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Message-ID: <45a44e480812302102i2fe91abbt553fa1168d458c93@mail.gmail.com>
Date: Wed, 31 Dec 2008 00:02:04 -0500
From: "Jaya Kumar" <jayakumar.lkml@gmail.com>
To: "Robin Getz" <rgetz@blackfin.uclinux.org>
Subject: Re: [RFC 2.6.27 1/1] gpiolib: add support for batch set of pins
Cc: "David Brownell" <david-b@pacbell.net>,
       "Eric Miao" <eric.y.miao@gmail.com>, "Sam Ravnborg" <sam@ravnborg.org>,
       "Eric Miao" <eric.miao@marvell.com>,
       "Haavard Skinnemoen" <hskinnemoen@atmel.com>,
       "Philipp Zabel" <philipp.zabel@gmail.com>,
       "Russell King" <rmk@arm.linux.org.uk>,
       "Ben Gardner" <bgardner@wabtec.com>, "Greg KH" <greg@kroah.com>,
       linux-arm-kernel@lists.arm.linux.org.uk,
       linux-fbdev-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
       linux-embedded@vger.kernel.org
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	 <200812281346.56703.rgetz@blackfin.uclinux.org>
	 <200812291156.12230.david-b@pacbell.net>
	 <200812302355.45193.rgetz@blackfin.uclinux.org>
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On Tue, Dec 30, 2008 at 11:58 PM, Jaya Kumar <jayakumar.lkml@gmail.com> wrote:
> On Tue, Dec 30, 2008 at 11:55 PM, Robin Getz <rgetz@blackfin.uclinux.org> wrote:
>> Yeah, I hadn't thought about spanning more than one gpio_chip. That's a good
>> point.
>
> The currently posted code already supports spanning more than one gpio_chip.

and btw, that was because the use case needed to span 2, since it
started at 58 and was 16 bits long on a platform where ngpio == 32.
this was explained at the start of the thread.

>
> +       do {
> +               chip = gpio_to_chip(gpio + i);
> +               WARN_ON(extra_checks && chip->can_sleep);
> +
> +               if (!chip->set_bus) {
> +                       while (((gpio + i) < (chip->base + chip->ngpio))
> +                               && bitwidth) {
> +                               value = values & (1 << i);
> +                               chip->set(chip, gpio + i - chip->base, value);
> +                               i++;
> +                               bitwidth--;
> +                       }
> +               } else {
> +                       value = values >> i; /* shift off the used stuff */
> +                       remwidth = ((chip->base + (int) chip->ngpio) -
> +                                       ((int) gpio + i));
> +                       width = min(bitwidth, remwidth);
> +
> +                       chip->set_bus(chip, gpio + i - chip->base, value,
> +                                       width);
> +                       i += width;
> +                       bitwidth -= width;
> +               }
> +       } while (bitwidth);
>
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