Add DT binding documentation for the Linux driver for the SiFive PRCI clock & reset control IP block, as found on the SiFive FU540 chip.
This version includes changes requested by Stephen Boyd <[email protected]> and Rob Herring <[email protected]>, and fixes some errors in the initial version. Signed-off-by: Paul Walmsley <[email protected]> Signed-off-by: Paul Walmsley <[email protected]> Cc: Michael Turquette <[email protected]> Cc: Stephen Boyd <[email protected]> Cc: Rob Herring <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Palmer Dabbelt <[email protected]> Cc: Megan Wachs <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] --- .../bindings/clock/sifive/fu540-prci.txt | 46 +++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 Documentation/devicetree/bindings/clock/sifive/fu540-prci.txt diff --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..349808f4fb8c --- /dev/null +++ b/Documentation/devicetree/bindings/clock/sifive/fu540-prci.txt @@ -0,0 +1,46 @@ +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". Only one value is + supported: "sifive,fu540-c000-prci" +- 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/dt-bindings/clock/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. These nodes should be present +underneath /, rather than /soc. + +Examples: + +/* under /, in PCB-specific DT data */ +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"; +}; + +/* under /soc, in SoC-specific DT data */ +prci: clock-controller@10000000 { + compatible = "sifive,fu540-c000-prci"; + reg = <0x0 0x10000000 0x0 0x1000>; + clocks = <&hfclk>, <&rtcclk>; + #clock-cells = <1>; +}; -- 2.20.1
