gpiolib: Initialize the hardware with a callback

After changing the drivers to use GPIO core to add an IRQ chip
it appears that some of them requires a hardware initialization
before adding the IRQ chip.

Add an optional callback ->init_hw() to allow that drivers
to initialize hardware if needed.

This change is a part of the fix NULL pointer dereference
brought to the several drivers recently.

Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 5833e4f380d60fe4f585debfd4b47c537bfb7b63..104ed299d5eaa41c439e61dbcde5eb70d620840c 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -86,6 +86,7 @@ static int gpiochip_add_irqchip(struct gpio_chip *gpiochip,
                                struct lock_class_key *lock_key,
                                struct lock_class_key *request_key);
 static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
+static int gpiochip_irqchip_init_hw(struct gpio_chip *gpiochip);
 static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip);
 static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gpiochip);
 
@@ -1406,6 +1407,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 
        machine_gpiochip_add(chip);
 
+       ret = gpiochip_irqchip_init_hw(chip);
+       if (ret)
+               goto err_remove_acpi_chip;
+
        ret = gpiochip_irqchip_init_valid_mask(chip);
        if (ret)
                goto err_remove_acpi_chip;
@@ -1622,6 +1627,16 @@ static struct gpio_chip *find_chip_by_name(const char *name)
  * The following is irqchip helper code for gpiochips.
  */
 
+static int gpiochip_irqchip_init_hw(struct gpio_chip *gc)
+{
+       struct gpio_irq_chip *girq = &gc->irq;
+
+       if (!girq->init_hw)
+               return 0;
+
+       return girq->init_hw(gc);
+}
+
 static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gc)
 {
        struct gpio_irq_chip *girq = &gc->irq;
@@ -2446,8 +2461,13 @@ static inline int gpiochip_add_irqchip(struct gpio_chip *gpiochip,
 {
        return 0;
 }
-
 static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip) {}
+
+static inline int gpiochip_irqchip_init_hw(struct gpio_chip *gpiochip)
+{
+       return 0;
+}
+
 static inline int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip)
 {
        return 0;

diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index f8245d67f07089774bca10017df85fb82ee39835..5dd9c982e2cbee6d10aa42fbcd888d702e6751cc 100644 (file)
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -201,6 +201,14 @@ struct gpio_irq_chip {
         */
        bool threaded;
 
+       /**
+        * @init_hw: optional routine to initialize hardware before
+        * an IRQ chip will be added. This is quite useful when
+        * a particular driver wants to clear IRQ related registers
+        * in order to avoid undesired events.
+        */
+       int (*init_hw)(struct gpio_chip *chip);
+
        /**
         * @init_valid_mask: optional routine to initialize @valid_mask, to be
         * used if not all GPIO lines are valid interrupts. Sometimes some