From: Mike Frysinger <vapier@gentoo.org>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH] S5P: new spi gpio bitbang driver
Date: Wed, 15 Sep 2010 14:06:32 -0400 [thread overview]
Message-ID: <201009151406.33814.vapier@gentoo.org> (raw)
In-Reply-To: <4C90565C.3000404@samsung.com>
On Wednesday, September 15, 2010 01:15:08 Donghwa Lee wrote:
> On Tuesday, September 14, 2010 20:48:11 Mike Frysinger wrote:
> > On Tuesday, September 14, 2010 03:38:11 Donghwa Lee wrote:
> >> This patch adds basic support for spi mode 0~3 by control gpio bitbang
> >> in S5P. Original name of this patch was "support spi gpio driver by
> >> control gpio bitbang". But, it had arch-specific features, S5P, so
> >> changed to this name.
> >
> > so why arent you implementing this with the common spi API ? then any of
> > the code in the tree would be able to use this spi driver without having
> > to change to your arch-specific API.
>
> I think common spi API is not appropriate for S5P arch. For example,
> arch-S5P gpio framework consists of many gpio bank structure, and gpio
> number. From here, gpio bank structures are groups of many gpio pin and
> gpio number indicates specific gpio pin of gpio bank group. To control any
> gpio pin in arch S5P, must know about gpio bank and its specific number.
> But, existing spi API is different from avobe.
> For example, spi_setup_slave() function, consists of 4 function parameter,
> bus, cs, max_hz and mode. bus and cs is specific gpio number that not gpio
> bank group. so I think it is hard to control gpio without modifying API
> format.
i dont see how this matters. implement the common gpio api and handle the
binding of a unique number to specific bank/pin there. then the spi/gpio
layer need not care about how gpios are implement on any arch.
the Blackfin port already does this. each variant has a different number of
gpio ports with a different number of pins in each bank. you can see in
arch/blackfin/include/asm/mach-*/gpio.h how we then normalize the banks/pins
into numbers from 0 to <gpio max for that arch>. then spi layer simply says
"give me gpio 12" and the gpio layer takes care of the port/pin layer.
-mike
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next prev parent reply other threads:[~2010-09-15 18:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-14 7:38 [U-Boot] [PATCH] S5P: new spi gpio bitbang driver Donghwa Lee
2010-09-14 11:48 ` Mike Frysinger
2010-09-15 5:15 ` Donghwa Lee
2010-09-15 18:06 ` Mike Frysinger [this message]
2010-09-16 2:38 ` Donghwa Lee
2010-09-16 6:17 ` Mike Frysinger
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