On Mon, Feb 22, 2016 at 04:47:06AM +0300, Sergei Ianovich wrote:
> ICP DAS LP-8841 contains a DS-1302 RTC. This driver provides an SPI
> master which makes the RTC usable. The driver is not supposed to work
> with anything else.
>
> The driver uses the standard MicroWire half-duplex transfer timing.
> Master output is set on low clock and sensed by the RTC on the rising
> edge. Master input is set by the RTC on the trailing edge and is sensed
> by the master on low clock.
>
> Signed-off-by: Sergei Ianovich <[email protected]>
> ---
> .../devicetree/bindings/spi/spi-lp8841-rtc.txt | 55 +++++
> drivers/spi/Kconfig | 10 +
> drivers/spi/Makefile | 1 +
> drivers/spi/spi-lp8841-rtc.c | 272
> +++++++++++++++++++++
> 4 files changed, 338 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/spi/spi-lp8841-rtc.txt
> create mode 100644 drivers/spi/spi-lp8841-rtc.c
>
> diff --git a/Documentation/devicetree/bindings/spi/spi-lp8841-rtc.txt
> b/Documentation/devicetree/bindings/spi/spi-lp8841-rtc.txt
> new file mode 100644
> index 0000000..f191aef
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/spi-lp8841-rtc.txt
> @@ -0,0 +1,55 @@
> +* ICP DAS LP-8841 SPI Controller for RTC
> +
> +ICP DAS LP-8841 contains a DS-1302 RTC. This driver provides an SPI
> +master which makes the RTC usable. The driver is not supposed to work
> +with anything else.
Bindings describe h/w not drivers.
> +The driver uses the standard MicroWire half-duplex transfer timing.
> +Master output is set on low clock and sensed by the RTC on the rising
> +edge. Master input is set by the RTC on the trailing edge and is sensed
> +by the master on low clock.
> +
> +Required properties:
> +
> +- #address-cells: should be 1
> +
> +- #size-cells: should be 0
> +
> +- compatible: should be "icpdas,spi-lp8841-rtc"
icpdas,lp8841-spi-rtc would be more inline with naming conventions.
> +
> +- reg: should provide IO memory address
> +
> +Requirements to SPI slave nodes:
> +
> +- There can be only one slave device.
> +
> +- The spi slave node should claim the following flags which are
> + required by the spi controller.
> +
> + - spi-3wire: The master itself has only 3 wire. It cannor work in
s/cannor/cannot/
> + full duplex mode.
> +
> + - spi-cs-high: DS-1302 has active high chip select line. The master
> + doesn't support active low.
> +
> + - spi-lsb-first: DS-1302 requires least significant bit first
> + transfers. The master only support this type of bit ordering.
> +
> +
> +Example:
> +
> +spi0@901c {
spi@901c
> + #address-cells = <1>;
> + #size-cells = <0>;
> + compatible = "icpdas,spi-lp8841-rtc";
> + reg = <0x901c 0x1>;
> +
> + rtc@0 {
> + compatible = "maxim,rtc-ds1302";
> + reg = <0>;
> + spi-max-frequency = <500000>;
> + spi-3wire;
> + spi-lsb-first;
> + spi-cs-high;
> + };
> +};
