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-rw-r--r--arch/mips/rb532/time.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/arch/mips/rb532/time.c b/arch/mips/rb532/time.c
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+++ b/arch/mips/rb532/time.c
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+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Carsten Langgaard, carstenl@mips.com
+ * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved.
+ *
+ * Setting up the clock on the MIPS boards.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/ptrace.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/mc146818rtc.h>
+#include <linux/irq.h>
+#include <linux/timex.h>
+
+#include <asm/mipsregs.h>
+#include <asm/time.h>
+#include <asm/mach-rc32434/rc32434.h>
+
+extern unsigned int idt_cpu_freq;
+
+/*
+ * Figure out the r4k offset, the amount to increment the compare
+ * register for each time tick. There is no RTC available.
+ *
+ * The RC32434 counts at half the CPU *core* speed.
+ */
+static unsigned long __init cal_r4koff(void)
+{
+ mips_hpt_frequency = idt_cpu_freq * IDT_CLOCK_MULT / 2;
+
+ return mips_hpt_frequency / HZ;
+}
+
+void __init plat_time_init(void)
+{
+ unsigned int est_freq;
+ unsigned long flags, r4k_offset;
+
+ local_irq_save(flags);
+
+ printk(KERN_INFO "calculating r4koff... ");
+ r4k_offset = cal_r4koff();
+ printk("%08lx(%d)\n", r4k_offset, (int) r4k_offset);
+
+ est_freq = 2 * r4k_offset * HZ;
+ est_freq += 5000; /* round */
+ est_freq -= est_freq % 10000;
+ printk(KERN_INFO "CPU frequency %d.%02d MHz\n", est_freq / 1000000,
+ (est_freq % 1000000) * 100 / 1000000);
+ local_irq_restore(flags);
+}