ARM: tegra: Add DT binding for Tegra186 GPIO controllers

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".

- 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.

- 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>;

};

/*

 * This header provides constants for binding nvidia,tegra186-gpio*.

 *

 * The first cell in Tegra's GPIO specifier is the GPIO ID. The macros below

 * provide names for this.

 *

 * The second cell contains standard flag values specified in gpio.h.

 */

#ifndef _DT_BINDINGS_GPIO_TEGRA_GPIO_H

#define _DT_BINDINGS_GPIO_TEGRA_GPIO_H

#include <dt-bindings/gpio/gpio.h>

/* GPIOs implemented by main GPIO controller */

#define TEGRA_MAIN_GPIO_PORT_A 0

#define TEGRA_MAIN_GPIO_PORT_B 1

#define TEGRA_MAIN_GPIO_PORT_C 2

#define TEGRA_MAIN_GPIO_PORT_D 3

#define TEGRA_MAIN_GPIO_PORT_E 4

#define TEGRA_MAIN_GPIO_PORT_F 5

#define TEGRA_MAIN_GPIO_PORT_G 6

#define TEGRA_MAIN_GPIO_PORT_H 7

#define TEGRA_MAIN_GPIO_PORT_I 8

#define TEGRA_MAIN_GPIO_PORT_J 9

#define TEGRA_MAIN_GPIO_PORT_K 10

#define TEGRA_MAIN_GPIO_PORT_L 11

#define TEGRA_MAIN_GPIO_PORT_M 12

#define TEGRA_MAIN_GPIO_PORT_N 13

#define TEGRA_MAIN_GPIO_PORT_O 14

#define TEGRA_MAIN_GPIO_PORT_P 15

#define TEGRA_MAIN_GPIO_PORT_Q 16

#define TEGRA_MAIN_GPIO_PORT_R 17

#define TEGRA_MAIN_GPIO_PORT_T 18

#define TEGRA_MAIN_GPIO_PORT_X 19

#define TEGRA_MAIN_GPIO_PORT_Y 20

#define TEGRA_MAIN_GPIO_PORT_BB 21

#define TEGRA_MAIN_GPIO_PORT_CC 22

#define TEGRA_MAIN_GPIO(port, offset) \

	((TEGRA_MAIN_GPIO_PORT_##port * 8) + offset)

/* GPIOs implemented by AON GPIO controller */

#define TEGRA_AON_GPIO_PORT_S 0

#define TEGRA_AON_GPIO_PORT_U 1

#define TEGRA_AON_GPIO_PORT_V 2

#define TEGRA_AON_GPIO_PORT_W 3

#define TEGRA_AON_GPIO_PORT_Z 4

#define TEGRA_AON_GPIO_PORT_AA 5

#define TEGRA_AON_GPIO_PORT_EE 6

#define TEGRA_AON_GPIO_PORT_FF 7

#define TEGRA_AON_GPIO(port, offset) \

	((TEGRA_AON_GPIO_PORT_##port * 8) + offset)

#endif