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-rw-r--r--drivers/gpio/gpio-mmio.c30
1 files changed, 16 insertions, 14 deletions
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;