cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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pinctrl-bindings.txt (4381B)


      1== Introduction ==
      2
      3Hardware modules that control pin multiplexing or configuration parameters
      4such as pull-up/down, tri-state, drive-strength etc are designated as pin
      5controllers. Each pin controller must be represented as a node in device tree,
      6just like any other hardware module.
      7
      8Hardware modules whose signals are affected by pin configuration are
      9designated client devices. Again, each client device must be represented as a
     10node in device tree, just like any other hardware module.
     11
     12For a client device to operate correctly, certain pin controllers must
     13set up certain specific pin configurations. Some client devices need a
     14single static pin configuration, e.g. set up during initialization. Others
     15need to reconfigure pins at run-time, for example to tri-state pins when the
     16device is inactive. Hence, each client device can define a set of named
     17states. The number and names of those states is defined by the client device's
     18own binding.
     19
     20The common pinctrl bindings defined in this file provide an infrastructure
     21for client device device tree nodes to map those state names to the pin
     22configuration used by those states.
     23
     24Note that pin controllers themselves may also be client devices of themselves.
     25For example, a pin controller may set up its own "active" state when the
     26driver loads. This would allow representing a board's static pin configuration
     27in a single place, rather than splitting it across multiple client device
     28nodes. The decision to do this or not somewhat rests with the author of
     29individual board device tree files, and any requirements imposed by the
     30bindings for the individual client devices in use by that board, i.e. whether
     31they require certain specific named states for dynamic pin configuration.
     32
     33== Pinctrl client devices ==
     34
     35For each client device individually, every pin state is assigned an integer
     36ID. These numbers start at 0, and are contiguous. For each state ID, a unique
     37property exists to define the pin configuration. Each state may also be
     38assigned a name. When names are used, another property exists to map from
     39those names to the integer IDs.
     40
     41Each client device's own binding determines the set of states that must be
     42defined in its device tree node, and whether to define the set of state
     43IDs that must be provided, or whether to define the set of state names that
     44must be provided.
     45
     46Required properties:
     47pinctrl-0:	List of phandles, each pointing at a pin configuration
     48		node. These referenced pin configuration nodes must be child
     49		nodes of the pin controller that they configure. Multiple
     50		entries may exist in this list so that multiple pin
     51		controllers may be configured, or so that a state may be built
     52		from multiple nodes for a single pin controller, each
     53		contributing part of the overall configuration. See the next
     54		section of this document for details of the format of these
     55		pin configuration nodes.
     56
     57		In some cases, it may be useful to define a state, but for it
     58		to be empty. This may be required when a common IP block is
     59		used in an SoC either without a pin controller, or where the
     60		pin controller does not affect the HW module in question. If
     61		the binding for that IP block requires certain pin states to
     62		exist, they must still be defined, but may be left empty.
     63
     64Optional properties:
     65pinctrl-1:	List of phandles, each pointing at a pin configuration
     66		node within a pin controller.
     67...
     68pinctrl-n:	List of phandles, each pointing at a pin configuration
     69		node within a pin controller.
     70pinctrl-names:	The list of names to assign states. List entry 0 defines the
     71		name for integer state ID 0, list entry 1 for state ID 1, and
     72		so on.
     73
     74For example:
     75
     76	/* For a client device requiring named states */
     77	device {
     78		pinctrl-names = "active", "idle";
     79		pinctrl-0 = <&state_0_node_a>;
     80		pinctrl-1 = <&state_1_node_a>, <&state_1_node_b>;
     81	};
     82
     83	/* For the same device if using state IDs */
     84	device {
     85		pinctrl-0 = <&state_0_node_a>;
     86		pinctrl-1 = <&state_1_node_a>, <&state_1_node_b>;
     87	};
     88
     89	/*
     90	 * For an IP block whose binding supports pin configuration,
     91	 * but in use on an SoC that doesn't have any pin control hardware
     92	 */
     93	device {
     94		pinctrl-names = "active", "idle";
     95		pinctrl-0 = <>;
     96		pinctrl-1 = <>;
     97	};
     98
     99== Pin controller devices ==
    100
    101See pinctrl.yaml
    102
    103== Generic pin multiplexing node content ==
    104
    105See pinmux-node.yaml
    106
    107== Generic pin configuration node content ==
    108
    109See pincfg-node.yaml