On Fri, May 15, 2020 at 04:46:03AM +0530, Syed Nayyar Waris wrote: > This patchset introduces a new generic version of for_each_set_clump. > The previous version of for_each_set_clump8 used a fixed size 8-bit > clump, but the new generic version can work with clump of any size but > less than or equal to BITS_PER_LONG. The patchset utilizes the new macro > in several GPIO drivers. > > The earlier 8-bit for_each_set_clump8 facilitated 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. > > But with the new for_each_set_clump the clump size can be different from 8 bits. > Moreover, the clump can be split at word boundary in situations where word > size is not multiple of clump size. Following are examples showing the working > of new macro for clump sizes of 24 bits and 6 bits. > > Example 1: > clump size: 24 bits, Number of clumps (or ports): 10 > bitmap stores the bit information from where successive clumps are retrieved. > > /* bitmap memory region */ > 0x00aa0000ff000000; /* Most significant bits */ > 0xaaaaaa0000ff0000; > 0x000000aa000000aa; > 0xbbbbabcdeffedcba; /* Least significant bits */ > > Different iterations of for_each_set_clump:- > 'offset' is the bit position and 'clump' is the 24 bit clump from the > above bitmap. > Iteration first: offset: 0 clump: 0xfedcba > Iteration second: offset: 24 clump: 0xabcdef > Iteration third: offset: 48 clump: 0xaabbbb > Iteration fourth: offset: 96 clump: 0xaa > Iteration fifth: offset: 144 clump: 0xff > Iteration sixth: offset: 168 clump: 0xaaaaaa > Iteration seventh: offset: 216 clump: 0xff > Loop breaks because in the end the remaining bits (0x00aa) size was less > than clump size of 24 bits. > > In above example it can be seen that in iteration third, the 24 bit clump > that was retrieved was split between bitmap[0] and bitmap[1]. This example > also shows that 24 bit zeroes if present in between, were skipped (preserving > the previous for_each_set_macro8 behaviour). > > Example 2: > clump size = 6 bits, Number of clumps (or ports) = 3. > > /* bitmap memory region */ > 0x00aa0000ff000000; /* Most significant bits */ > 0xaaaaaa0000ff0000; > 0x0f00000000000000; > 0x0000000000000ac0; /* Least significant bits */ > > Different iterations of for_each_set_clump: > 'offset' is the bit position and 'clump' is the 6 bit clump from the > above bitmap. > Iteration first: offset: 6 clump: 0x2b > Loop breaks because 6 * 3 = 18 bits traversed in bitmap. > Here 6 * 3 is clump size * no. of clumps. Thank you! Overall looks good to me, though I gave tags per individual patches (I'm not familiar with that GPIO drivers, so, I may not tag them). > > Changes in v6: > - [Patch 2/4]: Make 'for loop' inside test_for_each_set_clump more > succinct. > > Changes in v5: > - [Patch 4/4]: Minor change: Hardcode value for better code readability. > > Changes in v4: > - [Patch 2/4]: Use 'for' loop in test function of for_each_set_clump. > - [Patch 3/4]: Minor change: Inline value for better code readability. > - [Patch 4/4]: Minor change: Inline value for better code readability. > > Changes in v3: > - [Patch 3/4]: Change datatype of some variables from u64 to unsigned long > in function thunderx_gpio_set_multiple. > > CHanges in v2: > - [Patch 2/4]: Unify different tests for 'for_each_set_clump'. Pass test data as > function parameters. > - [Patch 2/4]: Remove unnecessary bitmap_zero calls. > > Syed Nayyar Waris (4): > bitops: Introduce the the for_each_set_clump macro > lib/test_bitmap.c: Add for_each_set_clump test cases > gpio: thunderx: Utilize for_each_set_clump macro > gpio: xilinx: Utilize for_each_set_clump macro > > drivers/gpio/gpio-thunderx.c | 11 ++- > drivers/gpio/gpio-xilinx.c | 62 ++++++------- > include/asm-generic/bitops/find.h | 19 ++++ > include/linux/bitmap.h | 61 +++++++++++++ > include/linux/bitops.h | 13 +++ > lib/find_bit.c | 14 +++ > lib/test_bitmap.c | 142 ++++++++++++++++++++++++++++++ > 7 files changed, 288 insertions(+), 34 deletions(-) > > > base-commit: 5f458e572071a54841b93f41e25fbe8ded82df79 > -- > 2.26.2 > -- With Best Regards, Andy Shevchenko
