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-rw-r--r--drivers/gpio/gpiolib.c50
-rw-r--r--include/asm-generic/gpio.h1
2 files changed, 48 insertions, 3 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 2ba6127c4fa..24c62b848bf 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -43,6 +43,7 @@ struct gpio_desc {
/* flag symbols are bit numbers */
#define FLAG_REQUESTED 0
#define FLAG_IS_OUT 1
+#define FLAG_RESERVED 2
#ifdef CONFIG_DEBUG_FS
const char *label;
@@ -88,9 +89,10 @@ static int gpiochip_find_base(int ngpio)
int base = -ENOSPC;
for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
- struct gpio_chip *chip = gpio_desc[i].chip;
+ struct gpio_desc *desc = &gpio_desc[i];
+ struct gpio_chip *chip = desc->chip;
- if (!chip) {
+ if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) {
spare++;
if (spare == ngpio) {
base = i;
@@ -98,7 +100,8 @@ static int gpiochip_find_base(int ngpio)
}
} else {
spare = 0;
- i -= chip->ngpio - 1;
+ if (chip)
+ i -= chip->ngpio - 1;
}
}
@@ -108,6 +111,47 @@ static int gpiochip_find_base(int ngpio)
}
/**
+ * gpiochip_reserve() - reserve range of gpios to use with platform code only
+ * @start: starting gpio number
+ * @ngpio: number of gpios to reserve
+ * Context: platform init, potentially before irqs or kmalloc will work
+ *
+ * Returns a negative errno if any gpio within the range is already reserved
+ * or registered, else returns zero as a success code. Use this function
+ * to mark a range of gpios as unavailable for dynamic gpio number allocation,
+ * for example because its driver support is not yet loaded.
+ */
+int __init gpiochip_reserve(int start, int ngpio)
+{
+ int ret = 0;
+ unsigned long flags;
+ int i;
+
+ if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio))
+ return -EINVAL;
+
+ spin_lock_irqsave(&gpio_lock, flags);
+
+ for (i = start; i < start + ngpio; i++) {
+ struct gpio_desc *desc = &gpio_desc[i];
+
+ if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) {
+ ret = -EBUSY;
+ goto err;
+ }
+
+ set_bit(FLAG_RESERVED, &desc->flags);
+ }
+
+ pr_debug("%s: reserved gpios from %d to %d\n",
+ __func__, start, start + ngpio - 1);
+err:
+ spin_unlock_irqrestore(&gpio_lock, flags);
+
+ return ret;
+}
+
+/**
* gpiochip_add() - register a gpio_chip
* @chip: the chip to register, with chip->base initialized
* Context: potentially before irqs or kmalloc will work
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 464c5b334dc..ecf675a59d2 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -74,6 +74,7 @@ struct gpio_chip {
extern const char *gpiochip_is_requested(struct gpio_chip *chip,
unsigned offset);
+extern int __init __must_check gpiochip_reserve(int start, int ngpio);
/* add/remove chips */
extern int gpiochip_add(struct gpio_chip *chip);