linux-kernel - Re: [PATCH 0/2] FTDI CBUS GPIO support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150623092219.GA28202@localhost>
Date:	Tue, 23 Jun 2015 11:22:19 +0200
From:	Johan Hovold <johan@...nel.org>
To:	Stefan Agner <stefan@...er.ch>
Cc:	Johan Hovold <johan@...nel.org>, linus.walleij@...aro.org,
	gnurou@...il.com, grant.likely@...retlab.ca,
	gregkh@...uxfoundation.org, x-linux@...ra-silbe.de,
	hachti@...hti.de, linux-usb@...r.kernel.org,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	Johan Hovold <jhovold@...il.com>
Subject: Re: [PATCH 0/2] FTDI CBUS GPIO support

On Mon, Jun 22, 2015 at 10:11:35PM +0200, Stefan Agner wrote:
> On 2015-06-22 19:26, Johan Hovold wrote:

> > Instead, hang the gpio chip directly off the usb interface (not the
> > port), add a new config option, and keep the gpio implementation under
> > drivers/usb/serial (possibly in its own file ftdi_sio-gpio.c).
> 
> Agreed sounds like a good plan. Will try this approach in v2.
> 
> Except I don't think hanging it directly to the USB interface is the
> right thing to do.
> 
> Looking at the block diagram of FT232R or FT232H, the CBUS pins seem to
> be part of the UART/FIFO controller. And I think the dual UART FT2232D
> actually supports controlling the CBUS pins of the two UART controllers
> individually, at least the block diagram thereof suggests so.

The port is a Linux abstraction, and for FTDI we happen to have exactly
one port child device per USB interface. As I see it, the gpio
controller for the CBUS pins should be a sibling rather than a child
device to the port.

Note that we'd still have two gpio-controllers on FT2232D (one per USB
interface).

I'm aware that this requires some restructuring of the ftdi_sio-driver
(e.g. the device type and ftdi-interface number should be a feature of
the usb-serial rather than usb-serial-port device).

Thanks,
Johan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/