gpio: add IRQ chip helpers in gpiolib

This provides a function gpiochip_irqchip_add() to set
up an irqchip for a GPIO controller, and a function
gpiochip_set_chained_irqchip() to chain it to a parent
irqchip.

Most GPIOs are of the type where a number of lines form
a cascaded interrupt controller chained onto
the primary system interrupt controller (or further down the
chain) so let's add this helper and factor the code to
request the lines to be used as IRQs, the .to_irq() function
and the irqdomain into the core as well.

Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 9fe283642253..c1c5c2368fc8 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -3,6 +3,9 @@
 
 #include <linux/types.h>
 #include <linux/module.h>
+#include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
 
 struct device;
 struct gpio_desc;
@@ -97,6 +100,17 @@ struct gpio_chip {
         bool                    can_sleep;
         bool                    exported;
 
+#ifdef CONFIG_GPIOLIB_IRQCHIP
+        /*
+         * With CONFIG_GPIO_IRQCHIP we get an irqchip inside the gpiolib
+         * to handle IRQs for most practical cases.
+         */
+        struct irq_chip         *irqchip;
+        struct irq_domain       *irqdomain;
+        irq_flow_handler_t      irq_handler;
+        unsigned int            irq_default_type;
+#endif
+
 #if defined(CONFIG_OF_GPIO)
         /*
          * If CONFIG_OF is enabled, then all GPIO controllers described in the
@@ -190,6 +204,21 @@ struct gpiod_lookup_table {
 
 void gpiod_add_lookup_table(struct gpiod_lookup_table *table);
 
+#ifdef CONFIG_GPIOLIB_IRQCHIP
+
+void gpiochip_set_chained_irqchip(struct gpio_chip *gpiochip,
+                struct irq_chip *irqchip,
+                int parent_irq,
+                irq_flow_handler_t parent_handler);
+
+int gpiochip_irqchip_add(struct gpio_chip *gpiochip,
+                struct irq_chip *irqchip,
+                unsigned int first_irq,
+                irq_flow_handler_t handler,
+                unsigned int type);
+
+#endif /* CONFIG_GPIO_IRQCHIP */
+
 #else /* CONFIG_GPIOLIB */
 
 static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)