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Diffstat (limited to 'Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt | 32 |
1 files changed, 27 insertions, 5 deletions
diff --git a/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt b/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt index 653c90c34a71..1ee3bc09f319 100644 --- a/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt +++ b/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt @@ -6,10 +6,11 @@ The actual devices are instantiated from the child nodes of a Device Bus node. Required properties: - - compatible: Currently only Armada 370/XP SoC are supported, - with this compatible string: + - compatible: Armada 370/XP SoC are supported using the + "marvell,mvebu-devbus" compatible string. - marvell,mvebu-devbus + Orion5x SoC are supported using the + "marvell,orion-devbus" compatible string. - reg: A resource specifier for the register space. This is the base address of a chip select within @@ -22,7 +23,14 @@ Required properties: integer values for each chip-select line in use: 0 <physical address of mapping> <size> -Mandatory timing properties for child nodes: +Optional properties: + + - devbus,keep-config This property can optionally be used to keep + using the timing parameters set by the + bootloader. It makes all the timing properties + described below unused. + +Timing properties for child nodes: Read parameters: @@ -30,21 +38,26 @@ Read parameters: drive the AD bus after the completion of a device read. This prevents contentions on the Device Bus after a read cycle from a slow device. + Mandatory, except if devbus,keep-config is used. - - devbus,bus-width: Defines the bus width (e.g. <16>) + - devbus,bus-width: Defines the bus width, in bits (e.g. <16>). + Mandatory, except if devbus,keep-config is used. - devbus,badr-skew-ps: Defines the time delay from from A[2:0] toggle, to read data sample. This parameter is useful for synchronous pipelined devices, where the address precedes the read data by one or two cycles. + Mandatory, except if devbus,keep-config is used. - devbus,acc-first-ps: Defines the time delay from the negation of ALE[0] to the cycle that the first read data is sampled by the controller. + Mandatory, except if devbus,keep-config is used. - devbus,acc-next-ps: Defines the time delay between the cycle that samples data N and the cycle that samples data N+1 (in burst accesses). + Mandatory, except if devbus,keep-config is used. - devbus,rd-setup-ps: Defines the time delay between DEV_CSn assertion to DEV_OEn assertion. If set to 0 (default), @@ -52,6 +65,8 @@ Read parameters: This parameter has no affect on <acc-first-ps> parameter (no affect on first data sample). Set <rd-setup-ps> to a value smaller than <acc-first-ps>. + Mandatory for "marvell,mvebu-devbus" compatible string, + except if devbus,keep-config is used. - devbus,rd-hold-ps: Defines the time between the last data sample to the de-assertion of DEV_CSn. If set to 0 (default), @@ -62,16 +77,20 @@ Read parameters: last data sampled. Also this parameter has no affect on <turn-off-ps> parameter. Set <rd-hold-ps> to a value smaller than <turn-off-ps>. + Mandatory for "marvell,mvebu-devbus" compatible string, + except if devbus,keep-config is used. Write parameters: - devbus,ale-wr-ps: Defines the time delay from the ALE[0] negation cycle to the DEV_WEn assertion. + Mandatory. - devbus,wr-low-ps: Defines the time during which DEV_WEn is active. A[2:0] and Data are kept valid as long as DEV_WEn is active. This parameter defines the setup time of address and data to DEV_WEn rise. + Mandatory. - devbus,wr-high-ps: Defines the time during which DEV_WEn is kept inactive (high) between data beats of a burst write. @@ -79,10 +98,13 @@ Write parameters: <wr-high-ps> - <tick> ps. This parameter defines the hold time of address and data after DEV_WEn rise. + Mandatory. - devbus,sync-enable: Synchronous device enable. 1: True 0: False + Mandatory for "marvell,mvebu-devbus" compatible string, + except if devbus,keep-config is used. An example for an Armada XP GP board, with a 16 MiB NOR device as child is showed below. Note that the Device Bus driver is in charge of allocating |