Commit a8ff510d authored by William Breathitt Gray's avatar William Breathitt Gray Committed by Linus Walleij

gpio: ws16c48: Implement get_multiple callback

The WinSystems WS16C48 device provides 48 lines of digital I/O accessed
via six 8-bit ports. Since eight input lines are acquired on a single
port input read, the WS16C48 GPIO driver may improve multiple input
reads by utilizing a get_multiple callback. This patch implements the
ws16c48_gpio_get_multiple function which serves as the respective
get_multiple callback.
Signed-off-by: William Breathitt Gray's avatarWilliam Breathitt Gray <>
Signed-off-by: default avatarLinus Walleij <>
parent 41b25131
......@@ -11,6 +11,7 @@
* General Public License for more details.
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/errno.h>
......@@ -129,6 +130,51 @@ static int ws16c48_gpio_get(struct gpio_chip *chip, unsigned offset)
return !!(port_state & mask);
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 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;
/* 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 */
/* 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;
return 0;
static void ws16c48_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
......@@ -383,6 +429,7 @@ static int ws16c48_probe(struct device *dev, unsigned int id)
ws16c48gpio->chip.direction_input = ws16c48_gpio_direction_input;
ws16c48gpio->chip.direction_output = ws16c48_gpio_direction_output;
ws16c48gpio->chip.get = ws16c48_gpio_get;
ws16c48gpio->chip.get_multiple = ws16c48_gpio_get_multiple;
ws16c48gpio->chip.set = ws16c48_gpio_set;
ws16c48gpio->chip.set_multiple = ws16c48_gpio_set_multiple;
ws16c48gpio->base = base[id];
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