diff options
Diffstat (limited to 'Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt | 29 |
1 files changed, 18 insertions, 11 deletions
diff --git a/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt b/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt index 55adde214627..1ee3bc09f319 100644 --- a/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt +++ b/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt @@ -23,6 +23,13 @@ Required properties: integer values for each chip-select line in use: 0 <physical address of mapping> <size> +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: @@ -31,26 +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. + Mandatory, except if devbus,keep-config is used. - devbus,bus-width: Defines the bus width, in bits (e.g. <16>). - Mandatory. + 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. + 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. + 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. + 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), @@ -58,8 +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, ignored otherwise. + 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), @@ -70,8 +77,8 @@ 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, ignored otherwise. + Mandatory for "marvell,mvebu-devbus" compatible string, + except if devbus,keep-config is used. Write parameters: @@ -96,8 +103,8 @@ Write parameters: - devbus,sync-enable: Synchronous device enable. 1: True 0: False - Mandatory for "marvell,mvebu-devbus" compatible - string, ignored otherwise. + 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 |