[net-next-2.6.git] / arch / i386 / kernel / tsc.c

/*
 * This code largely moved from arch/i386/kernel/timer/timer_tsc.c
 * which was originally moved from arch/i386/kernel/time.c.
 * See comments there for proper credits.
 */

#include <linux/clocksource.h>
#include <linux/workqueue.h>
#include <linux/cpufreq.h>
#include <linux/jiffies.h>
#include <linux/init.h>
#include <linux/dmi.h>

#include <asm/delay.h>
#include <asm/tsc.h>
#include <asm/io.h>

#include "mach_timer.h"

/*
 * On some systems the TSC frequency does not
 * change with the cpu frequency. So we need
 * an extra value to store the TSC freq
 */
unsigned int tsc_khz;

int tsc_disable __cpuinitdata = 0;

#ifdef CONFIG_X86_TSC
static int __init tsc_setup(char *str)
{
	printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, "
				"cannot disable TSC.\n");
	return 1;
}
#else
/*
 * disable flag for tsc. Takes effect by clearing the TSC cpu flag
 * in cpu/common.c
 */
static int __init tsc_setup(char *str)
{
	tsc_disable = 1;

	return 1;
}
#endif

__setup("notsc", tsc_setup);

/*
 * code to mark and check if the TSC is unstable
 * due to cpufreq or due to unsynced TSCs
 */
static int tsc_unstable;

static inline int check_tsc_unstable(void)
{
	return tsc_unstable;
}

void mark_tsc_unstable(void)
{
	tsc_unstable = 1;
}
EXPORT_SYMBOL_GPL(mark_tsc_unstable);

/* Accellerators for sched_clock()
 * 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@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.
 *
 *  We can use khz divisor instead of mhz to keep a better percision, since
 *  cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
 *  (mathieu.desnoyers@polymtl.ca)
 *
 *			-johnstul@us.ibm.com "math is hard, lets go shopping!"
 */
static unsigned long cyc2ns_scale __read_mostly;

#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;
}

/*
 * Scheduler clock - returns current time in nanosec units.
 */
unsigned long long sched_clock(void)
{
	unsigned long long this_offset;

	/*
	 * in the NUMA case we dont use the TSC as they are not
	 * synchronized across all CPUs.
	 */
#ifndef CONFIG_NUMA
	if (!cpu_khz || check_tsc_unstable())
#endif
		/* no locking but a rare wrong value is not a big deal */
		return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);

	/* read the Time Stamp Counter: */
	rdtscll(this_offset);

	/* return the value in ns */
	return cycles_2_ns(this_offset);
}

static unsigned long calculate_cpu_khz(void)
{
	unsigned long long start, end;
	unsigned long count;
	u64 delta64;
	int i;
	unsigned long flags;

	local_irq_save(flags);

	/* run 3 times to ensure the cache is warm */
	for (i = 0; i < 3; i++) {
		mach_prepare_counter();
		rdtscll(start);
		mach_countup(&count);
		rdtscll(end);
	}
	/*
	 * Error: ECTCNEVERSET
	 * The CTC wasn't reliable: we got a hit on the very first read,
	 * or the CPU was so fast/slow that the quotient wouldn't fit in
	 * 32 bits..
	 */
	if (count <= 1)
		goto err;

	delta64 = end - start;

	/* cpu freq too fast: */
	if (delta64 > (1ULL<<32))
		goto err;

	/* cpu freq too slow: */
	if (delta64 <= CALIBRATE_TIME_MSEC)
		goto err;

	delta64 += CALIBRATE_TIME_MSEC/2; /* round for do_div */
	do_div(delta64,CALIBRATE_TIME_MSEC);

	local_irq_restore(flags);
	return (unsigned long)delta64;
err:
	local_irq_restore(flags);
	return 0;
}

int recalibrate_cpu_khz(void)
{
#ifndef CONFIG_SMP
	unsigned long cpu_khz_old = cpu_khz;

	if (cpu_has_tsc) {
		cpu_khz = calculate_cpu_khz();
		tsc_khz = cpu_khz;
		cpu_data[0].loops_per_jiffy =
			cpufreq_scale(cpu_data[0].loops_per_jiffy,
					cpu_khz_old, cpu_khz);
		return 0;
	} else
		return -ENODEV;
#else
	return -ENODEV;
#endif
}

EXPORT_SYMBOL(recalibrate_cpu_khz);

void __init tsc_init(void)
{
	if (!cpu_has_tsc || tsc_disable)
		return;

	cpu_khz = calculate_cpu_khz();
	tsc_khz = cpu_khz;

	if (!cpu_khz)
		return;

	printk("Detected %lu.%03lu MHz processor.\n",
				(unsigned long)cpu_khz / 1000,
				(unsigned long)cpu_khz % 1000);

	set_cyc2ns_scale(cpu_khz);
	use_tsc_delay();
}

#ifdef CONFIG_CPU_FREQ

static unsigned int cpufreq_delayed_issched = 0;
static unsigned int cpufreq_init = 0;
static struct work_struct cpufreq_delayed_get_work;

static void handle_cpufreq_delayed_get(void *v)
{
	unsigned int cpu;

	for_each_online_cpu(cpu)
		cpufreq_get(cpu);

	cpufreq_delayed_issched = 0;
}

/*
 * if we notice cpufreq oddness, schedule a call to cpufreq_get() as it tries
 * to verify the CPU frequency the timing core thinks the CPU is running
 * at is still correct.
 */
static inline void cpufreq_delayed_get(void)
{
	if (cpufreq_init && !cpufreq_delayed_issched) {
		cpufreq_delayed_issched = 1;
		printk(KERN_DEBUG "Checking if CPU frequency changed.\n");
		schedule_work(&cpufreq_delayed_get_work);
	}
}

/*
 * if the CPU frequency is scaled, TSC-based delays will need a different
 * loops_per_jiffy value to function properly.
 */
static unsigned int ref_freq = 0;
static unsigned long loops_per_jiffy_ref = 0;
static unsigned long cpu_khz_ref = 0;

static int
time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
{
	struct cpufreq_freqs *freq = data;

	if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
		write_seqlock_irq(&xtime_lock);

	if (!ref_freq) {
		if (!freq->old){
			ref_freq = freq->new;
			goto end;
		}
		ref_freq = freq->old;
		loops_per_jiffy_ref = cpu_data[freq->cpu].loops_per_jiffy;
		cpu_khz_ref = cpu_khz;
	}

	if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
	    (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
	    (val == CPUFREQ_RESUMECHANGE)) {
		if (!(freq->flags & CPUFREQ_CONST_LOOPS))
			cpu_data[freq->cpu].loops_per_jiffy =
				cpufreq_scale(loops_per_jiffy_ref,
						ref_freq, freq->new);

		if (cpu_khz) {

			if (num_online_cpus() == 1)
				cpu_khz = cpufreq_scale(cpu_khz_ref,
						ref_freq, freq->new);
			if (!(freq->flags & CPUFREQ_CONST_LOOPS)) {
				tsc_khz = cpu_khz;
				set_cyc2ns_scale(cpu_khz);
				/*
				 * TSC based sched_clock turns
				 * to junk w/ cpufreq
				 */
				mark_tsc_unstable();
			}
		}
	}
end:
	if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
		write_sequnlock_irq(&xtime_lock);

	return 0;
}

static struct notifier_block time_cpufreq_notifier_block = {
	.notifier_call	= time_cpufreq_notifier
};

static int __init cpufreq_tsc(void)
{
	int ret;

	INIT_WORK(&cpufreq_delayed_get_work, handle_cpufreq_delayed_get, NULL);
	ret = cpufreq_register_notifier(&time_cpufreq_notifier_block,
					CPUFREQ_TRANSITION_NOTIFIER);
	if (!ret)
		cpufreq_init = 1;

	return ret;
}

core_initcall(cpufreq_tsc);

#endif

/* clock source code */

static unsigned long current_tsc_khz = 0;
static int tsc_update_callback(void);

static cycle_t read_tsc(void)
{
	cycle_t ret;

	rdtscll(ret);

	return ret;
}

static struct clocksource clocksource_tsc = {
	.name			= "tsc",
	.rating			= 300,
	.read			= read_tsc,
	.mask			= CLOCKSOURCE_MASK(64),
	.mult			= 0, /* to be set */
	.shift			= 22,
	.update_callback	= tsc_update_callback,
	.is_continuous		= 1,
};

static int tsc_update_callback(void)
{
	int change = 0;

	/* check to see if we should switch to the safe clocksource: */
	if (clocksource_tsc.rating != 0 && check_tsc_unstable()) {
		clocksource_tsc.rating = 0;
		clocksource_reselect();
		change = 1;
	}

	/* only update if tsc_khz has changed: */
	if (current_tsc_khz != tsc_khz) {
		current_tsc_khz = tsc_khz;
		clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
							clocksource_tsc.shift);
		change = 1;
	}

	return change;
}

static int __init dmi_mark_tsc_unstable(struct dmi_system_id *d)
{
	printk(KERN_NOTICE "%s detected: marking TSC unstable.\n",
		       d->ident);
	mark_tsc_unstable();
	return 0;
}

/* List of systems that have known TSC problems */
static struct dmi_system_id __initdata bad_tsc_dmi_table[] = {
	{
	 .callback = dmi_mark_tsc_unstable,
	 .ident = "IBM Thinkpad 380XD",
	 .matches = {
		     DMI_MATCH(DMI_BOARD_VENDOR, "IBM"),
		     DMI_MATCH(DMI_BOARD_NAME, "2635FA0"),
		     },
	 },
	 {}
};

#define TSC_FREQ_CHECK_INTERVAL (10*MSEC_PER_SEC) /* 10sec in MS */
static struct timer_list verify_tsc_freq_timer;

/* XXX - Probably should add locking */
static void verify_tsc_freq(unsigned long unused)
{
	static u64 last_tsc;
	static unsigned long last_jiffies;

	u64 now_tsc, interval_tsc;
	unsigned long now_jiffies, interval_jiffies;


	if (check_tsc_unstable())
		return;

	rdtscll(now_tsc);
	now_jiffies = jiffies;

	if (!last_jiffies) {
		goto out;
	}

	interval_jiffies = now_jiffies - last_jiffies;
	interval_tsc = now_tsc - last_tsc;
	interval_tsc *= HZ;
	do_div(interval_tsc, cpu_khz*1000);

	if (interval_tsc < (interval_jiffies * 3 / 4)) {
		printk("TSC appears to be running slowly. "
			"Marking it as unstable\n");
		mark_tsc_unstable();
		return;
	}

out:
	last_tsc = now_tsc;
	last_jiffies = now_jiffies;
	/* set us up to go off on the next interval: */
	mod_timer(&verify_tsc_freq_timer,
		jiffies + msecs_to_jiffies(TSC_FREQ_CHECK_INTERVAL));
}

/*
 * Make an educated guess if the TSC is trustworthy and synchronized
 * over all CPUs.
 */
static __init int unsynchronized_tsc(void)
{
	/*
	 * Intel systems are normally all synchronized.
	 * Exceptions must mark TSC as unstable:
	 */
	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
 		return 0;

	/* assume multi socket systems are not synchronized: */
 	return num_possible_cpus() > 1;
}

static int __init init_tsc_clocksource(void)
{

	if (cpu_has_tsc && tsc_khz && !tsc_disable) {
		/* check blacklist */
		dmi_check_system(bad_tsc_dmi_table);

		if (unsynchronized_tsc()) /* mark unstable if unsynced */
			mark_tsc_unstable();
		current_tsc_khz = tsc_khz;
		clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
							clocksource_tsc.shift);
		/* lower the rating if we already know its unstable: */
		if (check_tsc_unstable())
			clocksource_tsc.rating = 0;

		init_timer(&verify_tsc_freq_timer);
		verify_tsc_freq_timer.function = verify_tsc_freq;
		verify_tsc_freq_timer.expires =
			jiffies + msecs_to_jiffies(TSC_FREQ_CHECK_INTERVAL);
		add_timer(&verify_tsc_freq_timer);

		return clocksource_register(&clocksource_tsc);
	}

	return 0;
}

module_init(init_tsc_clocksource);
Commit	Line	Data
539eb11e JS	1	/*
	2	* This code largely moved from arch/i386/kernel/timer/timer_tsc.c
	3	* which was originally moved from arch/i386/kernel/time.c.
	4	* See comments there for proper credits.
	5	*/
	6
5d0cf410	7	#include <linux/clocksource.h>
539eb11e JS	8	#include <linux/workqueue.h>
	9	#include <linux/cpufreq.h>
	10	#include <linux/jiffies.h>
	11	#include <linux/init.h>
5d0cf410	12	#include <linux/dmi.h>
539eb11e	13
5d0cf410	14	#include <asm/delay.h>
539eb11e JS	15	#include <asm/tsc.h>
	16	#include <asm/io.h>
	17
	18	#include "mach_timer.h"
	19
	20	/*
	21	* On some systems the TSC frequency does not
	22	* change with the cpu frequency. So we need
	23	* an extra value to store the TSC freq
	24	*/
	25	unsigned int tsc_khz;
	26
	27	int tsc_disable __cpuinitdata = 0;
	28
	29	#ifdef CONFIG_X86_TSC
	30	static int __init tsc_setup(char *str)
	31	{
	32	printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, "
	33	"cannot disable TSC.\n");
	34	return 1;
	35	}
	36	#else
	37	/*
	38	* disable flag for tsc. Takes effect by clearing the TSC cpu flag
	39	* in cpu/common.c
	40	*/
	41	static int __init tsc_setup(char *str)
	42	{
	43	tsc_disable = 1;
	44
	45	return 1;
	46	}
	47	#endif
	48
	49	__setup("notsc", tsc_setup);
	50
539eb11e JS	51	/*
	52	* code to mark and check if the TSC is unstable
	53	* due to cpufreq or due to unsynced TSCs
	54	*/
	55	static int tsc_unstable;
	56
	57	static inline int check_tsc_unstable(void)
	58	{
	59	return tsc_unstable;
	60	}
	61
	62	void mark_tsc_unstable(void)
	63	{
	64	tsc_unstable = 1;
	65	}
	66	EXPORT_SYMBOL_GPL(mark_tsc_unstable);
	67
	68	/* Accellerators for sched_clock()
	69	* convert from cycles(64bits) => nanoseconds (64bits)
	70	* basic equation:
	71	* ns = cycles / (freq / ns_per_sec)
	72	* ns = cycles * (ns_per_sec / freq)
	73	* ns = cycles * (10^9 / (cpu_khz * 10^3))
	74	* ns = cycles * (10^6 / cpu_khz)
	75	*
	76	* Then we use scaling math (suggested by george@mvista.com) to get:
	77	* ns = cycles * (10^6 * SC / cpu_khz) / SC
	78	* ns = cycles * cyc2ns_scale / SC
	79	*
	80	* And since SC is a constant power of two, we can convert the div
	81	* into a shift.
	82	*
	83	* We can use khz divisor instead of mhz to keep a better percision, since
	84	* cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
	85	* (mathieu.desnoyers@polymtl.ca)
	86	*
	87	* -johnstul@us.ibm.com "math is hard, lets go shopping!"
	88	*/
	89	static unsigned long cyc2ns_scale __read_mostly;
	90
	91	#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
	92
	93	static inline void set_cyc2ns_scale(unsigned long cpu_khz)
	94	{
	95	cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
	96	}
	97
	98	static inline unsigned long long cycles_2_ns(unsigned long long cyc)
	99	{
	100	return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
	101	}
	102
	103	/*
	104	* Scheduler clock - returns current time in nanosec units.
	105	*/
	106	unsigned long long sched_clock(void)
	107	{
	108	unsigned long long this_offset;
	109
	110	/*
	111	* in the NUMA case we dont use the TSC as they are not
	112	* synchronized across all CPUs.
	113	*/
	114	#ifndef CONFIG_NUMA
115	if (!cpu_khz \|\| check_tsc_unstable())
116	#endif
117	/* no locking but a rare wrong value is not a big deal */
118	return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
119
120	/* read the Time Stamp Counter: */
121	rdtscll(this_offset);
122
123	/* return the value in ns */
124	return cycles_2_ns(this_offset);
125	}
126
127	static unsigned long calculate_cpu_khz(void)
128	{
129	unsigned long long start, end;
130	unsigned long count;
131	u64 delta64;
132	int i;
133	unsigned long flags;
134
135	local_irq_save(flags);
136
137	/* run 3 times to ensure the cache is warm */
138	for (i = 0; i < 3; i++) {
139	mach_prepare_counter();
140	rdtscll(start);
141	mach_countup(&count);
142	rdtscll(end);
143	}
144	/*
145	* Error: ECTCNEVERSET
146	* The CTC wasn't reliable: we got a hit on the very first read,
147	* or the CPU was so fast/slow that the quotient wouldn't fit in
148	* 32 bits..
149	*/
150	if (count <= 1)
151	goto err;
152
153	delta64 = end - start;
154
155	/* cpu freq too fast: */
156	if (delta64 > (1ULL<<32))
157	goto err;
158
159	/* cpu freq too slow: */
160	if (delta64 <= CALIBRATE_TIME_MSEC)
161	goto err;
162
163	delta64 += CALIBRATE_TIME_MSEC/2; /* round for do_div */
164	do_div(delta64,CALIBRATE_TIME_MSEC);
165
166	local_irq_restore(flags);
167	return (unsigned long)delta64;
168	err:
169	local_irq_restore(flags);
170	return 0;
171	}
172
173	int recalibrate_cpu_khz(void)
174	{
175	#ifndef CONFIG_SMP
176	unsigned long cpu_khz_old = cpu_khz;
177
178	if (cpu_has_tsc) {
179	cpu_khz = calculate_cpu_khz();
180	tsc_khz = cpu_khz;
181	cpu_data[0].loops_per_jiffy =
182	cpufreq_scale(cpu_data[0].loops_per_jiffy,
183	cpu_khz_old, cpu_khz);
184	return 0;
185	} else
186	return -ENODEV;
187	#else
188	return -ENODEV;
189	#endif
190	}
191
192	EXPORT_SYMBOL(recalibrate_cpu_khz);
193
c0d83745	194	void __init tsc_init(void)
539eb11e JS	195	{
	196	if (!cpu_has_tsc \|\| tsc_disable)
	197	return;
	198
	199	cpu_khz = calculate_cpu_khz();
	200	tsc_khz = cpu_khz;
	201
	202	if (!cpu_khz)
	203	return;
	204
	205	printk("Detected %lu.%03lu MHz processor.\n",
	206	(unsigned long)cpu_khz / 1000,
	207	(unsigned long)cpu_khz % 1000);
	208
	209	set_cyc2ns_scale(cpu_khz);
6f84fa2f	210	use_tsc_delay();
539eb11e JS	211	}
	212
	213	#ifdef CONFIG_CPU_FREQ
	214
	215	static unsigned int cpufreq_delayed_issched = 0;
	216	static unsigned int cpufreq_init = 0;
	217	static struct work_struct cpufreq_delayed_get_work;
	218
	219	static void handle_cpufreq_delayed_get(void *v)
	220	{
	221	unsigned int cpu;
	222
	223	for_each_online_cpu(cpu)
	224	cpufreq_get(cpu);
	225
	226	cpufreq_delayed_issched = 0;
	227	}
	228
	229	/*
	230	* if we notice cpufreq oddness, schedule a call to cpufreq_get() as it tries
	231	* to verify the CPU frequency the timing core thinks the CPU is running
	232	* at is still correct.
	233	*/
	234	static inline void cpufreq_delayed_get(void)
	235	{
	236	if (cpufreq_init && !cpufreq_delayed_issched) {
	237	cpufreq_delayed_issched = 1;
	238	printk(KERN_DEBUG "Checking if CPU frequency changed.\n");
	239	schedule_work(&cpufreq_delayed_get_work);
	240	}
	241	}
	242
	243	/*
	244	* if the CPU frequency is scaled, TSC-based delays will need a different
	245	* loops_per_jiffy value to function properly.
	246	*/
	247	static unsigned int ref_freq = 0;
	248	static unsigned long loops_per_jiffy_ref = 0;
	249	static unsigned long cpu_khz_ref = 0;
	250
	251	static int
	252	time_cpufreq_notifier(struct notifier_block nb, unsigned long val, void data)
	253	{
	254	struct cpufreq_freqs *freq = data;
	255
	256	if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
	257	write_seqlock_irq(&xtime_lock);
	258
	259	if (!ref_freq) {
	260	if (!freq->old){
	261	ref_freq = freq->new;
	262	goto end;
	263	}
	264	ref_freq = freq->old;
	265	loops_per_jiffy_ref = cpu_data[freq->cpu].loops_per_jiffy;
	266	cpu_khz_ref = cpu_khz;
	267	}
	268
	269	if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) \|\|
	270	(val == CPUFREQ_POSTCHANGE && freq->old > freq->new) \|\|
	271	(val == CPUFREQ_RESUMECHANGE)) {
	272	if (!(freq->flags & CPUFREQ_CONST_LOOPS))
	273	cpu_data[freq->cpu].loops_per_jiffy =
	274	cpufreq_scale(loops_per_jiffy_ref,
275	ref_freq, freq->new);
276
277	if (cpu_khz) {
278
279	if (num_online_cpus() == 1)
280	cpu_khz = cpufreq_scale(cpu_khz_ref,
281	ref_freq, freq->new);
282	if (!(freq->flags & CPUFREQ_CONST_LOOPS)) {
283	tsc_khz = cpu_khz;
284	set_cyc2ns_scale(cpu_khz);
285	/*
286	* TSC based sched_clock turns
287	* to junk w/ cpufreq
288	*/
289	mark_tsc_unstable();
290	}
291	}
292	}
293	end:
294	if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
295	write_sequnlock_irq(&xtime_lock);
296
297	return 0;
298	}
299
300	static struct notifier_block time_cpufreq_notifier_block = {
301	.notifier_call = time_cpufreq_notifier
302	};
303
304	static int __init cpufreq_tsc(void)
305	{
306	int ret;
307
308	INIT_WORK(&cpufreq_delayed_get_work, handle_cpufreq_delayed_get, NULL);
309	ret = cpufreq_register_notifier(&time_cpufreq_notifier_block,
310	CPUFREQ_TRANSITION_NOTIFIER);
311	if (!ret)
312	cpufreq_init = 1;
313
314	return ret;
315	}
316
317	core_initcall(cpufreq_tsc);
318
319	#endif
5d0cf410 JS	320
	321	/* clock source code */
	322
	323	static unsigned long current_tsc_khz = 0;
	324	static int tsc_update_callback(void);
	325
	326	static cycle_t read_tsc(void)
	327	{
	328	cycle_t ret;
	329
	330	rdtscll(ret);
	331
	332	return ret;
	333	}
	334
	335	static struct clocksource clocksource_tsc = {
	336	.name = "tsc",
	337	.rating = 300,
	338	.read = read_tsc,
7f9f303a	339	.mask = CLOCKSOURCE_MASK(64),
5d0cf410 JS	340	.mult = 0, /* to be set */
	341	.shift = 22,
	342	.update_callback = tsc_update_callback,
	343	.is_continuous = 1,
	344	};
	345
	346	static int tsc_update_callback(void)
	347	{
	348	int change = 0;
	349
	350	/* check to see if we should switch to the safe clocksource: */
3f4a0b91 JS	351	if (clocksource_tsc.rating != 0 && check_tsc_unstable()) {
3f4a0b91 JS	352	clocksource_tsc.rating = 0;
a2752549	353	clocksource_reselect();
5d0cf410 JS	354	change = 1;
	355	}
	356
	357	/* only update if tsc_khz has changed: */
	358	if (current_tsc_khz != tsc_khz) {
	359	current_tsc_khz = tsc_khz;
	360	clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
	361	clocksource_tsc.shift);
	362	change = 1;
	363	}
	364
	365	return change;
	366	}
	367
	368	static int __init dmi_mark_tsc_unstable(struct dmi_system_id *d)
	369	{
	370	printk(KERN_NOTICE "%s detected: marking TSC unstable.\n",
	371	d->ident);
	372	mark_tsc_unstable();
	373	return 0;
	374	}
	375
	376	/* List of systems that have known TSC problems */
	377	static struct dmi_system_id __initdata bad_tsc_dmi_table[] = {
	378	{
	379	.callback = dmi_mark_tsc_unstable,
	380	.ident = "IBM Thinkpad 380XD",
	381	.matches = {
	382	DMI_MATCH(DMI_BOARD_VENDOR, "IBM"),
	383	DMI_MATCH(DMI_BOARD_NAME, "2635FA0"),
	384	},
	385	},
	386	{}
	387	};
	388
	389	#define TSC_FREQ_CHECK_INTERVAL (10MSEC_PER_SEC) / 10sec in MS */
	390	static struct timer_list verify_tsc_freq_timer;
	391
	392	/* XXX - Probably should add locking */
	393	static void verify_tsc_freq(unsigned long unused)
	394	{
	395	static u64 last_tsc;
	396	static unsigned long last_jiffies;
	397
	398	u64 now_tsc, interval_tsc;
	399	unsigned long now_jiffies, interval_jiffies;
	400
	401
	402	if (check_tsc_unstable())
	403	return;
	404
	405	rdtscll(now_tsc);
	406	now_jiffies = jiffies;
	407
	408	if (!last_jiffies) {
	409	goto out;
	410	}
	411
	412	interval_jiffies = now_jiffies - last_jiffies;
	413	interval_tsc = now_tsc - last_tsc;
	414	interval_tsc *= HZ;
	415	do_div(interval_tsc, cpu_khz*1000);
	416
	417	if (interval_tsc < (interval_jiffies * 3 / 4)) {
418	printk("TSC appears to be running slowly. "
419	"Marking it as unstable\n");
420	mark_tsc_unstable();
421	return;
422	}
423
424	out:
425	last_tsc = now_tsc;
426	last_jiffies = now_jiffies;
427	/* set us up to go off on the next interval: */
428	mod_timer(&verify_tsc_freq_timer,
429	jiffies + msecs_to_jiffies(TSC_FREQ_CHECK_INTERVAL));
430	}
431
432	/*
433	* Make an educated guess if the TSC is trustworthy and synchronized
434	* over all CPUs.
435	*/
436	static __init int unsynchronized_tsc(void)
437	{
438	/*
439	* Intel systems are normally all synchronized.
440	* Exceptions must mark TSC as unstable:
441	*/
442	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
443	return 0;
444
445	/* assume multi socket systems are not synchronized: */
446	return num_possible_cpus() > 1;
447	}
448
449	static int __init init_tsc_clocksource(void)
450	{
451
452	if (cpu_has_tsc && tsc_khz && !tsc_disable) {
453	/* check blacklist */
454	dmi_check_system(bad_tsc_dmi_table);
455
456	if (unsynchronized_tsc()) /* mark unstable if unsynced */
457	mark_tsc_unstable();
458	current_tsc_khz = tsc_khz;
459	clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
460	clocksource_tsc.shift);
461	/* lower the rating if we already know its unstable: */
462	if (check_tsc_unstable())
3f4a0b91	463	clocksource_tsc.rating = 0;
5d0cf410 JS	464
	465	init_timer(&verify_tsc_freq_timer);
	466	verify_tsc_freq_timer.function = verify_tsc_freq;
	467	verify_tsc_freq_timer.expires =
	468	jiffies + msecs_to_jiffies(TSC_FREQ_CHECK_INTERVAL);
	469	add_timer(&verify_tsc_freq_timer);
	470
a2752549	471	return clocksource_register(&clocksource_tsc);
5d0cf410 JS	472	}
	473
	474	return 0;
	475	}
	476
	477	module_init(init_tsc_clocksource);