Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

#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 = (u64)ULLONG_MAX;

        int i;

        unsigned long flags;

        local_irq_save(flags);

        /* run 3 times to ensure the cache is warm and to get an accurate reading */

        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)

                        continue;

                /* cpu freq too slow: */

                if ((end - start) <= CALIBRATE_TIME_MSEC)

                        continue;

                /*

                 * We want the minimum time of all runs in case one of them

                 * is inaccurate due to SMI or other delay

                 */

                delta64 = min(delta64, (end - start));

        }

        /* cpu freq too fast (or every run was bad): */

        if (delta64 > (1ULL<<32))

                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;

}