summaryrefslogtreecommitdiffstats
path: root/kernel/arch/arm/common/icst.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/arch/arm/common/icst.c')
-rw-r--r--kernel/arch/arm/common/icst.c100
1 files changed, 100 insertions, 0 deletions
diff --git a/kernel/arch/arm/common/icst.c b/kernel/arch/arm/common/icst.c
new file mode 100644
index 000000000..2dc6da70a
--- /dev/null
+++ b/kernel/arch/arm/common/icst.c
@@ -0,0 +1,100 @@
+/*
+ * linux/arch/arm/common/icst307.c
+ *
+ * Copyright (C) 2003 Deep Blue Solutions, Ltd, All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Support functions for calculating clocks/divisors for the ICST307
+ * clock generators. See http://www.idt.com/ for more information
+ * on these devices.
+ *
+ * This is an almost identical implementation to the ICST525 clock generator.
+ * The s2div and idx2s files are different
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include <asm/hardware/icst.h>
+
+/*
+ * Divisors for each OD setting.
+ */
+const unsigned char icst307_s2div[8] = { 10, 2, 8, 4, 5, 7, 3, 6 };
+const unsigned char icst525_s2div[8] = { 10, 2, 8, 4, 5, 7, 9, 6 };
+EXPORT_SYMBOL(icst307_s2div);
+EXPORT_SYMBOL(icst525_s2div);
+
+unsigned long icst_hz(const struct icst_params *p, struct icst_vco vco)
+{
+ return p->ref * 2 * (vco.v + 8) / ((vco.r + 2) * p->s2div[vco.s]);
+}
+
+EXPORT_SYMBOL(icst_hz);
+
+/*
+ * Ascending divisor S values.
+ */
+const unsigned char icst307_idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 };
+const unsigned char icst525_idx2s[8] = { 1, 3, 4, 7, 5, 2, 6, 0 };
+EXPORT_SYMBOL(icst307_idx2s);
+EXPORT_SYMBOL(icst525_idx2s);
+
+struct icst_vco
+icst_hz_to_vco(const struct icst_params *p, unsigned long freq)
+{
+ struct icst_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max };
+ unsigned long f;
+ unsigned int i = 0, rd, best = (unsigned int)-1;
+
+ /*
+ * First, find the PLL output divisor such
+ * that the PLL output is within spec.
+ */
+ do {
+ f = freq * p->s2div[p->idx2s[i]];
+
+ if (f > p->vco_min && f <= p->vco_max)
+ break;
+ } while (i < 8);
+
+ if (i >= 8)
+ return vco;
+
+ vco.s = p->idx2s[i];
+
+ /*
+ * Now find the closest divisor combination
+ * which gives a PLL output of 'f'.
+ */
+ for (rd = p->rd_min; rd <= p->rd_max; rd++) {
+ unsigned long fref_div, f_pll;
+ unsigned int vd;
+ int f_diff;
+
+ fref_div = (2 * p->ref) / rd;
+
+ vd = (f + fref_div / 2) / fref_div;
+ if (vd < p->vd_min || vd > p->vd_max)
+ continue;
+
+ f_pll = fref_div * vd;
+ f_diff = f_pll - f;
+ if (f_diff < 0)
+ f_diff = -f_diff;
+
+ if ((unsigned)f_diff < best) {
+ vco.v = vd - 8;
+ vco.r = rd - 2;
+ if (f_diff == 0)
+ break;
+ best = f_diff;
+ }
+ }
+
+ return vco;
+}
+
+EXPORT_SYMBOL(icst_hz_to_vco);