From: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Add a new gpiolib mechanism: gpio_chip instances can provide
mappings between their (input) GPIOs and any associated IRQs.
This makes it easier for platforms to support IRQs that are
provided by board-specific external chips instead of as part
of their core (such as SOC-integrated GPIOs).
Also update the irq_to_gpio() description, saying to avoid it
becuase it's not always supported.
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Preview of a 2.6.28 feature, taken from MM to let OMAP stage
patches relying on this feature.
Documentation/gpio.txt | 5 +++--
drivers/gpio/gpiolib.c | 18 ++++++++++++++++++
include/asm-generic/gpio.h | 7 +++++++
3 files changed, 28 insertions(+), 2 deletions(-)
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -264,7 +264,7 @@ map between them using calls like:
/* map GPIO numbers to IRQ numbers */
int gpio_to_irq(unsigned gpio);
- /* map IRQ numbers to GPIO numbers */
+ /* map IRQ numbers to GPIO numbers (avoid using this) */
int irq_to_gpio(unsigned irq);
Those return either the corresponding number in the other namespace, or
@@ -284,7 +284,8 @@ system wakeup capabilities.
Non-error values returned from irq_to_gpio() would most commonly be used
with gpio_get_value(), for example to initialize or update driver state
-when the IRQ is edge-triggered.
+when the IRQ is edge-triggered. Note that some platforms don't support
+this reverse mapping, so you should avoid using it.
Emulating Open Drain Signals
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1008,6 +1008,24 @@ int __gpio_cansleep(unsigned gpio)
}
EXPORT_SYMBOL_GPL(__gpio_cansleep);
+/**
+ * __gpio_to_irq() - return the IRQ corresponding to a GPIO
+ * @gpio: gpio whose IRQ will be returned (already requested)
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_to_irq().
+ * It returns the number of the IRQ signaled by this (input) GPIO,
+ * or a negative errno.
+ */
+int __gpio_to_irq(unsigned gpio)
+{
+ struct gpio_chip *chip;
+
+ chip = gpio_to_chip(gpio);
+ return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO;
+}
+EXPORT_SYMBOL_GPL(__gpio_to_irq);
+
/* There's no value in making it easy to inline GPIO calls that may sleep.
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -40,6 +40,8 @@ struct module;
* returns either the value actually sensed, or zero
* @direction_output: configures signal "offset" as output, or returns error
* @set: assigns output value for signal "offset"
+ * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
+ * implementation may not sleep
* @dbg_show: optional routine to show contents in debugfs; default code
* will be used when this is omitted, but custom code can show extra
* state (such as pullup/pulldown configuration).
@@ -73,6 +75,10 @@ struct gpio_chip {
unsigned offset, int value);
void (*set)(struct gpio_chip *chip,
unsigned offset, int value);
+
+ int (*to_irq)(struct gpio_chip *chip,
+ unsigned offset);
+
void (*dbg_show)(struct seq_file *s,
struct gpio_chip *chip);
int base;
@@ -112,6 +118,7 @@ extern void __gpio_set_value(unsigned gp
extern int __gpio_cansleep(unsigned gpio);
+extern int __gpio_to_irq(unsigned gpio);
#ifdef CONFIG_GPIO_SYSFS
--
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