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Diffstat (limited to 'Documentation/devicetree/bindings/reset')
| -rw-r--r-- | Documentation/devicetree/bindings/reset/fsl,imx-src.txt | 49 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/reset/reset.txt | 75 |
2 files changed, 124 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/reset/fsl,imx-src.txt b/Documentation/devicetree/bindings/reset/fsl,imx-src.txt new file mode 100644 index 00000000000..13301777e11 --- /dev/null +++ b/Documentation/devicetree/bindings/reset/fsl,imx-src.txt @@ -0,0 +1,49 @@ +Freescale i.MX System Reset Controller +====================================== + +Please also refer to reset.txt in this directory for common reset +controller binding usage. + +Required properties: +- compatible: Should be "fsl,<chip>-src" +- reg: should be register base and length as documented in the + datasheet +- interrupts: Should contain SRC interrupt and CPU WDOG interrupt, + in this order. +- #reset-cells: 1, see below + +example: + +src: src@020d8000 { + compatible = "fsl,imx6q-src"; + reg = <0x020d8000 0x4000>; + interrupts = <0 91 0x04 0 96 0x04>; + #reset-cells = <1>; +}; + +Specifying reset lines connected to IP modules +============================================== + +The system reset controller can be used to reset the GPU, VPU, +IPU, and OpenVG IP modules on i.MX5 and i.MX6 ICs. Those device +nodes should specify the reset line on the SRC in their resets +property, containing a phandle to the SRC device node and a +RESET_INDEX specifying which module to reset, as described in +reset.txt + +example: + + ipu1: ipu@02400000 { + resets = <&src 2>; + }; + ipu2: ipu@02800000 { + resets = <&src 4>; + }; + +The following RESET_INDEX values are valid for i.MX5: +GPU_RESET 0 +VPU_RESET 1 +IPU1_RESET 2 +OPEN_VG_RESET 3 +The following additional RESET_INDEX value is valid for i.MX6: +IPU2_RESET 4 diff --git a/Documentation/devicetree/bindings/reset/reset.txt b/Documentation/devicetree/bindings/reset/reset.txt new file mode 100644 index 00000000000..31db6ff8490 --- /dev/null +++ b/Documentation/devicetree/bindings/reset/reset.txt @@ -0,0 +1,75 @@ += Reset Signal Device Tree Bindings = + +This binding is intended to represent the hardware reset signals present +internally in most IC (SoC, FPGA, ...) designs. Reset signals for whole +standalone chips are most likely better represented as GPIOs, although there +are likely to be exceptions to this rule. + +Hardware blocks typically receive a reset signal. This signal is generated by +a reset provider (e.g. power management or clock module) and received by a +reset consumer (the module being reset, or a module managing when a sub- +ordinate module is reset). This binding exists to represent the provider and +consumer, and provide a way to couple the two together. + +A reset signal is represented by the phandle of the provider, plus a reset +specifier - a list of DT cells that represents the reset signal within the +provider. The length (number of cells) and semantics of the reset specifier +are dictated by the binding of the reset provider, although common schemes +are described below. + +A word on where to place reset signal consumers in device tree: It is possible +in hardware for a reset signal to affect multiple logically separate HW blocks +at once. In this case, it would be unwise to represent this reset signal in +the DT node of each affected HW block, since if activated, an unrelated block +may be reset. Instead, reset signals should be represented in the DT node +where it makes most sense to control it; this may be a bus node if all +children of the bus are affected by the reset signal, or an individual HW +block node for dedicated reset signals. The intent of this binding is to give +appropriate software access to the reset signals in order to manage the HW, +rather than to slavishly enumerate the reset signal that affects each HW +block. + += Reset providers = + +Required properties: +#reset-cells: Number of cells in a reset specifier; Typically 0 for nodes + with a single reset output and 1 for nodes with multiple + reset outputs. + +For example: + + rst: reset-controller { + #reset-cells = <1>; + }; + += Reset consumers = + +Required properties: +resets: List of phandle and reset specifier pairs, one pair + for each reset signal that affects the device, or that the + device manages. Note: if the reset provider specifies '0' for + #reset-cells, then only the phandle portion of the pair will + appear. + +Optional properties: +reset-names: List of reset signal name strings sorted in the same order as + the resets property. Consumers drivers will use reset-names to + match reset signal names with reset specifiers. + +For example: + + device { + resets = <&rst 20>; + reset-names = "reset"; + }; + +This represents a device with a single reset signal named "reset". + + bus { + resets = <&rst 10> <&rst 11> <&rst 12> <&rst 11>; + reset-names = "i2s1", "i2s2", "dma", "mixer"; + }; + +This represents a bus that controls the reset signal of each of four sub- +ordinate devices. Consider for example a bus that fails to operate unless no +child device has reset asserted. |