linux-kernel - Re: [PATCH 1/4] usb: phy: add a new driver for usb3 phy

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Date:	Fri, 12 Oct 2012 14:38:26 +0530
From:	kishon <kishon@...com>
To:	Tony Lindgren <tony@...mide.com>, Rajendra Nayak <rnayak@...com>
CC:	<grant.likely@...retlab.ca>, <rob.herring@...xeda.com>,
	<rob@...dley.net>, <linux@....linux.org.uk>, <balbi@...com>,
	<linux-usb@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<devicetree-discuss@...ts.ozlabs.org>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	Moiz Sonasath <m-sonasath@...com>
Subject: Re: [PATCH 1/4] usb: phy: add a new driver for usb3 phy

Hi Tony,

On Thursday 11 October 2012 06:29 AM, Tony Lindgren wrote:
> Hi,
>
> * Kishon Vijay Abraham I <kishon@...com> [120919 04:32]:
>> Added a driver for usb3 phy that handles the interaction between usb phy
>> device and dwc3 controller.
>>
>> This also includes device tree support for usb3 phy driver and
>> the documentation with device tree binding information is updated.
>>
>> Currently writing to control module register is taken care in this
>> driver which will be removed once the control module driver is in place.
>
> You may be able to set up the control module register with one
> of the following Linux standard frameworks:
>
> 1. Fixed regulator defined in mach-omap2/control.c

Is it control.c?
>
>     In this case the PHY driver can pick up the regulator by name.

Do you mean we have to define something like fixed_voltage_config 
defined in board-4430sdp.c?
 From whatever I could make out from regulator/fixed.c, 
enabling/disabling of regulator is done using only gpio. I'm not sure 
how we can use that to write to control module register.
>
> 2. A mux mapped with pinctrl framework using pinctrl-single,bits
>     binding
>
>     And in this case the PHY driver can request the named pinctrl
>     states like "enabled" and "disabled".
>
>> --- a/Documentation/devicetree/bindings/usb/usb-phy.txt
>> +++ b/Documentation/devicetree/bindings/usb/usb-phy.txt
>> @@ -15,3 +15,21 @@ usb2phy@...ad080 {
>>   	reg = <0x4a0ad080 0x58>,
>>   	      <0x4a002300 0x4>;
>>   };
>
> The comments also apply to the omap_usb2.c driver for
> 0x4a002300 above.
>
>> +
>> +OMAP USB3 PHY
>> +
>> +Required properties:
>> + - compatible: Should be "ti,omap-usb3"
>> + - reg : Address and length of the register set for the device. Also
>> +add the address of control module phy power register until a driver for
>> +control module is added
>> +
>> +This is usually a subnode of ocp2scp to which it is connected.
>> +
>> +usb3phy@...84400 {
>> +	compatible = "ti,omap-usb3";
>> +	reg = <0x0x4a084400 0x80>,
>> +	      <0x4a084800 0x64>,
>> +	      <0x4a084c00 0x40>,
>> +	      <0x4a002370 0x4>;
>> +};
>
> And register 0x4a002370 here. Care to post some info what the
> 0x4a002370 register bits do? Is that same as CONTROL_DEV_CONF
> on omap4, or does it have other bits there too?

It's CONTROL_PHY_POWER_USB register and it's structure looks like this.
31:22 USB_PWRCTL_CLK_FREQ
21:14 USB_PWRCTL_CLK_CMD
13:0 RESERVED

CLK_CMD takes values to power up/down the TX and RX in various combinations.

And CLK_FREQ takes values for clock configuration.

Thanks
Kishon
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