On Mon, May 18, 2020 at 3:27 PM Serge Semin <sergey.se...@baikalelectronics.ru> wrote: > > On Mon, May 18, 2020 at 09:26:59AM -0600, Rob Herring wrote: > > 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. > > Ok. > > > > > > + 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? > > Yes, they are optional, but this is a constraint on the bus-width parameters. > DW APB SSI provides a single laned Tx and Rx.
Are you just trying to keep someone from saying 'spi-tx-bus-width: 2' for example? You could also say 'spi-tx-bus-width: false' here to disallow the property. I guess the above is fine. Rob
