[PATCH 12/13] Time: i386/x86-64 Clocksource Drivers

john stultz
2005-11-12T04:51:01Z

All,

This patch implements the time sources shared between i386 and x86-64
(acpi_pm, cyclone, hpet, pit, tsc and tsc-interp). The patch should
apply on top of the timeofday-arch-i386-part4 patch as well as the
arch-x86-64 patch

The patch should be fairly straight forward, only adding the new
clocksources.

thanks
-john

Signed-off-by: John Stultz <johnstul@us.ibm.com>

arch/i386/kernel/Makefile | 1
arch/i386/kernel/hpet.c | 66 ++++++++++++++++
arch/i386/kernel/i8253.c | 55 ++++++++++++++
arch/i386/kernel/tsc.c | 75 +++++++++++++++++++
drivers/Makefile | 1
drivers/clocksource/Makefile | 3
drivers/clocksource/acpi_pm.c | 152 +++++++++++++++++++++++++++++++++++++++
drivers/clocksource/cyclone.c | 144 ++++++++++++++++++++++++++++++++++++
drivers/clocksource/tsc-interp.c | 112 ++++++++++++++++++++++++++++
9 files changed, 609 insertions(+)

linux-2.6.14_timeofday-clocks-i386_B10.patch
============================================
diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
index 5d1d9c9..984d488 100644
--- a/arch/i386/kernel/Makefile
+++ b/arch/i386/kernel/Makefile
@@ -33,6 +33,7 @@ obj-$(CONFIG_ACPI_SRAT) += srat.o
obj-$(CONFIG_HPET_TIMER) += time_hpet.o
obj-$(CONFIG_EFI) += efi.o efi_stub.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
+obj-$(CONFIG_HPET_TIMER) += hpet.o

EXTRA_AFLAGS := -traditional

diff --git a/arch/i386/kernel/hpet.c b/arch/i386/kernel/hpet.c
new file mode 100644
index 0000000..67ebcf8
--- /dev/null
+++ b/arch/i386/kernel/hpet.c
@@ -0,0 +1,66 @@
+#include <linux/clocksource.h>
+#include <linux/hpet.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <asm/io.h>
+#include <asm/hpet.h>
+
+#define HPET_MASK (0xFFFFFFFF)
+#define HPET_SHIFT 22
+
+/* FSEC = 10^-15 NSEC = 10^-9 */
+#define FSEC_PER_NSEC 1000000
+
+static void *hpet_ptr;
+
+static cycle_t read_hpet(void)
+{
+ return (cycle_t)readl(hpet_ptr);
+}
+
+struct clocksource clocksource_hpet = {
+ .name = "hpet",
+ .rating = 250,
+ .read = read_hpet,
+ .mask = (cycle_t)HPET_MASK,
+ .mult = 0, /* set below */
+ .shift = HPET_SHIFT,
+ .is_continuous = 1,
+};
+
+static int __init init_hpet_clocksource(void)
+{
+ unsigned long hpet_period;
+ void __iomem* hpet_base;
+ u64 tmp;
+
+ if (!hpet_address)
+ return -ENODEV;
+
+ /* calculate the hpet address */
+ hpet_base =
+ (void __iomem*)ioremap_nocache(hpet_address, HPET_MMAP_SIZE);
+ hpet_ptr = hpet_base + HPET_COUNTER;
+
+ /* calculate the frequency */
+ hpet_period = readl(hpet_base + HPET_PERIOD);
+
+
+ /* 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;
+
+ register_clocksource(&clocksource_hpet);
+ return 0;
+}
+module_init(init_hpet_clocksource);
diff --git a/arch/i386/kernel/i8253.c b/arch/i386/kernel/i8253.c
index e11928d..320968e 100644
--- a/arch/i386/kernel/i8253.c
+++ b/arch/i386/kernel/i8253.c
@@ -6,6 +6,7 @@
#include <linux/jiffies.h>
#include <linux/spinlock.h>
#include <linux/sysdev.h>
+#include <linux/clocksource.h>
#include <linux/module.h>

#include <asm/delay.h>
@@ -55,3 +56,57 @@ static int __init init_timer_sysfs(void)
}

device_initcall(init_timer_sysfs);
+
+
+/* Since the PIT overflows every tick, its not very useful
+ * to just read by itself. So use jiffies to emulate a free
+ * running counter.
+ */
+
+static cycle_t pit_read(void)
+{
+ unsigned long flags, seq;
+ int count;
+ u64 jifs;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+
+ spin_lock_irqsave(&i8253_lock, flags);
+
+ outb_p(0x00, PIT_MODE); /* latch the count ASAP */
+ count = inb_p(PIT_CH0); /* read the latched count */
+ count |= inb_p(PIT_CH0) << 8;
+
+ /* VIA686a test code... reset the latch if count > max + 1 */
+ if (count > LATCH) {
+ outb_p(0x34, PIT_MODE);
+ outb_p(LATCH & 0xff, PIT_CH0);
+ outb(LATCH >> 8, PIT_CH0);
+ count = LATCH - 1;
+ }
+ spin_unlock_irqrestore(&i8253_lock, flags);
+ jifs = get_jiffies_64() - INITIAL_JIFFIES;
+ } while (read_seqretry(&xtime_lock, seq));
+
+ count = (LATCH-1) - count;
+
+ return (cycle_t)(jifs * LATCH) + count;
+}
+
+static struct clocksource clocksource_pit = {
+ .name = "pit",
+ .rating = 110,
+ .read = pit_read,
+ .mask = (cycle_t)-1,
+ .mult = 0,
+ .shift = 20,
+};
+
+static int __init init_pit_clocksource(void)
+{
+ clocksource_pit.mult = clocksource_hz2mult(CLOCK_TICK_RATE, 20);
+ register_clocksource(&clocksource_pit);
+ return 0;
+}
+module_init(init_pit_clocksource);
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index 5608c21..3f9d1e8 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -306,3 +306,78 @@ static int __init cpufreq_tsc(void)
core_initcall(cpufreq_tsc);

#endif
+
+/* Clock source code */
+#include <linux/clocksource.h>
+
+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 cycle_t read_tsc_c3(void)
+{
+ cycle_t ret;
+ rdtscll(ret);
+ return ret + tsc_read_c3_time();
+}
+
+
+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 (tsc_read_c3_time() &&
+ strncmp(clocksource_tsc.name, "c3tsc", 5)) {
+ printk("Falling back to C3 safe TSC\n");
+ clocksource_tsc.read = read_tsc_c3;
+ clocksource_tsc.name = "c3tsc";
+ change = 1;
+ }
+
+ 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 init_tsc_clocksource(void)
+{
+
+ /* TSC initialization is done in arch/i386/kernel/tsc.c */
+ if (cpu_has_tsc && tsc_khz) {
+ current_tsc_khz = tsc_khz;
+ clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
+ clocksource_tsc.shift);
+ register_clocksource(&clocksource_tsc);
+ }
+ return 0;
+}
+
+module_init(init_tsc_clocksource);
+
diff --git a/drivers/Makefile b/drivers/Makefile
index fac1e16..b23511f 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -69,3 +69,4 @@ obj-$(CONFIG_SGI_IOC4) += sn/
obj-y += firmware/
obj-$(CONFIG_CRYPTO) += crypto/
obj-$(CONFIG_SUPERH) += sh/
+obj-$(CONFIG_GENERIC_TIME) += clocksource/
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
new file mode 100644
index 0000000..45f60ad
--- /dev/null
+++ b/drivers/clocksource/Makefile
@@ -0,0 +1,3 @@
+#XXX doesn't boot! obj-$(CONFIG_X86) += tsc-interp.o
+obj-$(CONFIG_X86_CYCLONE_TIMER) += cyclone.o
+obj-$(CONFIG_X86_PM_TIMER) += acpi_pm.o
diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c
new file mode 100644
index 0000000..2523c71
--- /dev/null
+++ b/drivers/clocksource/acpi_pm.c
@@ -0,0 +1,152 @@
+/*
+ * linux/drivers/clocksource/acpi_pm.c
+ *
+ * This file contains the ACPI PM based clocksource.
+ *
+ * This code was largely moved from the i386 timer_pm.c file
+ * which was (C) Dominik Brodowski <linux@brodo.de> 2003
+ * and contained the following comments:
+ *
+ * Driver to use the Power Management Timer (PMTMR) available in some
+ * southbridges as primary timing source for the Linux kernel.
+ *
+ * Based on parts of linux/drivers/acpi/hardware/hwtimer.c, timer_pit.c,
+ * timer_hpet.c, and on Arjan van de Ven's implementation for 2.4.
+ *
+ * This file is licensed under the GPL v2.
+ */
+
+
+#include <linux/clocksource.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <asm/io.h>
+
+/* Number of PMTMR ticks expected during calibration run */
+#define PMTMR_TICKS_PER_SEC 3579545
+
+#if (defined(CONFIG_X86) && (!defined(CONFIG_X86_64)))
+#include "mach_timer.h"
+#define PMTMR_EXPECTED_RATE ((PMTMR_TICKS_PER_SEC*CALIBRATE_TIME_MSEC)/1000)
+#endif
+
+/* The I/O port the PMTMR resides at.
+ * The location is detected during setup_arch(),
+ * in arch/i386/acpi/boot.c */
+extern u32 acpi_pmtmr_ioport;
+extern int acpi_pmtmr_buggy;
+
+#define ACPI_PM_MASK 0xFFFFFF /* limit it to 24 bits */
+
+
+static inline u32 read_pmtmr(void)
+{
+ /* mask the output to 24 bits */
+ return inl(acpi_pmtmr_ioport) & ACPI_PM_MASK;
+}
+
+static cycle_t acpi_pm_read_verified(void)
+{
+ u32 v1=0,v2=0,v3=0;
+ /* It has been reported that because of various broken
+ * chipsets (ICH4, PIIX4 and PIIX4E) where the ACPI PM clock
+ * source is not latched, so you must read it multiple
+ * times to insure a safe value is read.
+ */
+ do {
+ v1 = read_pmtmr();
+ v2 = read_pmtmr();
+ v3 = read_pmtmr();
+ } while ((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
+ || (v3 > v1 && v3 < v2));
+
+ return (cycle_t)v2;
+}
+
+
+static cycle_t acpi_pm_read(void)
+{
+ return (cycle_t)read_pmtmr();
+}
+
+struct clocksource clocksource_acpi_pm = {
+ .name = "acpi_pm",
+ .rating = 200,
+ .read = acpi_pm_read,
+ .mask = (cycle_t)ACPI_PM_MASK,
+ .mult = 0, /*to be caluclated*/
+ .shift = 22,
+ .is_continuous = 1,
+};
+
+#if (defined(CONFIG_X86) && (!defined(CONFIG_X86_64)))
+/*
+ * Some boards have the PMTMR running way too fast. We check
+ * the PMTMR rate against PIT channel 2 to catch these cases.
+ */
+static int __init verify_pmtmr_rate(void)
+{
+ u32 value1, value2;
+ unsigned long count, delta;
+
+ mach_prepare_counter();
+ value1 = read_pmtmr();
+ mach_countup(&count);
+ value2 = read_pmtmr();
+ delta = (value2 - value1) & ACPI_PM_MASK;
+
+ /* Check that the PMTMR delta is within 5% of what we expect */
+ if (delta < (PMTMR_EXPECTED_RATE * 19) / 20 ||
+ delta > (PMTMR_EXPECTED_RATE * 21) / 20) {
+ printk(KERN_INFO "PM-Timer running at invalid rate: %lu%% of normal - aborting.\n", 100UL * delta / PMTMR_EXPECTED_RATE);
+ return -1;
+ }
+
+ return 0;
+}
+#else
+#define verify_pmtmr_rate() (0)
+#endif
+
+static int __init init_acpi_pm_clocksource(void)
+{
+ u32 value1, value2;
+ unsigned int i;
+
+ if (!acpi_pmtmr_ioport)
+ return -ENODEV;
+
+ clocksource_acpi_pm.mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC,
+ clocksource_acpi_pm.shift);
+
+ /* "verify" this timing source */
+ value1 = read_pmtmr();
+ for (i = 0; i < 10000; i++) {
+ value2 = read_pmtmr();
+ if (value2 == value1)
+ continue;
+ if (value2 > value1)
+ goto pm_good;
+ if ((value2 < value1) && ((value2) < 0xFFF))
+ goto pm_good;
+ printk(KERN_INFO "PM-Timer had inconsistent results: 0x%#x, 0x%#x - aborting.\n", value1, value2);
+ return -EINVAL;
+ }
+ printk(KERN_INFO "PM-Timer had no reasonable result: 0x%#x - aborting.\n", value1);
+ return -ENODEV;
+
+pm_good:
+ if (verify_pmtmr_rate() != 0)
+ return -ENODEV;
+
+ /* check to see if pmtmr is known buggy */
+ if (acpi_pmtmr_buggy) {
+ clocksource_acpi_pm.read = acpi_pm_read_verified;
+ clocksource_acpi_pm.rating = 110;
+ }
+
+ register_clocksource(&clocksource_acpi_pm);
+ return 0;
+}
+
+module_init(init_acpi_pm_clocksource);
diff --git a/drivers/clocksource/cyclone.c b/drivers/clocksource/cyclone.c
new file mode 100644
index 0000000..5630195
--- /dev/null
+++ b/drivers/clocksource/cyclone.c
@@ -0,0 +1,144 @@
+#include <linux/clocksource.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/timex.h>
+#include <linux/init.h>
+
+#include <asm/io.h>
+#include <asm/pgtable.h>
+#include "mach_timer.h"
+
+#define CYCLONE_CBAR_ADDR 0xFEB00CD0 /* base address ptr*/
+#define CYCLONE_PMCC_OFFSET 0x51A0 /* offset to control register */
+#define CYCLONE_MPCS_OFFSET 0x51A8 /* offset to select register */
+#define CYCLONE_MPMC_OFFSET 0x51D0 /* offset to count register */
+#define CYCLONE_TIMER_FREQ 100000000
+#define CYCLONE_TIMER_MASK (0xFFFFFFFF) /* 32 bit mask */
+
+int use_cyclone = 0;
+static void __iomem *cyclone_ptr;
+
+static cycle_t read_cyclone(void)
+{
+ return (cycle_t)readl(cyclone_ptr);
+}
+
+struct clocksource clocksource_cyclone = {
+ .name = "cyclone",
+ .rating = 250,
+ .read = read_cyclone,
+ .mask = (cycle_t)CYCLONE_TIMER_MASK,
+ .mult = 10,
+ .shift = 0,
+ .is_continuous = 1,
+};
+
+static unsigned long __init calibrate_cyclone(void)
+{
+ u64 delta64;
+ unsigned long start, end;
+ unsigned long i, count;
+ unsigned long cyclone_freq_khz;
+
+ /* repeat 3 times to make sure the cache is warm */
+ for(i=0; i < 3; i++) {
+ mach_prepare_counter();
+ start = readl(cyclone_ptr);
+ mach_countup(&count);
+ end = readl(cyclone_ptr);
+ }
+
+ delta64 = end - start;
+
+ delta64 += CALIBRATE_TIME_MSEC/2; /* round for do_div */
+ do_div(delta64,CALIBRATE_TIME_MSEC);
+
+ cyclone_freq_khz = (unsigned long)delta64;
+
+ printk("calculated cyclone_freq: %lu khz\n", cyclone_freq_khz);
+ return cyclone_freq_khz;
+}
+
+static int __init init_cyclone_clocksource(void)
+{
+ unsigned long base; /* saved value from CBAR */
+ unsigned long offset;
+ u32 __iomem* reg;
+ u32 __iomem* volatile cyclone_timer; /* Cyclone MPMC0 register */
+ unsigned long khz;
+ int i;
+
+ /*make sure we're on a summit box*/
+ if (!use_cyclone) return -ENODEV;
+
+ printk(KERN_INFO "Summit chipset: Starting Cyclone Counter.\n");
+
+ /* find base address */
+ offset = CYCLONE_CBAR_ADDR;
+ reg = ioremap_nocache(offset, sizeof(reg));
+ if(!reg){
+ printk(KERN_ERR "Summit chipset: Could not find valid CBAR register.\n");
+ return -ENODEV;
+ }
+ /* even on 64bit systems, this is only 32bits */
+ base = readl(reg);
+ if(!base){
+ printk(KERN_ERR "Summit chipset: Could not find valid CBAR value.\n");
+ return -ENODEV;
+ }
+ iounmap(reg);
+
+ /* setup PMCC */
+ offset = base + CYCLONE_PMCC_OFFSET;
+ reg = ioremap_nocache(offset, sizeof(reg));
+ if(!reg){
+ printk(KERN_ERR "Summit chipset: Could not find valid PMCC register.\n");
+ return -ENODEV;
+ }
+ writel(0x00000001,reg);
+ iounmap(reg);
+
+ /* setup MPCS */
+ offset = base + CYCLONE_MPCS_OFFSET;
+ reg = ioremap_nocache(offset, sizeof(reg));
+ if(!reg){
+ printk(KERN_ERR "Summit chipset: Could not find valid MPCS register.\n");
+ return -ENODEV;
+ }
+ writel(0x00000001,reg);
+ iounmap(reg);
+
+ /* map in cyclone_timer */
+ offset = base + CYCLONE_MPMC_OFFSET;
+ cyclone_timer = ioremap_nocache(offset, sizeof(u64));
+ if(!cyclone_timer){
+ printk(KERN_ERR "Summit chipset: Could not find valid MPMC register.\n");
+ return -ENODEV;
+ }
+
+ /*quick test to make sure its ticking*/
+ for(i=0; i<3; i++){
+ u32 old = readl(cyclone_timer);
+ int stall = 100;
+ while(stall--) barrier();
+ if(readl(cyclone_timer) == old){
+ printk(KERN_ERR "Summit chipset: Counter not counting! DISABLED\n");
+ iounmap(cyclone_timer);
+ cyclone_timer = NULL;
+ return -ENODEV;
+ }
+ }
+ cyclone_ptr = cyclone_timer;
+
+ /* sort out mult/shift values */
+ khz = calibrate_cyclone();
+ clocksource_cyclone.shift = 22;
+ clocksource_cyclone.mult = clocksource_khz2mult(khz,
+ clocksource_cyclone.shift);
+
+ register_clocksource(&clocksource_cyclone);
+
+ return 0;
+}
+
+module_init(init_cyclone_clocksource);
diff --git a/drivers/clocksource/tsc-interp.c b/drivers/clocksource/tsc-interp.c
new file mode 100644
index 0000000..fee083e
--- /dev/null
+++ b/drivers/clocksource/tsc-interp.c
@@ -0,0 +1,112 @@
+/* TSC-Jiffies Interpolation clocksource
+ Example interpolation clocksource.
+TODO:
+ o per-cpu TSC offsets
+*/
+#include <linux/clocksource.h>
+#include <linux/timer.h>
+#include <linux/timex.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/threads.h>
+#include <linux/smp.h>
+
+static unsigned long current_tsc_khz = 0;
+
+static seqlock_t tsc_interp_lock = SEQLOCK_UNLOCKED;
+static unsigned long tsc_then;
+static unsigned long jiffies_then;
+struct timer_list tsc_interp_timer;
+
+static unsigned long mult, shift;
+
+#define NSEC_PER_JIFFY ((((unsigned long long)NSEC_PER_SEC)<<8)/ACTHZ)
+#define SHIFT_VAL 22
+
+static cycle_t read_tsc_interp(void);
+static void tsc_interp_update_callback(void);
+
+static struct clocksource clocksource_tsc_interp = {
+ .name = "tsc-interp",
+ .rating = 150,
+ .type = CLOCKSOURCE_FUNCTION,
+ .read_fnct = read_tsc_interp,
+ .mask = (cycle_t)((1ULL<<32)-1),
+ .mult = 1<<SHIFT_VAL,
+ .shift = SHIFT_VAL,
+ .update_callback = tsc_interp_update_callback,
+};
+
+static void tsc_interp_sync(unsigned long unused)
+{
+ cycle_t tsc_now;
+ unsigned long jiffies_now;
+
+ do {
+ jiffies_now = jiffies;
+ rdtscll(tsc_now);
+ } while (jiffies_now != jiffies);
+
+ write_seqlock(&tsc_interp_lock);
+ jiffies_then = jiffies_now;
+ tsc_then = tsc_now;
+ write_sequnlock(&tsc_interp_lock);
+
+ mod_timer(&tsc_interp_timer, jiffies+1);
+}
+
+
+static cycle_t read_tsc_interp(void)
+{
+ cycle_t ret;
+ cycle_t now, then;
+ unsigned long jiffs_now, jiffs_then;
+ unsigned long seq;
+
+ do {
+ seq = read_seqbegin(&tsc_interp_lock);
+
+ jiffs_now = jiffies;
+ jiffs_then = jiffies_then;
+ then = tsc_then;
+
+ } while (read_seqretry(&tsc_interp_lock, seq));
+
+ rdtscll(now);
+ ret = (cycle_t)jiffs_then * NSEC_PER_JIFFY;
+ if (jiffs_then == jiffs_now)
+ ret += min((cycle_t)NSEC_PER_JIFFY,(cycle_t)((now - then)*mult)>> shift);
+ else
+ ret += (cycle_t)(jiffs_now - jiffs_then)*NSEC_PER_JIFFY;
+
+ return ret;
+}
+
+static void tsc_interp_update_callback(void)
+{
+ /* only update if tsc_khz has changed */
+ if (current_tsc_khz != tsc_khz){
+ current_tsc_khz = tsc_khz;
+ mult = clocksource_khz2mult(current_tsc_khz, shift);
+ }
+}
+
+
+static int __init init_tsc_interp_clocksource(void)
+{
+ /* TSC initialization is done in arch/i386/kernel/tsc.c */
+ if (cpu_has_tsc && tsc_khz) {
+ current_tsc_khz = tsc_khz;
+ shift = SHIFT_VAL;
+ mult = clocksource_khz2mult(current_tsc_khz, shift);
+ /* setup periodic soft-timer */
+ init_timer(&tsc_interp_timer);
+ tsc_interp_timer.function = tsc_interp_sync;
+ tsc_interp_timer.expires = jiffies;
+ add_timer(&tsc_interp_timer);
+
+ register_clocksource(&clocksource_tsc_interp);
+ }
+ return 0;
+}
+module_init(init_tsc_interp_clocksource);