Re: [PATCH v14 00/11] Introduce the for_each_set_clump8 macro

Andy Shevchenko
2019-03-29T11:38:25Z

On Fri, Mar 29, 2019 at 12:03:30PM +0900, William Breathitt Gray wrote:
> Changes in v14:
> - Redefine bitmap_get_value8, bitmap_set_value8, and find_next_clump8
> as static inline functions
> - Rename 'idx' variable to 'index' in the bitmap_get_value8 and
> bitmap_set_value8 functions
> - Remove superfluous parens in gen_74x164_set_multiple
>

Thank you!

FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> 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.
>
> William Breathitt Gray (11):
> bitops: Introduce the for_each_set_clump8 macro
> lib/test_bitmap.c: Add for_each_set_clump8 test cases
> gpio: 104-dio-48e: Utilize for_each_set_clump8 macro
> gpio: 104-idi-48: Utilize for_each_set_clump8 macro
> gpio: gpio-mm: Utilize for_each_set_clump8 macro
> gpio: ws16c48: Utilize for_each_set_clump8 macro
> gpio: pci-idio-16: Utilize for_each_set_clump8 macro
> gpio: pcie-idio-24: Utilize for_each_set_clump8 macro
> gpio: uniphier: Utilize for_each_set_clump8 macro
> gpio: 74x164: Utilize the for_each_set_clump8 macro
> thermal: intel: intel_soc_dts_iosf: Utilize for_each_set_clump8 macro
>
> drivers/gpio/gpio-104-dio-48e.c | 73 ++++----------
> drivers/gpio/gpio-104-idi-48.c | 36 ++-----
> drivers/gpio/gpio-74x164.c | 19 ++--
> drivers/gpio/gpio-gpio-mm.c | 73 ++++----------
> drivers/gpio/gpio-pci-idio-16.c | 75 +++++---------
> drivers/gpio/gpio-pcie-idio-24.c | 109 ++++++++-------------
> drivers/gpio/gpio-uniphier.c | 16 ++-
> drivers/gpio/gpio-ws16c48.c | 73 ++++----------
> drivers/thermal/intel/intel_soc_dts_iosf.c | 29 +++---
> drivers/thermal/intel/intel_soc_dts_iosf.h | 2 -
> include/asm-generic/bitops/find.h | 61 ++++++++++++
> include/linux/bitops.h | 5 +
> lib/test_bitmap.c | 65 ++++++++++++
> 13 files changed, 299 insertions(+), 337 deletions(-)
>
> --
> 2.21.0
>

--
With Best Regards,
Andy Shevchenko