Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Tony Lindgren | 3b59b6b | 2005-07-10 19:58:09 +0100 | [diff] [blame] | 2 | * linux/arch/arm/mach-omap1/time.c |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * |
| 4 | * OMAP Timers |
| 5 | * |
| 6 | * Copyright (C) 2004 Nokia Corporation |
Tony Lindgren | b3402cf | 2005-06-29 19:59:48 +0100 | [diff] [blame] | 7 | * Partial timer rewrite and additional dynamic tick timer support by |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 8 | * Tony Lindgen <tony@atomide.com> and |
| 9 | * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com> |
| 10 | * |
| 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> |
| 14 | * |
| 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. |
| 19 | * |
| 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. |
| 30 | * |
| 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. |
| 34 | */ |
| 35 | |
| 36 | #include <linux/config.h> |
| 37 | #include <linux/kernel.h> |
| 38 | #include <linux/init.h> |
| 39 | #include <linux/delay.h> |
| 40 | #include <linux/interrupt.h> |
| 41 | #include <linux/sched.h> |
| 42 | #include <linux/spinlock.h> |
| 43 | |
| 44 | #include <asm/system.h> |
| 45 | #include <asm/hardware.h> |
| 46 | #include <asm/io.h> |
| 47 | #include <asm/leds.h> |
| 48 | #include <asm/irq.h> |
| 49 | #include <asm/mach/irq.h> |
| 50 | #include <asm/mach/time.h> |
| 51 | |
| 52 | struct sys_timer omap_timer; |
| 53 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 54 | /* |
| 55 | * --------------------------------------------------------------------------- |
| 56 | * MPU timer |
| 57 | * --------------------------------------------------------------------------- |
| 58 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 59 | #define OMAP_MPU_TIMER_BASE OMAP_MPU_TIMER1_BASE |
| 60 | #define OMAP_MPU_TIMER_OFFSET 0x100 |
| 61 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 62 | /* cycles to nsec conversions taken from arch/i386/kernel/timers/timer_tsc.c, |
| 63 | * converted to use kHz by Kevin Hilman */ |
| 64 | /* convert from cycles(64bits) => nanoseconds (64bits) |
| 65 | * basic equation: |
| 66 | * ns = cycles / (freq / ns_per_sec) |
| 67 | * ns = cycles * (ns_per_sec / freq) |
| 68 | * ns = cycles * (10^9 / (cpu_khz * 10^3)) |
| 69 | * ns = cycles * (10^6 / cpu_khz) |
| 70 | * |
| 71 | * Then we use scaling math (suggested by george at mvista.com) to get: |
| 72 | * ns = cycles * (10^6 * SC / cpu_khz / SC |
| 73 | * ns = cycles * cyc2ns_scale / SC |
| 74 | * |
| 75 | * And since SC is a constant power of two, we can convert the div |
| 76 | * into a shift. |
| 77 | * -johnstul at us.ibm.com "math is hard, lets go shopping!" |
| 78 | */ |
| 79 | static unsigned long cyc2ns_scale; |
| 80 | #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ |
| 81 | |
| 82 | static inline void set_cyc2ns_scale(unsigned long cpu_khz) |
| 83 | { |
| 84 | cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz; |
| 85 | } |
| 86 | |
| 87 | static inline unsigned long long cycles_2_ns(unsigned long long cyc) |
| 88 | { |
| 89 | return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR; |
| 90 | } |
| 91 | |
| 92 | /* |
| 93 | * MPU_TICKS_PER_SEC must be an even number, otherwise machinecycles_to_usecs |
| 94 | * will break. On P2, the timer count rate is 6.5 MHz after programming PTV |
| 95 | * with 0. This divides the 13MHz input by 2, and is undocumented. |
| 96 | */ |
| 97 | #ifdef CONFIG_MACH_OMAP_PERSEUS2 |
| 98 | /* REVISIT: This ifdef construct should be replaced by a query to clock |
| 99 | * framework to see if timer base frequency is 12.0, 13.0 or 19.2 MHz. |
| 100 | */ |
| 101 | #define MPU_TICKS_PER_SEC (13000000 / 2) |
| 102 | #else |
| 103 | #define MPU_TICKS_PER_SEC (12000000 / 2) |
| 104 | #endif |
| 105 | |
| 106 | #define MPU_TIMER_TICK_PERIOD ((MPU_TICKS_PER_SEC / HZ) - 1) |
| 107 | |
| 108 | typedef struct { |
| 109 | u32 cntl; /* CNTL_TIMER, R/W */ |
| 110 | u32 load_tim; /* LOAD_TIM, W */ |
| 111 | u32 read_tim; /* READ_TIM, R */ |
| 112 | } omap_mpu_timer_regs_t; |
| 113 | |
| 114 | #define omap_mpu_timer_base(n) \ |
| 115 | ((volatile omap_mpu_timer_regs_t*)IO_ADDRESS(OMAP_MPU_TIMER_BASE + \ |
| 116 | (n)*OMAP_MPU_TIMER_OFFSET)) |
| 117 | |
| 118 | static inline unsigned long omap_mpu_timer_read(int nr) |
| 119 | { |
| 120 | volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr); |
| 121 | return timer->read_tim; |
| 122 | } |
| 123 | |
| 124 | static inline void omap_mpu_timer_start(int nr, unsigned long load_val) |
| 125 | { |
| 126 | volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr); |
| 127 | |
| 128 | timer->cntl = MPU_TIMER_CLOCK_ENABLE; |
| 129 | udelay(1); |
| 130 | timer->load_tim = load_val; |
| 131 | udelay(1); |
| 132 | timer->cntl = (MPU_TIMER_CLOCK_ENABLE | MPU_TIMER_AR | MPU_TIMER_ST); |
| 133 | } |
| 134 | |
| 135 | unsigned long omap_mpu_timer_ticks_to_usecs(unsigned long nr_ticks) |
| 136 | { |
| 137 | unsigned long long nsec; |
| 138 | |
| 139 | nsec = cycles_2_ns((unsigned long long)nr_ticks); |
| 140 | return (unsigned long)nsec / 1000; |
| 141 | } |
| 142 | |
| 143 | /* |
| 144 | * Last processed system timer interrupt |
| 145 | */ |
| 146 | static unsigned long omap_mpu_timer_last = 0; |
| 147 | |
| 148 | /* |
| 149 | * Returns elapsed usecs since last system timer interrupt |
| 150 | */ |
| 151 | static unsigned long omap_mpu_timer_gettimeoffset(void) |
| 152 | { |
| 153 | unsigned long now = 0 - omap_mpu_timer_read(0); |
| 154 | unsigned long elapsed = now - omap_mpu_timer_last; |
| 155 | |
| 156 | return omap_mpu_timer_ticks_to_usecs(elapsed); |
| 157 | } |
| 158 | |
| 159 | /* |
| 160 | * Elapsed time between interrupts is calculated using timer0. |
| 161 | * Latency during the interrupt is calculated using timer1. |
| 162 | * Both timer0 and timer1 are counting at 6MHz (P2 6.5MHz). |
| 163 | */ |
| 164 | static irqreturn_t omap_mpu_timer_interrupt(int irq, void *dev_id, |
| 165 | struct pt_regs *regs) |
| 166 | { |
| 167 | unsigned long now, latency; |
| 168 | |
| 169 | write_seqlock(&xtime_lock); |
| 170 | now = 0 - omap_mpu_timer_read(0); |
| 171 | latency = MPU_TICKS_PER_SEC / HZ - omap_mpu_timer_read(1); |
| 172 | omap_mpu_timer_last = now - latency; |
| 173 | timer_tick(regs); |
| 174 | write_sequnlock(&xtime_lock); |
| 175 | |
| 176 | return IRQ_HANDLED; |
| 177 | } |
| 178 | |
| 179 | static struct irqaction omap_mpu_timer_irq = { |
| 180 | .name = "mpu timer", |
Russell King | 09b8b5f | 2005-06-26 17:06:36 +0100 | [diff] [blame] | 181 | .flags = SA_INTERRUPT | SA_TIMER, |
| 182 | .handler = omap_mpu_timer_interrupt, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 183 | }; |
| 184 | |
| 185 | static unsigned long omap_mpu_timer1_overflows; |
| 186 | static irqreturn_t omap_mpu_timer1_interrupt(int irq, void *dev_id, |
| 187 | struct pt_regs *regs) |
| 188 | { |
| 189 | omap_mpu_timer1_overflows++; |
| 190 | return IRQ_HANDLED; |
| 191 | } |
| 192 | |
| 193 | static struct irqaction omap_mpu_timer1_irq = { |
| 194 | .name = "mpu timer1 overflow", |
| 195 | .flags = SA_INTERRUPT, |
Russell King | 09b8b5f | 2005-06-26 17:06:36 +0100 | [diff] [blame] | 196 | .handler = omap_mpu_timer1_interrupt, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 197 | }; |
| 198 | |
| 199 | static __init void omap_init_mpu_timer(void) |
| 200 | { |
| 201 | set_cyc2ns_scale(MPU_TICKS_PER_SEC / 1000); |
| 202 | omap_timer.offset = omap_mpu_timer_gettimeoffset; |
| 203 | setup_irq(INT_TIMER1, &omap_mpu_timer1_irq); |
| 204 | setup_irq(INT_TIMER2, &omap_mpu_timer_irq); |
| 205 | omap_mpu_timer_start(0, 0xffffffff); |
| 206 | omap_mpu_timer_start(1, MPU_TIMER_TICK_PERIOD); |
| 207 | } |
| 208 | |
| 209 | /* |
| 210 | * Scheduler clock - returns current time in nanosec units. |
| 211 | */ |
| 212 | unsigned long long sched_clock(void) |
| 213 | { |
| 214 | unsigned long ticks = 0 - omap_mpu_timer_read(0); |
| 215 | unsigned long long ticks64; |
| 216 | |
| 217 | ticks64 = omap_mpu_timer1_overflows; |
| 218 | ticks64 <<= 32; |
| 219 | ticks64 |= ticks; |
| 220 | |
| 221 | return cycles_2_ns(ticks64); |
| 222 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 223 | |
| 224 | /* |
| 225 | * --------------------------------------------------------------------------- |
| 226 | * Timer initialization |
| 227 | * --------------------------------------------------------------------------- |
| 228 | */ |
Tony Lindgren | 3b59b6b | 2005-07-10 19:58:09 +0100 | [diff] [blame] | 229 | static void __init omap_timer_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 230 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 231 | omap_init_mpu_timer(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 232 | } |
| 233 | |
| 234 | struct sys_timer omap_timer = { |
| 235 | .init = omap_timer_init, |
| 236 | .offset = NULL, /* Initialized later */ |
| 237 | }; |