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gpio: gpio-mm: Implement get_multiple callback

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The Diamond Systems GPIO-MM series of devices contain two 82C55A
devices, which each feature three 8-bit ports of I/O. Since eight input
lines are acquired on a single port input read, the GPIO-MM GPIO driver
may improve multiple input reads by utilizing a get_multiple callback.
This patch implements the gpiomm_gpio_get_multiple function which serves
as the respective get_multiple callback.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
William Breathitt Gray 2018-03-22 09:00:42 -04:00 committed by Linus Walleij
parent f72b10713c
commit 41b251318a
1 changed files with 47 additions and 0 deletions
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47
drivers/gpio/gpio-gpio-mm.c
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@ -14,6 +14,7 @@
* This driver supports the following Diamond Systems devices: GPIO-MM and
* GPIO-MM-12.
*/
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/errno.h>
@ -171,6 +172,51 @@ static int gpiomm_gpio_get(struct gpio_chip *chip, unsigned int offset)
return !!(port_state & mask);
}
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;
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 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]);
/* store acquired bits at respective bits array offset */
bits[word_index] |= port_state << word_offset;
}
return 0;
}
static void gpiomm_gpio_set(struct gpio_chip *chip, unsigned int offset,
int value)
{
@ -268,6 +314,7 @@ static int gpiomm_probe(struct device *dev, unsigned int id)
gpiommgpio->chip.direction_input = gpiomm_gpio_direction_input;
gpiommgpio->chip.direction_output = gpiomm_gpio_direction_output;
gpiommgpio->chip.get = gpiomm_gpio_get;
gpiommgpio->chip.get_multiple = gpiomm_gpio_get_multiple;
gpiommgpio->chip.set = gpiomm_gpio_set;
gpiommgpio->chip.set_multiple = gpiomm_gpio_set_multiple;
gpiommgpio->base = base[id];