[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>
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
new file mode 100644
index 0000000..e07287d
--- /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
+