0ed2badfd74613b3753c901d44f7da6cf9ebe8df
[linux-2.6.git] / arch / blackfin / kernel / time-ts.c
1 /*
2  * linux/arch/kernel/time-ts.c
3  *
4  * Based on arm clockevents implementation and old bfin time tick.
5  *
6  * Copyright(C) 2008, GeoTechnologies, Vitja Makarov
7  *
8  * This code is licenced under the GPL version 2. For details see
9  * kernel-base/COPYING.
10  */
11 #include <linux/module.h>
12 #include <linux/profile.h>
13 #include <linux/interrupt.h>
14 #include <linux/time.h>
15 #include <linux/timex.h>
16 #include <linux/irq.h>
17 #include <linux/clocksource.h>
18 #include <linux/clockchips.h>
19 #include <linux/cpufreq.h>
20
21 #include <asm/blackfin.h>
22 #include <asm/time.h>
23
24 #ifdef CONFIG_CYCLES_CLOCKSOURCE
25
26 /* Accelerators for sched_clock()
27  * convert from cycles(64bits) => nanoseconds (64bits)
28  *  basic equation:
29  *              ns = cycles / (freq / ns_per_sec)
30  *              ns = cycles * (ns_per_sec / freq)
31  *              ns = cycles * (10^9 / (cpu_khz * 10^3))
32  *              ns = cycles * (10^6 / cpu_khz)
33  *
34  *      Then we use scaling math (suggested by george@mvista.com) to get:
35  *              ns = cycles * (10^6 * SC / cpu_khz) / SC
36  *              ns = cycles * cyc2ns_scale / SC
37  *
38  *      And since SC is a constant power of two, we can convert the div
39  *  into a shift.
40  *
41  *  We can use khz divisor instead of mhz to keep a better precision, since
42  *  cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
43  *  (mathieu.desnoyers@polymtl.ca)
44  *
45  *                      -johnstul@us.ibm.com "math is hard, lets go shopping!"
46  */
47
48 static unsigned long cyc2ns_scale;
49 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
50
51 static inline void set_cyc2ns_scale(unsigned long cpu_khz)
52 {
53         cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR) / cpu_khz;
54 }
55
56 static inline unsigned long long cycles_2_ns(cycle_t cyc)
57 {
58         return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
59 }
60
61 static cycle_t read_cycles(void)
62 {
63         return __bfin_cycles_off + (get_cycles() << __bfin_cycles_mod);
64 }
65
66 unsigned long long sched_clock(void)
67 {
68         return cycles_2_ns(read_cycles());
69 }
70
71 static struct clocksource clocksource_bfin = {
72         .name           = "bfin_cycles",
73         .rating         = 350,
74         .read           = read_cycles,
75         .mask           = CLOCKSOURCE_MASK(64),
76         .shift          = 22,
77         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
78 };
79
80 static int __init bfin_clocksource_init(void)
81 {
82         set_cyc2ns_scale(get_cclk() / 1000);
83
84         clocksource_bfin.mult = clocksource_hz2mult(get_cclk(), clocksource_bfin.shift);
85
86         if (clocksource_register(&clocksource_bfin))
87                 panic("failed to register clocksource");
88
89         return 0;
90 }
91
92 #else
93 # define bfin_clocksource_init()
94 #endif
95
96 static int bfin_timer_set_next_event(unsigned long cycles,
97                                      struct clock_event_device *evt)
98 {
99         bfin_write_TCOUNT(cycles);
100         CSYNC();
101         return 0;
102 }
103
104 static void bfin_timer_set_mode(enum clock_event_mode mode,
105                                 struct clock_event_device *evt)
106 {
107         switch (mode) {
108         case CLOCK_EVT_MODE_PERIODIC: {
109                 unsigned long tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
110                 bfin_write_TCNTL(TMPWR);
111                 bfin_write_TSCALE(TIME_SCALE - 1);
112                 CSYNC();
113                 bfin_write_TPERIOD(tcount);
114                 bfin_write_TCOUNT(tcount);
115                 bfin_write_TCNTL(TMPWR | TMREN | TAUTORLD);
116                 CSYNC();
117                 break;
118         }
119         case CLOCK_EVT_MODE_ONESHOT:
120                 bfin_write_TSCALE(TIME_SCALE - 1);
121                 bfin_write_TCOUNT(0);
122                 bfin_write_TCNTL(TMPWR | TMREN);
123                 CSYNC();
124                 break;
125         case CLOCK_EVT_MODE_UNUSED:
126         case CLOCK_EVT_MODE_SHUTDOWN:
127                 bfin_write_TCNTL(0);
128                 CSYNC();
129                 break;
130         case CLOCK_EVT_MODE_RESUME:
131                 break;
132         }
133 }
134
135 static void __init bfin_timer_init(void)
136 {
137         /* power up the timer, but don't enable it just yet */
138         bfin_write_TCNTL(TMPWR);
139         CSYNC();
140
141         /*
142          * the TSCALE prescaler counter.
143          */
144         bfin_write_TSCALE(TIME_SCALE - 1);
145         bfin_write_TPERIOD(0);
146         bfin_write_TCOUNT(0);
147
148         /* now enable the timer */
149         CSYNC();
150 }
151
152 /*
153  * timer_interrupt() needs to keep up the real-time clock,
154  * as well as call the "do_timer()" routine every clocktick
155  */
156 #ifdef CONFIG_CORE_TIMER_IRQ_L1
157 __attribute__((l1_text))
158 #endif
159 irqreturn_t timer_interrupt(int irq, void *dev_id);
160
161 static struct clock_event_device clockevent_bfin = {
162         .name           = "bfin_core_timer",
163         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
164         .shift          = 32,
165         .set_next_event = bfin_timer_set_next_event,
166         .set_mode       = bfin_timer_set_mode,
167 };
168
169 static struct irqaction bfin_timer_irq = {
170         .name           = "Blackfin Core Timer",
171         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
172         .handler        = timer_interrupt,
173         .dev_id         = &clockevent_bfin,
174 };
175
176 irqreturn_t timer_interrupt(int irq, void *dev_id)
177 {
178         struct clock_event_device *evt = dev_id;
179         evt->event_handler(evt);
180         return IRQ_HANDLED;
181 }
182
183 static int __init bfin_clockevent_init(void)
184 {
185         unsigned long timer_clk;
186
187         timer_clk = get_cclk() / TIME_SCALE;
188
189         setup_irq(IRQ_CORETMR, &bfin_timer_irq);
190         bfin_timer_init();
191
192         clockevent_bfin.mult = div_sc(timer_clk, NSEC_PER_SEC, clockevent_bfin.shift);
193         clockevent_bfin.max_delta_ns = clockevent_delta2ns(-1, &clockevent_bfin);
194         clockevent_bfin.min_delta_ns = clockevent_delta2ns(100, &clockevent_bfin);
195         clockevent_bfin.cpumask = cpumask_of(0);
196         clockevents_register_device(&clockevent_bfin);
197
198         return 0;
199 }
200
201 void __init time_init(void)
202 {
203         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
204
205 #ifdef CONFIG_RTC_DRV_BFIN
206         /* [#2663] hack to filter junk RTC values that would cause
207          * userspace to have to deal with time values greater than
208          * 2^31 seconds (which uClibc cannot cope with yet)
209          */
210         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
211                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
212                 bfin_write_RTC_STAT(0);
213         }
214 #endif
215
216         /* Initialize xtime. From now on, xtime is updated with timer interrupts */
217         xtime.tv_sec = secs_since_1970;
218         xtime.tv_nsec = 0;
219         set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
220
221         bfin_clocksource_init();
222         bfin_clockevent_init();
223 }