patch-2.4.20 linux-2.4.20/arch/mips/mips-boards/sead/sead_time.c

• Lines: 150
• Date: Thu Nov 28 15:53:10 2002
• Orig file: linux-2.4.19/arch/mips/mips-boards/sead/sead_time.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.19/arch/mips/mips-boards/sead/sead_time.c linux-2.4.20/arch/mips/mips-boards/sead/sead_time.c
@@ -0,0 +1,149 @@
+/*
+ * Carsten Langgaard, carstenl@mips.com
+ * Copyright (C) 2002 MIPS Technologies, Inc.  All rights reserved.
+ *
+ * ########################################################################
+ *
+ *  This program is free software; you can distribute it and/or modify it
+ *  under the terms of the GNU General Public License (Version 2) as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * ########################################################################
+ *
+ * Setting up the clock on the MIPS boards.
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+
+#include <asm/mipsregs.h>
+#include <asm/ptrace.h>
+#include <asm/hardirq.h>
+#include <asm/cpu.h>
+
+#include <linux/interrupt.h>
+#include <linux/timex.h>
+
+#include <asm/mips-boards/generic.h>
+#include <asm/mips-boards/prom.h>
+
+extern volatile unsigned long wall_jiffies;
+
+static unsigned long r4k_offset; /* Amount to increment compare reg each time */
+static unsigned long r4k_cur;    /* What counter should be at next timer irq */
+extern rwlock_t xtime_lock;
+
+#define ALLINTS (IE_IRQ0 | IE_IRQ1 | IE_IRQ5)
+
+static char display_string[] = "        LINUX ON SEAD       ";
+
+static unsigned int display_count = 0;
+#define MAX_DISPLAY_COUNT (sizeof(display_string) - 8)
+
+#define MIPS_CPU_TIMER_IRQ 7
+
+static unsigned int timer_tick_count=0;
+
+static inline void ack_r4ktimer(unsigned long newval)
+{
+	write_32bit_cp0_register(CP0_COMPARE, newval);
+}
+
+/*
+ * There are a lot of conceptually broken versions of the MIPS timer interrupt
+ * handler floating around.  This one is rather different, but the algorithm
+ * is provably more robust.
+ */
+void mips_timer_interrupt(struct pt_regs *regs)
+{
+	int cpu = smp_processor_id();
+	int irq = MIPS_CPU_TIMER_IRQ;
+
+	irq_enter(cpu, irq);
+
+	do {
+		kstat.irqs[cpu][irq]++;
+		do_timer(regs);
+
+		if ((timer_tick_count++ % HZ) == 0) {
+		    mips_display_message(&display_string[display_count++]);
+		    if (display_count == MAX_DISPLAY_COUNT)
+		        display_count = 0;
+		}
+
+		r4k_cur += r4k_offset;
+		ack_r4ktimer(r4k_cur);
+
+	} while (((unsigned long)read_32bit_cp0_register(CP0_COUNT)
+	         - r4k_cur) < 0x7fffffff);
+
+	irq_exit(cpu, irq);
+	if (softirq_pending(cpu))
+		do_softirq();
+}
+
+/*
+ * Figure out the r4k offset, the amount to increment the compare
+ * register for each time tick.
+ */
+static unsigned long __init cal_r4koff(void)
+{
+	/*
+	 * The SEAD board doesn't have a real time clock, so we can't
+	 * really calculate the timer offset.
+	 * For now we hardwire the SEAD board frequency to 12MHz.
+	 */
+	return(6000000/HZ);
+}
+
+void __init mips_time_init(void)
+{
+        unsigned int est_freq, flags;
+
+	__save_and_cli(flags);
+
+        /* Start r4k counter. */
+        write_32bit_cp0_register(CP0_COUNT, 0);
+
+	printk("calculating r4koff... ");
+	r4k_offset = cal_r4koff();
+	printk("%08lx(%d)\n", r4k_offset, (int) r4k_offset);
+
+        if ((read_32bit_cp0_register(CP0_PRID) & 0xffff00) ==
+	    (PRID_COMP_MIPS | PRID_IMP_20KC))
+		est_freq = r4k_offset*HZ;
+	else
+		est_freq = 2*r4k_offset*HZ;
+
+	est_freq += 5000;    /* round */
+	est_freq -= est_freq%10000;
+	printk("CPU frequency %d.%02d MHz\n", est_freq/1000000,
+	       (est_freq%1000000)*100/1000000);
+
+	__restore_flags(flags);
+}
+
+void __init mips_timer_setup(struct irqaction *irq)
+{
+	/* we are using the cpu counter for timer interrupts */
+	irq->handler = no_action;     /* we use our own handler */
+	setup_irq(MIPS_CPU_TIMER_IRQ, irq);
+
+        /* to generate the first timer interrupt */
+	r4k_cur = (read_32bit_cp0_register(CP0_COUNT) + r4k_offset);
+	write_32bit_cp0_register(CP0_COMPARE, r4k_cur);
+	set_cp0_status(ALLINTS);
+}