As long as one or more GPIOs on a gpio chip are used its driver should not
be unloaded.
Signed-off-by: Guennadi Liakhovetski <[EMAIL PROTECTED]>
---
Note, that existing drivers do not have to be modified, for example those,
that are always statically linked in the kernel, as long as the respective
struct gpio_chip is nullified before calling gpiochip_add().
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d8db2f8..dd535e1 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -177,6 +177,9 @@ int gpio_request(unsigned gpio, const char *label)
if (desc->chip == NULL)
goto done;
+ if (!try_module_get(desc->chip->owner))
+ goto done;
+
/* NOTE: gpio_request() can be called in early boot,
* before IRQs are enabled.
*/
@@ -184,8 +187,10 @@ int gpio_request(unsigned gpio, const char *label)
if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
desc_set_label(desc, label ? : "?");
status = 0;
- } else
+ } else {
status = -EBUSY;
+ module_put(desc->chip->owner);
+ }
done:
if (status)
@@ -209,9 +214,10 @@ void gpio_free(unsigned gpio)
spin_lock_irqsave(&gpio_lock, flags);
desc = &gpio_desc[gpio];
- if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags))
+ if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags)) {
desc_set_label(desc, NULL);
- else
+ module_put(desc->chip->owner);
+ } else
WARN_ON(extra_checks);
spin_unlock_irqrestore(&gpio_lock, flags);
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 806b86c..f6d389a 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -3,6 +3,8 @@
#ifdef CONFIG_HAVE_GPIO_LIB
+#include <linux/module.h>
+
/* Platforms may implement their GPIO interface with library code,
* at a small performance cost for non-inlined operations and some
* extra memory (for code and for per-GPIO table entries).
@@ -52,6 +54,7 @@ struct seq_file;
*/
struct gpio_chip {
char *label;
+ struct module *owner;
int (*direction_input)(struct gpio_chip *chip,
unsigned offset);
--
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