apic.c

linux-2.4.29操作系统的源码

 * this function twice on the boot CPU, once with a bogus timeout
 * value, second time for real. The other (noncalibrating) CPUs
 * call this function only once, with the real, calibrated value.
 *
 * We do reads before writes even if unnecessary, to get around the
 * P5 APIC double write bug.
 */

#define APIC_DIVISOR 16

void __setup_APIC_LVTT(unsigned int clocks)
{
	unsigned int lvtt1_value, tmp_value;

	lvtt1_value = SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV) |
			APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
	apic_write_around(APIC_LVTT, lvtt1_value);

	/*
	 * Divide PICLK by 16
	 */
	tmp_value = apic_read(APIC_TDCR);
	apic_write_around(APIC_TDCR, (tmp_value
				& ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE))
				| APIC_TDR_DIV_16);

	apic_write_around(APIC_TMICT, clocks/APIC_DIVISOR);
}

void setup_APIC_timer(void * data)
{
	unsigned int clocks = (unsigned int) data, slice, t0, t1;
	unsigned long flags;
	int delta;

	__save_flags(flags);
	__sti();
	/*
	 * ok, Intel has some smart code in their APIC that knows
	 * if a CPU was in 'hlt' lowpower mode, and this increases
	 * its APIC arbitration priority. To avoid the external timer
	 * IRQ APIC event being in synchron with the APIC clock we
	 * introduce an interrupt skew to spread out timer events.
	 *
	 * The number of slices within a 'big' timeslice is smp_num_cpus+1
	 */

	slice = clocks / (smp_num_cpus+1);
	printk("cpu: %d, clocks: %d, slice: %d\n", smp_processor_id(), clocks, slice);

	/*
	 * Wait for IRQ0's slice:
	 */
	wait_8254_wraparound();

	__setup_APIC_LVTT(clocks);

	t0 = apic_read(APIC_TMICT)*APIC_DIVISOR;
	/* Wait till TMCCT gets reloaded from TMICT... */
	do {
		t1 = apic_read(APIC_TMCCT)*APIC_DIVISOR;
		delta = (int)(t0 - t1 - slice*(smp_processor_id()+1));
	} while (delta >= 0);
	/* Now wait for our slice for real. */
	do {
		t1 = apic_read(APIC_TMCCT)*APIC_DIVISOR;
		delta = (int)(t0 - t1 - slice*(smp_processor_id()+1));
	} while (delta < 0);

	__setup_APIC_LVTT(clocks);

	printk("CPU%d<T0:%d,T1:%d,D:%d,S:%d,C:%d>\n", smp_processor_id(), t0, t1, delta, slice, clocks);

	__restore_flags(flags);
}

/*
 * In this function we calibrate APIC bus clocks to the external
 * timer. Unfortunately we cannot use jiffies and the timer irq
 * to calibrate, since some later bootup code depends on getting
 * the first irq? Ugh.
 *
 * We want to do the calibration only once since we
 * want to have local timer irqs syncron. CPUs connected
 * by the same APIC bus have the very same bus frequency.
 * And we want to have irqs off anyways, no accidental
 * APIC irq that way.
 */

int __init calibrate_APIC_clock(void)
{
	unsigned long long t1 = 0, t2 = 0;
	long tt1, tt2;
	long result;
	int i;
	const int LOOPS = HZ/10;

	printk("calibrating APIC timer ...\n");

	/*
	 * Put whatever arbitrary (but long enough) timeout
	 * value into the APIC clock, we just want to get the
	 * counter running for calibration.
	 */
	__setup_APIC_LVTT(1000000000);

	/*
	 * The timer chip counts down to zero. Let's wait
	 * for a wraparound to start exact measurement:
	 * (the current tick might have been already half done)
	 */

	wait_8254_wraparound();

	/*
	 * We wrapped around just now. Let's start:
	 */
	if (cpu_has_tsc)
		rdtscll(t1);
	tt1 = apic_read(APIC_TMCCT);

	/*
	 * Let's wait LOOPS wraprounds:
	 */
	for (i = 0; i < LOOPS; i++)
		wait_8254_wraparound();

	tt2 = apic_read(APIC_TMCCT);
	if (cpu_has_tsc)
		rdtscll(t2);

	/*
	 * The APIC bus clock counter is 32 bits only, it
	 * might have overflown, but note that we use signed
	 * longs, thus no extra care needed.
	 *
	 * underflown to be exact, as the timer counts down ;)
	 */

	result = (tt1-tt2)*APIC_DIVISOR/LOOPS;

	if (cpu_has_tsc)
		printk("..... CPU clock speed is %ld.%04ld MHz.\n",
			((long)(t2-t1)/LOOPS)/(1000000/HZ),
			((long)(t2-t1)/LOOPS)%(1000000/HZ));

	printk("..... host bus clock speed is %ld.%04ld MHz.\n",
		result/(1000000/HZ),
		result%(1000000/HZ));

	return result;
}

static unsigned int calibration_result;

void __init setup_APIC_clocks (void)
{
	printk("Using local APIC timer interrupts.\n");
	using_apic_timer = 1;

	__cli();

	calibration_result = calibrate_APIC_clock();
	/*
	 * Now set up the timer for real.
	 */
	setup_APIC_timer((void *)calibration_result);

	__sti();

	/* and update all other cpus */
	smp_call_function(setup_APIC_timer, (void *)calibration_result, 1, 1);
}

void __init disable_APIC_timer(void)
{
	if (using_apic_timer) {
		unsigned long v;

		v = apic_read(APIC_LVTT);
		apic_write_around(APIC_LVTT, v | APIC_LVT_MASKED);
	}
}

void enable_APIC_timer(void)
{
	if (using_apic_timer) {
		unsigned long v;

		v = apic_read(APIC_LVTT);
		apic_write_around(APIC_LVTT, v & ~APIC_LVT_MASKED);
	}
}

/*
 * the frequency of the profiling timer can be changed
 * by writing a multiplier value into /proc/profile.
 */
int setup_profiling_timer(unsigned int multiplier)
{
	int i;

	/*
	 * Sanity check. [at least 500 APIC cycles should be
	 * between APIC interrupts as a rule of thumb, to avoid
	 * irqs flooding us]
	 */
	if ( (!multiplier) || (calibration_result/multiplier < 500))
		return -EINVAL;

	/* 
	 * Set the new multiplier for each CPU. CPUs don't start using the
	 * new values until the next timer interrupt in which they do process
	 * accounting. At that time they also adjust their APIC timers
	 * accordingly.
	 */
	for (i = 0; i < NR_CPUS; ++i)
		prof_multiplier[i] = multiplier;

	return 0;
}

#undef APIC_DIVISOR

/*
 * Local timer interrupt handler. It does both profiling and
 * process statistics/rescheduling.
 *
 * We do profiling in every local tick, statistics/rescheduling
 * happen only every 'profiling multiplier' ticks. The default
 * multiplier is 1 and it can be changed by writing the new multiplier
 * value into /proc/profile.
 */

inline void smp_local_timer_interrupt(struct pt_regs * regs)
{
	int user = user_mode(regs);
	int cpu = smp_processor_id();

	/*
	 * The profiling function is SMP safe. (nothing can mess
	 * around with "current", and the profiling counters are
	 * updated with atomic operations). This is especially
	 * useful with a profiling multiplier != 1
	 */
	if (!user)
		x86_do_profile(regs->eip);

	if (--prof_counter[cpu] <= 0) {
		/*
		 * The multiplier may have changed since the last time we got
		 * to this point as a result of the user writing to
		 * /proc/profile. In this case we need to adjust the APIC
		 * timer accordingly.
		 *
		 * Interrupts are already masked off at this point.
		 */
		prof_counter[cpu] = prof_multiplier[cpu];
		if (prof_counter[cpu] != prof_old_multiplier[cpu]) {
			__setup_APIC_LVTT(calibration_result/prof_counter[cpu]);
			prof_old_multiplier[cpu] = prof_counter[cpu];
		}

#ifdef CONFIG_SMP
		update_process_times(user);
#endif
	}

	/*
	 * We take the 'long' return path, and there every subsystem
	 * grabs the apropriate locks (kernel lock/ irq lock).
	 *
	 * we might want to decouple profiling from the 'long path',
	 * and do the profiling totally in assembly.
	 *
	 * Currently this isn't too much of an issue (performance wise),
	 * we can take more than 100K local irqs per second on a 100 MHz P5.
	 */
}

/*
 * Local APIC timer interrupt. This is the most natural way for doing
 * local interrupts, but local timer interrupts can be emulated by
 * broadcast interrupts too. [in case the hw doesn't support APIC timers]
 *
 * [ if a single-CPU system runs an SMP kernel then we call the local
 *   interrupt as well. Thus we cannot inline the local irq ... ]
 */
unsigned int apic_timer_irqs [NR_CPUS];

void smp_apic_timer_interrupt(struct pt_regs * regs)
{
	int cpu = smp_processor_id();

	/*
	 * the NMI deadlock-detector uses this.
	 */
	apic_timer_irqs[cpu]++;

	/*
	 * NOTE! We'd better ACK the irq immediately,
	 * because timer handling can be slow.
	 */
	ack_APIC_irq();
	/*
	 * update_process_times() expects us to have done irq_enter().
	 * Besides, if we don't timer interrupts ignore the global
	 * interrupt lock, which is the WrongThing (tm) to do.
	 */
	irq_enter(cpu, 0);
	smp_local_timer_interrupt(regs);
	irq_exit(cpu, 0);

	if (softirq_pending(cpu))
		do_softirq();
}

/*
 * This interrupt should _never_ happen with our APIC/SMP architecture
 */
asmlinkage void smp_spurious_interrupt(void)
{
	unsigned long v;

	/*
	 * Check if this really is a spurious interrupt and ACK it
	 * if it is a vectored one.  Just in case...
	 * Spurious interrupts should not be ACKed.
	 */
	v = apic_read(APIC_ISR + ((SPURIOUS_APIC_VECTOR & ~0x1f) >> 1));
	if (v & (1 << (SPURIOUS_APIC_VECTOR & 0x1f)))
		ack_APIC_irq();

	/* see sw-dev-man vol 3, chapter 7.4.13.5 */
	printk(KERN_INFO "spurious APIC interrupt on CPU#%d, should never happen.\n",
			smp_processor_id());
}

/*
 * This interrupt should never happen with our APIC/SMP architecture
 */

asmlinkage void smp_error_interrupt(void)
{
	unsigned long v, v1;

	/* First tickle the hardware, only then report what went on. -- REW */
	v = apic_read(APIC_ESR);
	apic_write(APIC_ESR, 0);
	v1 = apic_read(APIC_ESR);
	ack_APIC_irq();
	atomic_inc(&irq_err_count);

	/* Here is what the APIC error bits mean:
	   0: Send CS error
	   1: Receive CS error
	   2: Send accept error
	   3: Receive accept error
	   4: Reserved
	   5: Send illegal vector
	   6: Received illegal vector
	   7: Illegal register address
	*/
	printk (KERN_ERR "APIC error on CPU%d: %02lx(%02lx)\n",
	        smp_processor_id(), v , v1);
}

/*
 * This initializes the IO-APIC and APIC hardware if this is
 * a UP kernel.
 */
int __init APIC_init_uniprocessor (void)
{
	if (enable_local_apic < 0)
		clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);

	if (!smp_found_config && !cpu_has_apic)
		return -1;

	/*
	 * Complain if the BIOS pretends there is one.
	 */
	if (!cpu_has_apic && APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
		printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
			boot_cpu_physical_apicid);
		return -1;
	}

	verify_local_APIC();

	connect_bsp_APIC();

	phys_cpu_present_map = 1 << boot_cpu_physical_apicid;

	apic_pm_init2();

	setup_local_APIC();

	if (nmi_watchdog == NMI_LOCAL_APIC)
		check_nmi_watchdog();
#ifdef CONFIG_X86_IO_APIC
	if (smp_found_config)
		if (!skip_ioapic_setup && nr_ioapics)
			setup_IO_APIC();
#endif
	setup_APIC_clocks();

	return 0;
}