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GPIO fix for the v4.15 series, this fixes the bit fiddling in the

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MMIO GPIO driver.
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Merge tag 'gpio-v4.15-5' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull GPIO fix from Linus Walleij:
 "This is the (hopefully) last GPIO fix for v4.15, fixing the bit
  fiddling in the MMIO GPIO driver.

  Again the especially endowed screwer-upper who has been open coding
  bit fiddling is yours truly"

* tag 'gpio-v4.15-5' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio: mmio: Also read bits that are zero
This commit is contained in:
Linus Torvalds 2018-01-18 09:50:24 -08:00
commit 023080317d
1 changed files with 16 additions and 14 deletions
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30
drivers/gpio/gpio-mmio.c
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@ -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;