[PATCH 02/48] ARM: at91: Document new TCB bindings
From: robh@kernel.org (Rob Herring)
Date: 2016-06-14 21:47:42
Also in:
linux-devicetree, linux-pwm, lkml
On Sat, Jun 11, 2016 at 12:03:05AM +0200, Alexandre Belloni wrote:
The current binding for the TCB is not flexible enough for some use cases and prevents proper utilization of all the channels. Cc: Daniel Lezcano <redacted> Cc: Thierry Reding <redacted> Cc: linux-pwm at vger.kernel.org Cc: Rob Herring <robh+dt@kernel.org> Cc: devicetree at vger.kernel.org Signed-off-by: Alexandre Belloni <redacted> --- .../devicetree/bindings/arm/atmel-at91.txt | 32 ----------- .../devicetree/bindings/mfd/atmel-tcb.txt | 62 ++++++++++++++++++++++ .../devicetree/bindings/pwm/atmel-tcb-pwm.txt | 12 +++-- 3 files changed, 69 insertions(+), 37 deletions(-) create mode 100644 Documentation/devicetree/bindings/mfd/atmel-tcb.txt
[...]
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diff --git a/Documentation/devicetree/bindings/mfd/atmel-tcb.txt b/Documentation/devicetree/bindings/mfd/atmel-tcb.txt new file mode 100644 index 000000000000..48196752c78f --- /dev/null +++ b/Documentation/devicetree/bindings/mfd/atmel-tcb.txt@@ -0,0 +1,62 @@ +* Device tree bindings for Atmel Timer Counter Blocks +- compatible: Should be "atmel,<chip>-tcb", "simple-mfd", "syscon". + <chip> can be "at91rm9200" or "at91sam9x5" +- reg: Should contain registers location and length +- #address-cells: has to be 1 +- #size-cells: has to be 0 +- interrupts: Should contain all interrupts for the TC block + Note that you can specify several interrupt cells if the TC + block has one interrupt per channel. +- clock-names: tuple listing input clock names. + Required elements: "t0_clk", "slow_clk" + Optional elements: "t1_clk", "t2_clk" +- clocks: phandles to input clocks.
What is the order of clocks?
+ +The TCB can expose multiple subdevices: + * a clocksource and clockevent device
No. These compatible names are linuxisms. Describe features of the timers to be able to select which timer to use if you need to pick certain timers. For example, interrupt capability could be used to select the clkevt.
+ - compatible: Should be "atmel,tcb-clksrc"
+ - reg: Should contain the TCB channels to be used. If the
+ counter width is 16 bits (at91rm9200-tcb), two consecutive
+ channels are needed. Else, only one channel will be used.
+
+ * a clockevent device
+ - compatible: Should be "atmel,tcb-clkevt"
+ - reg: Should contain the TCB channel to be used
+
+ * a PWM chip: see ../pwm/atmel-tcb-pwm.txt
+
+Examples:
+
+One interrupt per TC block:
+ tcb0: timer at fff7c000 {
+ compatible = "atmel,at91rm9200-tcb", "simple-mfd", "syscon";
+ #address-cells = <1>;
+ #size-cells = <0>;
+ reg = <0xfff7c000 0x100>;
+ interrupts = <18 4>;
+ clocks = <&tcb0_clk>;
+ clock-names = "t0_clk";Missing slow_clk
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+ + timer at 0 { + compatible = "atmel,tcb-clksrc"; + reg = <0>, <1>; + }; + + timer at 2 { + compatible = "atmel,tcb-clkevt"; + reg = <2>; + }; + }; + +One interrupt per TC channel in a TC block: + tcb1: timer at fffdc000 { + compatible = "atmel,at91rm9200-tcb", "simple-mfd", "syscon"; + #address-cells = <1>; + #size-cells = <0>; + reg = <0xfffdc000 0x100>; + interrupts = <26 4>, <27 4>, <28 4>; + clocks = <&tcb1_clk>; + clock-names = "t0_clk"; + }; + +diff --git a/Documentation/devicetree/bindings/pwm/atmel-tcb-pwm.txt b/Documentation/devicetree/bindings/pwm/atmel-tcb-pwm.txt index 8031148bcf85..ab8fbd5ba184 100644 --- a/Documentation/devicetree/bindings/pwm/atmel-tcb-pwm.txt +++ b/Documentation/devicetree/bindings/pwm/atmel-tcb-pwm.txt@@ -2,15 +2,17 @@ Atmel TCB PWM controller Required properties: - compatible: should be "atmel,tcb-pwm" +- reg: tcb channel to use. Each channel can export 2 PWMs
Is there a difference in channels? If not, then this compatible should go.
- #pwm-cells: should be 3. See pwm.txt in this directory for a description of
the cells format. The only third cell flag supported by this binding is
PWM_POLARITY_INVERTED.
-- tc-block: The Timer Counter block to use as a PWM chip.
Example:
-pwm {
- compatible = "atmel,tcb-pwm";
- #pwm-cells = <3>;
- tc-block = <1>;
+tcb0: timer at f800c000 {
+ pwm at 0 {
+ compatible = "atmel,tcb-pwm";
+ reg = <0>;
+ #pwm-cells = <3>;
+ };
};
--
2.8.1