[PATCH] uml: Fix load average >=1
[linux-3.10.git] / arch / um / kernel / time_kern.c
1 /* 
2  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
3  * Licensed under the GPL
4  */
5
6 #include "linux/kernel.h"
7 #include "linux/module.h"
8 #include "linux/unistd.h"
9 #include "linux/stddef.h"
10 #include "linux/spinlock.h"
11 #include "linux/time.h"
12 #include "linux/sched.h"
13 #include "linux/interrupt.h"
14 #include "linux/init.h"
15 #include "linux/delay.h"
16 #include "asm/irq.h"
17 #include "asm/param.h"
18 #include "asm/current.h"
19 #include "kern_util.h"
20 #include "user_util.h"
21 #include "time_user.h"
22 #include "mode.h"
23 #include "os.h"
24
25 u64 jiffies_64 = INITIAL_JIFFIES;
26
27 EXPORT_SYMBOL(jiffies_64);
28
29 int hz(void)
30 {
31         return(HZ);
32 }
33
34 /*
35  * Scheduler clock - returns current time in nanosec units.
36  */
37 unsigned long long sched_clock(void)
38 {
39         return (unsigned long long)jiffies_64 * (1000000000 / HZ);
40 }
41
42 /* Changed at early boot */
43 int timer_irq_inited = 0;
44
45 static int first_tick;
46 static unsigned long long prev_usecs;
47 #ifdef CONFIG_UML_REAL_TIME_CLOCK
48 static long long delta;                 /* Deviation per interval */
49 #endif
50
51 void timer_irq(union uml_pt_regs *regs)
52 {
53         unsigned long long ticks = 0;
54
55         if(!timer_irq_inited){
56                 /* This is to ensure that ticks don't pile up when
57                  * the timer handler is suspended */
58                 first_tick = 0;
59                 return;
60         }
61
62         if(first_tick){
63 #ifdef CONFIG_UML_REAL_TIME_CLOCK
64                 /* We've had 1 tick */
65                 unsigned long long usecs = os_usecs();
66
67                 delta += usecs - prev_usecs;
68                 prev_usecs = usecs;
69
70                 /* Protect against the host clock being set backwards */
71                 if(delta < 0)
72                         delta = 0;
73
74                 ticks += (delta * HZ) / MILLION;
75                 delta -= (ticks * MILLION) / HZ;
76 #else
77                 ticks = 1;
78 #endif
79         }
80         else {
81                 prev_usecs = os_usecs();
82                 first_tick = 1;
83         }
84
85         while(ticks > 0){
86                 do_IRQ(TIMER_IRQ, regs);
87                 ticks--;
88         }
89 }
90
91 void boot_timer_handler(int sig)
92 {
93         struct pt_regs regs;
94
95         CHOOSE_MODE((void) 
96                     (UPT_SC(&regs.regs) = (struct sigcontext *) (&sig + 1)),
97                     (void) (regs.regs.skas.is_user = 0));
98         do_timer(&regs);
99 }
100
101 irqreturn_t um_timer(int irq, void *dev, struct pt_regs *regs)
102 {
103         unsigned long flags;
104
105         do_timer(regs);
106         write_seqlock_irqsave(&xtime_lock, flags);
107         timer();
108         write_sequnlock_irqrestore(&xtime_lock, flags);
109         return(IRQ_HANDLED);
110 }
111
112 long um_time(int __user *tloc)
113 {
114         struct timeval now;
115
116         do_gettimeofday(&now);
117         if (tloc) {
118                 if (put_user(now.tv_sec, tloc))
119                         now.tv_sec = -EFAULT;
120         }
121         return now.tv_sec;
122 }
123
124 long um_stime(int __user *tptr)
125 {
126         int value;
127         struct timespec new;
128
129         if (get_user(value, tptr))
130                 return -EFAULT;
131         new.tv_sec = value;
132         new.tv_nsec = 0;
133         do_settimeofday(&new);
134         return 0;
135 }
136
137 void timer_handler(int sig, union uml_pt_regs *regs)
138 {
139         local_irq_disable();
140         irq_enter();
141         update_process_times(CHOOSE_MODE(user_context(UPT_SP(regs)),
142                                          (regs)->skas.is_user));
143         irq_exit();
144         local_irq_enable();
145         if(current_thread->cpu == 0)
146                 timer_irq(regs);
147 }
148
149 static DEFINE_SPINLOCK(timer_spinlock);
150
151 unsigned long time_lock(void)
152 {
153         unsigned long flags;
154
155         spin_lock_irqsave(&timer_spinlock, flags);
156         return(flags);
157 }
158
159 void time_unlock(unsigned long flags)
160 {
161         spin_unlock_irqrestore(&timer_spinlock, flags);
162 }
163
164 int __init timer_init(void)
165 {
166         int err;
167
168         user_time_init();
169         err = request_irq(TIMER_IRQ, um_timer, SA_INTERRUPT, "timer", NULL);
170         if(err != 0)
171                 printk(KERN_ERR "timer_init : request_irq failed - "
172                        "errno = %d\n", -err);
173         timer_irq_inited = 1;
174         return(0);
175 }
176
177 __initcall(timer_init);
178
179 /*
180  * Overrides for Emacs so that we follow Linus's tabbing style.
181  * Emacs will notice this stuff at the end of the file and automatically
182  * adjust the settings for this buffer only.  This must remain at the end
183  * of the file.
184  * ---------------------------------------------------------------------------
185  * Local variables:
186  * c-file-style: "linux"
187  * End:
188  */