[PATCH v2 3/8] gpio: pci-idio-16: Implement get_multiple callback

From: William Breathitt Gray
Date: Thu Mar 15 2018 - 11:47:23 EST


The ACCES I/O PCI-IDIO-16 series of devices provides 16
optically-isolated digital inputs accessed via two 8-bit ports. Since
eight input lines are acquired on a single port input read, the
PCI-IDIO-16 GPIO driver may improve multiple input reads by utilizing a
get_multiple callback. This patch implements the
idio_16_gpio_get_multiple function which serves as the respective
get_multiple callback.

Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
---
drivers/gpio/gpio-pci-idio-16.c | 50 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)

diff --git a/drivers/gpio/gpio-pci-idio-16.c b/drivers/gpio/gpio-pci-idio-16.c
index 57d1b7fbf07b..ef43a37ccaff 100644
--- a/drivers/gpio/gpio-pci-idio-16.c
+++ b/drivers/gpio/gpio-pci-idio-16.c
@@ -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>
@@ -103,6 +104,54 @@ static int idio_16_gpio_get(struct gpio_chip *chip, unsigned int offset)
return !!(ioread8(&idio16gpio->reg->in8_15) & (mask >> 24));
}

+static int idio_16_gpio_get_multiple(struct gpio_chip *chip,
+ unsigned long *mask, unsigned long *bits)
+{
+ struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
+ size_t i;
+ const unsigned int gpio_reg_size = 8;
+ unsigned int bits_offset;
+ size_t word_index;
+ unsigned int word_offset;
+ unsigned long mask_word;
+ const unsigned long port_mask = GENMASK(gpio_reg_size, 0);
+ unsigned long port_state;
+ const u8 __iomem ports[] = {
+ idio16gpio->reg->out0_7, idio16gpio->reg->out8_15,
+ idio16gpio->reg->in0_7, idio16gpio->reg->in8_15
+ };
+
+ /* 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 = ioread8(ports + i);
+
+ /* store acquired bits at respective bits array offset */
+ bits[word_index] |= port_state << word_offset;
+ }
+
+ return 0;
+}
+
static void idio_16_gpio_set(struct gpio_chip *chip, unsigned int offset,
int value)
{
@@ -299,6 +348,7 @@ static int idio_16_probe(struct pci_dev *pdev, const struct pci_device_id *id)
idio16gpio->chip.direction_input = idio_16_gpio_direction_input;
idio16gpio->chip.direction_output = idio_16_gpio_direction_output;
idio16gpio->chip.get = idio_16_gpio_get;
+ idio16gpio->chip.get_multiple = idio_16_gpio_get_multiple;
idio16gpio->chip.set = idio_16_gpio_set;
idio16gpio->chip.set_multiple = idio_16_gpio_set_multiple;

--
2.16.2