[rtc-linux] Re: [PATCH v6] rtc: rewrite DS1302 using SPI
From: Rob Herring <robh@kernel.org>
Date: 2016-02-22 18:45:22
Also in:
linux-devicetree, lkml
On Mon, Feb 22, 2016 at 04:41:22AM +0300, Sergei Ianovich wrote:
quoted hunk ↗ jump to hunk
DS1302 is half-duplex SPI device. The driver respects this fact now. Pin configurations should be implemented using SPI subsystem. Signed-off-by: Sergei Ianovich <redacted> CC: Alexandre Belloni <redacted> CC: Rob Herring <robh@kernel.org> --- v5..v6 * rewrite the driver as an SPI slave device * use "maxim" for vendor name per Kconfig * stop touching device RAM in device presence test * only return time from device if valid * use burst mode for reading/writing time * droppped charging control. I cannot test it, and it looks broken v4..v5 * drop THIS_MODULE from struct platform driver * use "dallas" for vendor name per vendor-prefixes.txt v3..v4 * move DTS bindings to a different patch v2..v3 * use usleep_range instead of custom nsleep * number change (07/16 -> 09/21) v0..v2 * use device tree * use devm helpers where possible .../devicetree/bindings/rtc/rtc-ds1302.txt | 46 +++ drivers/rtc/Kconfig | 15 +- drivers/rtc/rtc-ds1302.c | 348 ++++++++++----------- 3 files changed, 212 insertions(+), 197 deletions(-) create mode 100644 Documentation/devicetree/bindings/rtc/rtc-ds1302.txtdiff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt new file mode 100644 index 0000000..b6c0973 --- /dev/null +++ b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt@@ -0,0 +1,46 @@ +* Maxim/Dallas Semiconductor DS-1302 RTC + +Simple device which could be used to store date/time between reboots. + +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: + +- compatible : Should be "maxim,rtc-ds1302"
Just maxim,ds1032. RTC is implied by the part number and inline with existing dallas,ds1307.
+
+Required SPI properties:
+
+- reg : Should be address of the device chip select within
+ the controller.
+
+- spi-max-frequency : DS-1302 has 500 kHz if powered at 2.2V,
+ and 2MHz if powered at 5V.
+
+- spi-3wire : The device has a shared signal IN/OUT line.
+
+- spi-lsb-first : DS-1302 requires least significant bit first
+ transfers.
+
+- spi-cs-high: DS-1302 has active high chip select line. This is
+ required unless inverted in hardware.
+
+Example:
+
+spi0@901c {spi@...
+ #address-cells = <1>; + #size-cells = <0>; + compatible = "icpdas,spi-lp8841-rtc";
And this will need updating...
+ reg = <0x901c 0x1>;
+
+ rtc@0 {
+ compatible = "maxim,rtc-ds1302";
+ reg = <0>;
+ spi-max-frequency = <500000>;
+ spi-3wire;
+ spi-lsb-first;
+ spi-cs-high;
+ };
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