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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 <ynvich@gmail.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Mark Brown <broonie@kernel.org>
55 lines
1.3 KiB
Plaintext
55 lines
1.3 KiB
Plaintext
* ICP DAS LP-8841 SPI Controller for RTC
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ICP DAS LP-8841 contains a DS-1302 RTC. RTC is connected to an IO
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memory register, which acts as an SPI master device.
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The device uses the standard MicroWire half-duplex transfer timing.
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Master output is set on low clock and sensed by the RTC on the rising
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edge. Master input is set by the RTC on the trailing edge and is sensed
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by the master on low clock.
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Required properties:
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- #address-cells: should be 1
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- #size-cells: should be 0
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- compatible: should be "icpdas,lp8841-spi-rtc"
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- reg: should provide IO memory address
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Requirements to SPI slave nodes:
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- There can be only one slave device.
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- The spi slave node should claim the following flags which are
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required by the spi controller.
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- spi-3wire: The master itself has only 3 wire. It cannor work in
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full duplex mode.
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- spi-cs-high: DS-1302 has active high chip select line. The master
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doesn't support active low.
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- spi-lsb-first: DS-1302 requires least significant bit first
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transfers. The master only support this type of bit ordering.
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Example:
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spi@901c {
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#address-cells = <1>;
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#size-cells = <0>;
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compatible = "icpdas,lp8841-spi-rtc";
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reg = <0x901c 0x1>;
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rtc@0 {
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compatible = "maxim,ds1302";
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reg = <0>;
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spi-max-frequency = <500000>;
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spi-3wire;
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spi-lsb-first;
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spi-cs-high;
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};
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};
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