1 files changed, 146 insertions, 0 deletions
diff --git a/src/CirrusClk.c b/src/CirrusClk.c
new file mode 100644
index 0000000..c548f1f
--- /dev/null
+++ b/src/CirrusClk.c
@@ -0,0 +1,146 @@
+/* $XFree86: xc/programs/Xserver/hw/xfree86/drivers/cirrus/CirrusClk.c,v 1.9 1999/12/26 18:24:14 robin Exp $ */
+
+/*
+ * Programming of the built-in Cirrus clock generator.
+ * Harm Hanemaayer <hhanemaa@cs.ruu.nl>
+ *
+ * VCO stability criterion code added by Koen Gadeyne (koen.gadeyne@barco.com)
+ * Max clock specification added by Harm Hanemaayer (H.Hanemaayer@inter.nl.net)
+ *
+ * Minor changes and cleanup Itai Nahshon.
+ *
+ * Made this completly chipset independent,  and moved chipset dependent parts
+ * into the specific sub-drivers.  Derek Fawcus <derek@spider.com>
+ */
+
+#include "xf86.h"
+#include "xf86_OSproc.h"
+#include "xf86_ansic.h"
+#include "xf86PciInfo.h"
+#include "xf86Pci.h"
+
+#include "cir.h"
+
+/* CLOCK_FACTOR is double the osc freq in kHz (osc = 14.31818 MHz) */
+#define CLOCK_FACTOR 28636
+
+/* Stability constraints for internal VCO -- MAX_VCO also determines
+ * the maximum Video pixel clock
+ */
+#define MIN_VCO CLOCK_FACTOR
+#define MAX_VCO 111000
+
+/* clock in kHz is (numer * CLOCK_FACTOR / (denom & 0x3E)) >> (denom & 1) */
+#define VCOVAL(n, d) \
+	((((n) & 0x7F) * CLOCK_FACTOR / ((d) & 0x3E)) )
+
+#define CLOCKVAL(n, d) \
+	(VCOVAL(n, d) >> ((d) & 1))
+
+typedef struct {
+	unsigned char numer;
+	unsigned char denom;
+} cirrusClockRec;
+
+static cirrusClockRec cirrusClockTab[] = {
+	{ 0x2C, 0x33 },		/* 12.599 */
+	{ 0x4A, 0x2B },		/* 25.227 */
+	{ 0x5B, 0x2F },		/* 28.325 */
+	{ 0x45, 0x30 },		/* 41.164 */
+	{ 0x7E, 0x33 },		/* 36.082 */
+	{ 0x42, 0x1F },		/* 31.500 */
+	{ 0x51, 0x3A },		/* 39.992 */
+	{ 0x55, 0x36 },		/* 45.076 */
+	{ 0x65, 0x3A },		/* 49.867 */
+	{ 0x76, 0x34 },		/* 64.983 */
+	{ 0x7E, 0x32 },		/* 72.163 */
+	{ 0x6E, 0x2A },		/* 75.000 */
+	{ 0x5F, 0x22 },		/* 80.013 */
+	{ 0x7D, 0x2A },		/* 85.226 */
+	{ 0x58, 0x1C },		/* 89.998 */
+	{ 0x49, 0x16 },		/* 95.019 */
+	{ 0x46, 0x14 },		/* 100.226 */
+	{ 0x53, 0x16 },		/* 108.035 */
+	{ 0x5C, 0x18 },		/* 110.248 */
+
+	{ 0x6D, 0x1A },		/* 120.050 */
+	{ 0x58, 0x14 },		/* 125.998 */
+	{ 0x6D, 0x18 },		/* 130.055 */
+	{ 0x42, 0x0E },		/* 134.998 */
+
+	{ 0x69, 0x14 },		/* 150.341 */
+	{ 0x5E, 0x10 },		/* 168.239 */
+	{ 0x5C, 0x0E },		/* 188.182 */
+	{ 0x67, 0x0E },		/* 210.682 */
+	{ 0x60, 0x0C },		/* 229.091 */
+};
+
+#define NU_FIXED_CLOCKS (sizeof(cirrusClockTab)/sizeof(cirrusClockTab[0]))
+
+
+/*
+ * This function returns the 7-bit numerator and 6-bit denominator/post-scalar
+ * value that corresponds to the closest clock found.
+ * If a frequency close to one of the tested clock values is found,
+ * use the tested clock since others can be unstable.
+ */
+
+Bool
+CirrusFindClock(int *rfreq, int max_clock, int *num_out, int *den_out)
+{
+	int n, i;
+	int num = 0, den = 0;
+	int freq, ffreq = 0, mindiff = 0;
+
+	freq = *rfreq;
+	/* Prefer a tested value if it matches within 0.1%. */
+	for (i = 0; i < NU_FIXED_CLOCKS; i++) {
+		int diff;
+		diff = abs(CLOCKVAL(cirrusClockTab[i].numer,
+					cirrusClockTab[i].denom) - freq);
+		if (diff < freq / 1000) {
+			num = cirrusClockTab[i].numer;
+			den = cirrusClockTab[i].denom;
+			ffreq = CLOCKVAL(num, den);
+			goto foundclock;
+		}
+	}
+
+	/*
+	 * If max_clock is greater than the MAX_VCO default, ignore
+	 * MAX_VCO. On the other hand, if MAX_VCO is higher than max_clock,
+	 * make use of the higher MAX_VCO value.
+	 */
+	if (MAX_VCO > max_clock)
+		max_clock = MAX_VCO;
+
+	mindiff = freq;
+	for (n = 0x10; n < 0x7f; n++) {
+		int d;
+		for (d = 0x14; d < 0x3f; d++) {
+			int c, diff;
+
+			/* Avoid combinations that can be unstable. */
+			if ((VCOVAL(n, d) < MIN_VCO) || (VCOVAL(n, d) > max_clock))
+				continue;
+			c = CLOCKVAL(n, d);
+			diff = abs(c - freq);
+			if (diff < mindiff) {
+				mindiff = diff;
+				num = n;
+				den = d;
+				ffreq = c;
+			}
+		}
+	}
+
+	if (0 == num || 0 == den)
+		return FALSE;
+
+foundclock:
+	*num_out = num;
+	*den_out = den;
+	*rfreq = ffreq;
+
+	return TRUE;
+}