| #include <linux/sched.h> |
| #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 <asm/timer.h> |
| |
| #include "mach_timer.h" |
| |
| static int tsc_enabled; |
| |
| /* |
| * 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; |
| EXPORT_SYMBOL_GPL(tsc_khz); |
| |
| int tsc_disable; |
| |
| #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; |
| |
| int check_tsc_unstable(void) |
| { |
| return tsc_unstable; |
| } |
| EXPORT_SYMBOL_GPL(check_tsc_unstable); |
| |
| /* Accelerators 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 precision, 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!" |
| */ |
| 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; |
| } |
| |
| /* |
| * Scheduler clock - returns current time in nanosec units. |
| */ |
| unsigned long long native_sched_clock(void) |
| { |
| unsigned long long this_offset; |
| |
| /* |
| * Fall back to jiffies if there's no TSC available: |
| * ( But note that we still use it if the TSC is marked |
| * unstable. We do this because unlike Time Of Day, |
| * the scheduler clock tolerates small errors and it's |
| * very important for it to be as fast as the platform |
| * can achive it. ) |
| */ |
| if (unlikely(!tsc_enabled && !tsc_unstable)) |
| /* 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); |
| } |
| |
| /* We need to define a real function for sched_clock, to override the |
| weak default version */ |
| #ifdef CONFIG_PARAVIRT |
| unsigned long long sched_clock(void) |
| { |
| return paravirt_sched_clock(); |
| } |
| #else |
| unsigned long long sched_clock(void) |
| __attribute__((alias("native_sched_clock"))); |
| #endif |
| |
| unsigned long native_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); |
| |
| #ifdef CONFIG_CPU_FREQ |
| |
| /* |
| * 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 (!ref_freq) { |
| if (!freq->old){ |
| ref_freq = freq->new; |
| return 0; |
| } |
| 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("cpufreq changes"); |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| static struct notifier_block time_cpufreq_notifier_block = { |
| .notifier_call = time_cpufreq_notifier |
| }; |
| |
| static int __init cpufreq_tsc(void) |
| { |
| return cpufreq_register_notifier(&time_cpufreq_notifier_block, |
| CPUFREQ_TRANSITION_NOTIFIER); |
| } |
| core_initcall(cpufreq_tsc); |
| |
| #endif |
| |
| /* clock source code */ |
| |
| static unsigned long current_tsc_khz = 0; |
| |
| 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, |
| .flags = CLOCK_SOURCE_IS_CONTINUOUS | |
| CLOCK_SOURCE_MUST_VERIFY, |
| }; |
| |
| void mark_tsc_unstable(char *reason) |
| { |
| if (!tsc_unstable) { |
| tsc_unstable = 1; |
| tsc_enabled = 0; |
| printk("Marking TSC unstable due to: %s.\n", reason); |
| /* Can be called before registration */ |
| if (clocksource_tsc.mult) |
| clocksource_change_rating(&clocksource_tsc, 0); |
| else |
| clocksource_tsc.rating = 0; |
| } |
| } |
| EXPORT_SYMBOL_GPL(mark_tsc_unstable); |
| |
| static int __init dmi_mark_tsc_unstable(const struct dmi_system_id *d) |
| { |
| printk(KERN_NOTICE "%s detected: marking TSC unstable.\n", |
| d->ident); |
| tsc_unstable = 1; |
| 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"), |
| }, |
| }, |
| {} |
| }; |
| |
| /* |
| * Make an educated guess if the TSC is trustworthy and synchronized |
| * over all CPUs. |
| */ |
| __cpuinit int unsynchronized_tsc(void) |
| { |
| if (!cpu_has_tsc || tsc_unstable) |
| return 1; |
| /* |
| * Intel systems are normally all synchronized. |
| * Exceptions must mark TSC as unstable: |
| */ |
| if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { |
| /* assume multi socket systems are not synchronized: */ |
| if (num_possible_cpus() > 1) |
| tsc_unstable = 1; |
| } |
| return tsc_unstable; |
| } |
| |
| /* |
| * Geode_LX - the OLPC CPU has a possibly a very reliable TSC |
| */ |
| #ifdef CONFIG_MGEODE_LX |
| /* RTSC counts during suspend */ |
| #define RTSC_SUSP 0x100 |
| |
| static void __init check_geode_tsc_reliable(void) |
| { |
| unsigned long res_low, res_high; |
| |
| rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high); |
| if (res_low & RTSC_SUSP) |
| clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY; |
| } |
| #else |
| static inline void check_geode_tsc_reliable(void) { } |
| #endif |
| |
| |
| void __init tsc_init(void) |
| { |
| if (!cpu_has_tsc || tsc_disable) |
| goto out_no_tsc; |
| |
| cpu_khz = calculate_cpu_khz(); |
| tsc_khz = cpu_khz; |
| |
| if (!cpu_khz) |
| goto out_no_tsc; |
| |
| 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(); |
| |
| /* Check and install the TSC clocksource */ |
| dmi_check_system(bad_tsc_dmi_table); |
| |
| unsynchronized_tsc(); |
| check_geode_tsc_reliable(); |
| 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; |
| clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS; |
| } else |
| tsc_enabled = 1; |
| |
| clocksource_register(&clocksource_tsc); |
| |
| return; |
| |
| out_no_tsc: |
| /* |
| * Set the tsc_disable flag if there's no TSC support, this |
| * makes it a fast flag for the kernel to see whether it |
| * should be using the TSC. |
| */ |
| tsc_disable = 1; |
| } |