linux-kernel - Re: [PATCH v5] GPIO: add support for 74x164 serial-in/parallel-out 8-bit shift register

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Message-ID: <AANLkTi==o4dJSfuC5HT64ZWb0f3ZMG-hjTiK8Sh9UYoR@mail.gmail.com>
Date:	Wed, 20 Oct 2010 09:52:13 +0200
From:	Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Florian Fainelli <florian@...nwrt.org>,
	David Brownell <david-b@...bell.net>, Willy Tarreau <w@....eu>,
	linux-kernel@...r.kernel.org, Samuel Ortiz <sameo@...ux.intel.com>,
	Miguel Gaio <miguel.gaio@...xo.com>,
	dbrownell@...rs.sourceforge.net, Juhos Gabor <juhosg@...nwrt.org>
Subject: Re: [PATCH v5] GPIO: add support for 74x164 serial-in/parallel-out
 8-bit shift register

On Wed, Oct 20, 2010 at 1:00 AM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Tue, 19 Oct 2010 09:26:42 +0200
> Miguel Ojeda <miguel.ojeda.sandonis@...il.com> wrote:
>
>> On Mon, Oct 18, 2010 at 9:35 PM, Florian Fainelli <florian@...nwrt.org> wrote:
>> > From: Miguel Gaio <miguel.gaio@...xo.com>
>> >
>> > This patch adds support for generic 74x164 serial-in/parallel-out 8-bits
>> > shift register. This driver can be used as a GPIO output expander.
>> >
>> ...
>> > +struct gen_74x164_chip {
>> > +       struct spi_device       *spi;
>> > +       struct gpio_chip        gpio_chip;
>> > +       struct mutex            lock;
>> > +       u8                      port_config;
>> > +};
>> ...
>> > +static void gen_74x164_set_value(struct gpio_chip *gc,
>> > +               unsigned offset, int val)
>> > +{
>> > +       struct gen_74x164_chip *chip = gpio_to_chip(gc);
>> > +       bool refresh;
>> > +
>> > +       mutex_lock(&chip->lock);
>> > +       if (val)
>> > +               chip->port_config |= (1 << offset);
>> > +       else
>> > +               chip->port_config &= ~(1 << offset);
>>
>> set_bit(), clear_bit() ?
>
> They're only to be used on `unsigned long' types, and `port_config' is
> u8.
>

Right as always! Maybe BIT()? Don't we have a {SET,CLEAR}_BIT()-like
macros somewhere?

#define SET_BIT(var,nr) (var) |= BIT((nr))
#define CLEAR_BIT(var,nr) (var) &= ~BIT((nr))
#define PUT_BIT(var,nr,value) do { \
        if ((value)) \
                SET_BIT((var), (nr)); \
        else \
                CLEAR_BIT((var), (nr)); \
} while(0)

May I make a patch and try to see who could use it? I suppose a
Coccinelle's semantic patch would be great here.
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