Hello Bartosz,
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_nbits.
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_nbits 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_nbits:-
'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_nbits:
'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 v4:
- [Patch 3/3]: Remove extra line and add few comments.
- [Patch 3/3]: Use single lock (and unlock) call instead of two
lock (and two unlock) calls.
- [Patch 3/3]: Use bitmap_from_arr32() where applicalble.
- [Patch 3/3]: Remove unnecessary 'const'.
Changes in v3:
- [Patch 1/3]: Rename for_each_set_clump to for_each_set_nbits.
- [Patch 1/3]: Shift function definitions outside 'ifdef CONFIG_DEBUG_FS'
macro guard to resolve build (linking) error in xilinx Patch[3/3].
- [Patch 2/3]: Rename for_each_set_clump to for_each_set_nbits.
Changes in v2:
- [Patch 1/3]: Shift the macros and related functions to gpiolib inside
gpio/. Reduce the visibilty of 'for_each_set_clump' to gpio.
- [Patch 1/3]: Remove __builtin_unreachable and simply use return
statement.
- Remove tests from lib/test_bitmap.c as 'for_each_set_clump' is
now localised inside gpio/ only.
Syed Nayyar Waris (3):
gpiolib: Introduce the for_each_set_nbits macro
gpio: thunderx: Utilize for_each_set_nbits macro
gpio: xilinx: Utilize generic bitmap_get_value and _set_value
drivers/gpio/gpio-thunderx.c | 13 ++++--
drivers/gpio/gpio-xilinx.c | 60 ++++++++++++------------
drivers/gpio/gpiolib.c | 90 ++++++++++++++++++++++++++++++++++++
drivers/gpio/gpiolib.h | 28 +++++++++++
4 files changed, 156 insertions(+), 35 deletions(-)
base-commit: e1b7033ecdac56c1cc4dff72d67cac25d449efc6
--
2.29.0
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 from 1 to BITS_PER_LONG. size less
than 1 or more than BITS_PER_LONG causes undefined behaviour.
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 the value from bitmap.
Cc: Linus Walleij <[email protected]>
Cc: Bartosz Gołaszewski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Signed-off-by: Syed Nayyar Waris <[email protected]>
Acked-by: William Breathitt Gray <[email protected]>
---
drivers/gpio/gpiolib.c | 90 ++++++++++++++++++++++++++++++++++++++++++
drivers/gpio/gpiolib.h | 28 +++++++++++++
2 files changed, 118 insertions(+)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 1427c1be749b..5576d1465c81 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -150,6 +150,96 @@ struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc,
}
EXPORT_SYMBOL_GPL(gpiochip_get_desc);
+/**
+ * bitmap_get_value - get a value of n-bits from the memory region
+ * @map: address to the bitmap memory region
+ * @start: bit offset of the n-bit value
+ * @nbits: size of value in bits (must be between 1 and BITS_PER_LONG inclusive).
+ *
+ * Returns value of nbits located at the @start bit offset within the @map
+ * memory region.
+ */
+unsigned long bitmap_get_value(const unsigned long *map,
+ unsigned long start,
+ unsigned long nbits)
+{
+ const size_t index = BIT_WORD(start);
+ const unsigned long offset = start % BITS_PER_LONG;
+ const unsigned long ceiling = round_up(start + 1, BITS_PER_LONG);
+ const unsigned long space = ceiling - start;
+ unsigned long value_low, value_high;
+
+ if (space >= nbits)
+ return (map[index] >> offset) & GENMASK(nbits - 1, 0);
+ else {
+ value_low = map[index] & BITMAP_FIRST_WORD_MASK(start);
+ value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits);
+ return (value_low >> offset) | (value_high << space);
+ }
+}
+EXPORT_SYMBOL_GPL(bitmap_get_value);
+
+/**
+ * bitmap_set_value - set value within a memory region
+ * @map: address to the bitmap memory region
+ * @nbits: size of map in bits
+ * @value: value of clump
+ * @value_width: size of value in bits (must be between 1 and BITS_PER_LONG inclusive)
+ * @start: bit offset of the value
+ */
+void bitmap_set_value(unsigned long *map, unsigned long nbits,
+ unsigned long value, unsigned long value_width,
+ unsigned long start)
+{
+ const unsigned long index = BIT_WORD(start);
+ const unsigned long length = BIT_WORD(nbits);
+ const unsigned long offset = start % BITS_PER_LONG;
+ const unsigned long ceiling = round_up(start + 1, BITS_PER_LONG);
+ const unsigned long space = ceiling - start;
+
+ value &= GENMASK(value_width - 1, 0);
+
+ if (space >= value_width) {
+ map[index] &= ~(GENMASK(value_width - 1, 0) << offset);
+ map[index] |= value << offset;
+ } else {
+ map[index + 0] &= ~BITMAP_FIRST_WORD_MASK(start);
+ map[index + 0] |= value << offset;
+
+ if (index + 1 >= length)
+ return;
+
+ map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + value_width);
+ map[index + 1] |= value >> space;
+ }
+}
+EXPORT_SYMBOL_GPL(bitmap_set_value);
+
+/**
+ * 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.
+ */
+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_GPL(find_next_clump);
+
/**
* desc_to_gpio - convert a GPIO descriptor to the integer namespace
* @desc: GPIO descriptor
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 30bc3f80f83e..af79784dfce3 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -141,6 +141,34 @@ int gpio_set_debounce_timeout(struct gpio_desc *desc, unsigned int debounce);
int gpiod_hog(struct gpio_desc *desc, const char *name,
unsigned long lflags, enum gpiod_flags dflags);
+unsigned long bitmap_get_value(const unsigned long *map,
+ unsigned long start,
+ unsigned long nbits);
+
+void bitmap_set_value(unsigned long *map, unsigned long nbits,
+ unsigned long value, unsigned long value_width,
+ unsigned long start);
+
+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))
+
+/**
+ * for_each_set_nbits - 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_nbits(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)))
+
/*
* Return the GPIO number of the passed descriptor relative to its chip
*/
--
2.29.0
This patch reimplements the thunderx_gpio_set_multiple function in
drivers/gpio/gpio-thunderx.c to use the new for_each_set_nbits 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.
Cc: Robert Richter <[email protected]>
Cc: Bartosz Golaszewski <[email protected]>
Signed-off-by: Syed Nayyar Waris <[email protected]>
Acked-by: William Breathitt Gray <[email protected]>
---
drivers/gpio/gpio-thunderx.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/drivers/gpio/gpio-thunderx.c b/drivers/gpio/gpio-thunderx.c
index 9f66deab46ea..4349e7393a1d 100644
--- a/drivers/gpio/gpio-thunderx.c
+++ b/drivers/gpio/gpio-thunderx.c
@@ -16,7 +16,7 @@
#include <linux/pci.h>
#include <linux/spinlock.h>
#include <asm-generic/msi.h>
-
+#include "gpiolib.h"
#define GPIO_RX_DAT 0x0
#define GPIO_TX_SET 0x8
@@ -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_nbits(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);
}
--
2.29.0
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.
Cc: Bartosz Golaszewski <[email protected]>
Cc: Michal Simek <[email protected]>
Signed-off-by: Syed Nayyar Waris <[email protected]>
Acked-by: William Breathitt Gray <[email protected]>
---
drivers/gpio/gpio-xilinx.c | 60 +++++++++++++++++++-------------------
1 file changed, 30 insertions(+), 30 deletions(-)
diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
index b411d3156e0b..e0ad3a81f216 100644
--- a/drivers/gpio/gpio-xilinx.c
+++ b/drivers/gpio/gpio-xilinx.c
@@ -18,6 +18,7 @@
#include <linux/of_platform.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
+#include "gpiolib.h"
/* Register Offset Definitions */
#define XGPIO_DATA_OFFSET (0x0) /* Data register */
@@ -161,37 +162,36 @@ static void xgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
{
unsigned long flags;
struct xgpio_instance *chip = gpiochip_get_data(gc);
- int index = xgpio_index(chip, 0);
- int offset, i;
- spin_lock_irqsave(&chip->gpio_lock, 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, flags);
- index = xgpio_index(chip, i);
- spin_lock_irqsave(&chip->gpio_lock, 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, flags);
+ u32 *state = chip->gpio_state;
+ unsigned int *width = chip->gpio_width;
+ DECLARE_BITMAP(old, 64);
+ DECLARE_BITMAP(new, 64);
+ DECLARE_BITMAP(changed, 64);
+
+ spin_lock_irqsave(&chip->gpio_lock, flags);
+
+ /* Copy initial value of state bits into 'old' bit-wise */
+ bitmap_set_value(old, 64, state[0], width[0], 0);
+ bitmap_set_value(old, 64, state[1], width[1], width[0]);
+ /* Copy value from 'old' into 'new' with mask applied */
+ bitmap_replace(new, old, bits, mask, gc->ngpio);
+
+ bitmap_from_arr32(old, state, 64);
+ /* Update 'state' */
+ state[0] = bitmap_get_value(new, 0, width[0]);
+ state[1] = bitmap_get_value(new, width[0], width[1]);
+ bitmap_from_arr32(new, state, 64);
+ /* XOR operation sets only changed bits */
+ 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_irqrestore(&chip->gpio_lock, flags);
}
/**
--
2.29.0
On Fri, Apr 2, 2021 at 3:42 PM Syed Nayyar Waris <[email protected]> wrote:
>
> 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.
>
> Cc: Bartosz Golaszewski <[email protected]>
> Cc: Michal Simek <[email protected]>
> Signed-off-by: Syed Nayyar Waris <[email protected]>
> Acked-by: William Breathitt Gray <[email protected]>
> ---
> drivers/gpio/gpio-xilinx.c | 60 +++++++++++++++++++-------------------
> 1 file changed, 30 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
> index b411d3156e0b..e0ad3a81f216 100644
> --- a/drivers/gpio/gpio-xilinx.c
> +++ b/drivers/gpio/gpio-xilinx.c
> @@ -18,6 +18,7 @@
> #include <linux/of_platform.h>
> #include <linux/pm_runtime.h>
> #include <linux/slab.h>
> +#include "gpiolib.h"
>
> /* Register Offset Definitions */
> #define XGPIO_DATA_OFFSET (0x0) /* Data register */
> @@ -161,37 +162,36 @@ static void xgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
> {
> unsigned long flags;
> struct xgpio_instance *chip = gpiochip_get_data(gc);
> - int index = xgpio_index(chip, 0);
> - int offset, i;
>
> - spin_lock_irqsave(&chip->gpio_lock, 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, flags);
> - index = xgpio_index(chip, i);
> - spin_lock_irqsave(&chip->gpio_lock, 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, flags);
> + u32 *state = chip->gpio_state;
> + unsigned int *width = chip->gpio_width;
> + DECLARE_BITMAP(old, 64);
> + DECLARE_BITMAP(new, 64);
> + DECLARE_BITMAP(changed, 64);
> +
> + spin_lock_irqsave(&chip->gpio_lock, flags);
> +
> + /* Copy initial value of state bits into 'old' bit-wise */
> + bitmap_set_value(old, 64, state[0], width[0], 0);
> + bitmap_set_value(old, 64, state[1], width[1], width[0]);
> + /* Copy value from 'old' into 'new' with mask applied */
> + bitmap_replace(new, old, bits, mask, gc->ngpio);
> +
> + bitmap_from_arr32(old, state, 64);
> + /* Update 'state' */
> + state[0] = bitmap_get_value(new, 0, width[0]);
> + state[1] = bitmap_get_value(new, width[0], width[1]);
> + bitmap_from_arr32(new, state, 64);
> + /* XOR operation sets only changed bits */
> + 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_irqrestore(&chip->gpio_lock, flags);
> }
>
> /**
> --
> 2.29.0
>
Hi All,
There were indentation errors reported. I am Re-sending the patchset.
I am keeping the version same as v4.
Kindly consider the "RESEND" prefixed v4 patchset for future.
Regards
Syed Nayyar Waris