Baikal-T1 Boot SPI is a part of the SoC System Controller and is responsible for the system bootup from an external SPI flash. It's a DW APB SSI-based SPI-controller with no interrupts, no DMA, with just one native chip-select available and a single reference clock. Since Baikal-T1 SoC is normally booted up from an external SPI flash this SPI controller in most of the cases is supposed to be connected to a single SPI-nor flash. Additionally in order to provide a transparent from CPU point of view initial code execution procedure the system designers created an IP block which physically maps the SPI flash found at CS0 to a memory region. Co-developed-by: Ramil Zaripov <Ramil.Zaripov@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Ramil Zaripov <Ramil.Zaripov@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx> Cc: Alexey Malahov <Alexey.Malahov@xxxxxxxxxxxxxxxxxxxx> Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> Cc: Paul Burton <paulburton@xxxxxxxxxx> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Cc: John Garry <john.garry@xxxxxxxxxx> Cc: Chuanhong Guo <gch981213@xxxxxxxxx> Cc: Tomer Maimon <tmaimon77@xxxxxxxxx> Cc: Lee Jones <lee.jones@xxxxxxxxxx> Cc: Miquel Raynal <miquel.raynal@xxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxxx Cc: linux-spi@xxxxxxxxxxxxxxx --- .../bindings/spi/baikal,bt1-sys-ssi.yaml | 100 ++++++++++++++++++ 1 file changed, 100 insertions(+) create mode 100644 Documentation/devicetree/bindings/spi/baikal,bt1-sys-ssi.yaml diff --git a/Documentation/devicetree/bindings/spi/baikal,bt1-sys-ssi.yaml b/Documentation/devicetree/bindings/spi/baikal,bt1-sys-ssi.yaml new file mode 100644 index 000000000000..d9d3257d78f4 --- /dev/null +++ b/Documentation/devicetree/bindings/spi/baikal,bt1-sys-ssi.yaml @@ -0,0 +1,100 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +# Copyright (C) 2020 BAIKAL ELECTRONICS, JSC +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/spi/baikal,bt1-sys-ssi.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Baikal-T1 System Boot SSI Controller + +description: | + Baikal-T1 System Controller includes a Boot SPI Controller, which is + responsible for loading chip bootup code from an external SPI flash. In order + to do this transparently from CPU point of view there is a dedicated IP block + mapping the 16MB flash to a dedicated MMIO range. The controller is based on + the DW APB SSI IP-core but equipped with very limited resources: no IRQ, + no DMA, a single native CS being necessarily connected to a 16MB SPI flash + (otherwise the system won't bootup from the flash), internal Tx/Rx FIFO of + just 8 bytes depth. Access to DW APB SSI controller registers is mutually + exclusive from normal MMIO interface and from physically mapped SPI Flash + memory. So either one or another way of using the controller functionality + can be enabled at a time. + +maintainers: + - Serge Semin <fancer.lancer@xxxxxxxxx> + +allOf: + - $ref: spi-controller.yaml# + +properties: + compatible: + const: baikal,bt1-sys-ssi + + reg: + items: + - description: Baikal-T1 Boot Controller configuration registers + - description: Physically mapped SPI flash ROM found at CS0 + + reg-names: + items: + - const: config + - const: map + + clocks: + description: SPI Controller reference clock source + maxItems: 1 + + clock-names: + items: + - const: ssi_clk + + num-cs: + const: 1 + +patternProperties: + "^.*@[0-9a-f]+": + type: object + properties: + reg: + minimum: 0 + maximum: 0 + + spi-rx-bus-width: + const: 1 + + spi-tx-bus-width: + const: 1 + +unevaluatedProperties: false + +required: + - compatible + - reg + - reg-names + - "#address-cells" + - "#size-cells" + - clocks + +examples: + - | + spi@1f040000 { + compatible = "baikal,bt1-sys-ssi"; + reg = <0x1f040000 0x1000>, + <0x1c000000 0x1000000>; + reg-names = "config", "map"; + #address-cells = <1>; + #size-cells = <0>; + + clocks = <&ccu_sys>; + clock-names = "ssi_clk"; + + boot_flash: flash@0 { + compatible = "jedec,spi-nor"; + #address-cells = <1>; + #size-cells = <1>; + reg = <0>; + + spi-max-frequency = <25000000>; + }; + }; +... -- 2.25.1
