forked from Minki/linux
169c474fb2
Pach series "Introduce the for_each_set_clump8 macro", v18.
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_clump8 macro and utilizes it
in several GPIO drivers. The for_each_set_clump macro8 facilitates a
for-loop syntax that iterates over a memory region entire groups of set
bits at a time.
For example, suppose you would like to iterate over a 32-bit integer 8
bits at a time, skipping over 8-bit groups with no set bit, where
XXXXXXXX represents the current 8-bit group:
Example: 10111110 00000000 11111111 00110011
First loop: 10111110 00000000 11111111 XXXXXXXX
Second loop: 10111110 00000000 XXXXXXXX 00110011
Third loop: XXXXXXXX 00000000 11111111 00110011
Each iteration of the loop returns the next 8-bit group that has at
least one set bit.
The for_each_set_clump8 macro has four parameters:
* start: set to the bit offset of the current clump
* clump: set to the current clump value
* bits: bitmap to search within
* size: bitmap size in number of bits
In this version of the patchset, the for_each_set_clump macro has been
reimplemented and simplified based on the suggestions provided by Rasmus
Villemoes and Andy Shevchenko in the version 4 submission.
In particular, the function of the for_each_set_clump macro has been
restricted to handle only 8-bit clumps; the drivers that use the
for_each_set_clump macro only handle 8-bit ports so a generic
for_each_set_clump implementation is not necessary. Thus, a solution
for large clumps (i.e. those larger than the width of a bitmap word)
can be postponed until a driver appears that actually requires such a
generic for_each_set_clump implementation.
For what it's worth, a semi-generic for_each_set_clump (i.e. for clumps
smaller than the width of a bitmap word) can be implemented by simply
replacing the hardcoded '8' and '0xFF' instances with respective
variables. I have not yet had a need for such an implementation, and
since it falls short of a true generic for_each_set_clump function, I
have decided to forgo such an implementation for now.
In addition, the bitmap_get_value8 and bitmap_set_value8 functions are
introduced to get and set 8-bit values respectively. Their use is based
on the behavior suggested in the patchset version 4 review.
This patch (of 14):
This macro iterates for each 8-bit group of bits (clump) with set bits,
within a bitmap memory region. For each iteration, "start" is set to
the bit offset of the found clump, while the respective clump value is
stored to the location pointed by "clump". Additionally, the
bitmap_get_value8 and bitmap_set_value8 functions are introduced to
respectively get and set an 8-bit value in a bitmap memory region.
[gustavo@embeddedor.com: fix potential sign-extension overflow]
Link: http://lkml.kernel.org/r/20191015184657.GA26541@embeddedor
[akpm@linux-foundation.org: s/ULL/UL/, per Joe]
[vilhelm.gray@gmail.com: add for_each_set_clump8 documentation]
Link: http://lkml.kernel.org/r/20191016161825.301082-1-vilhelm.gray@gmail.com
Link: http://lkml.kernel.org/r/893c3b4f03266c9496137cc98ac2b1bd27f92c73.1570641097.git.vilhelm.gray@gmail.com
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Suggested-by: Lukas Wunner <lukas@wunner.de>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Phil Reid <preid@electromag.com.au>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Mathias Duckeck <m.duckeck@kunbus.de>
Cc: Morten Hein Tiljeset <morten.tiljeset@prevas.dk>
Cc: Sean Nyekjaer <sean.nyekjaer@prevas.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
101 lines
3.2 KiB
C
101 lines
3.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_GENERIC_BITOPS_FIND_H_
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#define _ASM_GENERIC_BITOPS_FIND_H_
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#ifndef find_next_bit
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/**
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* find_next_bit - find the next set bit in a memory region
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* @addr: The address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The bitmap size in bits
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*
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* Returns the bit number for the next set bit
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* If no bits are set, returns @size.
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*/
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extern unsigned long find_next_bit(const unsigned long *addr, unsigned long
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size, unsigned long offset);
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#endif
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#ifndef find_next_and_bit
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/**
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* find_next_and_bit - find the next set bit in both memory regions
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* @addr1: The first address to base the search on
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* @addr2: The second address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The bitmap size in bits
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*
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* Returns the bit number for the next set bit
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* If no bits are set, returns @size.
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*/
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extern unsigned long find_next_and_bit(const unsigned long *addr1,
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const unsigned long *addr2, unsigned long size,
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unsigned long offset);
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#endif
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#ifndef find_next_zero_bit
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/**
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* find_next_zero_bit - find the next cleared bit in a memory region
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* @addr: The address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The bitmap size in bits
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*
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* Returns the bit number of the next zero bit
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* If no bits are zero, returns @size.
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*/
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extern unsigned long find_next_zero_bit(const unsigned long *addr, unsigned
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long size, unsigned long offset);
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#endif
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#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
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/**
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* find_first_bit - find the first set bit in a memory region
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* @addr: The address to start the search at
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* @size: The maximum number of bits to search
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*
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* Returns the bit number of the first set bit.
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* If no bits are set, returns @size.
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*/
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extern unsigned long find_first_bit(const unsigned long *addr,
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unsigned long size);
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/**
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* find_first_zero_bit - find the first cleared bit in a memory region
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* @addr: The address to start the search at
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* @size: The maximum number of bits to search
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*
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* Returns the bit number of the first cleared bit.
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* If no bits are zero, returns @size.
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*/
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extern unsigned long find_first_zero_bit(const unsigned long *addr,
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unsigned long size);
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#else /* CONFIG_GENERIC_FIND_FIRST_BIT */
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#ifndef find_first_bit
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#define find_first_bit(addr, size) find_next_bit((addr), (size), 0)
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#endif
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#ifndef find_first_zero_bit
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#define find_first_zero_bit(addr, size) find_next_zero_bit((addr), (size), 0)
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#endif
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#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
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/**
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* find_next_clump8 - find next 8-bit clump with set bits in a memory region
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* @clump: location to store copy of found clump
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* @addr: address to base the search on
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* @size: bitmap size in number of bits
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* @offset: bit offset at which to start searching
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*
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* Returns the bit offset for the next set clump; the found clump value is
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* copied to the location pointed by @clump. If no bits are set, returns @size.
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*/
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extern unsigned long find_next_clump8(unsigned long *clump,
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const unsigned long *addr,
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unsigned long size, unsigned long offset);
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#define find_first_clump8(clump, bits, size) \
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find_next_clump8((clump), (bits), (size), 0)
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#endif /*_ASM_GENERIC_BITOPS_FIND_H_ */
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