GK SDK 源码库: XMIPCLinuxV100R005C00SPC030 (kernel/tools/open_source excluded)

source/bootloader/u-boot-2020.01/arch/powerpc/lib/time.c

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+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2000, 2001
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ */
+
+#include <common.h>
+#include <time.h>
+#include <asm/io.h>
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * This function is intended for SHORT delays only.
+ * It will overflow at around 10 seconds @ 400MHz,
+ * or 20 seconds @ 200MHz.
+ */
+unsigned long usec2ticks(unsigned long usec)
+{
+	ulong ticks;
+
+	if (usec < 1000) {
+		ticks = ((usec * (get_tbclk()/1000)) + 500) / 1000;
+	} else {
+		ticks = ((usec / 10) * (get_tbclk() / 100000));
+	}
+
+	return (ticks);
+}
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * We implement the delay by converting the delay (the number of
+ * microseconds to wait) into a number of time base ticks; then we
+ * watch the time base until it has incremented by that amount.
+ */
+void __udelay(unsigned long usec)
+{
+	ulong ticks = usec2ticks (usec);
+	wait_ticks (ticks);
+}
+
+/* ------------------------------------------------------------------------- */
+#ifndef CONFIG_NAND_SPL
+unsigned long ticks2usec(unsigned long ticks)
+{
+	ulong tbclk = get_tbclk();
+
+	/* usec = ticks * 1000000 / tbclk
+	 * Multiplication would overflow at ~4.2e3 ticks,
+	 * so we break it up into
+	 * usec = ( ( ticks * 1000) / tbclk ) * 1000;
+	 */
+	ticks *= 1000L;
+	ticks /= tbclk;
+	ticks *= 1000L;
+
+	return ((ulong)ticks);
+}
+#endif
+/* ------------------------------------------------------------------------- */
+
+int timer_init(void)
+{
+	unsigned long temp;
+
+	/* reset */
+	asm volatile("li %0,0 ; mttbl %0 ; mttbu %0;"
+	     : "=&r"(temp) );
+
+	return (0);
+}
+/* ------------------------------------------------------------------------- */