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Commit a8ff510d authored by William Breathitt Gray's avatar William Breathitt Gray Committed by Linus Walleij
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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: default avatarWilliam Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 41b25131

drivers/gpio/gpio-ws16c48.c

+47 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * 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 */

			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;

	}



	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];