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1= Reset Signal Device Tree Bindings =2 3This binding is intended to represent the hardware reset signals present4internally in most IC (SoC, FPGA, ...) designs. Reset signals for whole5standalone chips are most likely better represented as GPIOs, although there6are likely to be exceptions to this rule.7 8Hardware blocks typically receive a reset signal. This signal is generated by9a reset provider (e.g. power management or clock module) and received by a10reset consumer (the module being reset, or a module managing when a sub-11ordinate module is reset). This binding exists to represent the provider and12consumer, and provide a way to couple the two together.13 14A reset signal is represented by the phandle of the provider, plus a reset15specifier - a list of DT cells that represents the reset signal within the16provider. The length (number of cells) and semantics of the reset specifier17are dictated by the binding of the reset provider, although common schemes18are described below.19 20A word on where to place reset signal consumers in device tree: It is possible21in hardware for a reset signal to affect multiple logically separate HW blocks22at once. In this case, it would be unwise to represent this reset signal in23the DT node of each affected HW block, since if activated, an unrelated block24may be reset. Instead, reset signals should be represented in the DT node25where it makes most sense to control it; this may be a bus node if all26children of the bus are affected by the reset signal, or an individual HW27block node for dedicated reset signals. The intent of this binding is to give28appropriate software access to the reset signals in order to manage the HW,29rather than to slavishly enumerate the reset signal that affects each HW30block.31 32= Reset providers =33 34Required properties:35#reset-cells: Number of cells in a reset specifier; Typically 0 for nodes36 with a single reset output and 1 for nodes with multiple37 reset outputs.38 39For example:40 41 rst: reset-controller {42 #reset-cells = <1>;43 };44 45= Reset consumers =46 47Required properties:48resets: List of phandle and reset specifier pairs, one pair49 for each reset signal that affects the device, or that the50 device manages. Note: if the reset provider specifies '0' for51 #reset-cells, then only the phandle portion of the pair will52 appear.53 54Optional properties:55reset-names: List of reset signal name strings sorted in the same order as56 the resets property. Consumers drivers will use reset-names to57 match reset signal names with reset specifiers.58 59For example:60 61 device {62 resets = <&rst 20>;63 reset-names = "reset";64 };65 66This represents a device with a single reset signal named "reset".67 68 bus {69 resets = <&rst 10> <&rst 11> <&rst 12> <&rst 11>;70 reset-names = "i2s1", "i2s2", "dma", "mixer";71 };72 73This represents a bus that controls the reset signal of each of four sub-74ordinate devices. Consider for example a bus that fails to operate unless no75child device has reset asserted.76