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+/*
+ * linux/arch/arm/mach-omap1/time.c
+ *
+ * OMAP Timers
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Partial timer rewrite and additional dynamic tick 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_TIMER_BASE OMAP_MPU_TIMER1_BASE
+#define OMAP_MPU_TIMER_OFFSET 0x100
+
+/* 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 | SA_TIMER,
+ .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)
+#if (32768 % HZ) != 0
+/* We cannot ignore modulo.
+ * Potential error can be as high as several percent.
+ */
+#define OMAP_32K_TICK_MODULO (32768 % HZ)
+static unsigned modulo_count = 0; /* Counts 1/HZ units */
+#endif
+
+/*
+ * 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 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) {
+#ifdef OMAP_32K_TICK_MODULO
+ /* Modulo addition may put omap_32k_last_tick ahead of now
+ * and cause unwanted repetition of the while loop.
+ */
+ if (unlikely(now - omap_32k_last_tick == ~0))
+ break;
+
+ modulo_count += OMAP_32K_TICK_MODULO;
+ if (modulo_count > HZ) {
+ ++omap_32k_last_tick;
+ modulo_count -= HZ;
+ }
+#endif
+ 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;
+}
+
+#ifdef CONFIG_NO_IDLE_HZ
+/*
+ * Programs the next timer interrupt needed. Called when dynamic tick is
+ * enabled, and to reprogram the ticks to skip from pm_idle. Note that
+ * we can keep the timer continuous, and don't need to set it to run in
+ * one-shot mode. This is because the timer will get reprogrammed again
+ * after next interrupt.
+ */
+void omap_32k_timer_reprogram(unsigned long next_tick)
+{
+ omap_32k_timer_start(JIFFIES_TO_HW_TICKS(next_tick, 32768) + 1);
+}
+
+static struct irqaction omap_32k_timer_irq;
+extern struct timer_update_handler timer_update;
+
+static int omap_32k_timer_enable_dyn_tick(void)
+{
+ /* No need to reprogram timer, just use the next interrupt */
+ return 0;
+}
+
+static int omap_32k_timer_disable_dyn_tick(void)
+{
+ omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
+ return 0;
+}
+
+static struct dyn_tick_timer omap_dyn_tick_timer = {
+ .enable = omap_32k_timer_enable_dyn_tick,
+ .disable = omap_32k_timer_disable_dyn_tick,
+ .reprogram = omap_32k_timer_reprogram,
+ .handler = omap_32k_timer_interrupt,
+};
+#endif /* CONFIG_NO_IDLE_HZ */
+
+static struct irqaction omap_32k_timer_irq = {
+ .name = "32KHz timer",
+ .flags = SA_INTERRUPT | SA_TIMER,
+ .handler = omap_32k_timer_interrupt,
+};
+
+static __init void omap_init_32k_timer(void)
+{
+
+#ifdef CONFIG_NO_IDLE_HZ
+ omap_timer.dyn_tick = &omap_dyn_tick_timer;
+#endif
+
+ 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
+ * ---------------------------------------------------------------------------
+ */
+static 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 */
+};