xen/arm: receive Xen events on ARM

Compile events.c on ARM.
Parse, map and enable the IRQ to get event notifications from the device
tree (node "/xen").

Signed-off-by: Stefano Stabellini <[e-mail]>
Acked-by: Konrad Rzeszutek Wilk <[e-mail]>

arch/arm/include/asm/xen/events.h

···
+#ifndef _ASM_ARM_XEN_EVENTS_H
+#define _ASM_ARM_XEN_EVENTS_H
+
+#include <asm/ptrace.h>
+
+enum ipi_vector {
+	XEN_PLACEHOLDER_VECTOR,
+
+	/* Xen IPIs go here */
+	XEN_NR_IPIS,
+};
+
+static inline int xen_irqs_disabled(struct pt_regs *regs)
+{
+	return raw_irqs_disabled_flags(regs->ARM_cpsr);
+}
+
+#endif /* _ASM_ARM_XEN_EVENTS_H */

arch/arm/xen/enlighten.c

···
 #include <xen/xen.h>
+#include <xen/events.h>
 #include <xen/grant_table.h>
 #include <xen/hvm.h>
 #include <xen/interface/xen.h>
···
 #include <xen/xenbus.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
···
 
 int xen_platform_pci_unplug = XEN_UNPLUG_ALL;
 EXPORT_SYMBOL_GPL(xen_platform_pci_unplug);
+
+static __read_mostly int xen_events_irq = -1;
 
 int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
 			       unsigned long addr,
···
 	if (of_address_to_resource(node, GRANT_TABLE_PHYSADDR, &res))
 		return 0;
 	xen_hvm_resume_frames = res.start >> PAGE_SHIFT;
+	xen_events_irq = irq_of_parse_and_map(node, 0);
+	pr_info("Xen %s support found, events_irq=%d gnttab_frame_pfn=%lx\n",
+			version, xen_events_irq, xen_hvm_resume_frames);
 	xen_domain_type = XEN_HVM_DOMAIN;
 
 	xen_setup_features();
···
 	return 0;
 }
 core_initcall(xen_guest_init);
+
+static irqreturn_t xen_arm_callback(int irq, void *arg)
+{
+	xen_hvm_evtchn_do_upcall();
+	return IRQ_HANDLED;
+}
+
+static int __init xen_init_events(void)
+{
+	if (!xen_domain() || xen_events_irq < 0)
+		return -ENODEV;
+
+	xen_init_IRQ();
+
+	if (request_percpu_irq(xen_events_irq, xen_arm_callback,
+			"events", xen_vcpu)) {
+		pr_err("Error requesting IRQ %d\n", xen_events_irq);
+		return -EINVAL;
+	}
+
+	enable_percpu_irq(xen_events_irq, 0);
+
+	return 0;
+}
+postcore_initcall(xen_init_events);

arch/x86/xen/enlighten.c

···
 #include <linux/memblock.h>
 
 #include <xen/xen.h>
+#include <xen/events.h>
 #include <xen/interface/xen.h>
 #include <xen/interface/version.h>
 #include <xen/interface/physdev.h>

arch/x86/xen/irq.c

···
 #include <xen/interface/xen.h>
 #include <xen/interface/sched.h>
 #include <xen/interface/vcpu.h>
+#include <xen/events.h>
 
 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>

arch/x86/xen/xen-ops.h

···
 
 char * __init xen_memory_setup(void);
 void __init xen_arch_setup(void);
-void __init xen_init_IRQ(void);
 void xen_enable_sysenter(void);
 void xen_enable_syscall(void);
 void xen_vcpu_restore(void);

drivers/xen/events.c

···
 #include <linux/irqnr.h>
 #include <linux/pci.h>
 
+#ifdef CONFIG_X86
 #include <asm/desc.h>
 #include <asm/ptrace.h>
 #include <asm/irq.h>
 #include <asm/idle.h>
 #include <asm/io_apic.h>
-#include <asm/sync_bitops.h>
 #include <asm/xen/page.h>
 #include <asm/xen/pci.h>
+#endif
+#include <asm/sync_bitops.h>
 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>
 
···
 #include <xen/interface/event_channel.h>
 #include <xen/interface/hvm/hvm_op.h>
 #include <xen/interface/hvm/params.h>
+#include <xen/interface/physdev.h>
+#include <xen/interface/sched.h>
+#include <asm/hw_irq.h>
 
 /*
  * This lock protects updates to the following mapping and reference-count
···
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
 
+#ifdef CONFIG_X86
 	exit_idle();
+#endif
 	irq_enter();
 
 	__xen_evtchn_do_upcall();
···
 void xen_callback_vector(void) {}
 #endif
 
-void __init xen_init_IRQ(void)
+void xen_init_IRQ(void)
 {
-	int i, rc;
+	int i;
 
 	evtchn_to_irq = kcalloc(NR_EVENT_CHANNELS, sizeof(*evtchn_to_irq),
 				    GFP_KERNEL);
···
 
 	pirq_needs_eoi = pirq_needs_eoi_flag;
 
+#ifdef CONFIG_X86
 	if (xen_hvm_domain()) {
 		xen_callback_vector();
 		native_init_IRQ();
···
 		 * __acpi_register_gsi can point at the right function */
 		pci_xen_hvm_init();
 	} else {
+		int rc;
 		struct physdev_pirq_eoi_gmfn eoi_gmfn;
 
 		irq_ctx_init(smp_processor_id());
···
 		} else
 			pirq_needs_eoi = pirq_check_eoi_map;
 	}
+#endif
 }
+EXPORT_SYMBOL_GPL(xen_init_IRQ);

include/xen/events.h

···
 /* Determine whether to ignore this IRQ if it is passed to a guest. */
 int xen_test_irq_shared(int irq);
 
+/* initialize Xen IRQ subsystem */
+void xen_init_IRQ(void);
 #endif	/* _XEN_EVENTS_H */