2 * linux/arch/arm/mach-omap1/time.c
6 * Copyright (C) 2004 Nokia Corporation
7 * Partial timer rewrite and additional dynamic tick timer support by
8 * Tony Lindgen <tony@atomide.com> and
9 * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
11 * MPU timer code based on the older MPU timer code for OMAP
12 * Copyright (C) 2000 RidgeRun, Inc.
13 * Author: Greg Lonnon <glonnon@ridgerun.com>
15 * This program is free software; you can redistribute it and/or modify it
16 * under the terms of the GNU General Public License as published by the
17 * Free Software Foundation; either version 2 of the License, or (at your
18 * option) any later version.
20 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
21 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
22 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
23 * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
26 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
27 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 * You should have received a copy of the GNU General Public License along
32 * with this program; if not, write to the Free Software Foundation, Inc.,
33 * 675 Mass Ave, Cambridge, MA 02139, USA.
36 #include <linux/kernel.h>
37 #include <linux/init.h>
38 #include <linux/delay.h>
39 #include <linux/interrupt.h>
40 #include <linux/sched.h>
41 #include <linux/spinlock.h>
42 #include <linux/clk.h>
43 #include <linux/err.h>
44 #include <linux/clocksource.h>
46 #include <asm/system.h>
47 #include <asm/hardware.h>
51 #include <asm/mach/irq.h>
52 #include <asm/mach/time.h>
55 #define OMAP_MPU_TIMER_BASE OMAP_MPU_TIMER1_BASE
56 #define OMAP_MPU_TIMER_OFFSET 0x100
58 /* cycles to nsec conversions taken from arch/i386/kernel/timers/timer_tsc.c,
59 * converted to use kHz by Kevin Hilman */
60 /* convert from cycles(64bits) => nanoseconds (64bits)
62 * ns = cycles / (freq / ns_per_sec)
63 * ns = cycles * (ns_per_sec / freq)
64 * ns = cycles * (10^9 / (cpu_khz * 10^3))
65 * ns = cycles * (10^6 / cpu_khz)
67 * Then we use scaling math (suggested by george at mvista.com) to get:
68 * ns = cycles * (10^6 * SC / cpu_khz / SC
69 * ns = cycles * cyc2ns_scale / SC
71 * And since SC is a constant power of two, we can convert the div
73 * -johnstul at us.ibm.com "math is hard, lets go shopping!"
75 static unsigned long cyc2ns_scale;
76 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
78 static inline void set_cyc2ns_scale(unsigned long cpu_khz)
80 cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
83 static inline unsigned long long cycles_2_ns(unsigned long long cyc)
85 return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
90 u32 cntl; /* CNTL_TIMER, R/W */
91 u32 load_tim; /* LOAD_TIM, W */
92 u32 read_tim; /* READ_TIM, R */
93 } omap_mpu_timer_regs_t;
95 #define omap_mpu_timer_base(n) \
96 ((volatile omap_mpu_timer_regs_t*)IO_ADDRESS(OMAP_MPU_TIMER_BASE + \
97 (n)*OMAP_MPU_TIMER_OFFSET))
99 static inline unsigned long omap_mpu_timer_read(int nr)
101 volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr);
102 return timer->read_tim;
105 static inline void omap_mpu_timer_start(int nr, unsigned long load_val)
107 volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr);
109 timer->cntl = MPU_TIMER_CLOCK_ENABLE;
111 timer->load_tim = load_val;
113 timer->cntl = (MPU_TIMER_CLOCK_ENABLE | MPU_TIMER_AR | MPU_TIMER_ST);
117 * ---------------------------------------------------------------------------
118 * MPU timer 1 ... count down to zero, interrupt, reload
119 * ---------------------------------------------------------------------------
121 static irqreturn_t omap_mpu_timer1_interrupt(int irq, void *dev_id)
123 write_seqlock(&xtime_lock);
124 /* NOTE: no lost-tick detection/handling! */
126 write_sequnlock(&xtime_lock);
131 static struct irqaction omap_mpu_timer1_irq = {
132 .name = "mpu_timer1",
133 .flags = IRQF_DISABLED | IRQF_TIMER,
134 .handler = omap_mpu_timer1_interrupt,
137 static __init void omap_init_mpu_timer(unsigned long rate)
139 set_cyc2ns_scale(rate / 1000);
141 setup_irq(INT_TIMER1, &omap_mpu_timer1_irq);
142 omap_mpu_timer_start(0, (rate / HZ) - 1);
146 * ---------------------------------------------------------------------------
147 * MPU timer 2 ... free running 32-bit clock source and scheduler clock
148 * ---------------------------------------------------------------------------
151 static unsigned long omap_mpu_timer2_overflows;
153 static irqreturn_t omap_mpu_timer2_interrupt(int irq, void *dev_id)
155 omap_mpu_timer2_overflows++;
159 static struct irqaction omap_mpu_timer2_irq = {
160 .name = "mpu_timer2",
161 .flags = IRQF_DISABLED,
162 .handler = omap_mpu_timer2_interrupt,
165 static cycle_t mpu_read(void)
167 return ~omap_mpu_timer_read(1);
170 static struct clocksource clocksource_mpu = {
171 .name = "mpu_timer2",
174 .mask = CLOCKSOURCE_MASK(32),
176 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
179 static void __init omap_init_clocksource(unsigned long rate)
181 static char err[] __initdata = KERN_ERR
182 "%s: can't register clocksource!\n";
185 = clocksource_khz2mult(rate/1000, clocksource_mpu.shift);
187 setup_irq(INT_TIMER2, &omap_mpu_timer2_irq);
188 omap_mpu_timer_start(1, ~0);
190 if (clocksource_register(&clocksource_mpu))
191 printk(err, clocksource_mpu.name);
196 * Scheduler clock - returns current time in nanosec units.
198 unsigned long long sched_clock(void)
200 unsigned long ticks = 0 - omap_mpu_timer_read(1);
201 unsigned long long ticks64;
203 ticks64 = omap_mpu_timer2_overflows;
207 return cycles_2_ns(ticks64);
211 * ---------------------------------------------------------------------------
212 * Timer initialization
213 * ---------------------------------------------------------------------------
215 static void __init omap_timer_init(void)
217 struct clk *ck_ref = clk_get(NULL, "ck_ref");
220 BUG_ON(IS_ERR(ck_ref));
222 rate = clk_get_rate(ck_ref);
228 omap_init_mpu_timer(rate);
229 omap_init_clocksource(rate);
232 struct sys_timer omap_timer = {
233 .init = omap_timer_init,