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Message-Id: <200803131552.22122.david-b@pacbell.net>
Date: Thu, 13 Mar 2008 14:52:21 -0800
From: David Brownell <david-b@...bell.net>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: lkml <linux-kernel@...r.kernel.org>,
Anton Vorontsov <avorontsov@...mvista.com>
Subject: [patch 2.6.25-rc5 2/2] gpiochip_reserve()
From: Anton Vorontsov <avorontsov@...mvista.com>
Add a new function gpiochip_reserve() to reserve ranges of gpios that
platform code has pre-allocated. That is, this marks gpio numbers which
will be claimed by drivers that haven't yet been loaded, and thus are
not available for dynamic gpio number allocation.
Signed-off-by: Anton Vorontsov <avorontsov@...mvista.com>
Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net>
---
drivers/gpio/gpiolib.c | 51 ++++++++++++++++++++++++++++++++++++++++++---
include/asm-generic/gpio.h | 1
2 files changed, 49 insertions(+), 3 deletions(-)
--- g26.orig/drivers/gpio/gpiolib.c 2008-03-13 14:51:50.000000000 -0700
+++ g26/drivers/gpio/gpiolib.c 2008-03-13 14:56:16.000000000 -0700
@@ -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 +111,48 @@ 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 __must_check 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;
+}
+EXPORT_SYMBOL_GPL(gpiochip_reserve);
+
+/**
* gpiochip_add() - register a gpio_chip
* @chip: the chip to register, with chip->base initialized
* Context: potentially before irqs or kmalloc will work
--- g26.orig/include/asm-generic/gpio.h 2008-03-13 14:41:52.000000000 -0700
+++ g26/include/asm-generic/gpio.h 2008-03-13 14:55:10.000000000 -0700
@@ -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);
--
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