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[tomato.git] / release / src-rt-6.x / linux / linux-2.6 / arch / x86_64 / kernel / hpet.c

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/mc146818rtc.h>
#include <linux/time.h>
#include <linux/clocksource.h>
#include <linux/ioport.h>
#include <linux/acpi.h>
#include <linux/hpet.h>
#include <asm/pgtable.h>
#include <asm/vsyscall.h>
#include <asm/timex.h>
#include <asm/hpet.h>

#define HPET_MASK       0xFFFFFFFF
#define HPET_SHIFT      22

/* FSEC = 10^-15 NSEC = 10^-9 */
#define FSEC_PER_NSEC   1000000

int nohpet __initdata;

unsigned long hpet_address;
unsigned long hpet_period;      /* fsecs / HPET clock */
unsigned long hpet_tick;        /* HPET clocks / interrupt */

int hpet_use_timer;             /* Use counter of hpet for time keeping,
                                 * otherwise PIT
                                 */

#ifdef  CONFIG_HPET
static __init int late_hpet_init(void)
{
        struct hpet_data        hd;
        unsigned int            ntimer;

        if (!hpet_address)
                return 0;

        memset(&hd, 0, sizeof(hd));

        ntimer = hpet_readl(HPET_ID);
        ntimer = (ntimer & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT;
        ntimer++;

        /*
         * Register with driver.
         * Timer0 and Timer1 is used by platform.
         */
        hd.hd_phys_address = hpet_address;
        hd.hd_address = (void __iomem *)fix_to_virt(FIX_HPET_BASE);
        hd.hd_nirqs = ntimer;
        hd.hd_flags = HPET_DATA_PLATFORM;
        hpet_reserve_timer(&hd, 0);
#ifdef  CONFIG_HPET_EMULATE_RTC
        hpet_reserve_timer(&hd, 1);
#endif
        hd.hd_irq[0] = HPET_LEGACY_8254;
        hd.hd_irq[1] = HPET_LEGACY_RTC;
        if (ntimer > 2) {
                struct hpet             *hpet;
                struct hpet_timer       *timer;
                int                     i;

                hpet = (struct hpet *) fix_to_virt(FIX_HPET_BASE);
                timer = &hpet->hpet_timers[2];
                for (i = 2; i < ntimer; timer++, i++)
                        hd.hd_irq[i] = (timer->hpet_config &
                                        Tn_INT_ROUTE_CNF_MASK) >>
                                Tn_INT_ROUTE_CNF_SHIFT;

        }

        hpet_alloc(&hd);
        return 0;
}
fs_initcall(late_hpet_init);
#endif

int hpet_timer_stop_set_go(unsigned long tick)
{
        unsigned int cfg;

/*
 * Stop the timers and reset the main counter.
 */

        cfg = hpet_readl(HPET_CFG);
        cfg &= ~(HPET_CFG_ENABLE | HPET_CFG_LEGACY);
        hpet_writel(cfg, HPET_CFG);
        hpet_writel(0, HPET_COUNTER);
        hpet_writel(0, HPET_COUNTER + 4);

/*
 * Set up timer 0, as periodic with first interrupt to happen at hpet_tick,
 * and period also hpet_tick.
 */
        if (hpet_use_timer) {
                hpet_writel(HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL |
                    HPET_TN_32BIT, HPET_T0_CFG);
                hpet_writel(hpet_tick, HPET_T0_CMP); /* next interrupt */
                hpet_writel(hpet_tick, HPET_T0_CMP); /* period */
                cfg |= HPET_CFG_LEGACY;
        }
/*
 * Go!
 */

        cfg |= HPET_CFG_ENABLE;
        hpet_writel(cfg, HPET_CFG);

        return 0;
}

static cycle_t read_hpet(void)
{
        return (cycle_t)hpet_readl(HPET_COUNTER);
}

static cycle_t __vsyscall_fn vread_hpet(void)
{
        return readl((void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
}

struct clocksource clocksource_hpet = {
        .name           = "hpet",
        .rating         = 250,
        .read           = read_hpet,
        .mask           = (cycle_t)HPET_MASK,
        .mult           = 0, /* set below */
        .shift          = HPET_SHIFT,
        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
        .vread          = vread_hpet,
};

int hpet_arch_init(void)
{
        unsigned int id;
        u64 tmp;

        if (!hpet_address)
                return -1;
        set_fixmap_nocache(FIX_HPET_BASE, hpet_address);
        __set_fixmap(VSYSCALL_HPET, hpet_address, PAGE_KERNEL_VSYSCALL_NOCACHE);

/*
 * Read the period, compute tick and quotient.
 */

        id = hpet_readl(HPET_ID);

        if (!(id & HPET_ID_VENDOR) || !(id & HPET_ID_NUMBER))
                return -1;

        hpet_period = hpet_readl(HPET_PERIOD);
        if (hpet_period < 100000 || hpet_period > 100000000)
                return -1;

        hpet_tick = (FSEC_PER_TICK + hpet_period / 2) / hpet_period;

        hpet_use_timer = (id & HPET_ID_LEGSUP);

        /*
         * hpet period is in femto seconds per cycle
         * so we need to convert this to ns/cyc units
         * aproximated by mult/2^shift
         *
         *  fsec/cyc * 1nsec/1000000fsec = nsec/cyc = mult/2^shift
         *  fsec/cyc * 1ns/1000000fsec * 2^shift = mult
         *  fsec/cyc * 2^shift * 1nsec/1000000fsec = mult
         *  (fsec/cyc << shift)/1000000 = mult
         *  (hpet_period << shift)/FSEC_PER_NSEC = mult
         */
        tmp = (u64)hpet_period << HPET_SHIFT;
        do_div(tmp, FSEC_PER_NSEC);
        clocksource_hpet.mult = (u32)tmp;
        clocksource_register(&clocksource_hpet);

        return hpet_timer_stop_set_go(hpet_tick);
}

int hpet_reenable(void)
{
        return hpet_timer_stop_set_go(hpet_tick);
}

/*
 * calibrate_tsc() calibrates the processor TSC in a very simple way, comparing
 * it to the HPET timer of known frequency.
 */

#define TICK_COUNT 100000000
#define TICK_MIN   5000
#define MAX_TRIES  5

/*
 * Some platforms take periodic SMI interrupts with 5ms duration. Make sure none
 * occurs between the reads of the hpet & TSC.
 */
static void __init read_hpet_tsc(int *hpet, int *tsc)
{
        int tsc1, tsc2, hpet1, i;

        for (i = 0; i < MAX_TRIES; i++) {
                tsc1 = get_cycles_sync();
                hpet1 = hpet_readl(HPET_COUNTER);
                tsc2 = get_cycles_sync();
                if (tsc2 - tsc1 > TICK_MIN)
                        break;
        }
        *hpet = hpet1;
        *tsc = tsc2;
}

unsigned int __init hpet_calibrate_tsc(void)
{
        int tsc_start, hpet_start;
        int tsc_now, hpet_now;
        unsigned long flags;

        local_irq_save(flags);

        read_hpet_tsc(&hpet_start, &tsc_start);

        do {
                local_irq_disable();
                read_hpet_tsc(&hpet_now, &tsc_now);
                local_irq_restore(flags);
        } while ((tsc_now - tsc_start) < TICK_COUNT &&
                (hpet_now - hpet_start) < TICK_COUNT);

        return (tsc_now - tsc_start) * 1000000000L
                / ((hpet_now - hpet_start) * hpet_period / 1000);
}

#ifdef CONFIG_HPET_EMULATE_RTC
/* HPET in LegacyReplacement Mode eats up RTC interrupt line. When, HPET
 * is enabled, we support RTC interrupt functionality in software.
 * RTC has 3 kinds of interrupts:
 * 1) Update Interrupt - generate an interrupt, every sec, when RTC clock
 *    is updated
 * 2) Alarm Interrupt - generate an interrupt at a specific time of day
 * 3) Periodic Interrupt - generate periodic interrupt, with frequencies
 *    2Hz-8192Hz (2Hz-64Hz for non-root user) (all freqs in powers of 2)
 * (1) and (2) above are implemented using polling at a frequency of
 * 64 Hz. The exact frequency is a tradeoff between accuracy and interrupt
 * overhead. (DEFAULT_RTC_INT_FREQ)
 * For (3), we use interrupts at 64Hz or user specified periodic
 * frequency, whichever is higher.
 */
#include <linux/rtc.h>

#define DEFAULT_RTC_INT_FREQ    64
#define RTC_NUM_INTS            1

static unsigned long UIE_on;
static unsigned long prev_update_sec;

static unsigned long AIE_on;
static struct rtc_time alarm_time;

static unsigned long PIE_on;
static unsigned long PIE_freq = DEFAULT_RTC_INT_FREQ;
static unsigned long PIE_count;

static unsigned long hpet_rtc_int_freq; /* RTC interrupt frequency */
static unsigned int hpet_t1_cmp; /* cached comparator register */

int is_hpet_enabled(void)
{
        return hpet_address != 0;
}

/*
 * Timer 1 for RTC, we do not use periodic interrupt feature,
 * even if HPET supports periodic interrupts on Timer 1.
 * The reason being, to set up a periodic interrupt in HPET, we need to
 * stop the main counter. And if we do that everytime someone diables/enables
 * RTC, we will have adverse effect on main kernel timer running on Timer 0.
 * So, for the time being, simulate the periodic interrupt in software.
 *
 * hpet_rtc_timer_init() is called for the first time and during subsequent
 * interuppts reinit happens through hpet_rtc_timer_reinit().
 */
int hpet_rtc_timer_init(void)
{
        unsigned int cfg, cnt;
        unsigned long flags;

        if (!is_hpet_enabled())
                return 0;
        /*
         * Set the counter 1 and enable the interrupts.
         */
        if (PIE_on && (PIE_freq > DEFAULT_RTC_INT_FREQ))
                hpet_rtc_int_freq = PIE_freq;
        else
                hpet_rtc_int_freq = DEFAULT_RTC_INT_FREQ;

        local_irq_save(flags);

        cnt = hpet_readl(HPET_COUNTER);
        cnt += ((hpet_tick*HZ)/hpet_rtc_int_freq);
        hpet_writel(cnt, HPET_T1_CMP);
        hpet_t1_cmp = cnt;

        cfg = hpet_readl(HPET_T1_CFG);
        cfg &= ~HPET_TN_PERIODIC;
        cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
        hpet_writel(cfg, HPET_T1_CFG);

        local_irq_restore(flags);

        return 1;
}

static void hpet_rtc_timer_reinit(void)
{
        unsigned int cfg, cnt, ticks_per_int, lost_ints;

        if (unlikely(!(PIE_on | AIE_on | UIE_on))) {
                cfg = hpet_readl(HPET_T1_CFG);
                cfg &= ~HPET_TN_ENABLE;
                hpet_writel(cfg, HPET_T1_CFG);
                return;
        }

        if (PIE_on && (PIE_freq > DEFAULT_RTC_INT_FREQ))
                hpet_rtc_int_freq = PIE_freq;
        else
                hpet_rtc_int_freq = DEFAULT_RTC_INT_FREQ;

        /* It is more accurate to use the comparator value than current count.*/
        ticks_per_int = hpet_tick * HZ / hpet_rtc_int_freq;
        hpet_t1_cmp += ticks_per_int;
        hpet_writel(hpet_t1_cmp, HPET_T1_CMP);

        /*
         * If the interrupt handler was delayed too long, the write above tries
         * to schedule the next interrupt in the past and the hardware would
         * not interrupt until the counter had wrapped around.
         * So we have to check that the comparator wasn't set to a past time.
         */
        cnt = hpet_readl(HPET_COUNTER);
        if (unlikely((int)(cnt - hpet_t1_cmp) > 0)) {
                lost_ints = (cnt - hpet_t1_cmp) / ticks_per_int + 1;
                /* Make sure that, even with the time needed to execute
                 * this code, the next scheduled interrupt has been moved
                 * back to the future: */
                lost_ints++;

                hpet_t1_cmp += lost_ints * ticks_per_int;
                hpet_writel(hpet_t1_cmp, HPET_T1_CMP);

                if (PIE_on)
                        PIE_count += lost_ints;

                if (printk_ratelimit())
                        printk(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n",
                               hpet_rtc_int_freq);
        }
}

/*
 * The functions below are called from rtc driver.
 * Return 0 if HPET is not being used.
 * Otherwise do the necessary changes and return 1.
 */
int hpet_mask_rtc_irq_bit(unsigned long bit_mask)
{
        if (!is_hpet_enabled())
                return 0;

        if (bit_mask & RTC_UIE)
                UIE_on = 0;
        if (bit_mask & RTC_PIE)
                PIE_on = 0;
        if (bit_mask & RTC_AIE)
                AIE_on = 0;

        return 1;
}

int hpet_set_rtc_irq_bit(unsigned long bit_mask)
{
        int timer_init_reqd = 0;

        if (!is_hpet_enabled())
                return 0;

        if (!(PIE_on | AIE_on | UIE_on))
                timer_init_reqd = 1;

        if (bit_mask & RTC_UIE) {
                UIE_on = 1;
        }
        if (bit_mask & RTC_PIE) {
                PIE_on = 1;
                PIE_count = 0;
        }
        if (bit_mask & RTC_AIE) {
                AIE_on = 1;
        }

        if (timer_init_reqd)
                hpet_rtc_timer_init();

        return 1;
}

int hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
{
        if (!is_hpet_enabled())
                return 0;

        alarm_time.tm_hour = hrs;
        alarm_time.tm_min = min;
        alarm_time.tm_sec = sec;

        return 1;
}

int hpet_set_periodic_freq(unsigned long freq)
{
        if (!is_hpet_enabled())
                return 0;

        PIE_freq = freq;
        PIE_count = 0;

        return 1;
}

int hpet_rtc_dropped_irq(void)
{
        if (!is_hpet_enabled())
                return 0;

        return 1;
}

irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
        struct rtc_time curr_time;
        unsigned long rtc_int_flag = 0;
        int call_rtc_interrupt = 0;

        hpet_rtc_timer_reinit();

        if (UIE_on | AIE_on) {
                rtc_get_rtc_time(&curr_time);
        }
        if (UIE_on) {
                if (curr_time.tm_sec != prev_update_sec) {
                        /* Set update int info, call real rtc int routine */
                        call_rtc_interrupt = 1;
                        rtc_int_flag = RTC_UF;
                        prev_update_sec = curr_time.tm_sec;
                }
        }
        if (PIE_on) {
                PIE_count++;
                if (PIE_count >= hpet_rtc_int_freq/PIE_freq) {
                        /* Set periodic int info, call real rtc int routine */
                        call_rtc_interrupt = 1;
                        rtc_int_flag |= RTC_PF;
                        PIE_count = 0;
                }
        }
        if (AIE_on) {
                if ((curr_time.tm_sec == alarm_time.tm_sec) &&
                    (curr_time.tm_min == alarm_time.tm_min) &&
                    (curr_time.tm_hour == alarm_time.tm_hour)) {
                        /* Set alarm int info, call real rtc int routine */
                        call_rtc_interrupt = 1;
                        rtc_int_flag |= RTC_AF;
                }
        }
        if (call_rtc_interrupt) {
                rtc_int_flag |= (RTC_IRQF | (RTC_NUM_INTS << 8));
                rtc_interrupt(rtc_int_flag, dev_id);
        }
        return IRQ_HANDLED;
}
#endif

static int __init nohpet_setup(char *s)
{
        nohpet = 1;
        return 1;
}

__setup("nohpet", nohpet_setup);