Xen: ARM: Add support for mapping AMBA device mmio

Add a bus_notifier for AMBA bus device in order to map the device
mmio regions when DOM0 booting with ACPI.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Tested-by: Julien Grall <julien.grall@arm.com>

drivers/xen/arm-device.c

@@ -151,3 +151,46 @@ static int __init register_xen_platform_notifier(void)
 }
 
 arch_initcall(register_xen_platform_notifier);
+
+#ifdef CONFIG_ARM_AMBA
+#include <linux/amba/bus.h>
+
+static int xen_amba_notifier(struct notifier_block *nb,
+			     unsigned long action, void *data)
+{
+	struct amba_device *adev = to_amba_device(data);
+	int r = 0;
+
+	switch (action) {
+	case BUS_NOTIFY_ADD_DEVICE:
+		r = xen_map_device_mmio(&adev->res, 1);
+		break;
+	case BUS_NOTIFY_DEL_DEVICE:
+		r = xen_unmap_device_mmio(&adev->res, 1);
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+	if (r)
+		dev_err(&adev->dev, "AMBA: Failed to %s device %s MMIO!\n",
+			action == BUS_NOTIFY_ADD_DEVICE ? "map" :
+			(action == BUS_NOTIFY_DEL_DEVICE ? "unmap" : "?"),
+			adev->dev.init_name);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block amba_device_nb = {
+	.notifier_call = xen_amba_notifier,
+};
+
+static int __init register_xen_amba_notifier(void)
+{
+	if (!xen_initial_domain() || acpi_disabled)
+		return 0;
+
+	return bus_register_notifier(&amba_bustype, &amba_device_nb);
+}
+
+arch_initcall(register_xen_amba_notifier);
+#endif