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Subject[PATCH 5/9] gpiolib: use gpio_chips list in gpiochip_find_base
Date
Re-implement gpiochip_find_base using the list of chips instead of the
global gpio_desc[] array. This makes it both simpler and more efficient,
and is needed to remove the global descriptors array.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
drivers/gpio/gpiolib.c | 37 ++++++++++++++++---------------------
1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e473ded..af4c350 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -126,30 +126,25 @@ struct gpio_chip *gpio_to_chip(unsigned gpio)
/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
static int gpiochip_find_base(int ngpio)
{
- int i;
- int spare = 0;
- int base = -ENOSPC;
-
- for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
- struct gpio_desc *desc = &gpio_desc[i];
- struct gpio_chip *chip = desc->chip;
-
- if (!chip) {
- spare++;
- if (spare == ngpio) {
- base = i;
- break;
- }
- } else {
- spare = 0;
- if (chip)
- i -= chip->ngpio - 1;
- }
+ struct gpio_chip *chip;
+ int base = ARCH_NR_GPIOS - ngpio;
+
+ list_for_each_entry_reverse(chip, &gpio_chips, list) {
+ /* found a free space? */
+ if (chip->base + chip->ngpio <= base)
+ break;
+ else
+ /* nope, check the space right before the chip */
+ base = chip->base - ngpio;
}

- if (gpio_is_valid(base))
+ if (gpio_is_valid(base)) {
pr_debug("%s: found new base at %d\n", __func__, base);
- return base;
+ return base;
+ } else {
+ pr_err("%s: cannot find free range\n", __func__);
+ return -ENOSPC;
+ }
}

/* caller ensures gpio is valid and requested, chip->get_direction may sleep */
--
1.8.1.1


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