Re: [PATCH v2 2/3] dt-bindings: clk: add documentation for the SiFive PRCI driver
From: Rob Herring <robh@kernel.org>
Date: 2018-10-24 18:48:02
Also in:
linux-clk, linux-riscv, lkml
On Sat, Oct 20, 2018 at 06:50:23AM -0700, Paul Walmsley wrote:
quoted hunk ↗ jump to hunk
Add DT binding documentation for the Linux driver for the SiFive PRCI clock & reset control IP block, as found on the SiFive FU540 chip. Cc: Michael Turquette <mturquette@baylibre.com> Cc: Stephen Boyd <sboyd@kernel.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Palmer Dabbelt <redacted> Cc: Megan Wachs <redacted> Cc: linux-clk@vger.kernel.org Cc: devicetree@vger.kernel.org Cc: linux-riscv@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Paul Walmsley <redacted> Signed-off-by: Paul Walmsley <paul@pwsan.com> --- v2: remove out-of-date example, add documentation for the compatible string and for the required PCB clock nodes .../bindings/clock/sifive/fu540-prci.txt | 43 +++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 Documentation/devicetree/bindings/clock/sifive/fu540-prci.txtdiff --git a/Documentation/devicetree/bindings/clock/sifive/fu540-prci.txt b/Documentation/devicetree/bindings/clock/sifive/fu540-prci.txt new file mode 100644 index 000000000000..d7c1e83fa5ed --- /dev/null +++ b/Documentation/devicetree/bindings/clock/sifive/fu540-prci.txt@@ -0,0 +1,43 @@ +SiFive FU540 PRCI bindings + +On the FU540 family of SoCs, most system-wide clock and reset integration +is via the PRCI IP block. + +Required properties: +- compatible: Should be "sifive,<chip>-prci<version>". As of the time this + file was written, only one value is supported: + "sifive,fu540-c000-prci0"
What happens with this depends on the discussion on the other bindings. Though here you are inconsistent without a fallback. Of course, I've never seen a clock controller be the same across SoCs.
+- reg: Should describe the PRCI's register target physical address region
+- clocks: Should point to the hfclk device tree node and the rtcclk
+ device tree node. The RTC clock here is not a time-of-day clock,
+ but is instead a high-stability clock source for system timers
+ and cycle counters.
+- #clock-cells: Should be <1>
+
+The clock consumer should specify the desired clock via the clock ID
+macros defined in include/linux/clk/sifive-fu540-prci.h. These macros
+begin with PRCI_CLK_.
+
+The hfclk and rtcclk nodes are required, and represent physical
+crystals or resonators located on the PCB.
+
+Examples:
+
+hfclk: hfclk {
+ #clock-cells = <0>;
+ compatible = "fixed-clock";
+ clock-frequency = <33333333>;
+ clock-output-names = "hfclk";
+};
+rtcclk: rtcclk {
+ #clock-cells = <0>;
+ compatible = "fixed-clock";
+ clock-frequency = <1000000>;
+ clock-output-names = "rtcclk";
+};
+prci0: prci@10000000 {clock-controller@...
+ compatible = "sifive,fu540-c000-prci0"; + reg = <0x0 0x10000000 0x0 0x1000>; + clocks = <&hfclk>, <&rtcclk>; + #clock-cells = <1>; +}; -- 2.19.1