| Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 1 | * ICP DAS LP-8841 SPI Controller for RTC |
| 2 | |
| 3 | ICP DAS LP-8841 contains a DS-1302 RTC. RTC is connected to an IO |
| 4 | memory register, which acts as an SPI master device. |
| 5 | |
| 6 | The device uses the standard MicroWire half-duplex transfer timing. |
| 7 | Master output is set on low clock and sensed by the RTC on the rising |
| 8 | edge. Master input is set by the RTC on the trailing edge and is sensed |
| 9 | by the master on low clock. |
| 10 | |
| 11 | Required properties: |
| 12 | |
| 13 | - #address-cells: should be 1 |
| 14 | |
| 15 | - #size-cells: should be 0 |
| 16 | |
| 17 | - compatible: should be "icpdas,lp8841-spi-rtc" |
| 18 | |
| 19 | - reg: should provide IO memory address |
| 20 | |
| 21 | Requirements to SPI slave nodes: |
| 22 | |
| 23 | - There can be only one slave device. |
| 24 | |
| 25 | - The spi slave node should claim the following flags which are |
| 26 | required by the spi controller. |
| 27 | |
| 28 | - spi-3wire: The master itself has only 3 wire. It cannor work in |
| 29 | full duplex mode. |
| 30 | |
| 31 | - spi-cs-high: DS-1302 has active high chip select line. The master |
| 32 | doesn't support active low. |
| 33 | |
| 34 | - spi-lsb-first: DS-1302 requires least significant bit first |
| 35 | transfers. The master only support this type of bit ordering. |
| 36 | |
| 37 | |
| 38 | Example: |
| 39 | |
| 40 | spi@901c { |
| 41 | #address-cells = <1>; |
| 42 | #size-cells = <0>; |
| 43 | compatible = "icpdas,lp8841-spi-rtc"; |
| 44 | reg = <0x901c 0x1>; |
| 45 | |
| 46 | rtc@0 { |
| 47 | compatible = "maxim,ds1302"; |
| 48 | reg = <0>; |
| 49 | spi-max-frequency = <500000>; |
| 50 | spi-3wire; |
| 51 | spi-lsb-first; |
| 52 | spi-cs-high; |
| 53 | }; |
| 54 | }; |