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Introduce the for_each_set_clump macro

PATCH Superseded Syed Nayyar Waris 4 participants 15 messages Jun 27, 2020 – Oct 2, 2020

Subsystems (8)

v9 of 12 Superseded Latest is v12 →

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#0 lore raw

v9 cover Introduce the for_each_set_clump macro

Hello Linus,

Since this patchset primarily affects GPIO drivers, would you like to pick it up through your GPIO tree?

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.

Changes in v9:
- [Patch 4/4]: Remove looping of 'for_each_set_clump' and instead process two halves of a 64-bit bitmap separately or individually. Use normal spin_lock call for second inner lock. And take the spin_lock_init call outside the 'if' condition in the probe function of driver.

Changes in v8:
- [Patch 2/4]: Minor change: Use '__initdata' for correct section mismatch in 'clump_test_data' array.

Changes in v7:
- [Patch 2/4]: Minor changes: Use macro 'DECLARE_BITMAP()' and split 'struct' definition and test data.

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 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 generic bitmap_get_value and _set_value.

 drivers/gpio/gpio-thunderx.c      |  11 ++-
 drivers/gpio/gpio-xilinx.c        |  66 +++++++-------
 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                 | 145 ++++++++++++++++++++++++++++++
 7 files changed, 292 insertions(+), 37 deletions(-)

base-commit: b3a9e3b9622ae10064826dccb4f7a52bd88c7407

Signature · 1 line
2.26.2
#1 lore raw

PATCH v9 1/4 bitops: Introduce the for_each_set_clump macro

This macro iterates for each 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_value and bitmap_set_value functions are introduced to respectively get and set a value of n-bits in a bitmap memory region. The n-bits can have any size less than or equal to BITS_PER_LONG. Moreover, during setting value of n-bit in bitmap, if a situation arise that the width of next n-bit is exceeding the word boundary, then it will divide itself such that some portion of it is stored in that word, while the remaining portion is stored in the next higher word. Similar situation occurs while retrieving value of n-bits from bitmap.

---
Changes in v9:
- No change.

Changes in v8:
- No change.

Changes in v7:
- No change.

Changes in v6:
- No change.

Changes in v5:
- No change.

Changes in v4:
- No change.

Changes in v3:
- No change.

Changes in v2:
- No change.

 include/asm-generic/bitops/find.h | 19 ++++++++++
 include/linux/bitmap.h            | 61 +++++++++++++++++++++++++++++++
 include/linux/bitops.h            | 13 +++++++
 lib/find_bit.c                    | 14 +++++++
 4 files changed, 107 insertions(+)
include/asm-generic/bitops/find.h +19 -0
index 9fdf21302fdf..4e6600759455 100644
@@ -97,4 +97,23 @@ extern unsigned long find_next_clump8(unsigned long *clump,
 #define find_first_clump8(clump, bits, size) \
 	find_next_clump8((clump), (bits), (size), 0)
 
+/**
+ * find_next_clump - find next clump with set bits in a memory region
+ * @clump: location to store copy of found clump
+ * @addr: address to base the search on
+ * @size: bitmap size in number of bits
+ * @offset: bit offset at which to start searching
+ * @clump_size: clump size in 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.
+ */
+extern unsigned long find_next_clump(unsigned long *clump,
+				      const unsigned long *addr,
+				      unsigned long size, unsigned long offset,
+				      unsigned long clump_size);
+
+#define find_first_clump(clump, bits, size, clump_size) \
+	find_next_clump((clump), (bits), (size), 0, (clump_size))
+
 #endif /*_ASM_GENERIC_BITOPS_FIND_H_ */
include/linux/bitmap.h +61 -0

80 lines not on this page · raw message

include/linux/bitops.h +13 -0
index 99f2ac30b1d9..36a445e4a7cc 100644
@@ -62,6 +62,19 @@ extern unsigned long __sw_hweight64(__u64 w);
 	     (start) < (size); \
 	     (start) = find_next_clump8(&(clump), (bits), (size), (start) + 8))
 
+/**
+ * for_each_set_clump - iterate over bitmap for each clump with set bits
+ * @start: bit offset to start search and to store the current iteration offset
+ * @clump: location to store copy of current 8-bit clump
+ * @bits: bitmap address to base the search on
+ * @size: bitmap size in number of bits
+ * @clump_size: clump size in bits
+ */
+#define for_each_set_clump(start, clump, bits, size, clump_size) \
+	for ((start) = find_first_clump(&(clump), (bits), (size), (clump_size)); \
+	     (start) < (size); \
+	     (start) = find_next_clump(&(clump), (bits), (size), (start) + (clump_size), (clump_size)))
+
 static inline int get_bitmask_order(unsigned int count)
 {
 	int order;
lib/find_bit.c +14 -0
index 49f875f1baf7..1341bd39b32a 100644
@@ -190,3 +190,17 @@ unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
 	return offset;
 }
 EXPORT_SYMBOL(find_next_clump8);
+
+unsigned long find_next_clump(unsigned long *clump, const unsigned long *addr,
+			       unsigned long size, unsigned long offset,
+			       unsigned long clump_size)
+{
+	offset = find_next_bit(addr, size, offset);
+	if (offset == size)
+		return size;
+
+	offset = rounddown(offset, clump_size);
+	*clump = bitmap_get_value(addr, offset, clump_size);
+	return offset;
+}
+EXPORT_SYMBOL(find_next_clump);
Signature · 1 line
2.26.2
#2 lore raw

PATCH v9 2/4 lib/test_bitmap.c: Add for_each_set_clump test cases

In reply to Syed Nayyar Waris

The introduction of the generic for_each_set_clump macro need test cases to verify the implementation. This patch adds test cases for scenarios in which clump sizes are 8 bits, 24 bits, 30 bits and 6 bits. The cases contain situations where clump is getting split at the word boundary and also when zeroes are present in the start and middle of bitmap.

---
Changes in v9:
- No change.

Changes in v8:
- [Patch 2/4]: Minor change: Use '__initdata' for correct section mismatch in 'clump_test_data' array.

Changes in v7:
- Minor changes: Use macro 'DECLARE_BITMAP()' and split 'struct' definition and test data.

Changes in v6:
- Make 'for loop' inside 'test_for_each_set_clump' more succinct.

Changes in v5:
- No change.

Changes in v4:
- Use 'for' loop in test function of 'for_each_set_clump'.

Changes in v3:
- No Change.

Changes in v2:
- Unify different tests for 'for_each_set_clump'. Pass test data as function parameters.
- Remove unnecessary bitmap_zero calls.

 lib/test_bitmap.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 145 insertions(+)
lib/test_bitmap.c +145 -0
index 6b13150667f5..78c0048870a6 100644
@@ -155,6 +155,38 @@ static bool __init __check_eq_clump8(const char *srcfile, unsigned int line,
 	return true;
 }
 
+static bool __init __check_eq_clump(const char *srcfile, unsigned int line,
+				    const unsigned int offset,
+				    const unsigned int size,
+				    const unsigned long *const clump_exp,
+				    const unsigned long *const clump,
+				    const unsigned long clump_size)
+{
+	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 / clump_size];
+	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;						\
@@ -172,6 +204,7 @@ static bool __init __check_eq_clump8(const char *srcfile, unsigned int line,
 #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__)
+#define expect_eq_clump(...)		__expect_eq(clump, ##__VA_ARGS__)
 
 static void __init test_zero_clear(void)
 {
@@ -577,6 +610,28 @@ static void noinline __init test_mem_optimisations(void)
 	}
 }
 
+static const unsigned long clump_bitmap_data[] __initconst = {
+	0x38000201,
+	0x05ff0f38,
+	0xeffedcba,
+	0xbbbbabcd,
+	0x000000aa,
+	0x000000aa,
+	0x00ff0000,
+	0xaaaaaa00,
+	0xff000000,
+	0x00aa0000,
+	0x00000000,
+	0x00000000,
+	0x00000000,
+	0x0f000000,
+	0x00ff0000,
+	0xaaaaaa00,
+	0xff000000,
+	0x00aa0000,
+	0x00000ac0,
+};
+
 static const unsigned char clump_exp[] __initconst = {
 	0x01,	/* 1 bit set */
 	0x02,	/* non-edge 1 bit set */
@@ -588,6 +643,95 @@ static const unsigned char clump_exp[] __initconst = {
 	0x05,	/* non-adjacent 2 bits set */
 };
 
+static const unsigned long clump_exp1[] __initconst = {
+	0x01,	/* 1 bit set */
+	0x02,	/* non-edge 1 bit set */
+	0x00,	/* zero bits set */
+	0x38,	/* 3 bits set across 4-bit boundary */
+	0x38,	/* Repeated clump */
+	0x0F,	/* 4 bits set */
+	0xFF,	/* all bits set */
+	0x05,	/* non-adjacent 2 bits set */
+};
+
+static const unsigned long clump_exp2[] __initconst = {
+	0xfedcba,	/* 24 bits */
+	0xabcdef,
+	0xaabbbb,	/* Clump split between 2 words */
+	0x000000,	/* zeroes in between */
+	0x0000aa,
+	0x000000,
+	0x0000ff,
+	0xaaaaaa,
+	0x000000,
+	0x0000ff,
+};
+
+static const unsigned long clump_exp3[] __initconst = {
+	0x00000000,	/* starting with 0s*/
+	0x00000000,	/* All 0s */
+	0x00000000,
+	0x00000000,
+	0x3f00000f,     /* Non zero set */
+	0x2aa80003,
+	0x00000aaa,
+	0x00003fc0,
+};
+
+static const unsigned long clump_exp4[] __initconst = {
+	0x00,
+	0x2b,
+};
+
+struct clump_test_data_params {
+	DECLARE_BITMAP(data, 256);
+	unsigned long count;
+	unsigned long offset;
+	unsigned long limit;
+	unsigned long clump_size;
+	unsigned long const *exp;
+};
+
+static struct clump_test_data_params clump_test_data[] __initdata =
+				      { {{0}, 2, 0, 64, 8, clump_exp1},
+					{{0}, 8, 2, 240, 24, clump_exp2},
+					{{0}, 8, 10, 240, 30, clump_exp3},
+					{{0}, 1, 18, 18, 6, clump_exp4} };
+
+static void __init prepare_test_data(unsigned int index)
+{
+	int i;
+	unsigned long width = 0;
+
+	for(i = 0; i < clump_test_data[index].count; i++)
+	{
+		bitmap_set_value(clump_test_data[index].data,
+			clump_bitmap_data[(clump_test_data[index].offset)++], width, 32);
+		width += 32;
+	}
+}
+
+static void __init execute_for_each_set_clump_test(unsigned int index)
+{
+	unsigned long start, clump;
+
+	for_each_set_clump(start, clump, clump_test_data[index].data,
+						clump_test_data[index].limit,
+						clump_test_data[index].clump_size)
+	expect_eq_clump(start, clump_test_data[index].limit, clump_test_data[index].exp,
+						&clump, clump_test_data[index].clump_size);
+}
+
+static void __init test_for_each_set_clump(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(clump_test_data); i++) {
+		prepare_test_data(i);
+		execute_for_each_set_clump_test(i);
+	}
+}
+
 static void __init test_for_each_set_clump8(void)
 {
 #define CLUMP_EXP_NUMBITS 64
@@ -623,6 +767,7 @@ static void __init selftest(void)
 	test_bitmap_parselist_user();
 	test_mem_optimisations();
 	test_for_each_set_clump8();
+	test_for_each_set_clump();
 }
 
 KSTM_MODULE_LOADERS(test_bitmap);
Signature · 1 line
2.26.2
#3 lore raw

PATCH v9 3/4 gpio: thunderx: Utilize for_each_set_clump macro

In reply to Syed Nayyar Waris

This patch reimplements the thunderx_gpio_set_multiple function in drivers/gpio/gpio-thunderx.c to use the new for_each_set_clump macro. Instead of looping for each bank in thunderx_gpio_set_multiple function, now we can skip bank which is not set and save cycles.

---
Changes in v9:
- No change.

Changes in v8:
- No change.

Changes in v7:
- No change.

Changes in v6:
- No change.

Changes in v5:
- No change.

Changes in v4:
- Minor change: Inline value '64' in code for better code readability.

Changes in v3:
- Change datatype of some variables from u64 to unsigned long in function thunderx_gpio_set_multiple.

Changes in v2:
- No change.

 drivers/gpio/gpio-thunderx.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
drivers/gpio/gpio-thunderx.c +7 -4
index 9f66deab46ea..58c9bb25a377 100644
@@ -275,12 +275,15 @@ static void thunderx_gpio_set_multiple(struct gpio_chip *chip,
 				       unsigned long *bits)
 {
 	int bank;
-	u64 set_bits, clear_bits;
+	unsigned long set_bits, clear_bits, gpio_mask;
+	unsigned long offset;
+
 	struct thunderx_gpio *txgpio = gpiochip_get_data(chip);
 
-	for (bank = 0; bank <= chip->ngpio / 64; bank++) {
-		set_bits = bits[bank] & mask[bank];
-		clear_bits = ~bits[bank] & mask[bank];
+	for_each_set_clump(offset, gpio_mask, mask, chip->ngpio, 64) {
+		bank = offset / 64;
+		set_bits = bits[bank] & gpio_mask;
+		clear_bits = ~bits[bank] & gpio_mask;
 		writeq(set_bits, txgpio->register_base + (bank * GPIO_2ND_BANK) + GPIO_TX_SET);
 		writeq(clear_bits, txgpio->register_base + (bank * GPIO_2ND_BANK) + GPIO_TX_CLR);
 	}
Signature · 1 line
2.26.2
#4 lore raw

PATCH v9 4/4 gpio: xilinx: Utilize generic bitmap_get_value and _set_value.

In reply to Syed Nayyar Waris

This patch reimplements the xgpio_set_multiple function in drivers/gpio/gpio-xilinx.c to use the new generic functions:
bitmap_get_value and bitmap_set_value. The code is now simpler
to read and understand. Moreover, instead of looping for each bit in xgpio_set_multiple function, now we can check each channel at
a time and save cycles.
---
Changes in v9:
- Remove looping of 'for_each_set_clump' and instead process two halves of a 64-bit bitmap separately or individually. Use normal spin_lock call for second inner lock. And take the spin_lock_init call outside the 'if' condition in the 'probe' function of driver.

Changes in v8:
- No change.

Changes in v7:
- No change.

Changes in v6:
- No change.

Changes in v5:
- Minor change: Inline values '32' and '64' in code for better code readability.

Changes in v4:
- Minor change: Inline values '32' and '64' in code for better code readability.

Changes in v3:
- No change.

Changes in v2:
- No change

 drivers/gpio/gpio-xilinx.c | 66 +++++++++++++++++++-------------------
 1 file changed, 33 insertions(+), 33 deletions(-)
drivers/gpio/gpio-xilinx.c +33 -33
index 67f9f82e0db0..48393d06fb55 100644
@@ -136,39 +136,39 @@ static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
 static void xgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
 			       unsigned long *bits)
 {
-	unsigned long flags;
+	unsigned long flag;
 	struct xgpio_instance *chip = gpiochip_get_data(gc);
-	int index = xgpio_index(chip, 0);
-	int offset, i;
-
-	spin_lock_irqsave(&chip->gpio_lock[index], flags);
-
-	/* Write to GPIO signals */
-	for (i = 0; i < gc->ngpio; i++) {
-		if (*mask == 0)
-			break;
-		/* Once finished with an index write it out to the register */
-		if (index !=  xgpio_index(chip, i)) {
-			xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
-				       index * XGPIO_CHANNEL_OFFSET,
-				       chip->gpio_state[index]);
-			spin_unlock_irqrestore(&chip->gpio_lock[index], flags);
-			index =  xgpio_index(chip, i);
-			spin_lock_irqsave(&chip->gpio_lock[index], flags);
-		}
-		if (__test_and_clear_bit(i, mask)) {
-			offset =  xgpio_offset(chip, i);
-			if (test_bit(i, bits))
-				chip->gpio_state[index] |= BIT(offset);
-			else
-				chip->gpio_state[index] &= ~BIT(offset);
-		}
-	}
-
-	xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
-		       index * XGPIO_CHANNEL_OFFSET, chip->gpio_state[index]);
-
-	spin_unlock_irqrestore(&chip->gpio_lock[index], flags);
+	u32 *const state = chip->gpio_state;
+	unsigned int *const width = chip->gpio_width;
+
+	DECLARE_BITMAP(old, 64);
+	DECLARE_BITMAP(new, 64);
+	DECLARE_BITMAP(changed, 64);
+
+	spin_lock_irqsave(&chip->gpio_lock[0], flag);
+	spin_lock(&chip->gpio_lock[1]);
+
+	bitmap_set_value(old, state[0], 0, width[0]);
+	bitmap_set_value(old, state[1], width[0], width[1]);
+	bitmap_replace(new, old, bits, mask, gc->ngpio);
+
+	bitmap_set_value(old, state[0], 0, 32);
+	bitmap_set_value(old, state[1], 32, 32);
+	state[0] = bitmap_get_value(new, 0, width[0]);
+	state[1] = bitmap_get_value(new, width[0], width[1]);
+	bitmap_set_value(new, state[0], 0, 32);
+	bitmap_set_value(new, state[1], 32, 32);
+	bitmap_xor(changed, old, new, 64);
+
+	if (((u32 *)changed)[0])
+		xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET,
+				state[0]);
+	if (((u32 *)changed)[1])
+		xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
+				XGPIO_CHANNEL_OFFSET, state[1]);
+
+	spin_unlock(&chip->gpio_lock[1]);
+	spin_unlock_irqrestore(&chip->gpio_lock[0], flag);
 }
 
 /**
@@ -292,6 +292,7 @@ static int xgpio_probe(struct platform_device *pdev)
 		chip->gpio_width[0] = 32;
 
 	spin_lock_init(&chip->gpio_lock[0]);
+	spin_lock_init(&chip->gpio_lock[1]);
 
 	if (of_property_read_u32(np, "xlnx,is-dual", &is_dual))
 		is_dual = 0;
@@ -314,7 +315,6 @@ static int xgpio_probe(struct platform_device *pdev)
 					 &chip->gpio_width[1]))
 			chip->gpio_width[1] = 32;
 
-		spin_lock_init(&chip->gpio_lock[1]);
 	}
 
 	chip->gc.base = -1;
Signature · 1 line
2.26.2
#5 lore raw

Re: [PATCH v9 4/4] gpio: xilinx: Utilize generic bitmap_get_value and _set_value.

Quoted 44 lines · Syed Nayyar Waris

This patch reimplements the xgpio_set_multiple function in drivers/gpio/gpio-xilinx.c to use the new generic functions:
bitmap_get_value and bitmap_set_value. The code is now simpler
to read and understand. Moreover, instead of looping for each bit in xgpio_set_multiple function, now we can check each channel at
a time and save cycles.
---
Changes in v9:
- Remove looping of 'for_each_set_clump' and instead process two halves of a 64-bit bitmap separately or individually. Use normal spin_lock call for second inner lock. And take the spin_lock_init call outside the 'if' condition in the 'probe' function of driver.

Changes in v8:
- No change.

Changes in v7:
- No change.

Changes in v6:
- No change.

Changes in v5:
- Minor change: Inline values '32' and '64' in code for better code readability.

Changes in v4:
- Minor change: Inline values '32' and '64' in code for better code readability.

Changes in v3:
- No change.

Changes in v2:
- No change

 drivers/gpio/gpio-xilinx.c | 66 +++++++++++++++++++-------------------
 1 file changed, 33 insertions(+), 33 deletions(-)
drivers/gpio/gpio-xilinx.c +0 -0
index 67f9f82e0db0..48393d06fb55 100644

drivers/gpio/gpio-xilinx.c static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val) · line 139

Quoted 5 lines
drivers/gpio/gpio-xilinx.c +1 -1
@@ -136,39 +136,39 @@ static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
 static void xgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
 			       unsigned long *bits)
 {
-	unsigned long flags;
+	unsigned long flag;

Hi Syed,

I have a couple minor suggestions in case you submit a version 10. Leave this variable named "flags" because it refers to CPU flags which will likely be more than one flag anyway.

drivers/gpio/gpio-xilinx.c static int xgpio_probe(struct platform_device *pdev) · line 317

Quoted 12 lines
drivers/gpio/gpio-xilinx.c +1 -0
@@ -292,6 +292,7 @@ static int xgpio_probe(struct platform_device *pdev)
 		chip->gpio_width[0] = 32;
 
 	spin_lock_init(&chip->gpio_lock[0]);
+	spin_lock_init(&chip->gpio_lock[1]);
 
 	if (of_property_read_u32(np, "xlnx,is-dual", &is_dual))
 		is_dual = 0;
@@ -314,7 +315,6 @@ static int xgpio_probe(struct platform_device *pdev)
 					 &chip->gpio_width[1]))
 			chip->gpio_width[1] = 32;
 

Remove this whitespace as well.

Thanks,

William Breathitt Gray

Quoted 7 lines
drivers/gpio/gpio-xilinx.c +0 -1
-		spin_lock_init(&chip->gpio_lock[1]);
 	}
 
 	chip->gc.base = -1;
Signature · 1 line
2.26.2
#6 lore raw
In reply to Syed Nayyar Waris
Quoted 128 lines · Syed Nayyar Waris

Hello Linus,

Since this patchset primarily affects GPIO drivers, would you like to pick it up through your GPIO tree?

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.

Changes in v9:
- [Patch 4/4]: Remove looping of 'for_each_set_clump' and instead process two halves of a 64-bit bitmap separately or individually. Use normal spin_lock call for second inner lock. And take the spin_lock_init call outside the 'if' condition in the probe function of driver.

Changes in v8:
- [Patch 2/4]: Minor change: Use '__initdata' for correct section mismatch in 'clump_test_data' array.

Changes in v7:
- [Patch 2/4]: Minor changes: Use macro 'DECLARE_BITMAP()' and split 'struct' definition and test data.

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 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 generic bitmap_get_value and _set_value.

 drivers/gpio/gpio-thunderx.c      |  11 ++-
 drivers/gpio/gpio-xilinx.c        |  66 +++++++-------
 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                 | 145 ++++++++++++++++++++++++++++++
 7 files changed, 292 insertions(+), 37 deletions(-)
Quoted 4 lines

base-commit: b3a9e3b9622ae10064826dccb4f7a52bd88c7407 --
2.26.2

Hi Andrew, Linus

What do you think about this patchset on 'for_each_set_clump' ?

if there's anything else you think that should be changed in this, or if this version looks good to you to pick up, kindly, let me know.

Regards
Syed Nayyar Waris

#7 lore raw
In reply to Syed Nayyar Waris

Hi Syed,

sorry for taking so long. I was on vacation and a bit snowed under by work.

Quoted 2 lines · Syed Nayyar Waris

Since this patchset primarily affects GPIO drivers, would you like to pick it up through your GPIO tree?

I have applied the patches to an immutable branch and pushed to kernelorg for testing (autobuilders will play with it I hope).

If all works fine I will merge this into my devel branch for v5.9.

It would be desirable if Andrew gave his explicit ACK on it too.

Yours,
Linus Walleij

#8 lore raw
Quoted 14 lines · Linus Walleij

Hi Syed,

sorry for taking so long. I was on vacation and a bit snowed under by work.

Quoted 2 lines · Syed Nayyar Waris

Since this patchset primarily affects GPIO drivers, would you like to pick it up through your GPIO tree?

I have applied the patches to an immutable branch and pushed to kernelorg for testing (autobuilders will play with it I hope).

Quoted 6 lines

If all works fine I will merge this into my devel branch for v5.9.

It would be desirable if Andrew gave his explicit ACK on it too.

Yours,
Linus Walleij

Hi Linus,

As a reminder, I would like to point out about the 'for_each_set_clump' patchset. If it's alright and if anything is needed to take it further so that it is finally accepted.

Regards
Syed Nayyar Waris

#9 lore raw
In reply to Linus Walleij
Quoted 13 lines · Linus Walleij

Hi Syed,

sorry for taking so long. I was on vacation and a bit snowed under by work.

Quoted 2 lines · Syed Nayyar Waris

Since this patchset primarily affects GPIO drivers, would you like to pick it up through your GPIO tree?

I have applied the patches to an immutable branch and pushed to kernelorg for testing (autobuilders will play with it I hope).

Quoted 6 lines

If all works fine I will merge this into my devel branch for v5.9.

It would be desirable if Andrew gave his explicit ACK on it too.

Yours,
Linus Walleij

Hi Linus,

What's the name of the branch with these patches on kernelorg; I'm having trouble finding it?

Btw, I'm CCing Andrew as well here because I notice him missing from the CC list earlier for this patchset.

Thanks,

William Breathitt Gray

#10 lore raw
Quoted 21 lines · William Breathitt Gray
Quoted 13 lines · Linus Walleij

Hi Syed,

sorry for taking so long. I was on vacation and a bit snowed under by work.

Quoted 2 lines · Syed Nayyar Waris

Since this patchset primarily affects GPIO drivers, would you like to pick it up through your GPIO tree?

I have applied the patches to an immutable branch and pushed to kernelorg for testing (autobuilders will play with it I hope).

Quoted 6 lines

If all works fine I will merge this into my devel branch for v5.9.

It would be desirable if Andrew gave his explicit ACK on it too.

Yours,
Linus Walleij

Quoted 7 lines

Hi Linus,

What's the name of the branch with these patches on kernelorg; I'm having trouble finding it?

Btw, I'm CCing Andrew as well here because I notice him missing from the CC list earlier for this patchset.

IIRC there were complaints from the zeroday build robot so I dropped the branch and I am still waiting for a fixed up patch series.

Yours,
Linus Walleij

#11 lore raw
Quoted 31 lines · Linus Walleij
Quoted 21 lines · William Breathitt Gray
Quoted 13 lines · Linus Walleij

Hi Syed,

sorry for taking so long. I was on vacation and a bit snowed under by work.

Quoted 2 lines · Syed Nayyar Waris

Since this patchset primarily affects GPIO drivers, would you like to pick it up through your GPIO tree?

I have applied the patches to an immutable branch and pushed to kernelorg for testing (autobuilders will play with it I hope).

Quoted 6 lines

If all works fine I will merge this into my devel branch for v5.9.

It would be desirable if Andrew gave his explicit ACK on it too.

Yours,
Linus Walleij

Quoted 7 lines

Hi Linus,

What's the name of the branch with these patches on kernelorg; I'm having trouble finding it?

Btw, I'm CCing Andrew as well here because I notice him missing from the CC list earlier for this patchset.

Quoted 6 lines

IIRC there were complaints from the zeroday build robot so I dropped the branch and I am still waiting for a fixed up patch series.

Yours,
Linus Walleij

My apologies, I wasn't aware a build error was reported. I'll be happy to help address the issue with Syed, but I can't seem to find a copy of the message on <https://lkml.org/lkml/2020/6/27/107> or my email logs. Do you have a link available to the zeroday build log?

Thanks,

William Breathitt Gray

#12 lore raw
Quoted 6 lines · William Breathitt Gray
Quoted 4 lines · Linus Walleij
Quoted 2 lines · William Breathitt Gray
Quoted 1 line · Linus Walleij

On Sat, Jun 27, 2020 at 10:10 AM Syed Nayyar Waris <[email protected]> wrote:

...

Quoted 6 lines
Quoted 6 lines
Quoted 5 lines

What's the name of the branch with these patches on kernelorg; I'm having trouble finding it?

Btw, I'm CCing Andrew as well here because I notice him missing from the CC list earlier for this patchset.

Quoted 8 lines
Quoted 3 lines

IIRC there were complaints from the zeroday build robot so I dropped the branch and I am still waiting for a fixed up patch series.

My apologies, I wasn't aware a build error was reported. I'll be happy to help address the issue with Syed, but I can't seem to find a copy of the message on <https://lkml.org/lkml/2020/6/27/107> or my email logs. Do you have a link available to the zeroday build log?

Time to open lore.kernel.org? [1][2]

Linus, are you referencing to [3]? It was fixed in GENMASK() implementation some time ago.

[1]: https://lore.kernel.org/lkml/[email protected]/
[2]: https://lore.kernel.org/lkml/[email protected]/
[3]: https://lore.kernel.org/lkml/202006171559.JSbGJXNw%[email protected]/

Signature · 2 lines
With Best Regards,
Andy Shevchenko
#14 lore raw
Quoted 8 lines · Linus Walleij
Quoted 3 lines · Andy Shevchenko

Linus, are you referencing to [3]? It was fixed in GENMASK() implementation some time ago.
[3]: https://lore.kernel.org/lkml/202006171559.JSbGJXNw%[email protected]/

Quoted 8 lines

Yup.

I tried to apply the patches again now to test it but now patch 2 needs to be rebased.

Sorry for all the trouble!

Syed can you rebase the patch set on v5.9-rc1 and resend as v10?

Sure Linus. I will send it as soon as possible.

Thanks
Syed Nayyar Waris