gpio: 74x164: Implement gpiochip.set_multiple()

This allows to set multiple outputs using a single SPI transfer.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Phil Reid <preid@electromag.com.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c
index c81224ff2dca..62291a81c97f 100644
--- a/drivers/gpio/gpio-74x164.c
+++ b/drivers/gpio/gpio-74x164.c
@@ -75,6 +75,29 @@ static void gen_74x164_set_value(struct gpio_chip *gc,
         mutex_unlock(&chip->lock);
 }
 
+static void gen_74x164_set_multiple(struct gpio_chip *gc, unsigned long *mask,
+                                    unsigned long *bits)
+{
+        struct gen_74x164_chip *chip = gpiochip_get_data(gc);
+        unsigned int i, idx, shift;
+        u8 bank, bankmask;
+
+        mutex_lock(&chip->lock);
+        for (i = 0, bank = chip->registers - 1; i < chip->registers;
+             i++, bank--) {
+                idx = i / sizeof(*mask);
+                shift = i % sizeof(*mask) * BITS_PER_BYTE;
+                bankmask = mask[idx] >> shift;
+                if (!bankmask)
+                        continue;
+
+                chip->buffer[bank] &= ~bankmask;
+                chip->buffer[bank] |= bankmask & (bits[idx] >> shift);
+        }
+        __gen_74x164_write_config(chip);
+        mutex_unlock(&chip->lock);
+}
+
 static int gen_74x164_direction_output(struct gpio_chip *gc,
                 unsigned offset, int val)
 {
@@ -114,6 +137,7 @@ static int gen_74x164_probe(struct spi_device *spi)
         chip->gpio_chip.direction_output = gen_74x164_direction_output;
         chip->gpio_chip.get = gen_74x164_get_value;
         chip->gpio_chip.set = gen_74x164_set_value;
+        chip->gpio_chip.set_multiple = gen_74x164_set_multiple;
         chip->gpio_chip.base = -1;
 
         chip->registers = nregs;