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Subject[PATCH v3 7/8] gpio: gpio-mm: Implement get_multiple callback
Date
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>
---
drivers/gpio/gpio-gpio-mm.c | 47 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)

diff --git a/drivers/gpio/gpio-gpio-mm.c b/drivers/gpio/gpio-gpio-mm.c
index 11ade5b288f8..94b86fca65ba 100644
--- a/drivers/gpio/gpio-gpio-mm.c
+++ b/drivers/gpio/gpio-gpio-mm.c
@@ -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, 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];
--
2.16.2
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