On 2016/8/1 20:43, Mark Rutland wrote:

On Mon, Aug 01, 2016 at 09:42:08AM +0800, Jian Yuan wrote:

quoted

From: yuanjian <redacted>

Add pwm driver for HiSilicon BVT SOCs

Reviewed-by: Jiancheng Xue <redacted>
Signed-off-by: Jian Yuan <redacted>
---
 .../devicetree/bindings/pwm/pwm-hibvt.txt          |  18 ++
 drivers/pwm/Kconfig                                |  10 +
 drivers/pwm/Makefile                               |   1 +
 drivers/pwm/pwm-hibvt.c                            | 272 +++++++++++++++++++++
 4 files changed, 301 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/pwm-hibvt.txt
 create mode 100644 drivers/pwm/pwm-hibvt.c

diff --git a/Documentation/devicetree/bindings/pwm/pwm-hibvt.txt b/Documentation/devicetree/bindings/pwm/pwm-hibvt.txt
new file mode 100644
index 0000000..4efd83e
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/pwm-hibvt.txt

@@ -0,0 +1,18 @@
+Hisilicon PWM controller
+
+Required properties:
+ - compatible: should be "hisilicon,hibvt-pwm" and one of the following:
+			"hisilicon,hi3516cv300-pwm".

I take it "hisilicon,hibvt-pwm" is the fallback entry.

It would be good to note that explicitly.

I do not understand what the fallback entry means.

"hisilicon,hibvt-pwm" is a general compatible string, which is available for most HiSilicon BVT SOCs.
Howerver, "hisilicon,hi3516cv300-pwm" is specially for hi3516cv300.

Maybe I should note the compatible string as described above, right?

quoted

+ - reg: physical base address and length of the controller's registers.
+ - clocks: phandle and clock specifier of the PWM reference clock.
+ - resets: offset address and offset bit for reset or unreset of the controller.
+ - pwm-nums: pwm number of the controller.

This should be 'num-pwms'.

I assume this is the number of PWMs exposed by this controller. Is this
not probeable, or dicoverable based on the compatible string?

How does this vary in practice?

"pwm-nums" means the maximum number of PWMS that this controller can support, which is the hardware capability.
E.g.,HI3516CV300 PWM controller supports 4 PWM, while other chips support 8 PWM.

I agree that the PWM number is probeable based on the compatible string. I shall change it, thanks.

quoted

+
+Example:
+	pwm: pwm@12130000 {
+		compatible = "hisilicon,hibvt-pwm";

This is missing "hisilicon,hi3516cv300-pwm" as per the requirements of
the binding.

Ok, it's right. I'll fix it in next v2 patch.

quoted

+		reg = <0x12130000 0x10000>;
+		clocks = <&crg_ctrl HI3516CV300_PWM_CLK>;
+		resets = <&crg_ctrl 0x38 0>;
+		pwm-nums = <4>;
+	};

Thanks,
Mark.

.

Thanks,
Jian.