gpio: 74x164: utilize the for_each_set_clump8 macro

Replace verbose implementation in set_multiple callback with
for_each_set_clump8 macro to simplify code and improve clarity.

Link: http://lkml.kernel.org/r/7ea2[e-mail]
Signed-off-by: William Breathitt Gray <[e-mail]>
Suggested-by: Andy Shevchenko <[e-mail]>
Tested-by: Andy Shevchenko <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Cc: Phil Reid <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Bartosz Golaszewski <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Cc: Linus Walleij <[e-mail]>
Cc: Lukas Wunner <[e-mail]>
Cc: Masahiro Yamada <[e-mail]>
Cc: Mathias Duckeck <[e-mail]>
Cc: Morten Hein Tiljeset <[e-mail]>
Cc: Rasmus Villemoes <[e-mail]>
Cc: Sean Nyekjaer <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/gpio/gpio-74x164.c

···
  *  Copyright (C) 2010 Miguel Gaio <[e-mail]>
  */
 
+#include <linux/bitops.h>
 #include <linux/gpio/consumer.h>
 #include <linux/gpio/driver.h>
 #include <linux/module.h>
···
 				    unsigned long *bits)
 {
 	struct gen_74x164_chip *chip = gpiochip_get_data(gc);
-	unsigned int i, idx, shift;
-	u8 bank, bankmask;
+	unsigned long offset;
+	unsigned long bankmask;
+	size_t bank;
+	unsigned long bitmask;
 
 	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;
+	for_each_set_clump8(offset, bankmask, mask, chip->registers * 8) {
+		bank = chip->registers - 1 - offset / 8;
+		bitmask = bitmap_get_value8(bits, offset) & bankmask;
 
 		chip->buffer[bank] &= ~bankmask;
-		chip->buffer[bank] |= bankmask & (bits[idx] >> shift);
+		chip->buffer[bank] |= bitmask;
 	}
 	__gen_74x164_write_config(chip);
 	mutex_unlock(&chip->lock);