dm: irq: Add support for interrupt controller types

There can be different types of interrupt controllers in a system and some
drivers may need to distinguish between these. In general this can be
handled using the device tree by adding the interrupt information to
device nodes.

However on x86 devices we have interrupt controllers which are not tied
to any particular device and not really used in U-Boot. These still need
to be inited, so a convenient method is to give each controller a type
and allow a particular controller type to be probed.

Add support for this in sandbox along with a test.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: remove the new bland line at EOF of test/dm/irq.c]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

include/irq.h

@@ -8,6 +8,17 @@
 #ifndef __irq_H
 #define __irq_H
 
+/*
+ * Interrupt controller types available. You can find a particular one with
+ * irq_first_device_type()
+ */
+enum irq_dev_t {
+	X86_IRQT_BASE,		/* Base controller */
+	X86_IRQT_ITSS,		/* ITSS controller, e.g. on APL */
+	X86_IRQT_ACPI_GPE,	/* ACPI General-Purpose Events controller */
+	SANDBOX_IRQT_BASE,	/* Sandbox testing */
+};
+
 /**
  * struct irq_ops - Operations for the IRQ
  */
@@ -85,4 +96,16 @@ int irq_snapshot_polarities(struct udevice *dev);
  */
 int irq_restore_polarities(struct udevice *dev);
 
+/**
+ * irq_first_device_type() - Get a particular interrupt controller
+ *
+ * On success this returns an activated interrupt device.
+ *
+ * @type: Type to find
+ * @devp: Returns the device, if found
+ * @return 0 if OK, -ENODEV if not found, other -ve error if uclass failed to
+ *	probe
+ */
+int irq_first_device_type(enum irq_dev_t type, struct udevice **devp);
+
 #endif