[RFC v2: PATCH 1/2] dt-bindings: Document the hi3660 reset bindings

[Philipp Zabel]

Am Freitag, den 25.11.2016, 18:42 +0800 schrieb zhangfei:
> 
> On 2016年11月25日 18:25, Philipp Zabel wrote:
> > Am Donnerstag, den 24.11.2016, 18:20 +0800 schrieb zhangfei:
> >> On 2016年11月24日 17:50, Philipp Zabel wrote:
> >>> Am Donnerstag, den 24.11.2016, 17:40 +0800 schrieb zhangfei:
> >>>> On 2016年11月24日 17:26, Philipp Zabel wrote:
> >>>>> Am Mittwoch, den 23.11.2016, 16:07 +0800 schrieb Zhangfei Gao:
> >>>>>> Add DT bindings documentation for hi3660 SoC reset controller.
> >>>>>>
> >>>>>> Signed-off-by: Zhangfei Gao <zhangfei.gao at linaro.org>
> >>>>>> ---
> >>>>>>     .../bindings/reset/hisilicon,hi3660-reset.txt      | 51 ++++++++++++++++++++++
> >>>>>>     1 file changed, 51 insertions(+)
> >>>>>>     create mode 100644 Documentation/devicetree/bindings/reset/hisilicon,hi3660-reset.txt
> >>>>>>
> >>>>>> diff --git a/Documentation/devicetree/bindings/reset/hisilicon,hi3660-reset.txt b/Documentation/devicetree/bindings/reset/hisilicon,hi3660-reset.txt
> >>>>>> new file mode 100644
> >>>>>> index 0000000..250daf2
> >>>>>> --- /dev/null
> >>>>>> +++ b/Documentation/devicetree/bindings/reset/hisilicon,hi3660-reset.txt
> >>>>>> @@ -0,0 +1,51 @@
> >>>>>> +Hisilicon System Reset Controller
> >>>>>> +======================================
> >>>>>> +
> >>>>>> +Please also refer to reset.txt in this directory for common reset
> >>>>>> +controller binding usage.
> >>>>>> +
> >>>>>> +The reset controller registers are part of the system-ctl block on
> >>>>>> +hi3660 SoC.
> >>>>>> +
> >>>>>> +Required properties:
> >>>>>> +- compatible: should be
> >>>>>> +		 "hisilicon,hi3660-reset"
> >>>>>> +- #reset-cells: 1, see below
> >>>>>> +- hisi,rst-syscon: phandle of the reset's syscon.
> >>>>>> +- hisi,reset-bits: Contains the reset control register information
> >>>>>> +		  Should contain 2 cells for each reset exposed to
> >>>>>> +		  consumers, defined as:
> >>>>>> +			Cell #1 : offset from the syscon register base
> >>>>>> +			Cell #2 : bits position of the control register
> >>>>>> +
> >>>>>> +Example:
> >>>>>> +	iomcu: iomcu at ffd7e000 {
> >>>>>> +		compatible = "hisilicon,hi3660-iomcu", "syscon";
> >>>>>> +		reg = <0x0 0xffd7e000 0x0 0x1000>;
> >>>>>> +	};
> >>>>>> +
> >>>>>> +	iomcu_rst: iomcu_rst_controller {
> >>>>> This should be
> >>>>> 	iomcu_rst: reset-controller {
> >>>>>
> >>>>>> +		compatible = "hisilicon,hi3660-reset";
> >>>>>> +		#reset-cells = <1>;
> >>>>>> +		hisi,rst-syscon = <&iomcu>;
> >>>>>> +		hisi,reset-bits = <0x20 0x8		/* 0: i2c0 */
> >>>>>> +				   0x20 0x10		/* 1: i2c1 */
> >>>>>> +				   0x20 0x20		/* 2: i2c2 */
> >>>>>> +				   0x20 0x8000000>;	/* 3: i2c6 */
> >>>>>> +	};
> >>>>> The reset lines are controlled through iomcu bits, is there a reason not
> >>>>> to put the iomcu_rst node inside the iomcu node? That way the
> >>>>> hisi,rst-syscon property could be removed and the syscon could be
> >>>>> retrieved via the reset-controller parent node.
> >>>> iomcu is common registers, controls clock and reset, etc.
> >>>> So we use syscon, without mapping the registers everywhere.
> >>>> It is common case in hisilicon, same in hi6220.
> >>>>
> >>>> Also the #clock-cells and #reset-cells can not be put in the same node,
> >>>> if they are both using probe, since reset_probe will not be called.
> >>>>
> >>>> So we use hisi,rst-syscon as a general solution.
> >>> What I meant is this:
> >>>
> >>> 	iomcu: iomcu at ffd7e000 {
> >>> 		compatible = "hisilicon,hi3660-iomcu", "syscon", "simple-mfd";
> >>> 		reg = <0x0 0xffd7e000 0x0 0x1000>;
> >> #clock-cells = <1>;
> >>
> >> In my test, if there add #clock-cells = <1>, reset_probe will not be
> >> called any more.
> >> Since clk_probe is called first.
> >> No matter iomcu_rst is child node or not.
> > I don't understand this, does the clock driver bind to the iomcu node
> > using CLK_OF_DECLARE_DRIVER(..., "hisilicon,hi3660-iomcu", ...)?
> 
> This method:CLK_OF_DECLARE_DRIVER is not prefered in clock,
> and we have to use probe instead, to make all driver build as modules as 
> possible.
> 
> For example hi3660.
> static struct platform_driver hi3660_clk_driver = {
>          .probe          = hi3660_clk_probe,
>          .driver         = {
>                  .name   = "hi3660-clk",
>                  .of_match_table = hi3660_clk_match_table,
>          },
> };

hi3660_clk_match_table contains the "hisilicon,hi3660-iomcu" compatible?
If so, you could call
	of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
from hi3660_clk_probe instead of using "simple-mfd" to probe the iomcu
node's children.

regards
Philipp