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Diffstat (limited to 'Documentation/devicetree/bindings/gpio/nvidia,tegra186-gpio.txt')
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diff --git a/Documentation/devicetree/bindings/gpio/nvidia,tegra186-gpio.txt b/Documentation/devicetree/bindings/gpio/nvidia,tegra186-gpio.txt new file mode 100644 index 000000000..adff16c71 --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/nvidia,tegra186-gpio.txt @@ -0,0 +1,165 @@ +NVIDIA Tegra186 GPIO controllers + +Tegra186 contains two GPIO controllers; a main controller and an "AON" +controller. This binding document applies to both controllers. The register +layouts for the controllers share many similarities, but also some significant +differences. Hence, this document describes closely related but different +bindings and compatible values. + +The Tegra186 GPIO controller allows software to set the IO direction of, and +read/write the value of, numerous GPIO signals. Routing of GPIO signals to +package balls is under the control of a separate pin controller HW block. Two +major sets of registers exist: + +a) Security registers, which allow configuration of allowed access to the GPIO +register set. These registers exist in a single contiguous block of physical +address space. The size of this block, and the security features available, +varies between the different GPIO controllers. + +Access to this set of registers is not necessary in all circumstances. Code +that wishes to configure access to the GPIO registers needs access to these +registers to do so. Code which simply wishes to read or write GPIO data does not +need access to these registers. + +b) GPIO registers, which allow manipulation of the GPIO signals. In some GPIO +controllers, these registers are exposed via multiple "physical aliases" in +address space, each of which access the same underlying state. See the hardware +documentation for rationale. Any particular GPIO client is expected to access +just one of these physical aliases. + +Tegra HW documentation describes a unified naming convention for all GPIOs +implemented by the SoC. Each GPIO is assigned to a port, and a port may control +a number of GPIOs. Thus, each GPIO is named according to an alphabetical port +name and an integer GPIO name within the port. For example, GPIO_PA0, GPIO_PN6, +or GPIO_PCC3. + +The number of ports implemented by each GPIO controller varies. The number of +implemented GPIOs within each port varies. GPIO registers within a controller +are grouped and laid out according to the port they affect. + +The mapping from port name to the GPIO controller that implements that port, and +the mapping from port name to register offset within a controller, are both +extremely non-linear. The header file <dt-bindings/gpio/tegra186-gpio.h> +describes the port-level mapping. In that file, the naming convention for ports +matches the HW documentation. The values chosen for the names are alphabetically +sorted within a particular controller. Drivers need to map between the DT GPIO +IDs and HW register offsets using a lookup table. + +Each GPIO controller can generate a number of interrupt signals. Each signal +represents the aggregate status for all GPIOs within a set of ports. Thus, the +number of interrupt signals generated by a controller varies as a rough function +of the number of ports it implements. Note that the HW documentation refers to +both the overall controller HW module and the sets-of-ports as "controllers". + +Each GPIO controller in fact generates multiple interrupts signals for each set +of ports. Each GPIO may be configured to feed into a specific one of the +interrupt signals generated by a set-of-ports. The intent is for each generated +signal to be routed to a different CPU, thus allowing different CPUs to each +handle subsets of the interrupts within a port. The status of each of these +per-port-set signals is reported via a separate register. Thus, a driver needs +to know which status register to observe. This binding currently defines no +configuration mechanism for this. By default, drivers should use register +GPIO_${port}_INTERRUPT_STATUS_G1_0. Future revisions to the binding could +define a property to configure this. + +Required properties: +- compatible + Array of strings. + One of: + - "nvidia,tegra186-gpio". + - "nvidia,tegra186-gpio-aon". + - "nvidia,tegra194-gpio". + - "nvidia,tegra194-gpio-aon". +- reg-names + Array of strings. + Contains a list of names for the register spaces described by the reg + property. May contain the following entries, in any order: + - "gpio": Mandatory. GPIO control registers. This may cover either: + a) The single physical alias that this OS should use. + b) All physical aliases that exist in the controller. This is + appropriate when the OS is responsible for managing assignment of + the physical aliases. + - "security": Optional. Security configuration registers. + Users of this binding MUST look up entries in the reg property by name, + using this reg-names property to do so. +- reg + Array of (physical base address, length) tuples. + Must contain one entry per entry in the reg-names property, in a matching + order. +- interrupts + Array of interrupt specifiers. + The interrupt outputs from the HW block, one per set of ports, in the + order the HW manual describes them. The number of entries required varies + depending on compatible value: + - "nvidia,tegra186-gpio": 6 entries. + - "nvidia,tegra186-gpio-aon": 1 entry. + - "nvidia,tegra194-gpio": 6 entries. + - "nvidia,tegra194-gpio-aon": 1 entry. +- gpio-controller + Boolean. + Marks the device node as a GPIO controller/provider. +- #gpio-cells + Single-cell integer. + Must be <2>. + Indicates how many cells are used in a consumer's GPIO specifier. + In the specifier: + - The first cell is the pin number. + See <dt-bindings/gpio/tegra186-gpio.h>. + - The second cell contains flags: + - Bit 0 specifies polarity + - 0: Active-high (normal). + - 1: Active-low (inverted). +- interrupt-controller + Boolean. + Marks the device node as an interrupt controller/provider. +- #interrupt-cells + Single-cell integer. + Must be <2>. + Indicates how many cells are used in a consumer's interrupt specifier. + In the specifier: + - The first cell is the GPIO number. + See <dt-bindings/gpio/tegra186-gpio.h>. + - The second cell is contains flags: + - Bits [3:0] indicate trigger type and level: + - 1: Low-to-high edge triggered. + - 2: High-to-low edge triggered. + - 4: Active high level-sensitive. + - 8: Active low level-sensitive. + Valid combinations are 1, 2, 3, 4, 8. + +Example: + +#include <dt-bindings/interrupt-controller/irq.h> + +gpio@2200000 { + compatible = "nvidia,tegra186-gpio"; + reg-names = "security", "gpio"; + reg = + <0x0 0x2200000 0x0 0x10000>, + <0x0 0x2210000 0x0 0x10000>; + interrupts = + <0 47 IRQ_TYPE_LEVEL_HIGH>, + <0 50 IRQ_TYPE_LEVEL_HIGH>, + <0 53 IRQ_TYPE_LEVEL_HIGH>, + <0 56 IRQ_TYPE_LEVEL_HIGH>, + <0 59 IRQ_TYPE_LEVEL_HIGH>, + <0 180 IRQ_TYPE_LEVEL_HIGH>; + gpio-controller; + #gpio-cells = <2>; + interrupt-controller; + #interrupt-cells = <2>; +}; + +gpio@c2f0000 { + compatible = "nvidia,tegra186-gpio-aon"; + reg-names = "security", "gpio"; + reg = + <0x0 0xc2f0000 0x0 0x1000>, + <0x0 0xc2f1000 0x0 0x1000>; + interrupts = + <0 60 IRQ_TYPE_LEVEL_HIGH>; + gpio-controller; + #gpio-cells = <2>; + interrupt-controller; + #interrupt-cells = <2>; +}; |