[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 3

The attached patches provides part 3 of an architecture implementation for the
Tensilica Xtensa CPU series.

Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 227 insertions, 0 deletions

diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
new file mode 100644
index 000000000000..e07287db5a40
--- /dev/null
+++ b/arch/xtensa/kernel/time.c
@@ -0,0 +1,227 @@
+/*
+ * arch/xtensa/kernel/time.c
+ *
+ * Timer and clock support.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2005 Tensilica Inc.
+ *
+ * Chris Zankel <chris@zankel.net>
+ */
+
+#include <linux/config.h>
+#include <linux/errno.h>
+#include <linux/time.h>
+#include <linux/timex.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/profile.h>
+#include <linux/delay.h>
+
+#include <asm/timex.h>
+#include <asm/platform.h>
+
+
+extern volatile unsigned long wall_jiffies;
+
+u64 jiffies_64 = INITIAL_JIFFIES;
+EXPORT_SYMBOL(jiffies_64);
+
+spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
+EXPORT_SYMBOL(rtc_lock);
+
+
+#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
+unsigned long ccount_per_jiffy;         /* per 1/HZ */
+unsigned long ccount_nsec;              /* nsec per ccount increment */
+#endif
+
+unsigned int last_ccount_stamp;
+static long last_rtc_update = 0;
+
+/*
+ * Scheduler clock - returns current tim in nanosec units.
+ */
+
+unsigned long long sched_clock(void)
+{
+        return (unsigned long long)jiffies * (1000000000 / HZ);
+}
+
+static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static struct irqaction timer_irqaction = {
+        .handler =      timer_interrupt,
+        .flags =        SA_INTERRUPT,
+        .name =         "timer",
+};
+
+void __init time_init(void)
+{
+        time_t sec_o, sec_n = 0;
+
+        /* The platform must provide a function to calibrate the processor
+         * speed for the CALIBRATE.
+         */
+
+#if CONFIG_XTENSA_CALIBRATE_CCOUNT
+        printk("Calibrating CPU frequency ");
+        platform_calibrate_ccount();
+        printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),
+                        (int)(ccount_per_jiffy/(10000/HZ))%100);
+#endif
+
+        /* Set time from RTC (if provided) */
+
+        if (platform_get_rtc_time(&sec_o) == 0)
+                while (platform_get_rtc_time(&sec_n))
+                        if (sec_o != sec_n)
+                                break;
+
+        xtime.tv_nsec = 0;
+        last_rtc_update = xtime.tv_sec = sec_n;
+        last_ccount_stamp = get_ccount();
+
+        set_normalized_timespec(&wall_to_monotonic,
+                -xtime.tv_sec, -xtime.tv_nsec);
+
+        /* Initialize the linux timer interrupt. */
+
+        setup_irq(LINUX_TIMER_INT, &timer_irqaction);
+        set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
+}
+
+
+int do_settimeofday(struct timespec *tv)
+{
+        time_t wtm_sec, sec = tv->tv_sec;
+        long wtm_nsec, nsec = tv->tv_nsec;
+        unsigned long ccount;
+
+        if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
+                return -EINVAL;
+
+        write_seqlock_irq(&xtime_lock);
+
+        /* This is revolting. We need to set "xtime" correctly. However, the
+         * value in this location is the value at the most recent update of
+         * wall time.  Discover what correction gettimeofday() would have
+         * made, and then undo it!
+         */
+        ccount = get_ccount();
+        nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC;
+        nsec -= (jiffies - wall_jiffies) * CCOUNT_PER_JIFFY * CCOUNT_NSEC;
+
+        wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
+        wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
+
+        set_normalized_timespec(&xtime, sec, nsec);
+        set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
+
+        time_adjust = 0;                /* stop active adjtime() */
+        time_status |= STA_UNSYNC;
+        time_maxerror = NTP_PHASE_LIMIT;
+        time_esterror = NTP_PHASE_LIMIT;
+        write_sequnlock_irq(&xtime_lock);
+        return 0;
+}
+
+EXPORT_SYMBOL(do_settimeofday);
+
+
+void do_gettimeofday(struct timeval *tv)
+{
+        unsigned long flags;
+        unsigned long sec, usec, delta, lost, seq;
+
+        do {
+                seq = read_seqbegin_irqsave(&xtime_lock, flags);
+
+                delta = get_ccount() - last_ccount_stamp;
+                sec = xtime.tv_sec;
+                usec = (xtime.tv_nsec / NSEC_PER_USEC);
+
+                lost = jiffies - wall_jiffies;
+
+        } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
+
+        usec += lost * (1000000UL/HZ) + (delta * CCOUNT_NSEC) / NSEC_PER_USEC;
+        for (; usec >= 1000000; sec++, usec -= 1000000)
+                ;
+
+        tv->tv_sec = sec;
+        tv->tv_usec = usec;
+}
+
+EXPORT_SYMBOL(do_gettimeofday);
+
+/*
+ * The timer interrupt is called HZ times per second.
+ */
+
+irqreturn_t timer_interrupt (int irq, void *dev_id, struct pt_regs *regs)
+{
+
+        unsigned long next;
+
+        next = get_linux_timer();
+
+again:
+        while ((signed long)(get_ccount() - next) > 0) {
+
+                profile_tick(CPU_PROFILING, regs);
+#ifndef CONFIG_SMP
+                update_process_times(user_mode(regs));
+#endif
+
+                write_seqlock(&xtime_lock);
+
+                last_ccount_stamp = next;
+                next += CCOUNT_PER_JIFFY;
+                do_timer (regs); /* Linux handler in kernel/timer.c */
+
+                if ((time_status & STA_UNSYNC) == 0 &&
+                    xtime.tv_sec - last_rtc_update >= 659 &&
+                    abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ &&
+                    jiffies - wall_jiffies == 1) {
+
+                        if (platform_set_rtc_time(xtime.tv_sec+1) == 0)
+                                last_rtc_update = xtime.tv_sec+1;
+                        else
+                                /* Do it again in 60 s */
+                                last_rtc_update += 60;
+                }
+                write_sequnlock(&xtime_lock);
+        }
+
+        /* NOTE: writing CCOMPAREn clears the interrupt.  */
+
+        set_linux_timer (next);
+
+        /* Make sure we didn't miss any tick... */
+
+        if ((signed long)(get_ccount() - next) > 0)
+                goto again;
+
+        /* Allow platform to do something usefull (Wdog). */
+
+        platform_heartbeat();
+
+        return IRQ_HANDLED;
+}
+
+#ifndef CONFIG_GENERIC_CALIBRATE_DELAY
+void __devinit calibrate_delay(void)
+{
+        loops_per_jiffy = CCOUNT_PER_JIFFY;
+        printk("Calibrating delay loop (skipped)... "
+               "%lu.%02lu BogoMIPS preset\n",
+               loops_per_jiffy/(1000000/HZ),
+               (loops_per_jiffy/(10000/HZ)) % 100);
+}
+#endif
+