x86_64: prepare shared kernel/hpet.c
authorThomas Gleixner <tglx@linutronix.de>
Thu, 11 Oct 2007 09:14:26 +0000 (11:14 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Thu, 11 Oct 2007 09:14:26 +0000 (11:14 +0200)
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86_64/kernel/Makefile
arch/x86_64/kernel/hpet.c [deleted file]
arch/x86_64/kernel/hpet_64.c [new file with mode: 0644]

index fbaba5335b66c2b9f269054202c7d72c882ae03d..e717a324bd8a1687915efe4cc040e6fe9b8aa637 100644 (file)
@@ -8,7 +8,7 @@ obj-y   := process.o signal.o entry.o traps_64.o irq.o \
                ptrace.o time.o ioport.o ldt.o setup.o i8259_64.o sys_x86_64.o \
                x8664_ksyms.o i387.o syscall.o vsyscall.o \
                setup64.o bootflag.o e820.o reboot.o quirks.o i8237.o \
-               pci-dma_64.o pci-nommu.o alternative.o hpet.o tsc.o bugs.o \
+               pci-dma_64.o pci-nommu.o alternative.o hpet_64.o tsc.o bugs.o \
                perfctr-watchdog.o
 
 obj-$(CONFIG_STACKTRACE)       += stacktrace.o
diff --git a/arch/x86_64/kernel/hpet.c b/arch/x86_64/kernel/hpet.c
deleted file mode 100644 (file)
index e2d1b91..0000000
+++ /dev/null
@@ -1,493 +0,0 @@
-#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 __init 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 SMI_THRESHOLD 50000
-#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) < SMI_THRESHOLD)
-                       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 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);
diff --git a/arch/x86_64/kernel/hpet_64.c b/arch/x86_64/kernel/hpet_64.c
new file mode 100644 (file)
index 0000000..e2d1b91
--- /dev/null
@@ -0,0 +1,493 @@
+#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 __init 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 SMI_THRESHOLD 50000
+#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) < SMI_THRESHOLD)
+                       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 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);