On Fri, May 08, 2020 at 12:36:20PM +0300, Serge Semin wrote:
> 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.zari...@baikalelectronics.ru>
> Signed-off-by: Ramil Zaripov <ramil.zari...@baikalelectronics.ru>
> Signed-off-by: Serge Semin <sergey.se...@baikalelectronics.ru>
> Cc: Alexey Malahov <alexey.mala...@baikalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbog...@alpha.franken.de>
> Cc: Paul Burton <paulbur...@kernel.org>
> Cc: Ralf Baechle <r...@linux-mips.org>
> Cc: John Garry <john.ga...@huawei.com>
> Cc: Chuanhong Guo <gch981...@gmail.com>
> Cc: Tomer Maimon <tmaimo...@gmail.com>
> Cc: Lee Jones <lee.jo...@linaro.org>
> Cc: Miquel Raynal <miquel.ray...@bootlin.com>
> Cc: Arnd Bergmann <a...@arndb.de>
> Cc: linux-m...@vger.kernel.org
> Cc: linux-...@vger.kernel.org
> ---
> .../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.lan...@gmail.com>
> +
> +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
Can drop this.
> + 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
What's the point of these 2 properties if they aren't required?
> +
> +unevaluatedProperties: false
> +
> +required:
> + - compatible
> + - reg
> + - reg-names
> + - "#address-cells"
> + - "#size-cells"
These 2 are required by spi-controller.yaml, so you can drop here.
> + - 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
>
