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Subject[PATCH v3 0/8] Introduce the for_each_set_clump macro
Date
Changes in v3:
- Replace "port word" nomenclature with "clump"
- Add test cases for for_each_set_clump in lib/test_bitmap.c
- Move kernel-doc comment for find_next_clump above C definition

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_clump macro and utilizes it in
several GPIO drivers. The for_each_set_clump 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
Third loop: XXXX 1110 0000 1111

Each iteration of the loop returns the next 4-bit group that has at
least one set bit.

The for_each_set_clump macro has six parameters:

* clump: set to current clump index for the iteration
* index: set to current bitmap word index for the iteration
* offset: bits offset of the found clump in the bitmap word
* bits: bitmap to search within
* size: bitmap size in number of clumps
* clump_size: clump size in number of bits

The clump_size argument can be an arbitrary number of bits and is not
required to be a multiple of 2.

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")

When I implemented the test_for_each_set_clump function, I used
bitmap_set to set the expected bitmap for the test. This method of
setting bits only segments at a time was rather tedious and error-prone;
is there a better way to accomplish what I did (set a bitmap after a
DECLARE_BITMAP)?

William Breathitt Gray

William Breathitt Gray (8):
bitops: Introduce the for_each_set_clump macro
lib/test_bitmap.c: Add for_each_set_clump test cases
gpio: 104-dio-48e: Utilize for_each_set_clump macro
gpio: 104-idi-48: Utilize for_each_set_clump macro
gpio: gpio-mm: Utilize for_each_set_clump macro
gpio: ws16c48: Utilize for_each_set_clump macro
gpio: pci-idio-16: Utilize for_each_set_clump macro
gpio: pcie-idio-24: Utilize for_each_set_clump 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 | 9 +++
include/linux/bitops.h | 7 ++
lib/find_bit.c | 40 ++++++++++++
lib/test_bitmap.c | 71 +++++++++++++++++++++
10 files changed, 236 insertions(+), 292 deletions(-)

--
2.17.0

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