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| -rw-r--r-- | Documentation/devicetree/bindings/bus/mvebu-mbus.txt | 276 |
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diff --git a/Documentation/devicetree/bindings/bus/mvebu-mbus.txt b/Documentation/devicetree/bindings/bus/mvebu-mbus.txt new file mode 100644 index 00000000000..7586fb68c07 --- /dev/null +++ b/Documentation/devicetree/bindings/bus/mvebu-mbus.txt @@ -0,0 +1,276 @@ + +* Marvell MBus + +Required properties: + +- compatible: Should be set to one of the following: + marvell,armada370-mbus + marvell,armadaxp-mbus + marvell,armada370-mbus + marvell,armadaxp-mbus + marvell,kirkwood-mbus + marvell,dove-mbus + marvell,orion5x-88f5281-mbus + marvell,orion5x-88f5182-mbus + marvell,orion5x-88f5181-mbus + marvell,orion5x-88f6183-mbus + marvell,mv78xx0-mbus + +- address-cells: Must be '2'. The first cell for the MBus ID encoding, + the second cell for the address offset within the window. + +- size-cells: Must be '1'. + +- ranges: Must be set up to provide a proper translation for each child. + See the examples below. + +- controller: Contains a single phandle referring to the MBus controller + node. This allows to specify the node that contains the + registers that control the MBus, which is typically contained + within the internal register window (see below). + +Optional properties: + +- pcie-mem-aperture: This optional property contains the aperture for + the memory region of the PCIe driver. + If it's defined, it must encode the base address and + size for the address decoding windows allocated for + the PCIe memory region. + +- pcie-io-aperture: Just as explained for the above property, this + optional property contains the aperture for the + I/O region of the PCIe driver. + +* Marvell MBus controller + +Required properties: + +- compatible: Should be set to "marvell,mbus-controller". + +- reg: Device's register space. + Two entries are expected (see the examples below): + the first one controls the devices decoding window and + the second one controls the SDRAM decoding window. + +Example: + + soc { + compatible = "marvell,armada370-mbus", "simple-bus"; + #address-cells = <2>; + #size-cells = <1>; + controller = <&mbusc>; + pcie-mem-aperture = <0xe0000000 0x8000000>; + pcie-io-aperture = <0xe8000000 0x100000>; + + internal-regs { + compatible = "simple-bus"; + + mbusc: mbus-controller@20000 { + compatible = "marvell,mbus-controller"; + reg = <0x20000 0x100>, <0x20180 0x20>; + }; + + /* more children ...*/ + }; + }; + +** MBus address decoding window specification + +The MBus children address space is comprised of two cells: the first one for +the window ID and the second one for the offset within the window. +In order to allow to describe valid and non-valid window entries, the +following encoding is used: + + 0xSIAA0000 0x00oooooo + +Where: + + S = 0x0 for a MBus valid window + S = 0xf for a non-valid window (see below) + +If S = 0x0, then: + + I = 4-bit window target ID + AA = windpw attribute + +If S = 0xf, then: + + I = don't care + AA = 1 for internal register + +Following the above encoding, for each ranges entry for a MBus valid window +(S = 0x0), an address decoding window is allocated. On the other side, +entries for translation that do not correspond to valid windows (S = 0xf) +are skipped. + + soc { + compatible = "marvell,armada370-mbus", "simple-bus"; + #address-cells = <2>; + #size-cells = <1>; + controller = <&mbusc>; + + ranges = <0xf0010000 0 0 0xd0000000 0x100000 + 0x01e00000 0 0 0xfff00000 0x100000>; + + bootrom { + compatible = "marvell,bootrom"; + reg = <0x01e00000 0 0x100000>; + }; + + /* other children */ + ... + + internal-regs { + compatible = "simple-bus"; + ranges = <0 0xf0010000 0 0x100000>; + + mbusc: mbus-controller@20000 { + compatible = "marvell,mbus-controller"; + reg = <0x20000 0x100>, <0x20180 0x20>; + }; + + /* more children ...*/ + }; + }; + +In the shown example, the translation entry in the 'ranges' property is what +makes the MBus driver create a static decoding window for the corresponding +given child device. Note that the binding does not require child nodes to be +present. Of course, child nodes are needed to probe the devices. + +Since each window is identified by its target ID and attribute ID there's +a special macro that can be use to simplify the translation entries: + +#define MBUS_ID(target,attributes) (((target) << 24) | ((attributes) << 16)) + +Using this macro, the above example would be: + + soc { + compatible = "marvell,armada370-mbus", "simple-bus"; + #address-cells = <2>; + #size-cells = <1>; + controller = <&mbusc>; + + ranges = < MBUS_ID(0xf0, 0x01) 0 0 0xd0000000 0x100000 + MBUS_ID(0x01, 0xe0) 0 0 0xfff00000 0x100000>; + + bootrom { + compatible = "marvell,bootrom"; + reg = <MBUS_ID(0x01, 0xe0) 0 0x100000>; + }; + + /* other children */ + ... + + internal-regs { + compatible = "simple-bus"; + #address-cells = <1>; + #size-cells = <1>; + ranges = <0 MBUS_ID(0xf0, 0x01) 0 0x100000>; + + mbusc: mbus-controller@20000 { + compatible = "marvell,mbus-controller"; + reg = <0x20000 0x100>, <0x20180 0x20>; + }; + + /* other children */ + ... + }; + }; + + +** About the window base address + +Remember the MBus controller allows a great deal of flexibility for choosing +the decoding window base address. When planning the device tree layout it's +possible to choose any address as the base address, provided of course there's +a region large enough available, and with the required alignment. + +Yet in other words: there's nothing preventing us from setting a base address +of 0xf0000000, or 0xd0000000 for the NOR device shown above, if such region is +unused. + +** Window allocation policy + +The mbus-node ranges property defines a set of mbus windows that are expected +to be set by the operating system and that are guaranteed to be free of overlaps +with one another or with the system memory ranges. + +Each entry in the property refers to exactly one window. If the operating system +choses to use a different set of mbus windows, it must ensure that any address +translations performed from downstream devices are adapted accordingly. + +The operating system may insert additional mbus windows that do not conflict +with the ones listed in the ranges, e.g. for mapping PCIe devices. +As a special case, the internal register window must be set up by the boot +loader at the address listed in the ranges property, since access to that region +is needed to set up the other windows. + +** Example + +See the example below, where a more complete device tree is shown: + + soc { + compatible = "marvell,armadaxp-mbus", "simple-bus"; + controller = <&mbusc>; + + ranges = <MBUS_ID(0xf0, 0x01) 0 0 0xd0000000 0x100000 /* internal-regs */ + MBUS_ID(0x01, 0x1d) 0 0 0xfff00000 0x100000 + MBUS_ID(0x01, 0x2f) 0 0 0xf0000000 0x8000000>; + + bootrom { + compatible = "marvell,bootrom"; + reg = <MBUS_ID(0x01, 0x1d) 0 0x100000>; + }; + + devbus-bootcs { + status = "okay"; + ranges = <0 MBUS_ID(0x01, 0x2f) 0 0x8000000>; + + /* NOR */ + nor { + compatible = "cfi-flash"; + reg = <0 0x8000000>; + bank-width = <2>; + }; + }; + + pcie-controller { + compatible = "marvell,armada-xp-pcie"; + status = "okay"; + device_type = "pci"; + + #address-cells = <3>; + #size-cells = <2>; + + ranges = + <0x82000000 0 0x40000 MBUS_ID(0xf0, 0x01) 0x40000 0 0x00002000 /* Port 0.0 registers */ + 0x82000000 0 0x42000 MBUS_ID(0xf0, 0x01) 0x42000 0 0x00002000 /* Port 2.0 registers */ + 0x82000000 0 0x44000 MBUS_ID(0xf0, 0x01) 0x44000 0 0x00002000 /* Port 0.1 registers */ + 0x82000000 0 0x48000 MBUS_ID(0xf0, 0x01) 0x48000 0 0x00002000 /* Port 0.2 registers */ + 0x82000000 0 0x4c000 MBUS_ID(0xf0, 0x01) 0x4c000 0 0x00002000 /* Port 0.3 registers */ + 0x82000800 0 0xe0000000 MBUS_ID(0x04, 0xe8) 0xe0000000 0 0x08000000 /* Port 0.0 MEM */ + 0x81000800 0 0 MBUS_ID(0x04, 0xe0) 0xe8000000 0 0x00100000 /* Port 0.0 IO */>; + + + pcie@1,0 { + /* Port 0, Lane 0 */ + status = "okay"; + }; + }; + + internal-regs { + compatible = "simple-bus"; + #address-cells = <1>; + #size-cells = <1>; + ranges = <0 MBUS_ID(0xf0, 0x01) 0 0x100000>; + + mbusc: mbus-controller@20000 { + reg = <0x20000 0x100>, <0x20180 0x20>; + }; + + interrupt-controller@20000 { + reg = <0x20a00 0x2d0>, <0x21070 0x58>; + }; + }; + }; |