ARM64: DTS: Add rk3399-firefly uart4 device, node as /dev/ttyS1
[firefly-linux-kernel-4.4.55.git] / arch / x86 / xen / irq.c
1 #include <linux/hardirq.h>
2
3 #include <asm/x86_init.h>
4
5 #include <xen/interface/xen.h>
6 #include <xen/interface/sched.h>
7 #include <xen/interface/vcpu.h>
8 #include <xen/features.h>
9 #include <xen/events.h>
10
11 #include <asm/xen/hypercall.h>
12 #include <asm/xen/hypervisor.h>
13
14 #include "xen-ops.h"
15
16 /*
17  * Force a proper event-channel callback from Xen after clearing the
18  * callback mask. We do this in a very simple manner, by making a call
19  * down into Xen. The pending flag will be checked by Xen on return.
20  */
21 void xen_force_evtchn_callback(void)
22 {
23         (void)HYPERVISOR_xen_version(0, NULL);
24 }
25
26 asmlinkage __visible unsigned long xen_save_fl(void)
27 {
28         struct vcpu_info *vcpu;
29         unsigned long flags;
30
31         vcpu = this_cpu_read(xen_vcpu);
32
33         /* flag has opposite sense of mask */
34         flags = !vcpu->evtchn_upcall_mask;
35
36         /* convert to IF type flag
37            -0 -> 0x00000000
38            -1 -> 0xffffffff
39         */
40         return (-flags) & X86_EFLAGS_IF;
41 }
42 PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl);
43
44 __visible void xen_restore_fl(unsigned long flags)
45 {
46         struct vcpu_info *vcpu;
47
48         /* convert from IF type flag */
49         flags = !(flags & X86_EFLAGS_IF);
50
51         /* See xen_irq_enable() for why preemption must be disabled. */
52         preempt_disable();
53         vcpu = this_cpu_read(xen_vcpu);
54         vcpu->evtchn_upcall_mask = flags;
55
56         if (flags == 0) {
57                 barrier(); /* unmask then check (avoid races) */
58                 if (unlikely(vcpu->evtchn_upcall_pending))
59                         xen_force_evtchn_callback();
60                 preempt_enable();
61         } else
62                 preempt_enable_no_resched();
63 }
64 PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl);
65
66 asmlinkage __visible void xen_irq_disable(void)
67 {
68         /* There's a one instruction preempt window here.  We need to
69            make sure we're don't switch CPUs between getting the vcpu
70            pointer and updating the mask. */
71         preempt_disable();
72         this_cpu_read(xen_vcpu)->evtchn_upcall_mask = 1;
73         preempt_enable_no_resched();
74 }
75 PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable);
76
77 asmlinkage __visible void xen_irq_enable(void)
78 {
79         struct vcpu_info *vcpu;
80
81         /*
82          * We may be preempted as soon as vcpu->evtchn_upcall_mask is
83          * cleared, so disable preemption to ensure we check for
84          * events on the VCPU we are still running on.
85          */
86         preempt_disable();
87
88         vcpu = this_cpu_read(xen_vcpu);
89         vcpu->evtchn_upcall_mask = 0;
90
91         /* Doesn't matter if we get preempted here, because any
92            pending event will get dealt with anyway. */
93
94         barrier(); /* unmask then check (avoid races) */
95         if (unlikely(vcpu->evtchn_upcall_pending))
96                 xen_force_evtchn_callback();
97
98         preempt_enable();
99 }
100 PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable);
101
102 static void xen_safe_halt(void)
103 {
104         /* Blocking includes an implicit local_irq_enable(). */
105         if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0)
106                 BUG();
107 }
108
109 static void xen_halt(void)
110 {
111         if (irqs_disabled())
112                 HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
113         else
114                 xen_safe_halt();
115 }
116
117 static const struct pv_irq_ops xen_irq_ops __initconst = {
118         .save_fl = PV_CALLEE_SAVE(xen_save_fl),
119         .restore_fl = PV_CALLEE_SAVE(xen_restore_fl),
120         .irq_disable = PV_CALLEE_SAVE(xen_irq_disable),
121         .irq_enable = PV_CALLEE_SAVE(xen_irq_enable),
122
123         .safe_halt = xen_safe_halt,
124         .halt = xen_halt,
125 #ifdef CONFIG_X86_64
126         .adjust_exception_frame = xen_adjust_exception_frame,
127 #endif
128 };
129
130 void __init xen_init_irq_ops(void)
131 {
132         /* For PVH we use default pv_irq_ops settings. */
133         if (!xen_feature(XENFEAT_hvm_callback_vector))
134                 pv_irq_ops = xen_irq_ops;
135         x86_init.irqs.intr_init = xen_init_IRQ;
136 }