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SubjectRe: [PATCH 1/4] gpiolib: Introduce chip addition/removal notifier
On Mon, Jan 25, 2010 at 10:34:29PM -0800, David Brownell wrote:
> On Monday 25 January 2010, Anton Vorontsov wrote:
> >
> > +config GPIOLIB_NOTIFIER
> > +       bool
> > +       help
> > +         This symbol is selected by subsystems that need to handle GPIO
> > +         chips addition and removal. E.g., this is used for the
> > +         OpenFirmware bindings.
> > +
>
> I'm no huge fan of notifiers, but I suppose they have their place.
>
> However ... I don't see a lot of win to making this optional.

OK, will remove it.

> Just
> inline the little two blocking_notifier_call_chain() calls directly,
> making this a *LOT* simpler.

I'd rather stay with gpio_call_chain() helper, it makes the code
a little bit prettier, IMO. Compare this:

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1103,6 +1107,9 @@ fail:
pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
chip->base, chip->base + chip->ngpio - 1,
chip->label ? : "generic");
+ else
+ blocking_notifier_call_chain(&gpio_notifier,
+ GPIO_NOTIFY_CHIP_ADDED, chip);
return status;
}
EXPORT_SYMBOL_GPL(gpiochip_add);
@@ -1119,6 +1126,13 @@ int gpiochip_remove(struct gpio_chip *chip)
int status = 0;
unsigned id;

+ /* Ask external subsystems to release the chip. */
+ status = blocking_notifier_call_chain(&gpio_notifier,
+ GPIO_NOTIFY_CHIP_REMOVE, chip);
+ status = notifier_to_errno(status);
+ if (status)
+ return status;
+
spin_lock_irqsave(&gpio_lock, flags);

for (id = chip->base; id < chip->base + chip->ngpio; id++) {
---
With the call_chain helper:

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1029,6 +1030,16 @@ static inline void gpiochip_unexport(struct gpio_chip *chip)

#endif /* CONFIG_GPIO_SYSFS */

+static int gpio_call_chain(struct gpio_chip *chip, enum gpio_notify_msg msg)
+{
+ int ret = blocking_notifier_call_chain(&gpio_notifier, msg, chip);
+
+ return notifier_to_errno(ret);
+}
+
/**
* gpiochip_add() - register a gpio_chip
* @chip: the chip to register, with chip->base initialized
@@ -1103,6 +1114,9 @@ fail:
pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
chip->base, chip->base + chip->ngpio - 1,
chip->label ? : "generic");
+ else
+ gpio_call_chain(chip, GPIO_NOTIFY_CHIP_ADDED);
+
return status;
}
EXPORT_SYMBOL_GPL(gpiochip_add);
@@ -1119,6 +1133,11 @@ int gpiochip_remove(struct gpio_chip *chip)
int status = 0;
unsigned id;

+ /* Ask external subsystems to release the chip. */
+ status = gpio_call_chain(chip, GPIO_NOTIFY_CHIP_REMOVE);
+ if (status)
+ return status;
+
spin_lock_irqsave(&gpio_lock, flags);

for (id = chip->base; id < chip->base + chip->ngpio; id++) {
---
Thanks!
--
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