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diff --git a/Documentation/devicetree/bindings/clock/baikal,bt1-ccu-div.yaml b/Documentation/devicetree/bindings/clock/baikal,bt1-ccu-div.yaml new file mode 100644 index 000000000..bd4cefbb1 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/baikal,bt1-ccu-div.yaml @@ -0,0 +1,192 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +# Copyright (C) 2020 BAIKAL ELECTRONICS, JSC +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/clock/baikal,bt1-ccu-div.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Baikal-T1 Clock Control Unit Dividers + +maintainers: + - Serge Semin <fancer.lancer@gmail.com> + +description: | + Clocks Control Unit is the core of Baikal-T1 SoC System Controller + responsible for the chip subsystems clocking and resetting. The CCU is + connected with an external fixed rate oscillator, which signal is transformed + into clocks of various frequencies and then propagated to either individual + IP-blocks or to groups of blocks (clock domains). The transformation is done + by means of an embedded into CCU PLLs and gateable/non-gateable dividers. The + later ones are described in this binding. Each clock domain can be also + individually reset by using the domain clocks divider configuration + registers. Baikal-T1 CCU is logically divided into the next components: + 1) External oscillator (normally XTAL's 25 MHz crystal oscillator, but + in general can provide any frequency supported by the CCU PLLs). + 2) PLLs clocks generators (PLLs). + 3) AXI-bus clock dividers (AXI) - described in this binding file. + 4) System devices reference clock dividers (SYS) - described in this binding + file. + which are connected with each other as shown on the next figure: + + +---------------+ + | Baikal-T1 CCU | + | +----+------|- MIPS P5600 cores + | +-|PLLs|------|- DDR controller + | | +----+ | + +----+ | | | | | + |XTAL|--|-+ | | +---+-| + +----+ | | | +-|AXI|-|- AXI-bus + | | | +---+-| + | | | | + | | +----+---+-|- APB-bus + | +-------|SYS|-|- Low-speed Devices + | +---+-|- High-speed Devices + +---------------+ + + Each sub-block is represented as a separate DT node and has an individual + driver to be bound with. + + In order to create signals of wide range frequencies the external oscillator + output is primarily connected to a set of CCU PLLs. Some of PLLs CLKOUT are + then passed over CCU dividers to create signals required for the target clock + domain (like AXI-bus or System Device consumers). The dividers have the + following structure: + + +--------------+ + CLKIN --|->+----+ 1|\ | + SETCLK--|--|/DIV|->| | | + CLKDIV--|--| | | |-|->CLKLOUT + LOCK----|--+----+ | | | + | |/ | + | | | + EN------|-----------+ | + RST-----|--------------|->RSTOUT + +--------------+ + + where CLKIN is the reference clock coming either from CCU PLLs or from an + external clock oscillator, SETCLK - a command to update the output clock in + accordance with a set divider, CLKDIV - clocks divider, LOCK - a signal of + the output clock stabilization, EN - enable/disable the divider block, + RST/RSTOUT - reset clocks domain signal. Depending on the consumer IP-core + peculiarities the dividers may lack of some functionality depicted on the + figure above (like EN, CLKDIV/LOCK/SETCLK). In this case the corresponding + clock provider just doesn't expose either switching functions, or the rate + configuration, or both of them. + + The clock dividers, which output clock is then consumed by the SoC individual + devices, are united into a single clocks provider called System Devices CCU. + Similarly the dividers with output clocks utilized as AXI-bus reference clocks + are called AXI-bus CCU. Both of them use the common clock bindings with no + custom properties. The list of exported clocks and reset signals can be found + in the files: 'include/dt-bindings/clock/bt1-ccu.h' and + 'include/dt-bindings/reset/bt1-ccu.h'. Since System Devices and AXI-bus CCU + are a part of the Baikal-T1 SoC System Controller their DT nodes are supposed + to be a children of later one. + +if: + properties: + compatible: + contains: + const: baikal,bt1-ccu-axi + +then: + properties: + clocks: + items: + - description: CCU SATA PLL output clock + - description: CCU PCIe PLL output clock + - description: CCU Ethernet PLL output clock + + clock-names: + items: + - const: sata_clk + - const: pcie_clk + - const: eth_clk + +else: + properties: + clocks: + items: + - description: External reference clock + - description: CCU SATA PLL output clock + - description: CCU PCIe PLL output clock + - description: CCU Ethernet PLL output clock + + clock-names: + items: + - const: ref_clk + - const: sata_clk + - const: pcie_clk + - const: eth_clk + +properties: + compatible: + enum: + - baikal,bt1-ccu-axi + - baikal,bt1-ccu-sys + + reg: + maxItems: 1 + + "#clock-cells": + const: 1 + + "#reset-cells": + const: 1 + + clocks: true + + clock-names: true + +additionalProperties: false + +required: + - compatible + - "#clock-cells" + - clocks + - clock-names + +examples: + # AXI-bus Clock Control Unit node: + - | + #include <dt-bindings/clock/bt1-ccu.h> + + clock-controller@1f04d030 { + compatible = "baikal,bt1-ccu-axi"; + reg = <0x1f04d030 0x030>; + #clock-cells = <1>; + #reset-cells = <1>; + + clocks = <&ccu_pll CCU_SATA_PLL>, + <&ccu_pll CCU_PCIE_PLL>, + <&ccu_pll CCU_ETH_PLL>; + clock-names = "sata_clk", "pcie_clk", "eth_clk"; + }; + # System Devices Clock Control Unit node: + - | + #include <dt-bindings/clock/bt1-ccu.h> + + clock-controller@1f04d060 { + compatible = "baikal,bt1-ccu-sys"; + reg = <0x1f04d060 0x0a0>; + #clock-cells = <1>; + #reset-cells = <1>; + + clocks = <&clk25m>, + <&ccu_pll CCU_SATA_PLL>, + <&ccu_pll CCU_PCIE_PLL>, + <&ccu_pll CCU_ETH_PLL>; + clock-names = "ref_clk", "sata_clk", "pcie_clk", + "eth_clk"; + }; + # Required Clock Control Unit PLL node: + - | + ccu_pll: clock-controller@1f04d000 { + compatible = "baikal,bt1-ccu-pll"; + reg = <0x1f04d000 0x028>; + #clock-cells = <1>; + + clocks = <&clk25m>; + clock-names = "ref_clk"; + }; +... |