--- /dev/null
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * vineetg: Jan 1011
+ * -sched_clock( ) no longer jiffies based. Uses the same clocksource
+ * as gtod
+ *
+ * Rajeshwarr/Vineetg: Mar 2008
+ * -Implemented CONFIG_GENERIC_TIME (rather deleted arch specific code)
+ * for arch independent gettimeofday()
+ * -Implemented CONFIG_GENERIC_CLOCKEVENTS as base for hrtimers
+ *
+ * Vineetg: Mar 2008: Forked off from time.c which now is time-jiff.c
+ */
+
+/* ARC700 has two 32bit independent prog Timers: TIMER0 and TIMER1
+ * Each can programmed to go from @count to @limit and optionally
+ * interrupt when that happens.
+ * A write to Control Register clears the Interrupt
+ *
+ * We've designated TIMER0 for events (clockevents)
+ * while TIMER1 for free running (clocksource)
+ *
+ * Newer ARC700 cores have 64bit clk fetching RTSC insn, preferred over TIMER1
+ */
+
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/timex.h>
+#include <linux/profile.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <asm/irq.h>
+#include <asm/arcregs.h>
+#include <asm/clk.h>
+
+#define ARC_TIMER_MAX 0xFFFFFFFF
+
+/********** Clock Source Device *********/
+
+#ifdef CONFIG_ARC_HAS_RTSC
+
+int __cpuinit arc_counter_setup(void)
+{
+ /* RTSC insn taps into cpu clk, needs no setup */
+
+ /* For SMP, only allowed if cross-core-sync, hence usable as cs */
+ return 1;
+}
+
+static cycle_t arc_counter_read(struct clocksource *cs)
+{
+ unsigned long flags;
+ union {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+ struct { u32 high, low; };
+#else
+ struct { u32 low, high; };
+#endif
+ cycle_t full;
+ } stamp;
+
+ flags = arch_local_irq_save();
+
+ __asm__ __volatile(
+ " .extCoreRegister tsch, 58, r, cannot_shortcut \n"
+ " rtsc %0, 0 \n"
+ " mov %1, tsch \n" /* TSCH is extn core reg 58 */
+ : "=r" (stamp.low), "=r" (stamp.high));
+
+ arch_local_irq_restore(flags);
+
+ return stamp.full;
+}
+
+static struct clocksource arc_counter = {
+ .name = "ARC RTSC",
+ .rating = 300,
+ .read = arc_counter_read,
+ .mask = CLOCKSOURCE_MASK(64),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#else /* !CONFIG_ARC_HAS_RTSC */
+
+static bool is_usable_as_clocksource(void)
+{
+#ifdef CONFIG_SMP
+ return 0;
+#else
+ return 1;
+#endif
+}
+
+/*
+ * set 32bit TIMER1 to keep counting monotonically and wraparound
+ */
+int __cpuinit arc_counter_setup(void)
+{
+ write_aux_reg(ARC_REG_TIMER1_LIMIT, ARC_TIMER_MAX);
+ write_aux_reg(ARC_REG_TIMER1_CNT, 0);
+ write_aux_reg(ARC_REG_TIMER1_CTRL, TIMER_CTRL_NH);
+
+ return is_usable_as_clocksource();
+}
+
+static cycle_t arc_counter_read(struct clocksource *cs)
+{
+ return (cycle_t) read_aux_reg(ARC_REG_TIMER1_CNT);
+}
+
+static struct clocksource arc_counter = {
+ .name = "ARC Timer1",
+ .rating = 300,
+ .read = arc_counter_read,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#endif
+
+/********** Clock Event Device *********/
+
+/*
+ * Arm the timer to interrupt after @limit cycles
+ * The distinction for oneshot/periodic is done in arc_event_timer_ack() below
+ */
+static void arc_timer_event_setup(unsigned int limit)
+{
+ write_aux_reg(ARC_REG_TIMER0_LIMIT, limit);
+ write_aux_reg(ARC_REG_TIMER0_CNT, 0); /* start from 0 */
+
+ write_aux_reg(ARC_REG_TIMER0_CTRL, TIMER_CTRL_IE | TIMER_CTRL_NH);
+}
+
+/*
+ * Acknowledge the interrupt (oneshot) and optionally re-arm it (periodic)
+ * -Any write to CTRL Reg will ack the intr (NH bit: Count when not halted)
+ * -Rearming is done by setting the IE bit
+ *
+ * Small optimisation: Normal code would have been
+ * if (irq_reenable)
+ * CTRL_REG = (IE | NH);
+ * else
+ * CTRL_REG = NH;
+ * However since IE is BIT0 we can fold the branch
+ */
+static void arc_timer_event_ack(unsigned int irq_reenable)
+{
+ write_aux_reg(ARC_REG_TIMER0_CTRL, irq_reenable | TIMER_CTRL_NH);
+}
+
+static int arc_clkevent_set_next_event(unsigned long delta,
+ struct clock_event_device *dev)
+{
+ arc_timer_event_setup(delta);
+ return 0;
+}
+
+static void arc_clkevent_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *dev)
+{
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ arc_timer_event_setup(arc_get_core_freq() / HZ);
+ break;
+ case CLOCK_EVT_MODE_ONESHOT:
+ break;
+ default:
+ break;
+ }
+
+ return;
+}
+
+static DEFINE_PER_CPU(struct clock_event_device, arc_clockevent_device) = {
+ .name = "ARC Timer0",
+ .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
+ .mode = CLOCK_EVT_MODE_UNUSED,
+ .rating = 300,
+ .irq = TIMER0_IRQ, /* hardwired, no need for resources */
+ .set_next_event = arc_clkevent_set_next_event,
+ .set_mode = arc_clkevent_set_mode,
+};
+
+static irqreturn_t timer_irq_handler(int irq, void *dev_id)
+{
+ struct clock_event_device *clk = &__get_cpu_var(arc_clockevent_device);
+
+ arc_timer_event_ack(clk->mode == CLOCK_EVT_MODE_PERIODIC);
+ clk->event_handler(clk);
+ return IRQ_HANDLED;
+}
+
+static struct irqaction arc_timer_irq = {
+ .name = "Timer0 (clock-evt-dev)",
+ .flags = IRQF_TIMER | IRQF_PERCPU,
+ .handler = timer_irq_handler,
+};
+
+/*
+ * Setup the local event timer for @cpu
+ * N.B. weak so that some exotic ARC SoCs can completely override it
+ */
+void __attribute__((weak)) __cpuinit arc_local_timer_setup(unsigned int cpu)
+{
+ struct clock_event_device *clk = &per_cpu(arc_clockevent_device, cpu);
+
+ clockevents_calc_mult_shift(clk, arc_get_core_freq(), 5);
+
+ clk->max_delta_ns = clockevent_delta2ns(ARC_TIMER_MAX, clk);
+ clk->cpumask = cpumask_of(cpu);
+
+ clockevents_register_device(clk);
+
+ /*
+ * setup the per-cpu timer IRQ handler - for all cpus
+ * For non boot CPU explicitly unmask at intc
+ * setup_irq() -> .. -> irq_startup() already does this on boot-cpu
+ */
+ if (!cpu)
+ setup_irq(TIMER0_IRQ, &arc_timer_irq);
+ else
+ arch_unmask_irq(TIMER0_IRQ);
+}
+
+/*
+ * Called from start_kernel() - boot CPU only
+ *
+ * -Sets up h/w timers as applicable on boot cpu
+ * -Also sets up any global state needed for timer subsystem:
+ * - for "counting" timer, registers a clocksource, usable across CPUs
+ * (provided that underlying counter h/w is synchronized across cores)
+ * - for "event" timer, sets up TIMER0 IRQ (as that is platform agnostic)
+ */
+void __init time_init(void)
+{
+ /*
+ * sets up the timekeeping free-flowing counter which also returns
+ * whether the counter is usable as clocksource
+ */
+ if (arc_counter_setup())
+ /*
+ * CLK upto 4.29 GHz can be safely represented in 32 bits
+ * because Max 32 bit number is 4,294,967,295
+ */
+ clocksource_register_hz(&arc_counter, arc_get_core_freq());
+
+ /* sets up the periodic event timer */
+ arc_local_timer_setup(smp_processor_id());
+}
+
+#ifdef CONFIG_ARC_HAS_RTSC
+/*
+ * sched_clock math assist
+ * ns = cycles * (ns_per_sec / cpu_freq_hz)
+ * ns = cycles * (10^6 / cpu_freq_khz)
+ * ns = cycles * (10^6 * 2^SF / cpu_freq_khz) / 2^SF
+ * ns = cycles * cyc2ns_scale >> SF
+ */
+#define CYC2NS_SF 10 /* 2^10, carefully chosen */
+#define CYC2NS_SCALE ((1000000 << CYC2NS_SF) / (arc_get_core_freq() / 1000))
+
+static unsigned long long cycles2ns(unsigned long long cyc)
+{
+ return (cyc * CYC2NS_SCALE ) >> CYC2NS_SF;
+}
+
+/*
+ * Scheduler clock - a monotonically increasing clock in nanosec units.
+ * It's return value must NOT wrap around.
+ *
+ * - Since 32bit TIMER1 will overflow almost immediately (53sec @ 80MHz), it
+ * can't be used directly.
+ * - Using getrawmonotonic (TIMER1 based, but with state for last + current
+ * snapshots), is no-good either because of seqlock deadlock possibilities
+ * - So only with native 64bit timer we do this, otherwise fallback to generic
+ * jiffies based version - which despite not being fine grained gaurantees
+ * the monotonically increasing semantics.
+ */
+unsigned long long sched_clock(void)
+{
+ return cycles2ns(arc_counter_read(NULL));
+}
+#endif
projects / ~andy / linux / blobdiff