---

yaml
---
r: 1146
b: refs/heads/master
c: 312df5f
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 0af2be0b721997512191e981a051fcb070b87260
+refs/heads/master: 312df5f1a1da780e084b328bcabb02a6dcd044c3

trunk/arch/x86_64/Kconfig

@@ -303,6 +303,20 @@ config HPET_TIMER
 	  as it is off-chip.  You can find the HPET spec at
 	  <http://www.intel.com/labs/platcomp/hpet/hpetspec.htm>.
 
+config X86_PM_TIMER
+	bool "PM timer"
+	default y
+	help
+	  Support the ACPI PM timer for time keeping. This is slow,
+	  but is useful on some chipsets without HPET on systems with more
+	  than one CPU. On a single processor or single socket multi core
+	  system it is normally not required.
+	  When the PM timer is active 64bit vsyscalls are disabled
+	  and should not be enabled (/proc/sys/kernel/vsyscall64 should
+	  not be changed).
+	  The kernel selects the PM timer only as a last resort, so it is
+	  useful to enable just in case.
+
 config HPET_EMULATE_RTC
 	bool "Provide RTC interrupt"
 	depends on HPET_TIMER && RTC=y

trunk/arch/x86_64/kernel/Makefile

@@ -28,6 +28,7 @@ obj-$(CONFIG_GART_IOMMU)	+= pci-gart.o aperture.o
 obj-$(CONFIG_DUMMY_IOMMU)	+= pci-nommu.o pci-dma.o
 obj-$(CONFIG_SWIOTLB)		+= swiotlb.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o
+obj-$(CONFIG_X86_PM_TIMER)	+= pmtimer.o
 
 obj-$(CONFIG_MODULES)		+= module.o
 

trunk/arch/x86_64/kernel/pmtimer.c

@@ -0,0 +1,101 @@
+/* Ported over from i386 by AK, original copyright was:
+ *
+ * (C) Dominik Brodowski <linux@brodo.de> 2003
+ *
+ * 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.
+ *
+ * Dropped all the hardware bug workarounds for now. Hopefully they
+ * are not needed on 64bit chipsets.
+ */
+
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/cpumask.h>
+#include <asm/io.h>
+#include <asm/proto.h>
+#include <asm/msr.h>
+#include <asm/vsyscall.h>
+
+/* The I/O port the PMTMR resides at.
+ * The location is detected during setup_arch(),
+ * in arch/i386/kernel/acpi/boot.c */
+u32 pmtmr_ioport;
+
+/* value of the Power timer at last timer interrupt */
+static u32 offset_delay;
+static u32 last_pmtmr_tick;
+
+#define ACPI_PM_MASK 0xFFFFFF /* limit it to 24 bits */
+
+static inline u32 cyc2us(u32 cycles)
+{
+	/* The Power Management Timer ticks at 3.579545 ticks per microsecond.
+	 * 1 / PM_TIMER_FREQUENCY == 0.27936511 =~ 286/1024 [error: 0.024%]
+	 *
+	 * Even with HZ = 100, delta is at maximum 35796 ticks, so it can
+	 * easily be multiplied with 286 (=0x11E) without having to fear
+	 * u32 overflows.
+	 */
+	cycles *= 286;
+	return (cycles >> 10);
+}
+
+int pmtimer_mark_offset(void)
+{
+	static int first_run = 1;
+	unsigned long tsc;
+	u32 lost;
+
+	u32 tick = inl(pmtmr_ioport);
+	u32 delta;
+
+	delta = cyc2us((tick - last_pmtmr_tick) & ACPI_PM_MASK);
+
+	last_pmtmr_tick = tick;
+	monotonic_base += delta * NSEC_PER_USEC;
+
+	delta += offset_delay;
+
+	lost = delta / (USEC_PER_SEC / HZ);
+	offset_delay = delta % (USEC_PER_SEC / HZ);
+
+	rdtscll(tsc);
+	vxtime.last_tsc = tsc - offset_delay * cpu_khz;
+
+	/* don't calculate delay for first run,
+	   or if we've got less then a tick */
+	if (first_run || (lost < 1)) {
+		first_run = 0;
+		offset_delay = 0;
+	}
+
+	return lost - 1;
+}
+
+unsigned int do_gettimeoffset_pm(void)
+{
+	u32 now, offset, delta = 0;
+
+	offset = last_pmtmr_tick;
+	now = inl(pmtmr_ioport);
+	delta = (now - offset) & ACPI_PM_MASK;
+
+	return offset_delay + cyc2us(delta);
+}
+
+
+static int __init nopmtimer_setup(char *s)
+{
+	pmtmr_ioport = 0;
+	return 0;
+}
+
+__setup("nopmtimer", nopmtimer_setup);

trunk/arch/x86_64/kernel/time.c

@@ -26,6 +26,8 @@
 #include <linux/sysdev.h>
 #include <linux/bcd.h>
 #include <linux/kallsyms.h>
+#include <linux/acpi.h>
+#include <acpi/achware.h>	/* for PM timer frequency */
 #include <asm/8253pit.h>
 #include <asm/pgtable.h>
 #include <asm/vsyscall.h>
@@ -396,6 +398,10 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 			(offset - vxtime.last)*(NSEC_PER_SEC/HZ) / hpet_tick;
 
 		vxtime.last = offset;
+#ifdef CONFIG_X86_PM_TIMER
+	} else if (vxtime.mode == VXTIME_PMTMR) {
+		lost = pmtimer_mark_offset();
+#endif
 	} else {
 		offset = (((tsc - vxtime.last_tsc) *
 			   vxtime.tsc_quot) >> 32) - (USEC_PER_SEC / HZ);
@@ -898,6 +904,13 @@ void __init time_init(void)
 			hpet_period;
 		cpu_khz = hpet_calibrate_tsc();
 		timename = "HPET";
+#ifdef CONFIG_X86_PM_TIMER
+	} else if (pmtmr_ioport) {
+		vxtime_hz = PM_TIMER_FREQUENCY;
+		timename = "PM";
+		pit_init();
+		cpu_khz = pit_calibrate_tsc();
+#endif
 	} else {
 		pit_init();
 		cpu_khz = pit_calibrate_tsc();
@@ -922,36 +935,51 @@ void __init time_init(void)
 #endif
 }
 
+/*
+ * Make an educated guess if the TSC is trustworthy and synchronized
+ * over all CPUs.
+ */
+static __init int unsynchronized_tsc(void)
+{
+#ifdef CONFIG_SMP
+	if (oem_force_hpet_timer())
+		return 1;
+ 	/* Intel systems are normally all synchronized. Exceptions
+ 	   are handled in the OEM check above. */
+ 	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+ 		return 0;
+ 	/* All in a single socket - should be synchronized */
+ 	if (cpus_weight(cpu_core_map[0]) == num_online_cpus())
+ 		return 0;
+#endif
+ 	/* Assume multi socket systems are not synchronized */
+ 	return num_online_cpus() > 1;
+}
+
 /*
  * Decide after all CPUs are booted what mode gettimeofday should use.
  */
 void __init time_init_gtod(void)
 {
 	char *timetype;
 
-	/*
-	 * AMD systems with more than one CPU don't have fully synchronized
-	 * TSCs. Always use HPET gettimeofday for these, although it is slower.
-	 * Intel SMP systems usually have synchronized TSCs, so use always
-	 * the TSC.
-	 *
-	 * Exceptions:
-	 * IBM Summit2 checked by oem_force_hpet_timer().
- 	 * AMD dual core may also not need HPET. Check me.
-	 *
-	 * Can be turned off with "notsc".
-	 */
-	if (num_online_cpus() > 1 &&
-	    boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
-		notsc = 1;
-	/* Some systems will want to disable TSC and use HPET. */
-	if (oem_force_hpet_timer())
+	if (unsynchronized_tsc())
 		notsc = 1;
 	if (vxtime.hpet_address && notsc) {
 		timetype = "HPET";
 		vxtime.last = hpet_readl(HPET_T0_CMP) - hpet_tick;
 		vxtime.mode = VXTIME_HPET;
 		do_gettimeoffset = do_gettimeoffset_hpet;
+#ifdef CONFIG_X86_PM_TIMER
+	/* Using PM for gettimeofday is quite slow, but we have no other
+	   choice because the TSC is too unreliable on some systems. */
+	} else if (pmtmr_ioport && !vxtime.hpet_address && notsc) {
+		timetype = "PM";
+		do_gettimeoffset = do_gettimeoffset_pm;
+		vxtime.mode = VXTIME_PMTMR;
+		sysctl_vsyscall = 0;
+		printk(KERN_INFO "Disabling vsyscall due to use of PM timer\n");
+#endif
 	} else {
 		timetype = vxtime.hpet_address ? "HPET/TSC" : "PIT/TSC";
 		vxtime.mode = VXTIME_TSC;

trunk/arch/x86_64/kernel/vsyscall.c

@@ -65,7 +65,7 @@ static force_inline void do_vgettimeofday(struct timeval * tv)
 		usec = (__xtime.tv_nsec / 1000) +
 			(__jiffies - __wall_jiffies) * (1000000 / HZ);
 
-		if (__vxtime.mode == VXTIME_TSC) {
+		if (__vxtime.mode != VXTIME_HPET) {
 			sync_core();
 			rdtscll(t);
 			if (t < __vxtime.last_tsc)
@@ -217,7 +217,6 @@ static int __init vsyscall_init(void)
 	BUG_ON((unsigned long) &vtime != VSYSCALL_ADDR(__NR_vtime));
 	BUG_ON((VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE)));
 	map_vsyscall();
-	sysctl_vsyscall = 1;
 	register_sysctl_table(kernel_root_table2, 0);
 	return 0;
 }

trunk/include/asm-x86_64/proto.h

@@ -30,6 +30,11 @@ extern void ia32_syscall(void);
 extern void iommu_hole_init(void);
 
 extern void time_init_gtod(void);
+extern int pmtimer_mark_offset(void);
+extern unsigned int do_gettimeoffset_pm(void);
+extern u32 pmtmr_ioport;
+extern unsigned long long monotonic_base;
+extern int sysctl_vsyscall;
 
 extern void do_softirq_thunk(void);
 

trunk/include/asm-x86_64/vsyscall.h

@@ -25,6 +25,7 @@ enum vsyscall_num {
 
 #define VXTIME_TSC	1
 #define VXTIME_HPET	2
+#define VXTIME_PMTMR	3
 
 struct vxtime_data {
 	long hpet_address;	/* HPET base address */
@@ -54,6 +55,8 @@ extern struct timezone sys_tz;
 extern int sysctl_vsyscall;
 extern seqlock_t xtime_lock;
 
+extern int sysctl_vsyscall;
+
 #define ARCH_HAVE_XTIME_LOCK 1
 
 #endif /* __KERNEL__ */