diff --git a/drivers/gpio/gpio-mmio.c b/drivers/gpio/gpio-mmio.c index f9042bcc27a4..7b14d6280e44 100644 --- a/drivers/gpio/gpio-mmio.c +++ b/drivers/gpio/gpio-mmio.c @@ -152,14 +152,13 @@ static int bgpio_get_set_multiple(struct gpio_chip *gc, unsigned long *mask, { unsigned long get_mask = 0; unsigned long set_mask = 0; - int bit = 0; - while ((bit = find_next_bit(mask, gc->ngpio, bit)) != gc->ngpio) { - if (gc->bgpio_dir & BIT(bit)) - set_mask |= BIT(bit); - else - get_mask |= BIT(bit); - } + /* Make sure we first clear any bits that are zero when we read the register */ + *bits &= ~*mask; + + /* Exploit the fact that we know which directions are set */ + set_mask = *mask & gc->bgpio_dir; + get_mask = *mask & ~gc->bgpio_dir; if (set_mask) *bits |= gc->read_reg(gc->reg_set) & set_mask; @@ -176,13 +175,13 @@ static int bgpio_get(struct gpio_chip *gc, unsigned int gpio) /* * This only works if the bits in the GPIO register are in native endianness. - * It is dirt simple and fast in this case. (Also the most common case.) */ static int bgpio_get_multiple(struct gpio_chip *gc, unsigned long *mask, unsigned long *bits) { - - *bits = gc->read_reg(gc->reg_dat) & *mask; + /* Make sure we first clear any bits that are zero when we read the register */ + *bits &= ~*mask; + *bits |= gc->read_reg(gc->reg_dat) & *mask; return 0; } @@ -196,9 +195,12 @@ static int bgpio_get_multiple_be(struct gpio_chip *gc, unsigned long *mask, unsigned long val; int bit; + /* Make sure we first clear any bits that are zero when we read the register */ + *bits &= ~*mask; + /* Create a mirrored mask */ - bit = 0; - while ((bit = find_next_bit(mask, gc->ngpio, bit)) != gc->ngpio) + bit = -1; + while ((bit = find_next_bit(mask, gc->ngpio, bit + 1)) < gc->ngpio) readmask |= bgpio_line2mask(gc, bit); /* Read the register */ @@ -208,8 +210,8 @@ static int bgpio_get_multiple_be(struct gpio_chip *gc, unsigned long *mask, * Mirror the result into the "bits" result, this will give line 0 * in bit 0 ... line 31 in bit 31 for a 32bit register. */ - bit = 0; - while ((bit = find_next_bit(&val, gc->ngpio, bit)) != gc->ngpio) + bit = -1; + while ((bit = find_next_bit(&val, gc->ngpio, bit + 1)) < gc->ngpio) *bits |= bgpio_line2mask(gc, bit); return 0;