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Diffstat (limited to 'arch/arm/mach-omap/time.c')
| -rw-r--r-- | arch/arm/mach-omap/time.c | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/arch/arm/mach-omap/time.c b/arch/arm/mach-omap/time.c new file mode 100644 index 00000000000..4205fdcb632 --- /dev/null +++ b/arch/arm/mach-omap/time.c @@ -0,0 +1,384 @@ +/* + * linux/arch/arm/mach-omap/time.c + * + * OMAP Timers + * + * Copyright (C) 2004 Nokia Corporation + * Partial timer rewrite and additional VST timer support by + * Tony Lindgen <tony@atomide.com> and + * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com> + * + * MPU timer code based on the older MPU timer code for OMAP + * Copyright (C) 2000 RidgeRun, Inc. + * Author: Greg Lonnon <glonnon@ridgerun.com> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN + * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON + * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/interrupt.h> +#include <linux/sched.h> +#include <linux/spinlock.h> + +#include <asm/system.h> +#include <asm/hardware.h> +#include <asm/io.h> +#include <asm/leds.h> +#include <asm/irq.h> +#include <asm/mach/irq.h> +#include <asm/mach/time.h> + +struct sys_timer omap_timer; + +#ifdef CONFIG_OMAP_MPU_TIMER + +/* + * --------------------------------------------------------------------------- + * MPU timer + * --------------------------------------------------------------------------- + */ +#define OMAP_MPU_TIMER1_BASE (0xfffec500) +#define OMAP_MPU_TIMER2_BASE (0xfffec600) +#define OMAP_MPU_TIMER3_BASE (0xfffec700) +#define OMAP_MPU_TIMER_BASE OMAP_MPU_TIMER1_BASE +#define OMAP_MPU_TIMER_OFFSET 0x100 + +#define MPU_TIMER_FREE (1 << 6) +#define MPU_TIMER_CLOCK_ENABLE (1 << 5) +#define MPU_TIMER_AR (1 << 1) +#define MPU_TIMER_ST (1 << 0) + +/* cycles to nsec conversions taken from arch/i386/kernel/timers/timer_tsc.c, + * converted to use kHz by Kevin Hilman */ +/* convert from cycles(64bits) => nanoseconds (64bits) + * basic equation: + * ns = cycles / (freq / ns_per_sec) + * ns = cycles * (ns_per_sec / freq) + * ns = cycles * (10^9 / (cpu_khz * 10^3)) + * ns = cycles * (10^6 / cpu_khz) + * + * Then we use scaling math (suggested by george at mvista.com) to get: + * ns = cycles * (10^6 * SC / cpu_khz / SC + * ns = cycles * cyc2ns_scale / SC + * + * And since SC is a constant power of two, we can convert the div + * into a shift. + * -johnstul at us.ibm.com "math is hard, lets go shopping!" + */ +static unsigned long cyc2ns_scale; +#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ + +static inline void set_cyc2ns_scale(unsigned long cpu_khz) +{ + cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz; +} + +static inline unsigned long long cycles_2_ns(unsigned long long cyc) +{ + return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR; +} + +/* + * MPU_TICKS_PER_SEC must be an even number, otherwise machinecycles_to_usecs + * will break. On P2, the timer count rate is 6.5 MHz after programming PTV + * with 0. This divides the 13MHz input by 2, and is undocumented. + */ +#ifdef CONFIG_MACH_OMAP_PERSEUS2 +/* REVISIT: This ifdef construct should be replaced by a query to clock + * framework to see if timer base frequency is 12.0, 13.0 or 19.2 MHz. + */ +#define MPU_TICKS_PER_SEC (13000000 / 2) +#else +#define MPU_TICKS_PER_SEC (12000000 / 2) +#endif + +#define MPU_TIMER_TICK_PERIOD ((MPU_TICKS_PER_SEC / HZ) - 1) + +typedef struct { + u32 cntl; /* CNTL_TIMER, R/W */ + u32 load_tim; /* LOAD_TIM, W */ + u32 read_tim; /* READ_TIM, R */ +} omap_mpu_timer_regs_t; + +#define omap_mpu_timer_base(n) \ +((volatile omap_mpu_timer_regs_t*)IO_ADDRESS(OMAP_MPU_TIMER_BASE + \ + (n)*OMAP_MPU_TIMER_OFFSET)) + +static inline unsigned long omap_mpu_timer_read(int nr) +{ + volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr); + return timer->read_tim; +} + +static inline void omap_mpu_timer_start(int nr, unsigned long load_val) +{ + volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr); + + timer->cntl = MPU_TIMER_CLOCK_ENABLE; + udelay(1); + timer->load_tim = load_val; + udelay(1); + timer->cntl = (MPU_TIMER_CLOCK_ENABLE | MPU_TIMER_AR | MPU_TIMER_ST); +} + +unsigned long omap_mpu_timer_ticks_to_usecs(unsigned long nr_ticks) +{ + unsigned long long nsec; + + nsec = cycles_2_ns((unsigned long long)nr_ticks); + return (unsigned long)nsec / 1000; +} + +/* + * Last processed system timer interrupt + */ +static unsigned long omap_mpu_timer_last = 0; + +/* + * Returns elapsed usecs since last system timer interrupt + */ +static unsigned long omap_mpu_timer_gettimeoffset(void) +{ + unsigned long now = 0 - omap_mpu_timer_read(0); + unsigned long elapsed = now - omap_mpu_timer_last; + + return omap_mpu_timer_ticks_to_usecs(elapsed); +} + +/* + * Elapsed time between interrupts is calculated using timer0. + * Latency during the interrupt is calculated using timer1. + * Both timer0 and timer1 are counting at 6MHz (P2 6.5MHz). + */ +static irqreturn_t omap_mpu_timer_interrupt(int irq, void *dev_id, + struct pt_regs *regs) +{ + unsigned long now, latency; + + write_seqlock(&xtime_lock); + now = 0 - omap_mpu_timer_read(0); + latency = MPU_TICKS_PER_SEC / HZ - omap_mpu_timer_read(1); + omap_mpu_timer_last = now - latency; + timer_tick(regs); + write_sequnlock(&xtime_lock); + + return IRQ_HANDLED; +} + +static struct irqaction omap_mpu_timer_irq = { + .name = "mpu timer", + .flags = SA_INTERRUPT, + .handler = omap_mpu_timer_interrupt +}; + +static unsigned long omap_mpu_timer1_overflows; +static irqreturn_t omap_mpu_timer1_interrupt(int irq, void *dev_id, + struct pt_regs *regs) +{ + omap_mpu_timer1_overflows++; + return IRQ_HANDLED; +} + +static struct irqaction omap_mpu_timer1_irq = { + .name = "mpu timer1 overflow", + .flags = SA_INTERRUPT, + .handler = omap_mpu_timer1_interrupt +}; + +static __init void omap_init_mpu_timer(void) +{ + set_cyc2ns_scale(MPU_TICKS_PER_SEC / 1000); + omap_timer.offset = omap_mpu_timer_gettimeoffset; + setup_irq(INT_TIMER1, &omap_mpu_timer1_irq); + setup_irq(INT_TIMER2, &omap_mpu_timer_irq); + omap_mpu_timer_start(0, 0xffffffff); + omap_mpu_timer_start(1, MPU_TIMER_TICK_PERIOD); +} + +/* + * Scheduler clock - returns current time in nanosec units. + */ +unsigned long long sched_clock(void) +{ + unsigned long ticks = 0 - omap_mpu_timer_read(0); + unsigned long long ticks64; + + ticks64 = omap_mpu_timer1_overflows; + ticks64 <<= 32; + ticks64 |= ticks; + + return cycles_2_ns(ticks64); +} +#endif /* CONFIG_OMAP_MPU_TIMER */ + +#ifdef CONFIG_OMAP_32K_TIMER + +#ifdef CONFIG_ARCH_OMAP1510 +#error OMAP 32KHz timer does not currently work on 1510! +#endif + +/* + * --------------------------------------------------------------------------- + * 32KHz OS timer + * + * This currently works only on 16xx, as 1510 does not have the continuous + * 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track + * of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer + * on 1510 would be possible, but the timer would not be as accurate as + * with the 32KHz synchronized timer. + * --------------------------------------------------------------------------- + */ +#define OMAP_32K_TIMER_BASE 0xfffb9000 +#define OMAP_32K_TIMER_CR 0x08 +#define OMAP_32K_TIMER_TVR 0x00 +#define OMAP_32K_TIMER_TCR 0x04 + +#define OMAP_32K_TICKS_PER_HZ (32768 / HZ) + +/* + * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1 + * so with HZ = 100, TVR = 327.68. + */ +#define OMAP_32K_TIMER_TICK_PERIOD ((32768 / HZ) - 1) +#define MAX_SKIP_JIFFIES 25 +#define TIMER_32K_SYNCHRONIZED 0xfffbc410 + +#define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate) \ + (((nr_jiffies) * (clock_rate)) / HZ) + +static inline void omap_32k_timer_write(int val, int reg) +{ + omap_writew(val, reg + OMAP_32K_TIMER_BASE); +} + +static inline unsigned long omap_32k_timer_read(int reg) +{ + return omap_readl(reg + OMAP_32K_TIMER_BASE) & 0xffffff; +} + +/* + * The 32KHz synchronized timer is an additional timer on 16xx. + * It is always running. + */ +static inline unsigned long omap_32k_sync_timer_read(void) +{ + return omap_readl(TIMER_32K_SYNCHRONIZED); +} + +static inline void omap_32k_timer_start(unsigned long load_val) +{ + omap_32k_timer_write(load_val, OMAP_32K_TIMER_TVR); + omap_32k_timer_write(0x0f, OMAP_32K_TIMER_CR); +} + +static inline void omap_32k_timer_stop(void) +{ + omap_32k_timer_write(0x0, OMAP_32K_TIMER_CR); +} + +/* + * Rounds down to nearest usec + */ +static inline unsigned long omap_32k_ticks_to_usecs(unsigned long ticks_32k) +{ + return (ticks_32k * 5*5*5*5*5*5) >> 9; +} + +static unsigned long omap_32k_last_tick = 0; + +/* + * Returns elapsed usecs since last 32k timer interrupt + */ +static unsigned long omap_32k_timer_gettimeoffset(void) +{ + unsigned long now = omap_32k_sync_timer_read(); + return omap_32k_ticks_to_usecs(now - omap_32k_last_tick); +} + +/* + * Timer interrupt for 32KHz timer. When dynamic tick is enabled, this + * function is also called from other interrupts to remove latency + * issues with dynamic tick. In the dynamic tick case, we need to lock + * with irqsave. + */ +static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id, + struct pt_regs *regs) +{ + unsigned long flags; + unsigned long now; + + write_seqlock_irqsave(&xtime_lock, flags); + now = omap_32k_sync_timer_read(); + + while (now - omap_32k_last_tick >= OMAP_32K_TICKS_PER_HZ) { + omap_32k_last_tick += OMAP_32K_TICKS_PER_HZ; + timer_tick(regs); + } + + /* Restart timer so we don't drift off due to modulo or dynamic tick. + * By default we program the next timer to be continuous to avoid + * latencies during high system load. During dynamic tick operation the + * continuous timer can be overridden from pm_idle to be longer. + */ + omap_32k_timer_start(omap_32k_last_tick + OMAP_32K_TICKS_PER_HZ - now); + write_sequnlock_irqrestore(&xtime_lock, flags); + + return IRQ_HANDLED; +} + +static struct irqaction omap_32k_timer_irq = { + .name = "32KHz timer", + .flags = SA_INTERRUPT, + .handler = omap_32k_timer_interrupt +}; + +static __init void omap_init_32k_timer(void) +{ + setup_irq(INT_OS_TIMER, &omap_32k_timer_irq); + omap_timer.offset = omap_32k_timer_gettimeoffset; + omap_32k_last_tick = omap_32k_sync_timer_read(); + omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD); +} +#endif /* CONFIG_OMAP_32K_TIMER */ + +/* + * --------------------------------------------------------------------------- + * Timer initialization + * --------------------------------------------------------------------------- + */ +void __init omap_timer_init(void) +{ +#if defined(CONFIG_OMAP_MPU_TIMER) + omap_init_mpu_timer(); +#elif defined(CONFIG_OMAP_32K_TIMER) + omap_init_32k_timer(); +#else +#error No system timer selected in Kconfig! +#endif +} + +struct sys_timer omap_timer = { + .init = omap_timer_init, + .offset = NULL, /* Initialized later */ +}; |