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
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_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:
* aaf96e51de11 ("gpio: pci-idio-16: Fix port memory offset for get_multiple callback")
* 304440aa96c6 ("gpio: pcie-idio-24: Fix port memory offset for get_multiple/set_multiple callbacks")
* 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 | 24 +++++++
include/linux/bitops.h | 9 +++
lib/find_bit.c | 28 ++++++++
9 files changed, 170 insertions(+), 292 deletions(-)
--
2.17.0
