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Subject[PATCH v3 6/8] gpio: 104-idi-48: Implement get_multiple callback
Date
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>
---
drivers/gpio/gpio-104-idi-48.c | 47 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)

diff --git a/drivers/gpio/gpio-104-idi-48.c b/drivers/gpio/gpio-104-idi-48.c
index add859d59766..2c230415eeba 100644
--- a/drivers/gpio/gpio-104-idi-48.c
+++ b/drivers/gpio/gpio-104-idi-48.c
@@ -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, 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);
--
2.16.2
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