diff mbox

[RFT,4/5] gpio: gpio-pl061: use the generic request/free implementations

Message ID 5612772B.8090706@openwrt.org
State New
Headers show

Commit Message

Jonas Gorski Oct. 5, 2015, 1:12 p.m. UTC 
On 05.10.2015 11:19, Linus Walleij wrote:
> On Sun, Sep 13, 2015 at 3:21 PM, Jonas Gorski <jogo@openwrt.org> wrote:
> 
>>         spin_lock_init(&chip->lock);
>> -       if (of_property_read_bool(dev->of_node, "gpio-ranges"))
>> -               chip->uses_pinctrl = true;
>> +       if (of_property_read_bool(dev->of_node, "gpio-ranges")) {
>> +               chip->gc.request = gpiochip_generic_request;
>> +               chip->gc.free = gpiochip_generic_free;
>> +       }
> 
> This is way better.
> 
> But now this code is starting to multiply in drivers.
> 
> Can we think of a way to do this even more generic:
> could gpiochip_generic_request() check if the range is
> there instead?

I thought about this, and AFAICT this would open a window in which gpio
requests could bypass the pinctrl subsystem, as ranges are only registered
after the gpio chip was registered.
pinctrl_request_gpio() -> pinctrl_get_device_gpio_range() returns -EPROBEDEFER if
it can't find a range for that reason.

To solve this we could introduce a gpiochip_add_with_range(), then we can assign
the generic _request/_free in gpiochip_add in case the callbacks aren't set yet
(and keep the way _request/_free are implemented).

If the gpio-ranges property is used, we could then check for its existence to
assign the callbacks.

So my idea is something like the following. The conversion would be then

chip->request = foo_request;
chip->free = foo_free;
gpiochip_add(chip);
gpiochip_add_pin_range(chip, "foo", 0, 0, npins);

=>

static const struct __initconst pinctrl_gpio_range foo_range = {
	.base = 0,
	.pinbase = 0,
	.npins = npins,
};

gpiochip_add_with_ranges(chip, "foo", &foo_range, 1);

which would be a bit more verbose, but for drivers like pinctrl-cygnus-gpio,
which registers 51(!) pinranges for the same gpio chip, it would mean quite a
bit of code reduction.

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Comments

Linus Walleij Oct. 6, 2015, 7:23 a.m. UTC | #1 
On Mon, Oct 5, 2015 at 3:12 PM, Jonas Gorski <jogo@openwrt.org> wrote:
> [Me]
>> Can we think of a way to do this even more generic:
>> could gpiochip_generic_request() check if the range is
>> there instead?
>
> I thought about this, and AFAICT this would open a window in which gpio
> requests could bypass the pinctrl subsystem, as ranges are only registered
> after the gpio chip was registered.
> pinctrl_request_gpio() -> pinctrl_get_device_gpio_range() returns -EPROBEDEFER if
> it can't find a range for that reason.
>
> To solve this we could introduce a gpiochip_add_with_range(), then we can assign
> the generic _request/_free in gpiochip_add in case the callbacks aren't set yet
> (and keep the way _request/_free are implemented).

Hm! That sounds like a good idea. Alexandre, what do you think?

> static const struct __initconst pinctrl_gpio_range foo_range = {
>         .base = 0,
>         .pinbase = 0,
>         .npins = npins,
> };
>
> gpiochip_add_with_ranges(chip, "foo", &foo_range, 1);

Neato.

> which would be a bit more verbose, but for drivers like pinctrl-cygnus-gpio,
> which registers 51(!) pinranges for the same gpio chip, it would mean quite a
> bit of code reduction.

Now we're talking.

Are you interested in doing this refactoring? It'd be awesome.

(Do it on top of this series though, so we can merge this first.)

Yours,
Linus Walleij
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diff mbox

Patch

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index fa6e3c8..b4c6119 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -415,6 +415,11 @@  static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
 	return 0;
 }
 
+bool of_gpiochip_has_pin_range(struct gpio_chip *chip)
+{
+	return !!of_find_property(chip->of_node, "gpio-ranges", NULL);
+}
+
 #else
 static int of_gpiochip_add_pin_range(struct gpio_chip *chip) { return 0; }
 #endif
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e0853fb..33f79b0 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -236,14 +236,23 @@  static int gpiochip_add_to_list(struct gpio_chip *chip)
  * If chip->base is negative, this requests dynamic assignment of
  * a range of valid GPIOs.
  */
-int gpiochip_add(struct gpio_chip *chip)
+int gpiochip_add_with_ranges(struct gpio_chip *chip, const char *pinctl_name,
+			     const struct pinctrl_gpio_range *ranges,
+			     unsigned int nranges)
 {
 	unsigned long	flags;
 	int		status = 0;
-	unsigned	id;
+	unsigned	id, i;
 	int		base = chip->base;
 	struct gpio_desc *descs;
 
+	if ((nranges > 0) || of_gpiochip_has_pin_range(chip)) {
+		if (!chip->request)
+			chip->request = gpiochip_generic_request;
+		if (!chip->free)
+			chip->free = gpiochip_generic_free;
+	}
+
 	descs = kcalloc(chip->ngpio, sizeof(descs[0]), GFP_KERNEL);
 	if (!descs)
 		return -ENOMEM;
@@ -295,6 +304,16 @@  int gpiochip_add(struct gpio_chip *chip)
 	if (status)
 		goto err_remove_chip;
 
+	for (i = 0; i < nranges; i++) {
+		const struct pinctrl_gpio_range *range = ranges[i];
+
+		status = gpiochip_add_pin_range(chip, pinctl_name,
+						chip->base + range->base,
+						range->pinbase, range->npins);
+		if (status)
+			goto err_remove_chip;
+	}
+
 	acpi_gpiochip_add(chip);
 
 	status = gpiochip_sysfs_register(chip);
@@ -309,6 +328,7 @@  int gpiochip_add(struct gpio_chip *chip)
 
 err_remove_chip:
 	acpi_gpiochip_remove(chip);
+	gpiochip_remove_pin_ranges(chip);
 	gpiochip_free_hogs(chip);
 	of_gpiochip_remove(chip);
 	spin_lock_irqsave(&gpio_lock, flags);
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index bf34300..05a71da 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -72,6 +72,15 @@  struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
 
 struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip, u16 hwnum);
 
+#if defined(CONFIG_OF_GPIO) && defined(CONFIG_PINCTRL)
+bool of_gpiochip_has_pin_range(struct gpio_chip *chip);
+#else
+static inline bool of_gpiochip_has_pin_range(struct gpio_chip *chip)
+{
+	return false;
+}
+#endif
+
 extern struct spinlock gpio_lock;
 extern struct list_head gpio_chips;
 
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 0857c28..ea8a630 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -166,7 +166,14 @@  extern const char *gpiochip_is_requested(struct gpio_chip *chip,
 			unsigned offset);
 
 /* add/remove chips */
-extern int gpiochip_add(struct gpio_chip *chip);
+static inline int gpiochip_add(struct gpio_chip *chip)
+{
+	return gpiochip_add_with_ranges(chip, NULL, NULL, 0);
+}
+
+int gpiochip_add_with_ranges(struct gpio_chip *chip, const char *pinctl_name,
+			     const struct pinctrl_gpio_range *ranges,
+			     unsigned int nranges);
 extern void gpiochip_remove(struct gpio_chip *chip);
 extern struct gpio_chip *gpiochip_find(void *data,
 			      int (*match)(struct gpio_chip *chip, void *data));