/* * 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>#include <asm/mach_desc.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, 0	\n"	: "=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(32),	.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()); 	if (machine_desc->init_time)		machine_desc->init_time();}