55 lines
1.3 KiB
Plaintext
Executable file
55 lines
1.3 KiB
Plaintext
Executable file
* ICP DAS LP-8841 SPI Controller for RTC
|
|
|
|
ICP DAS LP-8841 contains a DS-1302 RTC. RTC is connected to an IO
|
|
memory register, which acts as an SPI master device.
|
|
|
|
The device 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,lp8841-spi-rtc"
|
|
|
|
- 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
|
|
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:
|
|
|
|
spi@901c {
|
|
#address-cells = <1>;
|
|
#size-cells = <0>;
|
|
compatible = "icpdas,lp8841-spi-rtc";
|
|
reg = <0x901c 0x1>;
|
|
|
|
rtc@0 {
|
|
compatible = "maxim,ds1302";
|
|
reg = <0>;
|
|
spi-max-frequency = <500000>;
|
|
spi-3wire;
|
|
spi-lsb-first;
|
|
spi-cs-high;
|
|
};
|
|
};
|