| /* |
| * 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/delay.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 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 = (cycle_t)-1, |
| .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 != 50 && check_tsc_unstable()) { |
| clocksource_tsc.rating = 50; |
| reselect_clocksource(); |
| 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 = 50; |
| |
| 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 register_clocksource(&clocksource_tsc); |
| } |
| |
| return 0; |
| } |
| |
| module_init(init_tsc_clocksource); |