linux-2.5.40_timer-changes_A3 (1/3 - infrastructure)

diff -Nru a/arch/i386/kernel/timer.c b/arch/i386/kernel/timer.c
@@ -0,0 +1,26 @@
+#include <linux/kernel.h>
+#include <asm/timer.h>
+
+/* list of externed timers */
+/* eg: extern struct timer_opts timer_XXX*/;
+
+/* list of timers, ordered by preference */
+struct timer_opts* timers[] = {
+	/* eg: &timer_XXX */
+};
+
+#define NR_TIMERS (sizeof(timers)/sizeof(timers[0]))
+
+/* iterates through the list of timers, returning the first 
+ * one that initializes successfully.
+ */
+struct timer_opts* select_timer(void)
+{
+	int i;
+	/* find most preferred working timer */
+	for(i=0; i < NR_TIMERS; i++)
+		if(timers[i]->init())
+			return timers[i];
+	panic("select_timer: Cannot find a suitable timer\n");
+	return 0;
+}

diff -Nru a/include/asm-i386/timer.h b/include/asm-i386/timer.h
@@ -0,0 +1,14 @@
+#ifndef _ASMi386_TIMER_H
+#define _ASMi386_TIMER_H
+
+struct timer_opts{
+	/* probes and initializes timer. returns 1 on sucess, 0 on failure */
+	int (*init)(void);
+	/* called by the timer interrupt */
+	void (*mark_offset)(void);
+	/* called by gettimeofday. returns # ms since the last timer interrupt */
+	unsigned long (*get_offset)(void);
+};
+
+struct timer_opts* select_timer(void);
+#endif

diff -Nru a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
@@ -73,51 +73,11 @@
 
 unsigned long cpu_khz;	/* Detected as we calibrate the TSC */
 
-/* Number of usecs that the last interrupt was delayed */
-static int delay_at_last_interrupt;
-
-static unsigned long last_tsc_low; /* lsb 32 bits of Time Stamp Counter */
-
-/* Cached *multiplier* to convert TSC counts to microseconds.
- * (see the equation below).
- * Equal to 2^32 * (1 / (clocks per usec) ).
- * Initialized in time_init.
- */
-unsigned long fast_gettimeoffset_quotient;
-
 extern rwlock_t xtime_lock;
 extern unsigned long wall_jiffies;
 
 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
 
-static inline unsigned long do_fast_gettimeoffset(void)
-{
-	register unsigned long eax, edx;
-
-	/* Read the Time Stamp Counter */
-
-	rdtsc(eax,edx);
-
-	/* .. relative to previous jiffy (32 bits is enough) */
-	eax -= last_tsc_low;	/* tsc_low delta */
-
-	/*
-         * Time offset = (tsc_low delta) * fast_gettimeoffset_quotient
-         *             = (tsc_low delta) * (usecs_per_clock)
-         *             = (tsc_low delta) * (usecs_per_jiffy / clocks_per_jiffy)
-	 *
-	 * Using a mull instead of a divl saves up to 31 clock cycles
-	 * in the critical path.
-         */
-
-	__asm__("mull %2"
-		:"=a" (eax), "=d" (edx)
-		:"rm" (fast_gettimeoffset_quotient),
-		 "0" (eax));
-
-	/* our adjusted time offset in microseconds */
-	return delay_at_last_interrupt + edx;
-}
 
 #define TICK_SIZE (tick_nsec / 1000)
 

@@ -125,104 +85,6 @@
 EXPORT_SYMBOL(i8253_lock);
 
 #ifndef CONFIG_X86_TSC
-
-/* This function must be called with interrupts disabled 
- * It was inspired by Steve McCanne's microtime-i386 for BSD.  -- jrs
- * 
- * However, the pc-audio speaker driver changes the divisor so that
- * it gets interrupted rather more often - it loads 64 into the
- * counter rather than 11932! This has an adverse impact on
- * do_gettimeoffset() -- it stops working! What is also not
- * good is that the interval that our timer function gets called
- * is no longer 10.0002 ms, but 9.9767 ms. To get around this
- * would require using a different timing source. Maybe someone
- * could use the RTC - I know that this can interrupt at frequencies
- * ranging from 8192Hz to 2Hz. If I had the energy, I'd somehow fix
- * it so that at startup, the timer code in sched.c would select
- * using either the RTC or the 8253 timer. The decision would be
- * based on whether there was any other device around that needed
- * to trample on the 8253. I'd set up the RTC to interrupt at 1024 Hz,
- * and then do some jiggery to have a version of do_timer that 
- * advanced the clock by 1/1024 s. Every time that reached over 1/100
- * of a second, then do all the old code. If the time was kept correct
- * then do_gettimeoffset could just return 0 - there is no low order
- * divider that can be accessed.
- *
- * Ideally, you would be able to use the RTC for the speaker driver,
- * but it appears that the speaker driver really needs interrupt more
- * often than every 120 us or so.
- *
- * Anyway, this needs more thought....		pjsg (1993-08-28)
- * 
- * If you are really that interested, you should be reading
- * comp.protocols.time.ntp!
- */
-
-static unsigned long do_slow_gettimeoffset(void)
-{
-	int count;
-
-	static int count_p = LATCH;    /* for the first call after boot */
-	static unsigned long jiffies_p = 0;
-
-	/*
-	 * cache volatile jiffies temporarily; we have IRQs turned off. 
-	 */
-	unsigned long jiffies_t;
-
-	/* gets recalled with irq locally disabled */
-	spin_lock(&i8253_lock);
-	/* timer count may underflow right here */
-	outb_p(0x00, 0x43);	/* latch the count ASAP */
-
-	count = inb_p(0x40);	/* read the latched count */
-
-	/*
-	 * We do this guaranteed double memory access instead of a _p 
-	 * postfix in the previous port access. Wheee, hackady hack
-	 */
- 	jiffies_t = jiffies;
-
-	count |= inb_p(0x40) << 8;
-	
-        /* VIA686a test code... reset the latch if count > max + 1 */
-        if (count > LATCH) {
-                outb_p(0x34, 0x43);
-                outb_p(LATCH & 0xff, 0x40);
-                outb(LATCH >> 8, 0x40);
-                count = LATCH - 1;
-        }
-	
-	spin_unlock(&i8253_lock);
-
-	/*
-	 * avoiding timer inconsistencies (they are rare, but they happen)...
-	 * there are two kinds of problems that must be avoided here:
-	 *  1. the timer counter underflows
-	 *  2. hardware problem with the timer, not giving us continuous time,
-	 *     the counter does small "jumps" upwards on some Pentium systems,
-	 *     (see c't 95/10 page 335 for Neptun bug.)
-	 */
-
-
-	if( jiffies_t == jiffies_p ) {
-		if( count > count_p ) {
-			/* the nutcase */
-			count = do_timer_overflow(count);
-		}
-	} else
-		jiffies_p = jiffies_t;
-
-	count_p = count;
-
-	count = ((LATCH-1) - count) * TICK_SIZE;
-	count = (count + LATCH/2) / LATCH;
-
-	return count;
-}
-
-static unsigned long (*do_gettimeoffset)(void) = do_slow_gettimeoffset;
-
 #else
 
 #define do_gettimeoffset()	do_fast_gettimeoffset()

@@ -433,34 +295,7 @@
 	 */
 	write_lock(&xtime_lock);
 
-	if (use_tsc)
-	{
-		/*
-		 * It is important that these two operations happen almost at
-		 * the same time. We do the RDTSC stuff first, since it's
-		 * faster. To avoid any inconsistencies, we need interrupts
-		 * disabled locally.
-		 */
-
-		/*
-		 * Interrupts are just disabled locally since the timer irq
-		 * has the SA_INTERRUPT flag set. -arca
-		 */
 	
-		/* read Pentium cycle counter */
-
-		rdtscl(last_tsc_low);
-
-		spin_lock(&i8253_lock);
-		outb_p(0x00, 0x43);     /* latch the count ASAP */
-
-		count = inb_p(0x40);    /* read the latched count */
-		count |= inb(0x40) << 8;
-		spin_unlock(&i8253_lock);
-
-		count = ((LATCH-1) - count) * TICK_SIZE;
-		delay_at_last_interrupt = (count + LATCH/2) / LATCH;
-	}
  
 	do_timer_interrupt(irq, NULL, regs);
 

@@ -510,85 +345,6 @@
 	return mktime(year, mon, day, hour, min, sec);
 }
 
-/* ------ Calibrate the TSC ------- 
- * Return 2^32 * (1 / (TSC clocks per usec)) for do_fast_gettimeoffset().
- * Too much 64-bit arithmetic here to do this cleanly in C, and for
- * accuracy's sake we want to keep the overhead on the CTC speaker (channel 2)
- * output busy loop as low as possible. We avoid reading the CTC registers
- * directly because of the awkward 8-bit access mechanism of the 82C54
- * device.
- */
-
-#define CALIBRATE_LATCH	(5 * LATCH)
-#define CALIBRATE_TIME	(5 * 1000020/HZ)
-
-#ifdef CONFIG_X86_TSC
-static unsigned long __init calibrate_tsc(void)
-{
-       /* Set the Gate high, disable speaker */
-	outb((inb(0x61) & ~0x02) | 0x01, 0x61);
-
-	/*
-	 * Now let's take care of CTC channel 2
-	 *
-	 * Set the Gate high, program CTC channel 2 for mode 0,
-	 * (interrupt on terminal count mode), binary count,
-	 * load 5 * LATCH count, (LSB and MSB) to begin countdown.
-	 */
-	outb(0xb0, 0x43);			/* binary, mode 0, LSB/MSB, Ch 2 */
-	outb(CALIBRATE_LATCH & 0xff, 0x42);	/* LSB of count */
-	outb(CALIBRATE_LATCH >> 8, 0x42);	/* MSB of count */
-
-	{
-		unsigned long startlow, starthigh;
-		unsigned long endlow, endhigh;
-		unsigned long count;
-
-		rdtsc(startlow,starthigh);
-		count = 0;
-		do {
-			count++;
-		} while ((inb(0x61) & 0x20) == 0);
-		rdtsc(endlow,endhigh);
-
-		last_tsc_low = endlow;
-
-		/* Error: ECTCNEVERSET */
-		if (count <= 1)
-			goto bad_ctc;
-
-		/* 64-bit subtract - gcc just messes up with long longs */
-		__asm__("subl %2,%0\n\t"
-			"sbbl %3,%1"
-			:"=a" (endlow), "=d" (endhigh)
-			:"g" (startlow), "g" (starthigh),
-			 "0" (endlow), "1" (endhigh));
-
-		/* Error: ECPUTOOFAST */
-		if (endhigh)
-			goto bad_ctc;
-
-		/* Error: ECPUTOOSLOW */
-		if (endlow <= CALIBRATE_TIME)
-			goto bad_ctc;
-
-		__asm__("divl %2"
-			:"=a" (endlow), "=d" (endhigh)
-			:"r" (endlow), "0" (0), "1" (CALIBRATE_TIME));
-
-		return endlow;
-	}
-
-	/*
-	 * 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..
-	 */
-bad_ctc:
-	return 0;
-}
-#endif /* CONFIG_X86_TSC */
-
 static struct sys_device device_i8253 = {
 	.name		= "rtc",
 	.id		= 0,

@@ -605,119 +361,12 @@
 device_initcall(time_init_device);
 
 
-#ifdef CONFIG_CPU_FREQ
-
-static int
-time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
-		       void *data)
-{
-	struct cpufreq_freqs *freq = data;
-	unsigned int i;
-
-	if (!cpu_has_tsc)
-		return 0;
-
-	switch (val) {
-	case CPUFREQ_PRECHANGE:
-		if ((freq->old < freq->new) &&
-		((freq->cpu == CPUFREQ_ALL_CPUS) || (freq->cpu == 0)))  {
-			cpu_khz = cpufreq_scale(cpu_khz, freq->old, freq->new);
-		        fast_gettimeoffset_quotient = cpufreq_scale(fast_gettimeoffset_quotient, freq->new, freq->old);
-		}
-		for (i=0; i<NR_CPUS; i++)
-			if ((freq->cpu == CPUFREQ_ALL_CPUS) || (freq->cpu == i))
-				cpu_data[i].loops_per_jiffy = cpufreq_scale(cpu_data[i].loops_per_jiffy, freq->old, freq->new);
-		break;
-
-	case CPUFREQ_POSTCHANGE:
-		if ((freq->new < freq->old) &&
-		((freq->cpu == CPUFREQ_ALL_CPUS) || (freq->cpu == 0)))  {
-			cpu_khz = cpufreq_scale(cpu_khz, freq->old, freq->new);
-		        fast_gettimeoffset_quotient = cpufreq_scale(fast_gettimeoffset_quotient, freq->new, freq->old);
-		}
-		for (i=0; i<NR_CPUS; i++)
-			if ((freq->cpu == CPUFREQ_ALL_CPUS) || (freq->cpu == i))
-				cpu_data[i].loops_per_jiffy = cpufreq_scale(cpu_data[i].loops_per_jiffy, freq->old, freq->new);
-		break;
-	}
-
-	return 0;
-}
-
-static struct notifier_block time_cpufreq_notifier_block = {
-	notifier_call:	time_cpufreq_notifier
-};
-#endif
-
-
 void __init time_init(void)
 {
-#ifdef CONFIG_X86_TSC
-	extern int x86_udelay_tsc;
-#endif
 	
 	xtime.tv_sec = get_cmos_time();
 	xtime.tv_nsec = 0;
 
-/*
- * If we have APM enabled or the CPU clock speed is variable
- * (CPU stops clock on HLT or slows clock to save power)
- * then the TSC timestamps may diverge by up to 1 jiffy from
- * 'real time' but nothing will break.
- * The most frequent case is that the CPU is "woken" from a halt
- * state by the timer interrupt itself, so we get 0 error. In the
- * rare cases where a driver would "wake" the CPU and request a
- * timestamp, the maximum error is < 1 jiffy. But timestamps are
- * still perfectly ordered.
- * Note that the TSC counter will be reset if APM suspends
- * to disk; this won't break the kernel, though, 'cuz we're
- * smart.  See arch/i386/kernel/apm.c.
- */
-#ifdef CONFIG_X86_TSC
- 	/*
- 	 *	Firstly we have to do a CPU check for chips with
- 	 * 	a potentially buggy TSC. At this point we haven't run
- 	 *	the ident/bugs checks so we must run this hook as it
- 	 *	may turn off the TSC flag.
- 	 *
- 	 *	NOTE: this doesnt yet handle SMP 486 machines where only
- 	 *	some CPU's have a TSC. Thats never worked and nobody has
- 	 *	moaned if you have the only one in the world - you fix it!
- 	 */
- 
- 	dodgy_tsc();
- 	
-	if (cpu_has_tsc) {
-		unsigned long tsc_quotient = calibrate_tsc();
-		if (tsc_quotient) {
-			fast_gettimeoffset_quotient = tsc_quotient;
-			use_tsc = 1;
-			/*
-			 *	We could be more selective here I suspect
-			 *	and just enable this for the next intel chips ?
-			 */
-			x86_udelay_tsc = 1;
-#ifndef do_gettimeoffset
-			do_gettimeoffset = do_fast_gettimeoffset;
-#endif
-
-			/* report CPU clock rate in Hz.
-			 * The formula is (10^6 * 2^32) / (2^32 * 1 / (clocks/us)) =
-			 * clock/second. Our precision is about 100 ppm.
-			 */
-			{	unsigned long eax=0, edx=1000;
-				__asm__("divl %2"
-		       		:"=a" (cpu_khz), "=d" (edx)
-        	       		:"r" (tsc_quotient),
-	                	"0" (eax), "1" (edx));
-				printk("Detected %lu.%03lu MHz processor.\n", cpu_khz / 1000, cpu_khz % 1000);
-			}
-#ifdef CONFIG_CPU_FREQ
-			cpufreq_register_notifier(&time_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
-#endif
-		}
-	}
-#endif /* CONFIG_X86_TSC */
 
 	time_init_hook();
 }

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diff -Nru a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
@@ -53,6 +53,7 @@
 #include <asm/mpspec.h>
 #include <asm/uaccess.h>
 #include <asm/processor.h>
+#include <asm/timer.h>
 
 #include <linux/mc146818rtc.h>
 #include <linux/timex.h>

@@ -78,18 +79,10 @@
 
 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
 
-
-#define TICK_SIZE (tick_nsec / 1000)
-
 spinlock_t i8253_lock = SPIN_LOCK_UNLOCKED;
 EXPORT_SYMBOL(i8253_lock);
 
-#ifndef CONFIG_X86_TSC
-#else
-
-#define do_gettimeoffset()	do_fast_gettimeoffset()
-
-#endif
+struct timer_opts* timer;
 
 /*
  * This version of gettimeofday has microsecond resolution

@@ -101,7 +94,7 @@
 	unsigned long usec, sec;
 
 	read_lock_irqsave(&xtime_lock, flags);
-	usec = do_gettimeoffset();
+	usec = timer->get_offset();
 	{
 		unsigned long lost = jiffies - wall_jiffies;
 		if (lost)

@@ -129,7 +122,7 @@
 	 * wall time.  Discover what correction gettimeofday() would have
 	 * made, and then undo it!
 	 */
-	tv->tv_usec -= do_gettimeoffset();
+	tv->tv_usec -= timer->get_offset();
 	tv->tv_usec -= (jiffies - wall_jiffies) * (1000000 / HZ);
 
 	while (tv->tv_usec < 0) {

@@ -295,7 +288,7 @@
 	 */
 	write_lock(&xtime_lock);
 
-	
+	timer->mark_offset();
  
 	do_timer_interrupt(irq, NULL, regs);
 

@@ -345,6 +338,7 @@
 	return mktime(year, mon, day, hour, min, sec);
 }
 
+/* XXX this driverfs stuff should probably go elsewhere later -john */
 static struct sys_device device_i8253 = {
 	.name		= "rtc",
 	.id		= 0,

@@ -368,5 +362,6 @@
 	xtime.tv_nsec = 0;
 
 
+	timer = select_timer();
 	time_init_hook();
 }

diff -Nru a/arch/i386/kernel/timer.c b/arch/i386/kernel/timer.c
@@ -2,11 +2,17 @@
 #include <asm/timer.h>
 
 /* list of externed timers */
-/* eg: extern struct timer_opts timer_XXX*/;
+#ifndef CONFIG_X86_TSC
+extern struct timer_opts timer_pit;
+#endif
+extern struct timer_opts timer_tsc;
 
 /* list of timers, ordered by preference */
 struct timer_opts* timers[] = {
-	/* eg: &timer_XXX */
+	&timer_tsc
+#ifndef CONFIG_X86_TSC
+	,&timer_pit
+#endif
 };
 
 #define NR_TIMERS (sizeof(timers)/sizeof(timers[0]))

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diff -Nru a/include/asm-i386/timer.h b/include/asm-i386/timer.h
@@ -9,6 +9,6 @@
 	/* called by gettimeofday. returns # ms since the last timer interrupt */
 	unsigned long (*get_offset)(void);
 };
-
+#define TICK_SIZE (tick_nsec / 1000)
 struct timer_opts* select_timer(void);
 #endif

diff -Nru a/arch/i386/kernel/timer.c b/arch/i386/kernel/timer.c
@@ -2,6 +2,9 @@
 #include <asm/timer.h>
 
 /* list of externed timers */
+#ifdef CONFIG_X86_CYCLONE
+extern struct timer_opts timer_cyclone;
+#endif
 #ifndef CONFIG_X86_TSC
 extern struct timer_opts timer_pit;
 #endif

@@ -9,6 +12,9 @@
 
 /* list of timers, ordered by preference */
 struct timer_opts* timers[] = {
+#ifdef CONFIG_X86_CYCLONE
+	&timer_cyclone,
+#endif
 	&timer_tsc
 #ifndef CONFIG_X86_TSC
 	,&timer_pit

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diff -Nru a/include/asm-i386/fixmap.h b/include/asm-i386/fixmap.h
@@ -65,6 +65,9 @@
 #ifdef CONFIG_X86_F00F_BUG
 	FIX_F00F_IDT,	/* Virtual mapping for IDT */
 #endif
+#ifdef CONFIG_X86_CYCLONE
+	FIX_CYCLONE_TIMER, /*cyclone timer register*/
+#endif 
 #ifdef CONFIG_HIGHMEM
 	FIX_KMAP_BEGIN,	/* reserved pte's for temporary kernel mappings */
 	FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,