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gpio: 104-idi-48: Implement get_multiple callback 

The ACCES I/O 104-IDI-48 series of devices provides 48
optically-isolated inputs accessed via six 8-bit ports. Since eight
input lines are acquired on a single port input read, the 104-IDI-48
GPIO driver may improve multiple input reads by utilizing a get_multiple
callback. This patch implements the idi_48_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 09:00:31 -04:00 committed by Linus Walleij
parent d2d02bcdd5
commit f72b10713c
1 changed files with 47 additions and 0 deletions
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47
drivers/gpio/gpio-104-idi-48.c
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@ -14,6 +14,7 @@
* This driver supports the following ACCES devices: 104-IDI-48A,
* 104-IDI-48AC, 104-IDI-48B, and 104-IDI-48BC.
*/
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/errno.h>
@ -88,6 +89,51 @@ static int idi_48_gpio_get(struct gpio_chip *chip, unsigned offset)
return 0;
}
static int idi_48_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
unsigned long *bits)
{
struct idi_48_gpio *const idi48gpio = 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(idi48gpio->base + ports[i]);
/* store acquired bits at respective bits array offset */
bits[word_index] |= port_state << word_offset;
}
return 0;
}
static void idi_48_irq_ack(struct irq_data *data)
{
}
@ -256,6 +302,7 @@ static int idi_48_probe(struct device *dev, unsigned int id)
idi48gpio->chip.get_direction = idi_48_gpio_get_direction;
idi48gpio->chip.direction_input = idi_48_gpio_direction_input;
idi48gpio->chip.get = idi_48_gpio_get;
idi48gpio->chip.get_multiple = idi_48_gpio_get_multiple;
idi48gpio->base = base[id];
raw_spin_lock_init(&idi48gpio->lock);