- Add new cvs code to cvs

git-svn-id: svn://svn.coreboot.org/coreboot/trunk@1657 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

src/cpu/x86/tsc/delay_tsc.c

@@ -0,0 +1,165 @@
+#include <console/console.h>
+#include <arch/io.h>
+#include <cpu/x86/msr.h>
+#include <cpu/x86/tsc.h>
+#include <smp/spinlock.h>
+#include <delay.h>
+
+static unsigned long clocks_per_usec;
+
+#if (CONFIG_TSC_X86RDTSC_CALIBRATE_WITH_TIMER2 == 1)
+#define CLOCK_TICK_RATE	1193180U /* Underlying HZ */
+
+/* ------ Calibrate the TSC ------- 
+ * 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_INTERVAL ((20*CLOCK_TICK_RATE)/1000) /* 20ms */
+#define CALIBRATE_DIVISOR  (20*1000) /* 20ms / 20000 == 1usec */
+
+static unsigned long long 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_INTERVAL	& 0xff, 0x42);	/* LSB of count */
+	outb(CALIBRATE_INTERVAL	>> 8, 0x42);	/* MSB of count */
+
+	{
+		tsc_t start;
+		tsc_t end;
+		unsigned long count;
+
+		start = rdtsc();
+		count = 0;
+		do {
+			count++;
+		} while ((inb(0x61) & 0x20) == 0);
+		end = rdtsc();
+
+		/* 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" (end.lo), "=d" (end.hi)
+			:"g" (start.lo), "g" (start.hi),
+			 "0" (end.lo), "1" (end.hi));
+
+		/* Error: ECPUTOOFAST */
+		if (end.hi)
+			goto bad_ctc;
+
+
+		/* Error: ECPUTOOSLOW */
+		if (end.lo <= CALIBRATE_DIVISOR)
+			goto bad_ctc;
+
+		return (end.lo + CALIBRATE_DIVISOR -1)/CALIBRATE_DIVISOR;
+	}
+
+	/*
+	 * 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:
+	printk_err("bad_ctc\n");
+	return 0;
+}
+
+#else /*  CONFIG_TSC_X86RDTSC_CALIBRATE_WITH_TIMER2 */
+
+/*
+ * this is the "no timer2" version.
+ * to calibrate tsc, we get a TSC reading, then do 1,000,000 outbs to port 0x80
+ * then we read TSC again, and divide the difference by 1,000,000
+ * we have found on a wide range of machines that this gives us a a 
+ * good microsecond value
+ * to +- 10%. On a dual AMD 1.6 Ghz box, it gives us .97 microseconds, and on a
+ * 267 Mhz. p5, it gives us 1.1 microseconds.
+ * also, since gcc now supports long long, we use that.
+ * also no unsigned long long / operator, so we play games.
+ * about the only thing you can do with long longs, it seems, 
+ *is return them and assign them.
+ * (and do asm on them, yuck)
+ * so avoid all ops on long longs.
+ */
+static unsigned long long calibrate_tsc(void)
+{
+	unsigned long long start, end, delta;
+	unsigned long allones = (unsigned long) -1, result;
+	unsigned long count;
+	
+	start = rdtscll();
+	// no udivdi3, dammit.
+	// so we count to 1<< 20 and then right shift 20
+	for(count = 0; count < (1<<20); count ++)
+		outb(0x80, 0x80);
+	end = rdtscll();
+
+#if 0
+	// make delta be (endhigh - starthigh) + (endlow - startlow)
+	// but >> 20
+	// do it this way to avoid gcc warnings.
+	start = tsc_start.hi;
+	start <<= 32;
+	start |= start.lo;
+	end = tsc_end.hi;
+	end <<= 32;
+	end |= tsc_end.lo;
+#endif
+	delta = end - start;
+	// at this point we have a delta for 1,000,000 outbs. Now rescale for one microsecond.
+	delta >>= 20;
+	// save this for microsecond timing.
+	result = delta;
+	printk_spew("end %x:%x, start %x:%x\n",
+		endhigh, endlow, starthigh, startlow);
+	printk_spew("32-bit delta %d\n", (unsigned long) delta);
+	
+	printk_spew(__FUNCTION__ " 32-bit result is %d\n", result);
+	return delta;
+}
+
+
+#endif /* CONFIG_TSC_X86RDTSC_CALIBRATE_WITH_TIMER2*/
+
+void init_timer(void)
+{
+	if (!clocks_per_usec) {
+		clocks_per_usec = calibrate_tsc();
+		printk_info("clocks_per_usec: %u\n", clocks_per_usec);
+	}
+}
+
+void udelay(unsigned us)
+{
+        unsigned long long count;
+        unsigned long long stop;
+        unsigned long long clocks;
+
+	init_timer();
+	clocks = us;
+	clocks *= clocks_per_usec;
+        count = rdtscll();
+        stop = clocks + count;
+        while(stop > count) {
+		cpu_relax();
+		count = rdtscll();
+        }
+}