primecell";
+       reg = <0x40005000 0x1000>;
+       clocks = <&ccu1 CLK_CPU_EMCDIV>, <&ccu1 CLK_CPU_EMC>;
+       clock-names = "mpmcclk", "apb_pclk";
+       #address-cells = <2>;
+       #size-cells = <1>;
+       ranges = <0 0 0x1c000000 0x1000000
+                 1 0 0x1d000000 0x1000000
+                 2 0 0x1e000000 0x1000000
+                 3 0 0x1f000000 0x1000000>;
+
+       cs0 {
+               #address-cells = <2>;
+               #size-cells = <1>;
+               ranges;
+
+               mpmc,cs = <0>;
+               mpmc,memory-width = <16>;
+               mpmc,byte-lane-low;
+               mpmc,write-enable-delay = <0>;
+               mpmc,output-enable-delay = <0>;
+               mpmc,read-enable-delay = <70>;
+               mpmc,page-mode-read-delay = <70>;
+
+               flash@0,0 {
+                       compatible = "sst,sst39vf320", "cfi-flash";
+                       reg = <0 0 0x400000>;
+                       bank-width = <2>;
+                       #address-cells = <1>;
+                       #size-cells = <1>;
+                       partition@0 {
+                               label = "data";
+                               reg = <0 0x400000>;
+                       };
+               };
+       };
+};