LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: William Breathitt Gray <vilhelm.gray@gmail.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Linux-Arch <linux-arch@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 0/7] Introduce the for_each_set_port_word macro
Date: Mon, 14 May 2018 08:57:54 -0400	[thread overview]
Message-ID: <20180514125743.GA20325@sophia> (raw)
In-Reply-To: <CAHp75Vf8TLhj07VKeDdvzqHvViHqgRkd6=n2hZR_yY7in52SHA@mail.gmail.com>

On Sun, May 13, 2018 at 06:11:45PM +0300, Andy Shevchenko wrote:
>On Tue, May 8, 2018 at 4:26 PM, William Breathitt Gray
><vilhelm.gray@gmail.com> wrote:
>
>> While adding GPIO get_multiple/set_multiple callback support for various
>> drivers, I noticed a pattern of looping manifesting that would be useful
>> standardized as a macro.
>>
>> This patchset introduces the for_each_set_port_word macro and utilizes
>> it in several GPIO drivers. The for_each_set_port_word macro facilitates
>> a for-loop syntax that iterates over entire groups of set bits at a
>> time.
>>
>> For example, suppose you would like to iterate over a 16-bit integer 4
>> bits at a time, skipping over 4-bit groups with no set bit, where XXXX
>> represents the current 4-bit group:
>>
>>     Example:        1011 1110 0000 1111
>>     First loop:     1011 1110 0000 XXXX
>
>>     Second loop:    1011 XXXX 0000 1111
>
>8-bit itteration. Is it correct?

This case is 4-bit iteration for the sake of example, but the idea is
to have the for_each_set_port_word macro to be capable of 8-bit
iteration, as well as any other number of bits, as specified by the
port_size parameter.

>
>>     Third loop:     XXXX 1110 0000 1111
>
>Looking at the example above I highly recommend to introduce some test
>cases for your helper function.
>
>Consider extending lib/test_bitmap.c for this purpose.

That's a good idea. I'll add in some test cases to lib/test_bitmap.c to
help check the implementation of these functions and macro.

William Breathitt Gray

>
>>
>> Each iteration of the loop returns the next 4-bit group that has at
>> least one set bit.
>>
>> The for_each_set_port_word macro has six parameters:
>>
>>     * port_word: set to current port word index for the iteration
>>     * word_index: set to current bitmap word index for the iteration
>>     * word_offset: bits offset of the found port word in the bitmap word
>>     * bits: bitmap to search within
>>     * size: bitmap size in number of port words
>>     * port_size: port word size in number of bits
>>
>> The port_size argument can be an arbitrary number of bits and is not
>> required to be a multiple of 2.
>>
>> I've called the group of bits a "port word" which may be a confusing
>> naming convention; I was afraid calling that them a "group" may be too
>> vague. Should a different name be chosen; what would you suggest?
>>
>> This patchset was rebased on top of the following three commits:
>>
>>     * commit aaf96e51de11 ("gpio: pci-idio-16: Fix port memory offset for get_multiple callback")
>>     * commit 304440aa96c6 ("gpio: pcie-idio-24: Fix port memory offset for get_multiple/set_multiple callbacks")
>>     * commit e026646c178d ("gpio: pcie-idio-24: Fix off-by-one error in get_multiple loop")
>>
>> William Breathitt Gray
>>
>> William Breathitt Gray (7):
>>   bitops: Introduce the for_each_set_port_word macro
>>   gpio: 104-dio-48e: Utilize for_each_set_port_word macro
>>   gpio: 104-idi-48: Utilize for_each_set_port_word macro
>>   gpio: gpio-mm: Utilize for_each_set_port_word macro
>>   gpio: ws16c48: Utilize for_each_set_port_word macro
>>   gpio: pci-idio-16: Utilize for_each_set_port_word macro
>>   gpio: pcie-idio-24: Utilize for_each_set_port_word macro
>>
>>  drivers/gpio/gpio-104-dio-48e.c   |  67 +++++---------------
>>  drivers/gpio/gpio-104-idi-48.c    |  32 ++--------
>>  drivers/gpio/gpio-gpio-mm.c       |  67 +++++---------------
>>  drivers/gpio/gpio-pci-idio-16.c   |  67 ++++++--------------
>>  drivers/gpio/gpio-pcie-idio-24.c  | 102 +++++++++++-------------------
>>  drivers/gpio/gpio-ws16c48.c       |  66 +++++--------------
>>  include/asm-generic/bitops/find.h |  26 ++++++++
>>  include/linux/bitops.h            |   9 +++
>>  lib/find_bit.c                    |  28 ++++++++
>>  9 files changed, 172 insertions(+), 292 deletions(-)
>>
>> --
>> 2.17.0
>>
>
>
>
>-- 
>With Best Regards,
>Andy Shevchenko

      reply	other threads:[~2018-05-14 12:58 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-08 13:26 William Breathitt Gray
2018-05-08 13:26 ` [PATCH v2 1/7] bitops: " William Breathitt Gray
2018-05-13 15:06   ` Andy Shevchenko
2018-05-14 13:04     ` William Breathitt Gray
2018-05-14 17:08       ` Andy Shevchenko
2018-05-08 13:27 ` [PATCH v2 2/7] gpio: 104-dio-48e: Utilize " William Breathitt Gray
2018-05-08 13:27 ` [PATCH v2 3/7] gpio: 104-idi-48: " William Breathitt Gray
2018-05-08 13:27 ` [PATCH v2 4/7] gpio: gpio-mm: " William Breathitt Gray
2018-05-08 13:27 ` [PATCH v2 5/7] gpio: ws16c48: " William Breathitt Gray
2018-05-08 13:28 ` [PATCH v2 6/7] gpio: pci-idio-16: " William Breathitt Gray
2018-05-08 13:28 ` [PATCH v2 7/7] gpio: pcie-idio-24: " William Breathitt Gray
2018-05-13 15:11 ` [PATCH v2 0/7] Introduce the " Andy Shevchenko
2018-05-14 12:57   ` William Breathitt Gray [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180514125743.GA20325@sophia \
    --to=vilhelm.gray@gmail.com \
    --cc=andy.shevchenko@gmail.com \
    --cc=linus.walleij@linaro.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-gpio@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: [PATCH v2 0/7] Introduce the for_each_set_port_word macro' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).