[PATCH v8 0/8] Introduce the for_each_set_clump8 macro

[PATCH v8 0/8] Introduce the for_each_set_clump8 macro

[William Breathitt Gray]

Changes in v8:
  - Return unsigned long for bitmap_get_value8 for consistency
  - Add clobbering risk warning to bitmap_set_value8 documentation
  - Reimplement bitmap_get_value8 and bitmap_set_value8 to account for
    clumps that fall across bitmap word boundaries
  - Add a bitmap size argument to the bitmap_get_value8 and
    bitmap_set_value8 functions

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 (8):
  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

 drivers/gpio/gpio-104-dio-48e.c   |  73 ++++++--------------
 drivers/gpio/gpio-104-idi-48.c    |  37 +++-------
 drivers/gpio/gpio-gpio-mm.c       |  73 ++++++--------------
 drivers/gpio/gpio-pci-idio-16.c   |  75 ++++++++------------
 drivers/gpio/gpio-pcie-idio-24.c  | 111 +++++++++++-------------------
 drivers/gpio/gpio-ws16c48.c       |  72 ++++++-------------
 include/asm-generic/bitops/find.h |  14 ++++
 include/linux/bitops.h            |   5 ++
 lib/find_bit.c                    |  81 ++++++++++++++++++++++
 lib/test_bitmap.c                 |  65 +++++++++++++++++
 10 files changed, 307 insertions(+), 299 deletions(-)

-- 
2.20.1

[PATCH v8 1/8] bitops: Introduce the for_each_set_clump8 macro

[William Breathitt Gray]

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.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 include/asm-generic/bitops/find.h | 14 ++++++
 include/linux/bitops.h            |  5 ++
 lib/find_bit.c                    | 81 +++++++++++++++++++++++++++++++
 3 files changed, 100 insertions(+)

diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
index 8a1ee10014de..9a76adff59c6 100644
--- a/include/asm-generic/bitops/find.h
+++ b/include/asm-generic/bitops/find.h
@@ -80,4 +80,18 @@ extern unsigned long find_first_zero_bit(const unsigned long *addr,
 
 #endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
 
+unsigned long bitmap_get_value8(const unsigned long *const bitmap,
+				const unsigned int size,
+				const unsigned int start);
+
+void bitmap_set_value8(unsigned long *const bitmap, const unsigned int size,
+		       const unsigned long value, const unsigned int start);
+
+unsigned int find_next_clump8(unsigned long *const clump,
+			      const unsigned long *const addr,
+			      unsigned int offset, const unsigned int size);
+
+#define find_first_clump8(clump, bits, size) \
+	find_next_clump8((clump), (bits), 0, (size))
+
 #endif /*_ASM_GENERIC_BITOPS_FIND_H_ */
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 705f7c442691..61c10f20079e 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -40,6 +40,11 @@ extern unsigned long __sw_hweight64(__u64 w);
 	     (bit) < (size);					\
 	     (bit) = find_next_zero_bit((addr), (size), (bit) + 1))
 
+#define for_each_set_clump8(start, clump, bits, size) \
+	for ((start) = find_first_clump8(&(clump), (bits), (size)); \
+	     (start) < (size); \
+	     (start) = find_next_clump8(&(clump), (bits), (start) + 8, (size)))
+
 static inline int get_bitmask_order(unsigned int count)
 {
 	int order;
diff --git a/lib/find_bit.c b/lib/find_bit.c
index ee3df93ba69a..c2af1f013ea2 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -218,3 +218,84 @@ EXPORT_SYMBOL(find_next_bit_le);
 #endif
 
 #endif /* __BIG_ENDIAN */
+
+/**
+ * bitmap_get_value8 - get an 8-bit value within a memory region
+ * @bitmap: address to the bitmap memory region
+ * @size: bitmap size in number of bits
+ * @start: bit offset of the 8-bit value
+ *
+ * Returns the 8-bit value located at the @start bit offset within the @bitmap
+ * memory region.
+ */
+unsigned long bitmap_get_value8(const unsigned long *const bitmap,
+				const unsigned int size,
+				const unsigned int start)
+{
+	const size_t index = BIT_WORD(start);
+	const unsigned int offset = start % BITS_PER_LONG;
+	const unsigned int low_width = (offset + 8 > BITS_PER_LONG) ?
+				       BITS_PER_LONG - offset : 8;
+	const unsigned long low = bitmap[index] >> offset;
+	const unsigned long high = (low_width < 8 && start + 8 <= size) ?
+				   bitmap[index + 1] << low_width : 0;
+
+	return (low | high) & 0xFF;
+}
+EXPORT_SYMBOL(bitmap_get_value8);
+
+/**
+ * bitmap_set_value8 - set an 8-bit value within a memory region
+ * @bitmap: address to the bitmap memory region
+ * @size: bitmap size in number of bits
+ * @value: the 8-bit value; values wider than 8 bits may clobber bitmap
+ * @start: bit offset of the 8-bit value
+ */
+void bitmap_set_value8(unsigned long *const bitmap, const unsigned int size,
+		       const unsigned long value, const unsigned int start)
+{
+	const size_t index = BIT_WORD(start);
+	const unsigned int offset = start % BITS_PER_LONG;
+	const unsigned int low_width = (offset + 8 > BITS_PER_LONG) ?
+				       BITS_PER_LONG - offset : 8;
+	const unsigned long low_mask = GENMASK(offset + low_width - 1, offset);
+	const unsigned int high_width = 8 - low_width;
+	const unsigned long high_mask = GENMASK(high_width - 1, 0);
+
+	/* set lower portion */
+	bitmap[index] &= ~low_mask;
+	bitmap[index] |= value << offset;
+
+	/* set higher portion if space available in bitmap */
+	if (high_width && start + 8 <= size) {
+		bitmap[index + 1] &= ~high_mask;
+		bitmap[index + 1] |= value >> low_width;
+	}
+}
+EXPORT_SYMBOL(bitmap_set_value8);
+
+/**
+ * find_next_clump8 - find next 8-bit clump with set bits in a memory region
+ * @clump: location to store copy of found clump
+ * @addr: address to base the search on
+ * @offset: bit offset at which to start searching
+ * @size: bitmap size in number of bits
+ *
+ * Returns the bit offset for the next set clump; the found clump value is
+ * copied to the location pointed by @clump. If no bits are set, returns @size.
+ */
+unsigned int find_next_clump8(unsigned long *const clump,
+			      const unsigned long *const addr,
+			      unsigned int offset, const unsigned int size)
+{
+	for (; offset < size; offset += 8) {
+		*clump = bitmap_get_value8(addr, size, offset);
+		if (!*clump)
+			continue;
+
+		return offset;
+	}
+
+	return size;
+}
+EXPORT_SYMBOL(find_next_clump8);
-- 
2.20.1

[PATCH v8 2/8] lib/test_bitmap.c: Add for_each_set_clump8 test cases

[William Breathitt Gray]

The introduction of the for_each_set_clump8 macro warrants test cases to
verify the implementation. This patch adds test case checks for whether
an out-of-bounds clump index is returned, a zero clump is returned, or
the returned clump value differs from the expected clump value.

Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 lib/test_bitmap.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index 6cd7d0740005..66ddb3fb98cb 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -88,6 +88,36 @@ __check_eq_u32_array(const char *srcfile, unsigned int line,
 	return true;
 }
 
+static bool __init __check_eq_clump8(const char *srcfile, unsigned int line,
+				    const unsigned int offset,
+				    const unsigned int size,
+				    const unsigned char *const clump_exp,
+				    const unsigned long *const clump)
+{
+	unsigned long exp;
+
+	if (offset >= size) {
+		pr_warn("[%s:%u] bit offset for clump out-of-bounds: expected less than %u, got %u\n",
+			srcfile, line, size, offset);
+		return false;
+	}
+
+	exp = clump_exp[offset / 8];
+	if (!exp) {
+		pr_warn("[%s:%u] bit offset for zero clump: expected nonzero clump, got bit offset %u with clump value 0",
+			srcfile, line, offset);
+		return false;
+	}
+
+	if (*clump != exp) {
+		pr_warn("[%s:%u] expected clump value of 0x%lX, got clump value of 0x%lX",
+			srcfile, line, exp, *clump);
+		return false;
+	}
+
+	return true;
+}
+
 #define __expect_eq(suffix, ...)					\
 	({								\
 		int result = 0;						\
@@ -104,6 +134,7 @@ __check_eq_u32_array(const char *srcfile, unsigned int line,
 #define expect_eq_bitmap(...)		__expect_eq(bitmap, ##__VA_ARGS__)
 #define expect_eq_pbl(...)		__expect_eq(pbl, ##__VA_ARGS__)
 #define expect_eq_u32_array(...)	__expect_eq(u32_array, ##__VA_ARGS__)
+#define expect_eq_clump8(...)		__expect_eq(clump8, ##__VA_ARGS__)
 
 static void __init test_zero_clear(void)
 {
@@ -361,6 +392,39 @@ static void noinline __init test_mem_optimisations(void)
 	}
 }
 
+static const unsigned char clump_exp[] __initconst = {
+	0x01,	/* 1 bit set */
+	0x02,	/* non-edge 1 bit set */
+	0x00,	/* zero bits set */
+	0x28,	/* 3 bits set across 4-bit boundary */
+	0x28,	/* Repeated clump */
+	0x0F,	/* 4 bits set */
+	0xFF,	/* all bits set */
+	0x05,	/* non-adjacent 2 bits set */
+};
+
+static void __init test_for_each_set_clump8(void)
+{
+#define CLUMP_EXP_NUMBITS 64
+	DECLARE_BITMAP(bits, CLUMP_EXP_NUMBITS);
+	unsigned int start;
+	unsigned long clump;
+
+	/* set bitmap to test case */
+	bitmap_zero(bits, CLUMP_EXP_NUMBITS);
+	bitmap_set(bits, 0, 1);		/* 0x01 */
+	bitmap_set(bits, 8, 1);		/* 0x02 */
+	bitmap_set(bits, 27, 3);	/* 0x28 */
+	bitmap_set(bits, 35, 3);	/* 0x28 */
+	bitmap_set(bits, 40, 4);	/* 0x0F */
+	bitmap_set(bits, 48, 8);	/* 0xFF */
+	bitmap_set(bits, 56, 1);	/* 0x05 - part 1 */
+	bitmap_set(bits, 58, 1);	/* 0x05 - part 2 */
+
+	for_each_set_clump8(start, clump, bits, CLUMP_EXP_NUMBITS)
+		expect_eq_clump8(start, CLUMP_EXP_NUMBITS, clump_exp, &clump);
+}
+
 static int __init test_bitmap_init(void)
 {
 	test_zero_clear();
@@ -369,6 +433,7 @@ static int __init test_bitmap_init(void)
 	test_bitmap_arr32();
 	test_bitmap_parselist();
 	test_mem_optimisations();
+	test_for_each_set_clump8();
 
 	if (failed_tests == 0)
 		pr_info("all %u tests passed\n", total_tests);
-- 
2.20.1

[PATCH v8 3/8] gpio: 104-dio-48e: Utilize for_each_set_clump8 macro

[William Breathitt Gray]

Replace verbose implementation in get_multiple/set_multiple callbacks
with for_each_set_clump8 macro to simplify code and improve clarity.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 drivers/gpio/gpio-104-dio-48e.c | 73 ++++++++++-----------------------
 1 file changed, 22 insertions(+), 51 deletions(-)

diff --git a/drivers/gpio/gpio-104-dio-48e.c b/drivers/gpio/gpio-104-dio-48e.c
index 92c8f944bf64..23413d90e944 100644
--- a/drivers/gpio/gpio-104-dio-48e.c
+++ b/drivers/gpio/gpio-104-dio-48e.c
@@ -183,46 +183,26 @@ static int dio48e_gpio_get(struct gpio_chip *chip, unsigned offset)
 	return !!(port_state & mask);
 }
 
+static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
+
 static int dio48e_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
 	unsigned long *bits)
 {
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
-	size_t i;
-	static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
-	const unsigned int gpio_reg_size = 8;
-	unsigned int bits_offset;
-	size_t word_index;
-	unsigned int word_offset;
-	unsigned long word_mask;
-	const unsigned long port_mask = GENMASK(gpio_reg_size - 1, 0);
+	unsigned int offset;
+	unsigned long gpio_mask;
+	const unsigned int ngpio = ARRAY_SIZE(ports) * 8;
+	unsigned int port_addr;
 	unsigned long port_state;
 
 	/* clear bits array to a clean slate */
 	bitmap_zero(bits, chip->ngpio);
 
-	/* get bits are evaluated a gpio port register at a time */
-	for (i = 0; i < ARRAY_SIZE(ports); i++) {
-		/* gpio offset in bits array */
-		bits_offset = i * gpio_reg_size;
-
-		/* word index for bits array */
-		word_index = BIT_WORD(bits_offset);
-
-		/* gpio offset within current word of bits array */
-		word_offset = bits_offset % BITS_PER_LONG;
-
-		/* mask of get bits for current gpio within current word */
-		word_mask = mask[word_index] & (port_mask << word_offset);
-		if (!word_mask) {
-			/* no get bits in this port so skip to next one */
-			continue;
-		}
-
-		/* read bits from current gpio port */
-		port_state = inb(dio48egpio->base + ports[i]);
+	for_each_set_clump8(offset, gpio_mask, mask, ngpio) {
+		port_addr = dio48egpio->base + ports[offset / 8];
+		port_state = inb(port_addr) & gpio_mask;
 
-		/* store acquired bits at respective bits array offset */
-		bits[word_index] |= (port_state << word_offset) & word_mask;
+		bitmap_set_value8(bits, ngpio, port_state, offset);
 	}
 
 	return 0;
@@ -252,37 +232,28 @@ static void dio48e_gpio_set_multiple(struct gpio_chip *chip,
 	unsigned long *mask, unsigned long *bits)
 {
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
-	unsigned int i;
-	const unsigned int gpio_reg_size = 8;
-	unsigned int port;
-	unsigned int out_port;
+	unsigned int offset;
+	unsigned long gpio_mask;
+	const unsigned int ngpio = ARRAY_SIZE(ports) * 8;
+	size_t index;
+	unsigned int port_addr;
 	unsigned int bitmask;
 	unsigned long flags;
 
-	/* set bits are evaluated a gpio register size at a time */
-	for (i = 0; i < chip->ngpio; i += gpio_reg_size) {
-		/* no more set bits in this mask word; skip to the next word */
-		if (!mask[BIT_WORD(i)]) {
-			i = (BIT_WORD(i) + 1) * BITS_PER_LONG - gpio_reg_size;
-			continue;
-		}
+	for_each_set_clump8(offset, gpio_mask, mask, ngpio) {
+		index = offset / 8;
+		port_addr = dio48egpio->base + ports[index];
 
-		port = i / gpio_reg_size;
-		out_port = (port > 2) ? port + 1 : port;
-		bitmask = mask[BIT_WORD(i)] & bits[BIT_WORD(i)];
+		bitmask = bitmap_get_value8(bits, ngpio, offset) & gpio_mask;
 
 		raw_spin_lock_irqsave(&dio48egpio->lock, flags);
 
 		/* update output state data and set device gpio register */
-		dio48egpio->out_state[port] &= ~mask[BIT_WORD(i)];
-		dio48egpio->out_state[port] |= bitmask;
-		outb(dio48egpio->out_state[port], dio48egpio->base + out_port);
+		dio48egpio->out_state[index] &= ~gpio_mask;
+		dio48egpio->out_state[index] |= bitmask;
+		outb(dio48egpio->out_state[index], port_addr);
 
 		raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
-
-		/* prepare for next gpio register set */
-		mask[BIT_WORD(i)] >>= gpio_reg_size;
-		bits[BIT_WORD(i)] >>= gpio_reg_size;
 	}
 }
 
-- 
2.20.1

[PATCH v8 4/8] gpio: 104-idi-48: Utilize for_each_set_clump8 macro

[William Breathitt Gray]

Replace verbose implementation in get_multiple/set_multiple callbacks
with for_each_set_clump8 macro to simplify code and improve clarity.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 drivers/gpio/gpio-104-idi-48.c | 37 ++++++++--------------------------
 1 file changed, 8 insertions(+), 29 deletions(-)

diff --git a/drivers/gpio/gpio-104-idi-48.c b/drivers/gpio/gpio-104-idi-48.c
index 88dc6f2449f6..59c571aecf9a 100644
--- a/drivers/gpio/gpio-104-idi-48.c
+++ b/drivers/gpio/gpio-104-idi-48.c
@@ -93,42 +93,21 @@ static int idi_48_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
 	unsigned long *bits)
 {
 	struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
-	size_t i;
+	unsigned int offset;
+	unsigned long gpio_mask;
 	static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
-	const unsigned int gpio_reg_size = 8;
-	unsigned int bits_offset;
-	size_t word_index;
-	unsigned int word_offset;
-	unsigned long word_mask;
-	const unsigned long port_mask = GENMASK(gpio_reg_size - 1, 0);
+	const unsigned int ngpio = ARRAY_SIZE(ports) * 8;
+	unsigned int port_addr;
 	unsigned long port_state;
 
 	/* clear bits array to a clean slate */
 	bitmap_zero(bits, chip->ngpio);
 
-	/* get bits are evaluated a gpio port register at a time */
-	for (i = 0; i < ARRAY_SIZE(ports); i++) {
-		/* gpio offset in bits array */
-		bits_offset = i * gpio_reg_size;
+	for_each_set_clump8(offset, gpio_mask, mask, ngpio) {
+		port_addr = idi48gpio->base + ports[offset / 8];
+		port_state = inb(port_addr) & gpio_mask;
 
-		/* word index for bits array */
-		word_index = BIT_WORD(bits_offset);
-
-		/* gpio offset within current word of bits array */
-		word_offset = bits_offset % BITS_PER_LONG;
-
-		/* mask of get bits for current gpio within current word */
-		word_mask = mask[word_index] & (port_mask << word_offset);
-		if (!word_mask) {
-			/* no get bits in this port so skip to next one */
-			continue;
-		}
-
-		/* read bits from current gpio port */
-		port_state = inb(idi48gpio->base + ports[i]);
-
-		/* store acquired bits at respective bits array offset */
-		bits[word_index] |= (port_state << word_offset) & word_mask;
+		bitmap_set_value8(bits, ngpio, port_state, offset);
 	}
 
 	return 0;
-- 
2.20.1

[PATCH v8 5/8] gpio: gpio-mm: Utilize for_each_set_clump8 macro

[William Breathitt Gray]

Replace verbose implementation in get_multiple/set_multiple callbacks
with for_each_set_clump8 macro to simplify code and improve clarity.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 drivers/gpio/gpio-gpio-mm.c | 73 +++++++++++--------------------------
 1 file changed, 22 insertions(+), 51 deletions(-)

diff --git a/drivers/gpio/gpio-gpio-mm.c b/drivers/gpio/gpio-gpio-mm.c
index 8c150fd68d9d..4c1037a005ab 100644
--- a/drivers/gpio/gpio-gpio-mm.c
+++ b/drivers/gpio/gpio-gpio-mm.c
@@ -172,46 +172,26 @@ static int gpiomm_gpio_get(struct gpio_chip *chip, unsigned int offset)
 	return !!(port_state & mask);
 }
 
+static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
+
 static int gpiomm_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
 	unsigned long *bits)
 {
 	struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
-	size_t i;
-	static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
-	const unsigned int gpio_reg_size = 8;
-	unsigned int bits_offset;
-	size_t word_index;
-	unsigned int word_offset;
-	unsigned long word_mask;
-	const unsigned long port_mask = GENMASK(gpio_reg_size - 1, 0);
+	unsigned int offset;
+	unsigned long gpio_mask;
+	const unsigned int ngpio = ARRAY_SIZE(ports) * 8;
+	unsigned int port_addr;
 	unsigned long port_state;
 
 	/* clear bits array to a clean slate */
 	bitmap_zero(bits, chip->ngpio);
 
-	/* get bits are evaluated a gpio port register at a time */
-	for (i = 0; i < ARRAY_SIZE(ports); i++) {
-		/* gpio offset in bits array */
-		bits_offset = i * gpio_reg_size;
-
-		/* word index for bits array */
-		word_index = BIT_WORD(bits_offset);
-
-		/* gpio offset within current word of bits array */
-		word_offset = bits_offset % BITS_PER_LONG;
-
-		/* mask of get bits for current gpio within current word */
-		word_mask = mask[word_index] & (port_mask << word_offset);
-		if (!word_mask) {
-			/* no get bits in this port so skip to next one */
-			continue;
-		}
-
-		/* read bits from current gpio port */
-		port_state = inb(gpiommgpio->base + ports[i]);
+	for_each_set_clump8(offset, gpio_mask, mask, ngpio) {
+		port_addr = gpiommgpio->base + ports[offset / 8];
+		port_state = inb(port_addr) & gpio_mask;
 
-		/* store acquired bits at respective bits array offset */
-		bits[word_index] |= (port_state << word_offset) & word_mask;
+		bitmap_set_value8(bits, ngpio, port_state, offset);
 	}
 
 	return 0;
@@ -242,37 +222,28 @@ static void gpiomm_gpio_set_multiple(struct gpio_chip *chip,
 	unsigned long *mask, unsigned long *bits)
 {
 	struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
-	unsigned int i;
-	const unsigned int gpio_reg_size = 8;
-	unsigned int port;
-	unsigned int out_port;
+	unsigned int offset;
+	unsigned long gpio_mask;
+	const unsigned int ngpio = ARRAY_SIZE(ports) * 8;
+	size_t index;
+	unsigned int port_addr;
 	unsigned int bitmask;
 	unsigned long flags;
 
-	/* set bits are evaluated a gpio register size at a time */
-	for (i = 0; i < chip->ngpio; i += gpio_reg_size) {
-		/* no more set bits in this mask word; skip to the next word */
-		if (!mask[BIT_WORD(i)]) {
-			i = (BIT_WORD(i) + 1) * BITS_PER_LONG - gpio_reg_size;
-			continue;
-		}
+	for_each_set_clump8(offset, gpio_mask, mask, ngpio) {
+		index = offset / 8;
+		port_addr = gpiommgpio->base + ports[index];
 
-		port = i / gpio_reg_size;
-		out_port = (port > 2) ? port + 1 : port;
-		bitmask = mask[BIT_WORD(i)] & bits[BIT_WORD(i)];
+		bitmask = bitmap_get_value8(bits, ngpio, offset) & gpio_mask;
 
 		spin_lock_irqsave(&gpiommgpio->lock, flags);
 
 		/* update output state data and set device gpio register */
-		gpiommgpio->out_state[port] &= ~mask[BIT_WORD(i)];
-		gpiommgpio->out_state[port] |= bitmask;
-		outb(gpiommgpio->out_state[port], gpiommgpio->base + out_port);
+		gpiommgpio->out_state[index] &= ~gpio_mask;
+		gpiommgpio->out_state[index] |= bitmask;
+		outb(gpiommgpio->out_state[index], port_addr);
 
 		spin_unlock_irqrestore(&gpiommgpio->lock, flags);
-
-		/* prepare for next gpio register set */
-		mask[BIT_WORD(i)] >>= gpio_reg_size;
-		bits[BIT_WORD(i)] >>= gpio_reg_size;
 	}
 }
 
-- 
2.20.1

[PATCH v8 6/8] gpio: ws16c48: Utilize for_each_set_clump8 macro

[William Breathitt Gray]

Replace verbose implementation in get_multiple/set_multiple callbacks
with for_each_set_clump8 macro to simplify code and improve clarity.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 drivers/gpio/gpio-ws16c48.c | 72 +++++++++++--------------------------
 1 file changed, 20 insertions(+), 52 deletions(-)

diff --git a/drivers/gpio/gpio-ws16c48.c b/drivers/gpio/gpio-ws16c48.c
index 5cf3697bfb15..1d071a3d3e81 100644
--- a/drivers/gpio/gpio-ws16c48.c
+++ b/drivers/gpio/gpio-ws16c48.c
@@ -134,42 +134,19 @@ static int ws16c48_gpio_get_multiple(struct gpio_chip *chip,
 	unsigned long *mask, unsigned long *bits)
 {
 	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
-	const unsigned int gpio_reg_size = 8;
-	size_t i;
-	const size_t num_ports = chip->ngpio / gpio_reg_size;
-	unsigned int bits_offset;
-	size_t word_index;
-	unsigned int word_offset;
-	unsigned long word_mask;
-	const unsigned long port_mask = GENMASK(gpio_reg_size - 1, 0);
+	unsigned int offset;
+	unsigned long gpio_mask;
+	unsigned int port_addr;
 	unsigned long port_state;
 
 	/* clear bits array to a clean slate */
 	bitmap_zero(bits, chip->ngpio);
 
-	/* get bits are evaluated a gpio port register at a time */
-	for (i = 0; i < num_ports; i++) {
-		/* gpio offset in bits array */
-		bits_offset = i * gpio_reg_size;
+	for_each_set_clump8(offset, gpio_mask, mask, chip->ngpio) {
+		port_addr = ws16c48gpio->base + offset / 8;
+		port_state = inb(port_addr) & gpio_mask;
 
-		/* word index for bits array */
-		word_index = BIT_WORD(bits_offset);
-
-		/* gpio offset within current word of bits array */
-		word_offset = bits_offset % BITS_PER_LONG;
-
-		/* mask of get bits for current gpio within current word */
-		word_mask = mask[word_index] & (port_mask << word_offset);
-		if (!word_mask) {
-			/* no get bits in this port so skip to next one */
-			continue;
-		}
-
-		/* read bits from current gpio port */
-		port_state = inb(ws16c48gpio->base + i);
-
-		/* store acquired bits at respective bits array offset */
-		bits[word_index] |= (port_state << word_offset) & word_mask;
+		bitmap_set_value8(bits, chip->ngpio, port_state, offset);
 	}
 
 	return 0;
@@ -203,39 +180,30 @@ static void ws16c48_gpio_set_multiple(struct gpio_chip *chip,
 	unsigned long *mask, unsigned long *bits)
 {
 	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
-	unsigned int i;
-	const unsigned int gpio_reg_size = 8;
-	unsigned int port;
-	unsigned int iomask;
+	unsigned int offset;
+	unsigned long gpio_mask;
+	size_t index;
+	unsigned int port_addr;
 	unsigned int bitmask;
 	unsigned long flags;
 
-	/* set bits are evaluated a gpio register size at a time */
-	for (i = 0; i < chip->ngpio; i += gpio_reg_size) {
-		/* no more set bits in this mask word; skip to the next word */
-		if (!mask[BIT_WORD(i)]) {
-			i = (BIT_WORD(i) + 1) * BITS_PER_LONG - gpio_reg_size;
-			continue;
-		}
-
-		port = i / gpio_reg_size;
+	for_each_set_clump8(offset, gpio_mask, mask, chip->ngpio) {
+		index = offset / 8;
+		port_addr = ws16c48gpio->base + index;
 
 		/* mask out GPIO configured for input */
-		iomask = mask[BIT_WORD(i)] & ~ws16c48gpio->io_state[port];
-		bitmask = iomask & bits[BIT_WORD(i)];
+		gpio_mask &= ~ws16c48gpio->io_state[index];
+		bitmask = bitmap_get_value8(bits, chip->ngpio, offset) &
+			  gpio_mask;
 
 		raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
 		/* update output state data and set device gpio register */
-		ws16c48gpio->out_state[port] &= ~iomask;
-		ws16c48gpio->out_state[port] |= bitmask;
-		outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
+		ws16c48gpio->out_state[index] &= ~gpio_mask;
+		ws16c48gpio->out_state[index] |= bitmask;
+		outb(ws16c48gpio->out_state[index], port_addr);
 
 		raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
-
-		/* prepare for next gpio register set */
-		mask[BIT_WORD(i)] >>= gpio_reg_size;
-		bits[BIT_WORD(i)] >>= gpio_reg_size;
 	}
 }
 
-- 
2.20.1

[PATCH v8 7/8] gpio: pci-idio-16: Utilize for_each_set_clump8 macro

[William Breathitt Gray]

Replace verbose implementation in get_multiple/set_multiple callbacks
with for_each_set_clump8 macro to simplify code and improve clarity.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 drivers/gpio/gpio-pci-idio-16.c | 75 ++++++++++++---------------------
 1 file changed, 28 insertions(+), 47 deletions(-)

diff --git a/drivers/gpio/gpio-pci-idio-16.c b/drivers/gpio/gpio-pci-idio-16.c
index 6b7349783223..b0ed6bb68296 100644
--- a/drivers/gpio/gpio-pci-idio-16.c
+++ b/drivers/gpio/gpio-pci-idio-16.c
@@ -108,45 +108,24 @@ static int idio_16_gpio_get_multiple(struct gpio_chip *chip,
 	unsigned long *mask, unsigned long *bits)
 {
 	struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
-	size_t i;
-	const unsigned int gpio_reg_size = 8;
-	unsigned int bits_offset;
-	size_t word_index;
-	unsigned int word_offset;
-	unsigned long word_mask;
-	const unsigned long port_mask = GENMASK(gpio_reg_size - 1, 0);
-	unsigned long port_state;
+	unsigned int offset;
+	unsigned long gpio_mask;
 	void __iomem *ports[] = {
 		&idio16gpio->reg->out0_7, &idio16gpio->reg->out8_15,
 		&idio16gpio->reg->in0_7, &idio16gpio->reg->in8_15,
 	};
+	const unsigned int ngpio = ARRAY_SIZE(ports) * 8;
+	void __iomem *port_addr;
+	unsigned long port_state;
 
 	/* clear bits array to a clean slate */
 	bitmap_zero(bits, chip->ngpio);
 
-	/* get bits are evaluated a gpio port register at a time */
-	for (i = 0; i < ARRAY_SIZE(ports); i++) {
-		/* gpio offset in bits array */
-		bits_offset = i * gpio_reg_size;
-
-		/* word index for bits array */
-		word_index = BIT_WORD(bits_offset);
-
-		/* gpio offset within current word of bits array */
-		word_offset = bits_offset % BITS_PER_LONG;
+	for_each_set_clump8(offset, gpio_mask, mask, ngpio) {
+		port_addr = ports[offset / 8];
+		port_state = ioread8(port_addr) & gpio_mask;
 
-		/* mask of get bits for current gpio within current word */
-		word_mask = mask[word_index] & (port_mask << word_offset);
-		if (!word_mask) {
-			/* no get bits in this port so skip to next one */
-			continue;
-		}
-
-		/* read bits from current gpio port */
-		port_state = ioread8(ports[i]);
-
-		/* store acquired bits at respective bits array offset */
-		bits[word_index] |= (port_state << word_offset) & word_mask;
+		bitmap_set_value8(bits, ngpio, port_state, offset);
 	}
 
 	return 0;
@@ -186,30 +165,32 @@ static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
 	unsigned long *mask, unsigned long *bits)
 {
 	struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
+	unsigned int offset;
+	unsigned long gpio_mask;
+	void __iomem *ports[] = {
+		&idio16gpio->reg->out0_7, &idio16gpio->reg->out8_15,
+	};
+	const unsigned int ngpio = ARRAY_SIZE(ports) * 8;
+	size_t index;
+	void __iomem *port_addr;
+	unsigned int bitmask;
 	unsigned long flags;
 	unsigned int out_state;
 
-	raw_spin_lock_irqsave(&idio16gpio->lock, flags);
+	for_each_set_clump8(offset, gpio_mask, mask, ngpio) {
+		index = offset / 8;
+		port_addr = ports[index];
 
-	/* process output lines 0-7 */
-	if (*mask & 0xFF) {
-		out_state = ioread8(&idio16gpio->reg->out0_7) & ~*mask;
-		out_state |= *mask & *bits;
-		iowrite8(out_state, &idio16gpio->reg->out0_7);
-	}
+		bitmask = bitmap_get_value8(bits, ngpio, offset) & gpio_mask;
+
+		raw_spin_lock_irqsave(&idio16gpio->lock, flags);
 
-	/* shift to next output line word */
-	*mask >>= 8;
+		out_state = ioread8(port_addr) & ~gpio_mask;
+		out_state |= bitmask;
+		iowrite8(out_state, port_addr);
 
-	/* process output lines 8-15 */
-	if (*mask & 0xFF) {
-		*bits >>= 8;
-		out_state = ioread8(&idio16gpio->reg->out8_15) & ~*mask;
-		out_state |= *mask & *bits;
-		iowrite8(out_state, &idio16gpio->reg->out8_15);
+		raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
 	}
-
-	raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
 }
 
 static void idio_16_irq_ack(struct irq_data *data)
-- 
2.20.1

[PATCH v8 8/8] gpio: pcie-idio-24: Utilize for_each_set_clump8 macro

[William Breathitt Gray]

Replace verbose implementation in get_multiple/set_multiple callbacks
with for_each_set_clump8 macro to simplify code and improve clarity.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 drivers/gpio/gpio-pcie-idio-24.c | 111 ++++++++++++-------------------
 1 file changed, 42 insertions(+), 69 deletions(-)

diff --git a/drivers/gpio/gpio-pcie-idio-24.c b/drivers/gpio/gpio-pcie-idio-24.c
index 52f1647a46fd..2ceff1f5d8fd 100644
--- a/drivers/gpio/gpio-pcie-idio-24.c
+++ b/drivers/gpio/gpio-pcie-idio-24.c
@@ -198,52 +198,35 @@ static int idio_24_gpio_get_multiple(struct gpio_chip *chip,
 	unsigned long *mask, unsigned long *bits)
 {
 	struct idio_24_gpio *const idio24gpio = gpiochip_get_data(chip);
-	size_t i;
-	const unsigned int gpio_reg_size = 8;
-	unsigned int bits_offset;
-	size_t word_index;
-	unsigned int word_offset;
-	unsigned long word_mask;
-	const unsigned long port_mask = GENMASK(gpio_reg_size - 1, 0);
-	unsigned long port_state;
+	unsigned int offset;
+	unsigned long gpio_mask;
 	void __iomem *ports[] = {
 		&idio24gpio->reg->out0_7, &idio24gpio->reg->out8_15,
 		&idio24gpio->reg->out16_23, &idio24gpio->reg->in0_7,
 		&idio24gpio->reg->in8_15, &idio24gpio->reg->in16_23,
 	};
+	const unsigned int ngpio = ARRAY_SIZE(ports) * 8;
+	size_t index;
+	unsigned long port_state;
 	const unsigned long out_mode_mask = BIT(1);
 
 	/* clear bits array to a clean slate */
 	bitmap_zero(bits, chip->ngpio);
 
-	/* get bits are evaluated a gpio port register at a time */
-	for (i = 0; i < ARRAY_SIZE(ports) + 1; i++) {
-		/* gpio offset in bits array */
-		bits_offset = i * gpio_reg_size;
-
-		/* word index for bits array */
-		word_index = BIT_WORD(bits_offset);
-
-		/* gpio offset within current word of bits array */
-		word_offset = bits_offset % BITS_PER_LONG;
-
-		/* mask of get bits for current gpio within current word */
-		word_mask = mask[word_index] & (port_mask << word_offset);
-		if (!word_mask) {
-			/* no get bits in this port so skip to next one */
-			continue;
-		}
+	for_each_set_clump8(offset, gpio_mask, mask, ngpio) {
+		index = offset / 8;
 
 		/* read bits from current gpio port (port 6 is TTL GPIO) */
-		if (i < 6)
-			port_state = ioread8(ports[i]);
+		if (index < 6)
+			port_state = ioread8(ports[index]);
 		else if (ioread8(&idio24gpio->reg->ctl) & out_mode_mask)
 			port_state = ioread8(&idio24gpio->reg->ttl_out0_7);
 		else
 			port_state = ioread8(&idio24gpio->reg->ttl_in0_7);
 
-		/* store acquired bits at respective bits array offset */
-		bits[word_index] |= (port_state << word_offset) & word_mask;
+		port_state &= gpio_mask;
+
+		bitmap_set_value8(bits, ngpio, port_state, offset);
 	}
 
 	return 0;
@@ -294,59 +277,49 @@ static void idio_24_gpio_set_multiple(struct gpio_chip *chip,
 	unsigned long *mask, unsigned long *bits)
 {
 	struct idio_24_gpio *const idio24gpio = gpiochip_get_data(chip);
-	size_t i;
-	unsigned long bits_offset;
+	unsigned int offset;
 	unsigned long gpio_mask;
-	const unsigned int gpio_reg_size = 8;
-	const unsigned long port_mask = GENMASK(gpio_reg_size, 0);
-	unsigned long flags;
-	unsigned int out_state;
 	void __iomem *ports[] = {
 		&idio24gpio->reg->out0_7, &idio24gpio->reg->out8_15,
 		&idio24gpio->reg->out16_23
 	};
+	const unsigned int ngpio = ARRAY_SIZE(ports) * 8;
+	size_t index;
+	unsigned int bitmask;
+	unsigned long flags;
+	unsigned int out_state;
 	const unsigned long out_mode_mask = BIT(1);
-	const unsigned int ttl_offset = 48;
-	const size_t ttl_i = BIT_WORD(ttl_offset);
-	const unsigned int word_offset = ttl_offset % BITS_PER_LONG;
-	const unsigned long ttl_mask = (mask[ttl_i] >> word_offset) & port_mask;
-	const unsigned long ttl_bits = (bits[ttl_i] >> word_offset) & ttl_mask;
-
-	/* set bits are processed a gpio port register at a time */
-	for (i = 0; i < ARRAY_SIZE(ports); i++) {
-		/* gpio offset in bits array */
-		bits_offset = i * gpio_reg_size;
-
-		/* check if any set bits for current port */
-		gpio_mask = (*mask >> bits_offset) & port_mask;
-		if (!gpio_mask) {
-			/* no set bits for this port so move on to next port */
-			continue;
-		}
 
-		raw_spin_lock_irqsave(&idio24gpio->lock, flags);
+	for_each_set_clump8(offset, gpio_mask, mask, ngpio) {
+		index = offset / 8;
 
-		/* process output lines */
-		out_state = ioread8(ports[i]) & ~gpio_mask;
-		out_state |= (*bits >> bits_offset) & gpio_mask;
-		iowrite8(out_state, ports[i]);
+		bitmask = bitmap_get_value8(bits, ngpio, offset) & gpio_mask;
 
-		raw_spin_unlock_irqrestore(&idio24gpio->lock, flags);
-	}
+		raw_spin_lock_irqsave(&idio24gpio->lock, flags);
 
-	/* check if setting TTL lines and if they are in output mode */
-	if (!ttl_mask || !(ioread8(&idio24gpio->reg->ctl) & out_mode_mask))
-		return;
+		/* read bits from current gpio port (port 6 is TTL GPIO) */
+		if (index < 6) {
+			out_state = ioread8(ports[index]);
+		} else if (ioread8(&idio24gpio->reg->ctl) & out_mode_mask) {
+			out_state = ioread8(&idio24gpio->reg->ttl_out0_7);
+		} else {
+			/* skip TTL GPIO if set for input */
+			raw_spin_unlock_irqrestore(&idio24gpio->lock, flags);
+			continue;
+		}
 
-	/* handle TTL output */
-	raw_spin_lock_irqsave(&idio24gpio->lock, flags);
+		/* set requested bit states */
+		out_state &= ~gpio_mask;
+		out_state |= bitmask;
 
-	/* process output lines */
-	out_state = ioread8(&idio24gpio->reg->ttl_out0_7) & ~ttl_mask;
-	out_state |= ttl_bits;
-	iowrite8(out_state, &idio24gpio->reg->ttl_out0_7);
+		/* write bits for current gpio port (port 6 is TTL GPIO) */
+		if (index < 6)
+			iowrite8(out_state, ports[index]);
+		else
+			iowrite8(out_state, &idio24gpio->reg->ttl_out0_7);
 
-	raw_spin_unlock_irqrestore(&idio24gpio->lock, flags);
+		raw_spin_unlock_irqrestore(&idio24gpio->lock, flags);
+	}
 }
 
 static void idio_24_irq_ack(struct irq_data *data)
-- 
2.20.1

Re: [PATCH v8 0/8] Introduce the for_each_set_clump8 macro

[Andrew Morton]

On Mon, 14 Jan 2019 15:19:17 +0900 William Breathitt Gray <vilhelm.gray@gmail.com> wrote:

> 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.

Nice-looking code.

>  drivers/gpio/gpio-104-dio-48e.c   |  73 ++++++--------------
>  drivers/gpio/gpio-104-idi-48.c    |  37 +++-------
>  drivers/gpio/gpio-gpio-mm.c       |  73 ++++++--------------
>  drivers/gpio/gpio-pci-idio-16.c   |  75 ++++++++------------
>  drivers/gpio/gpio-pcie-idio-24.c  | 111 +++++++++++-------------------
>  drivers/gpio/gpio-ws16c48.c       |  72 ++++++-------------
>  include/asm-generic/bitops/find.h |  14 ++++
>  include/linux/bitops.h            |   5 ++
>  lib/find_bit.c                    |  81 ++++++++++++++++++++++
>  lib/test_bitmap.c                 |  65 +++++++++++++++++
>  10 files changed, 307 insertions(+), 299 deletions(-)

It's a shame that it doesn't actually dercease the kernel line count,
but there are other benefits.

The patches are missing the hoped-for acks, but I think you maintain
most/all of those drivers.

Do we have any expectation that these facilities will be used by
anything other than GPIO?  If not then perhaps they should be sited
within drivers/gpio (presumably as a standalone module) until such a
need is found?

Re: [PATCH v8 0/8] Introduce the for_each_set_clump8 macro

[Linus Walleij]

On Wed, Jan 30, 2019 at 2:07 AM Andrew Morton <akpm@linux-foundation.org> wrote:
> On Mon, 14 Jan 2019 15:19:17 +0900 William Breathitt Gray <vilhelm.gray@gmail.com> wrote:

> >  drivers/gpio/gpio-104-dio-48e.c   |  73 ++++++--------------
> >  drivers/gpio/gpio-104-idi-48.c    |  37 +++-------
> >  drivers/gpio/gpio-gpio-mm.c       |  73 ++++++--------------
> >  drivers/gpio/gpio-pci-idio-16.c   |  75 ++++++++------------
> >  drivers/gpio/gpio-pcie-idio-24.c  | 111 +++++++++++-------------------
> >  drivers/gpio/gpio-ws16c48.c       |  72 ++++++-------------
> >  include/asm-generic/bitops/find.h |  14 ++++
> >  include/linux/bitops.h            |   5 ++
> >  lib/find_bit.c                    |  81 ++++++++++++++++++++++
> >  lib/test_bitmap.c                 |  65 +++++++++++++++++
> >  10 files changed, 307 insertions(+), 299 deletions(-)
>
> It's a shame that it doesn't actually dercease the kernel line count,
> but there are other benefits.
>
> The patches are missing the hoped-for acks, but I think you maintain
> most/all of those drivers.

He does, but FWIW:
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

Re: [PATCH v8 0/8] Introduce the for_each_set_clump8 macro

[William Breathitt Gray]

On Tue, Jan 29, 2019 at 05:07:34PM -0800, Andrew Morton wrote:
> Do we have any expectation that these facilities will be used by
> anything other than GPIO?  If not then perhaps they should be sited
> within drivers/gpio (presumably as a standalone module) until such a
> need is found?

I can move it within drivers/gpio since my only use at moment is for
these gpio drivers I maintain. However, moving it to the gpio subsystem
does make it less likely to be seen by authors in other subsystems who
may have use for it -- so there is the chance that this becomes isolated
and untilized only amonst the gpio drivers. That may not be such a bad
thing in the end; I suspect it will be easy to spot if other subsystems
start implementing their own for_each_set_clump (if other subsystems
would even have such a need for it).

Linus, if I move the for_each_set_clump macro and related functions to
drivers/gpio, should I move the code into the gpiolib.h and gpiolib.c
files? Or would it be best to implement this as a separate standalone
module, and make a Kconfig dependency for those gpio drivers which
require it? A standalone module feels somewhat overkill for such little
code in my opinion.

William Breathitt Gray

Re: [PATCH v8 0/8] Introduce the for_each_set_clump8 macro

[Linus Walleij]

On Wed, Jan 30, 2019 at 11:17 AM William Breathitt Gray
<vilhelm.gray@gmail.com> wrote:
> On Tue, Jan 29, 2019 at 05:07:34PM -0800, Andrew Morton wrote:

> > Do we have any expectation that these facilities will be used by
> > anything other than GPIO?  If not then perhaps they should be sited
> > within drivers/gpio (presumably as a standalone module) until such a
> > need is found?
>
> I can move it within drivers/gpio since my only use at moment is for
> these gpio drivers I maintain. However, moving it to the gpio subsystem
> does make it less likely to be seen by authors in other subsystems who
> may have use for it -- so there is the chance that this becomes isolated
> and untilized only amonst the gpio drivers. That may not be such a bad
> thing in the end; I suspect it will be easy to spot if other subsystems
> start implementing their own for_each_set_clump (if other subsystems
> would even have such a need for it).

I would sure prefer to have these in the generic core where this patch
puts them. I don't see the problem with that. We have to start generic
code from some point.

> Linus, if I move the for_each_set_clump macro and related functions to
> drivers/gpio, should I move the code into the gpiolib.h and gpiolib.c
> files? Or would it be best to implement this as a separate standalone
> module, and make a Kconfig dependency for those gpio drivers which
> require it? A standalone module feels somewhat overkill for such little
> code in my opinion.

Yeah. I was however thinking about that we should create a helper
library for port-mapped IO along the lines of gpio-mmio.c so we might
as well get started with that in that case, just call it gpio-port-mapped-io.c
and put these in first or something.

Yours,
Linus Walleij

Re: [PATCH v8 0/8] Introduce the for_each_set_clump8 macro

[Andy Shevchenko]

On Tue, Jan 29, 2019 at 05:07:34PM -0800, Andrew Morton wrote:
> On Mon, 14 Jan 2019 15:19:17 +0900 William Breathitt Gray <vilhelm.gray@gmail.com> wrote:

> It's a shame that it doesn't actually dercease the kernel line count,
> but there are other benefits.
> 
> The patches are missing the hoped-for acks, but I think you maintain
> most/all of those drivers.

I'm okay with the code as well, so,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Do we have any expectation that these facilities will be used by
> anything other than GPIO?  If not then perhaps they should be sited
> within drivers/gpio (presumably as a standalone module) until such a
> need is found?

I think I have an example out of GPIO realm. But I need time to prove that.
In any case I tend to bend to the generic exposure than to local one.

-- 
With Best Regards,
Andy Shevchenko