[rtc-linux] RE: [PATCH 2/5] rtc: Add rtc-sh

[Chris Brandt <Chris.Brandt@renesas.com>]

Hi Alexandre and Geert,


On Friday, March 17, 2017, Alexandre Belloni wrote:
> On 17/03/2017 at 14:55:48 +0100, Geert Uytterhoeven wrote:
> > >> it would still be good to have phandles to the external clock
> > >> sources as well, as that describes the hardware topology.
> > >
> > > I'm confused, you mean make new clocks node for RTC_X1 (fixed at
> > > 32.768kHZ) and
> > > RTC_X3 (fixed at 4MHz), but then not really do anything with then?
> > > (the driver
> >
> > You still do something with them, as they'll be linked from the rtc
> device node.
> >
> > > doesn't need them)
> >
> > The driver may use them in the future.
> > E.g. to select among X1, X3, or EXTAL, depending on availability.
> >
> 
> I'm on Geert's side here, I wouldn't rely on the bootloader to set
> everything up correctly.

Part of my hesitation to putting in the clock source selection was that
this RTC block is used in a lot of parts, and it's always the same,
except for the last 3 registers which are different from device to
device because different SoCs have different clock sources options
and ways to set them up. So, making a driver that just 'reads' the
time seemed safer/easier.
Anyway, I'll add the clock setup in if that's the general consensus.


But, before I send out an updated version, what were you thinking
my DT should look like?

Should I make a "count-source" property for user to select what clock
will be used for the actually counting?


	clocks {
		ranges;
		#address-cells = <1>;
		#size-cells = <1>;
            . . .

+		rtc_x1_clk: rtc_x1 {
+			#clock-cells = <0>;
+			compatible = "fixed-clock";
+			/* If clk present, value must be set by board to 32678 */
+			clock-frequency = <0>;
+		};
+
+		rtc_x3_clk: rtc_x3 {
+			#clock-cells = <0>;
+			compatible = "fixed-clock";
+			/* If clk present, value must be set by board to 4000000 */
+			clock-frequency = <0>;
+		};
+




+	rtc: rtc@fcff1000 {
+		compatible = "renesas,r7s72100-rtc", "renesas,sh-rtc";
+		reg = <0xfcff1000 0x2e>;
+		interrupts = <GIC_SPI 276 IRQ_TYPE_EDGE_RISING
+			      GIC_SPI 277 IRQ_TYPE_EDGE_RISING
+			      GIC_SPI 278 IRQ_TYPE_EDGE_RISING>;
+		interrupt-names = "alarm", "period", "carry";
+		clocks = <&mstp6_clks R7S72100_CLK_RTC>, <&rtc_x1_clk>,
+			  <&extal_clk> , <&rtc_x3_clk>;
+		clock-names = "fck", "rtc_x1", "extal", "rtc_x3";
+		power-domains = <&cpg_clocks>;
+		count-source = "rtc_x1";    <<<<<<< this would be in the board dts file
+		status = "disabled";
+	};


Thank you,
Chris

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