Re: [PATCH v4 4/8] dt-bindings: Add doc for the Ingenic TCU drivers

From: Paul Cercueil
Date: Wed Mar 28 2018 - 11:33:40 EST

Le 2018-03-27 16:46, Rob Herring a ÃcritÂ:
On Sun, Mar 18, 2018 at 12:28:57AM +0100, Paul Cercueil wrote:
Add documentation about how to properly use the Ingenic TCU
(Timer/Counter Unit) drivers from devicetree.

Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
---
.../bindings/clock/ingenic,tcu-clocks.txt | 42 ++++++++++++++++
.../bindings/interrupt-controller/ingenic,tcu.txt | 39 +++++++++++++++
.../devicetree/bindings/mfd/ingenic,tcu.txt | 56 ++++++++++++++++++++++
.../devicetree/bindings/timer/ingenic,tcu.txt | 41 ++++++++++++++++
4 files changed, 178 insertions(+)
create mode 100644 Documentation/devicetree/bindings/clock/ingenic,tcu-clocks.txt
create mode 100644 Documentation/devicetree/bindings/interrupt-controller/ingenic,tcu.txt
create mode 100644 Documentation/devicetree/bindings/mfd/ingenic,tcu.txt
create mode 100644 Documentation/devicetree/bindings/timer/ingenic,tcu.txt

v4: New patch in this series. Corresponds to V2 patches 3-4-5 with
added content.

diff --git a/Documentation/devicetree/bindings/clock/ingenic,tcu-clocks.txt b/Documentation/devicetree/bindings/clock/ingenic,tcu-clocks.txt
new file mode 100644
index 000000000000..471d27078599
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/ingenic,tcu-clocks.txt
@@ -0,0 +1,42 @@
+Ingenic SoC TCU binding
+
+The TCU is the Timer/Counter Unit present in all Ingenic SoCs. It features 8
+channels, each one having its own clock, that can be started and stopped,
+reparented, and reclocked.
+
+Required properties:
+- compatible : One of:
+ * ingenic,jz4740-tcu-clocks,
+ * ingenic,jz4770-tcu-clocks,
+ * ingenic,jz4780-tcu-clocks.
+- clocks : List of phandle & clock specifiers for clocks external to the TCU.
+ The "pclk", "rtc" and "ext" clocks should be provided.
+- clock-names : List of name strings for the external clocks.
+- #clock-cells: Should be 1.
+ Clock consumers specify this argument to identify a clock. The valid values
+ may be found in <dt-bindings/clock/ingenic,tcu.h>.
+
+Example:

Let's just put one complete example in instead of all these duplicated
and incomplete examples.

Alright.

+
+/ {
+ tcu: mfd@10002000 {
+ compatible = "ingenic,tcu", "simple-mfd", "syscon";
+ reg = <0x10002000 0x1000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0x0 0x10002000 0x1000>;
+
+ tcu_clk: clocks@10 {
+ compatible = "ingenic,jz4740-tcu-clocks";
+ reg = <0x10 0xff0>;
+
+ clocks = <&ext>, <&rtc>, <&pclk>;
+ clock-names = "ext", "rtc", "pclk";
+
+ #clock-cells = <1>;
+ };
+ };
+};
+
+For information about the top-level "ingenic,tcu" compatible node and other
+children nodes, see Documentation/devicetree/bindings/mfd/ingenic,tcu.txt.
diff --git a/Documentation/devicetree/bindings/interrupt-controller/ingenic,tcu.txt b/Documentation/devicetree/bindings/interrupt-controller/ingenic,tcu.txt
new file mode 100644
index 000000000000..7f3af2da77cd
--- /dev/null
+++ b/Documentation/devicetree/bindings/interrupt-controller/ingenic,tcu.txt
@@ -0,0 +1,39 @@
+Ingenic SoCs Timer/Counter Unit Interrupt Controller
+
+Required properties:
+
+- compatible : should be "ingenic,<socname>-tcu-intc". Valid strings are:
+ * ingenic,jz4740-tcu-intc
+ * ingenic,jz4770-tcu-intc
+ * ingenic,jz4780-tcu-intc
+- interrupt-controller : Identifies the node as an interrupt controller
+- #interrupt-cells : Specifies the number of cells needed to encode an
+ interrupt source. The value shall be 1.
+- interrupt-parent : phandle of the interrupt controller.
+- interrupts : Specifies the interrupt the controller is connected to.
+
+Example:
+
+/ {
+ tcu: mfd@10002000 {
+ compatible = "ingenic,tcu", "simple-mfd", "syscon";
+ reg = <0x10002000 0x1000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0x0 0x10002000 0x1000>;
+
+ tcu_irq: interrupt-controller@20 {
+ compatible = "ingenic,jz4740-tcu-intc";
+ reg = <0x20 0x20>;
+
+ interrupt-controller;
+ #interrupt-cells = <1>;
+
+ interrupt-parent = <&intc>;
+ interrupts = <15>;

The interrupt controller doesn't require any clocks?

It doesn't. The TCU registers not related to TCU channels are always active.

+ };
+ };
+};
+
+For information about the top-level "ingenic,tcu" compatible node and other
+children nodes, see Documentation/devicetree/bindings/mfd/ingenic,tcu.txt.
diff --git a/Documentation/devicetree/bindings/mfd/ingenic,tcu.txt b/Documentation/devicetree/bindings/mfd/ingenic,tcu.txt
new file mode 100644
index 000000000000..5742c3f21550
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/ingenic,tcu.txt
@@ -0,0 +1,56 @@
+Ingenic JZ47xx SoCs Timer/Counter Unit devicetree bindings
+----------------------------------------------------------
+
+For a description of the TCU hardware and drivers, have a look at
+Documentation/mips/ingenic-tcu.txt.
+
+The TCU is implemented as a parent node, whose role is to create the
+regmap, and child nodes for the various drivers listed in the aforementioned
+document.
+
+Required properties:
+
+- compatible: must be "ingenic,tcu", "simple-mfd", "syscon";
+- reg: Should be the offset/length value corresponding to the TCU registers
+- #address-cells: Should be <1>;
+- #size-cells: Should be <1>;
+- ranges: Should be one range for the full TCU registers area
+
+Accepted children nodes:
+- Documentation/devicetree/bindings/interrupt-controller/ingenic,tcu.txt
+- Documentation/devicetree/bindings/clock/ingenic,tcu-clocks.txt
+- Documentation/devicetree/bindings/timer/ingenic,tcu.txt
+
+
+Example:
+
+/ {
+ tcu: mfd@10002000 {
+ compatible = "ingenic,tcu", "simple-mfd", "syscon";
+ reg = <0x10002000 0x1000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0x0 0x10002000 0x1000>;
+
+ tcu_irq: interrupt-controller@20 {
+ compatible = "ingenic,jz4740-tcu-intc";
+ reg = <0x20 0x20>;

I think you should drop this node and make the parent node the interrupt
controller. That is the normal pattern where the parent node handles
all the common functions. Otherwise, there is no need to have the parent
node. You should then also drop simple-mfd as then you can control
initialization order by initializing interrupt controller before
its clients.

Alright, good idea.

+ ...
+ };
+
+ tcu_clk: clocks@10 {
+ compatible = "ingenic,jz4740-tcu-clocks";
+ reg = <0x10 0xff0>;
+ ...
+ };
+
+ tcu_timer: timer@10 {
+ compatible = "ingenic,jz4740-tcu";
+ reg = <0x10 0xff0>;

Is this copy-n-paste or you really have 2 nodes at the same address? The
latter is not valid.

I do have 2 nodes at the same address...

+ ...
+ };
+ };
+};
+
+For more information about the children node, refer to the documents listed
+above in the "Accepted children nodes" section.
diff --git a/Documentation/devicetree/bindings/timer/ingenic,tcu.txt b/Documentation/devicetree/bindings/timer/ingenic,tcu.txt
new file mode 100644
index 000000000000..f910b7e96783
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/ingenic,tcu.txt
@@ -0,0 +1,41 @@
+Ingenic JZ47xx SoCs Timer/Counter Unit driver
+---------------------------------------------
+
+Required properties:
+
+- compatible : should be "ingenic,<socname>-tcu". Valid strings are:
+ * ingenic,jz4740-tcu
+ * ingenic,jz4770-tcu
+ * ingenic,jz4780-tcu
+- interrupt-parent : phandle of the TCU interrupt controller.
+- interrupts : Specifies the interrupts the controller is connected to.
+- clocks : List of phandle & clock specifiers for the TCU clocks.
+- clock-names : List of name strings for the TCU clocks.
+
+Example:
+
+/ {
+ tcu: mfd@10002000 {
+ compatible = "ingenic,tcu", "simple-mfd", "syscon";
+ reg = <0x10002000 0x1000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0x0 0x10002000 0x1000>;
+
+ tcu_timer: timer@10 {
+ compatible = "ingenic,jz4740-tcu";
+ reg = <0x10 0xff0>;
+
+ clocks = <&tcu_clk 0>, <&tcu_clk 1>, <&tcu_clk 2>, <&tcu_clk 3>,
+ <&tcu_clk 4>, <&tcu_clk 5>, <&tcu_clk 6>, <&tcu_clk 7>;
+ clock-names = "timer0", "timer1", "timer2", "timer3",
+ "timer4", "timer5", "timer6", "timer7";
+
+ interrupt-parent = <&tcu_irq>;
+ interrupts = <0 1 2 3 4 5 6 7>;

Thinking about this some more... You simply have 8 timers (and no other
functions?) with some internal clock and irq controls for each timer. I
don't think it really makes sense to create separate clock and irq
drivers in that case. That would be like creating clock drivers for
every clock divider in timers, pwms, uarts, etc. Unless the clocks get
exposed to other parts of the system, then there is no point.

I have 8 timers with some internal clock and IRQ controls, that can be used
as PWM. But the TCU also controls the IRQ of the OS Timer (which is separate),
as well as masking of the clocks for the OS timer and the watchdog.

I thought having clean drivers for different frameworks working on the same
regmap was cleaner than having one big-ass driver handling everything.

+ };
+ };
+};
+
+For information about the top-level "ingenic,tcu" compatible node and other
+children nodes, see Documentation/devicetree/bindings/mfd/ingenic,tcu.txt.
--
2.11.0