Re: [PATCH 3/6] dt-bindings: mtu3: add devicetree bindings

[chunfeng yun]

Hi,

On Wed, 2016-05-11 at 09:54 -0500, Rob Herring wrote:
> On Tue, May 10, 2016 at 04:23:31PM +0800, Chunfeng Yun wrote:
> > add a DT binding doc for MediaTek USB3 DRD driver
> > 
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
> > ---
> >  Documentation/devicetree/bindings/usb/mtu3.txt |   86 ++++++++++++++++++++++++
> >  1 file changed, 86 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/usb/mtu3.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/usb/mtu3.txt b/Documentation/devicetree/bindings/usb/mtu3.txt
> > new file mode 100644
> > index 0000000..ff142a5
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/usb/mtu3.txt
> > @@ -0,0 +1,86 @@
> > +The device node for Mediatek USB3.0 DRD controller
> > +
> > +Required properties:
> > + - compatible : should be "mediatek,mt8173-mtu3"
> > + - reg : specifies physical base address and size of the registers
> > + - reg-names: should be "mac" for device IP and "ippc" for IP port control
> > + - interrupts : interrupt used by the device IP
> > + - power-domains : a phandle to USB power domain node to control USB's
> > +	mtcmos
> > + - vusb33-supply : regulator of USB avdd3.3v
> > + - clocks : a list of phandle + clock-specifier pairs, one for each
> > +	entry in clock-names
> > + - clock-names : must contain "sys_ck" for clock of controller;
> > +	"wakeup_deb_p0" and "wakeup_deb_p1" are optional, they are
> > +	depends on "mediatek,enable-wakeup"
> > + - phys : a list of phandle + phy specifier pairs
> 
> How many?
It depends on implementation; there are two phys on mt8173 platform

> 
> > + - dr_mode : should be one of "host", "peripheral" or "otg",
> > +	refer to usb/generic.txt
> > +
> > +Optional properties:
> > + - #address-cells, #size-cells : should be '2' if the device has sub-nodes
> > +	with 'reg' property
> > + - ranges : allows valid 1:1 translation between child's address space and
> > +	parent's address space
> > + - extcon : external connector for vbus and idpin changes detection, needed
> > +	when supports dual-role mode.
> > + - vbus-supply : reference to the VBUS regulator, needed when supports
> > +	dual-role mode.
> > + - pinctl-names : a pinctrl state named "default" must be defined,
> > +	"id_float" and "id_ground" are optinal which depends on
> > +	"mediatek,enable-manual-drd"
> > + - pinctrl-0 : pin control group
> > +	See: Documentation/devicetree/bindings/pinctrl/pinctrl-binding.txt
> > +
> > + - maximum-speed : valid arguments are "super-speed", "high-speed" and
> > +	"full-speed"; refer to usb/generic.txt
> > + - mediatek,enable-wakeup : supports ip sleep wakeup used by host mode
> > + - mediatek,syscon-wakeup : phandle to syscon used to access USB wakeup
> > +	control register, it depends on "mediatek,enable-wakeup".
> 
> There is a standard wake-up source binding. That assumes asserting the 
> device's irq (or one of the irqs) will cause wake-up.
> 
> The syscon-wakeup should probably get implemented as a stacked 
> irqdomain.
> 
Syscon-wakeup is used to control which usb wakeup mode we want to use,
such as ip sleep(usb suspend/resume signal), or line state(changes of D
+/-). And it doesn't trigger device's interrupt, so can't implement
device's irq to wake up system.

> > + - mediatek,enable-manual-drd : supports manual dual-role switch by sysfs
> > +	interface; only used when receptacle is TYPE-A and also wants to support
> > +	dual-role mode.
> 
> sysfs is a Linux detail that doesn't apply to the binding. Does the 
> property mean "the IP block supports or doesn't support switching"  or 
> "I want to enable switching feature". Only the former belongs in DT.
> 
It is the former case, and has little relation with sysfs interface.
I will modify it later, sorry for my unclear description. 

> As far as the sysfs interface, it should be generic, not Mediatek 
> specific.
> 
> > +
> > +Sub-nodes:
> > +The xhci should be added as subnode to mtu3 as shown in the following example
> > +if host mode is enabled. The DT binding details of xhci can be found in:
> > +Documentation/devicetree/bindings/usb/mt8173-xhci.txt
> 
> Is XHCI really a sub-block? It seems mostly independent.
Yes, the mtk's usb3 controller contains three parts: mu3d IP, xHCI IP
and IPPC (IP power and control).

> 
> > +
> > +Example:
> > +ssusb: usb@11271000 {
> > +	compatible = "mediatek,mt8173-mtu3";
> > +	reg = <0 0x11271000 0 0x3000>,
> > +	      <0 0x11280700 0 0x0100>;
> > +	reg-names = "mac", "ippc";
> > +	interrupts = <GIC_SPI 64 IRQ_TYPE_LEVEL_LOW>;
> > +	phys = <&phy_port0 PHY_TYPE_USB3>,
> > +	       <&phy_port1 PHY_TYPE_USB2>;
> > +	power-domains = <&scpsys MT8173_POWER_DOMAIN_USB>;
> > +	clocks = <&topckgen CLK_TOP_USB30_SEL>,
> > +		 <&pericfg CLK_PERI_USB0>,
> > +		 <&pericfg CLK_PERI_USB1>;
> > +	clock-names = "sys_ck",
> > +		      "wakeup_deb_p0",
> > +		      "wakeup_deb_p1";
> > +	vusb33-supply = <&mt6397_vusb_reg>;
> > +	vbus-supply = <&usb_p0_vbus>;
> > +	extcon = <&extcon_usb>;
> > +	dr_mode = "otg";
> > +	mediatek,enable-wakeup;
> > +	mediatek,syscon-wakeup = <&pericfg>;
> > +	#address-cells = <2>;
> > +	#size-cells = <2>;
> > +	ranges;
> > +	status = "disabled";
> > +
> > +	usb_host: xhci@11270000 {
> > +		compatible = "mediatek,mt8173-xhci";
> > +		reg = <0 0x11270000 0 0x1000>;
> > +		interrupts = <GIC_SPI 115 IRQ_TYPE_LEVEL_LOW>;
> > +		power-domains = <&scpsys MT8173_POWER_DOMAIN_USB>;
> > +		clocks = <&topckgen CLK_TOP_USB30_SEL>;
> > +		clock-names = "sys_ck";
> > +		vusb33-supply = <&mt6397_vusb_reg>;
> > +		status = "disabled";
> > +	};
> > +};
> > -- 
> > 1.7.9.5
> >