linux-kernel - RE: [RFC PATCH v1 03/14] usb:cdns3: Driver initialization code.

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Date:   Thu, 8 Nov 2018 11:38:23 +0000
From:   Pawel Laszczak <pawell@...ence.com>
To:     Roger Quadros <rogerq@...com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Alan Douglas <adouglas@...ence.com>,
        "jbergsagel@...com" <jbergsagel@...com>,
        "peter.chen@....com" <peter.chen@....com>,
        Pawel Jez <pjez@...ence.com>, Rahul Kumar <kurahul@...ence.com>
Subject: RE: [RFC PATCH v1 03/14] usb:cdns3: Driver initialization code.

>On 03/11/18 19:51, Pawel Laszczak wrote:
>> Patch adds core.c and core.h file that implements initialization
>> of platform driver and adds function responsible for selecting,
>> switching and running appropriate Device/Host mode.
>>
>> Patch also adds gadget.c, host.c, gadget-export.h, host-export.h.
>> These files contains templates functions used during initialization.
>> The implementation will be added in next patches.
>>
>> Signed-off-by: Pawel Laszczak <pawell@...ence.com>
>> ---
>>  drivers/usb/cdns3/Kconfig         |  20 ++
>>  drivers/usb/cdns3/Makefile        |   4 +
>>  drivers/usb/cdns3/core.c          | 373 ++++++++++++++++++++++++++++++
>>  drivers/usb/cdns3/core.h          |  88 +++++++
>>  drivers/usb/cdns3/gadget-export.h |  27 +++
>>  drivers/usb/cdns3/gadget.c        |  36 +++
>>  drivers/usb/cdns3/host-export.h   |  30 +++
>>  drivers/usb/cdns3/host.c          |  28 +++
>>  8 files changed, 606 insertions(+)
>>  create mode 100644 drivers/usb/cdns3/core.c
>>  create mode 100644 drivers/usb/cdns3/core.h
>>  create mode 100644 drivers/usb/cdns3/gadget-export.h
>>  create mode 100644 drivers/usb/cdns3/gadget.c
>>  create mode 100644 drivers/usb/cdns3/host-export.h
>>  create mode 100644 drivers/usb/cdns3/host.c
>>
>
>
><snip>
>
>> diff --git a/drivers/usb/cdns3/core.h b/drivers/usb/cdns3/core.h
>> new file mode 100644
>> index 000000000000..e7159c474308
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/core.h
>> @@ -0,0 +1,88 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Cadence USBSS DRD Driver.
>> + *
>> + * Copyright (C) 2017 NXP
>> + * Copyright (C) 2018 Cadence.
>> + *
>> + * Authors: Peter Chen <peter.chen@....com>
>> + *          Pawel Laszczak <pawell@...ence.com>
>> + */
>> +#include <linux/usb/otg.h>
>> +
>> +#ifndef __LINUX_CDNS3_CORE_H
>> +#define __LINUX_CDNS3_CORE_H
>> +
>> +struct cdns3;
>> +enum cdns3_roles {
>> +	CDNS3_ROLE_HOST = 0,
>> +	CDNS3_ROLE_GADGET,
>> +	CDNS3_ROLE_END,
>> +	CDNS3_ROLE_OTG,
>> +};
>> +
>> +/**
>> + * struct cdns3_role_driver - host/gadget role driver
>> + * @start: start this role
>> + * @stop: stop this role
>> + * @suspend: suspend callback for this role
>> + * @resume: resume callback for this role
>> + * @irq: irq handler for this role
>> + * @name: role name string (host/gadget)
>> + */
>> +struct cdns3_role_driver {
>> +	int (*start)(struct cdns3 *cdns);
>> +	void (*stop)(struct cdns3 *cdns);
>> +	int (*suspend)(struct cdns3 *cdns, bool do_wakeup);
>> +	int (*resume)(struct cdns3 *cdns, bool hibernated);
>> +	irqreturn_t (*irq)(struct cdns3 *cdns);
>
>Why does role driver need hook to irq handler?
>
>Can't each driver host or gadget handle it's respective irq
>on its own? If the same IRQ line is used it could be requested
>as a shared IRQ.

When controller is working as Device then host part of controller is held in reset and 
vice versa, so driver has restricted access to registers. 

>> +	const char *name;
>> +};
>> +
>
>cheers,
>-roger
>
>--
>Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
>Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Thanks,
Cheers,
Pawel Laszczak