[POWERPC] Implement generic time of day clocksource for powerpc

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 98 insertions, 172 deletions

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index b94e4dffba19..e71a0d8c597a 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -65,17 +65,44 @@
 #include <asm/div64.h>
 #include <asm/smp.h>
 #include <asm/vdso_datapage.h>
-#ifdef CONFIG_PPC64
 #include <asm/firmware.h>
-#endif
 #ifdef CONFIG_PPC_ISERIES
 #include <asm/iseries/it_lp_queue.h>
 #include <asm/iseries/hv_call_xm.h>
 #endif
 
+/* powerpc clocksource/clockevent code */
+
+#include <linux/clocksource.h>
+
+static cycle_t rtc_read(void);
+static struct clocksource clocksource_rtc = {
+        .name         = "rtc",
+        .rating       = 400,
+        .flags        = CLOCK_SOURCE_IS_CONTINUOUS,
+        .mask         = CLOCKSOURCE_MASK(64),
+        .shift        = 22,
+        .mult         = 0,      /* To be filled in */
+        .read         = rtc_read,
+};
+
+static cycle_t timebase_read(void);
+static struct clocksource clocksource_timebase = {
+        .name         = "timebase",
+        .rating       = 400,
+        .flags        = CLOCK_SOURCE_IS_CONTINUOUS,
+        .mask         = CLOCKSOURCE_MASK(64),
+        .shift        = 22,
+        .mult         = 0,      /* To be filled in */
+        .read         = timebase_read,
+};
+
 #ifdef CONFIG_PPC_ISERIES
 static unsigned long __initdata iSeries_recal_titan;
 static signed long __initdata iSeries_recal_tb;
+
+/* Forward declaration is only needed for iSereis compiles */
+void __init clocksource_init(void);
 #endif
 
 #define XSEC_PER_SEC (1024*1024)
@@ -343,65 +370,6 @@ void udelay(unsigned long usecs)
 }
 EXPORT_SYMBOL(udelay);
 
-/*
- * This version of gettimeofday has microsecond resolution.
- */
-static inline void __do_gettimeofday(struct timeval *tv)
-{
-        unsigned long sec, usec;
-        u64 tb_ticks, xsec;
-        struct gettimeofday_vars *temp_varp;
-        u64 temp_tb_to_xs, temp_stamp_xsec;
-
-        /*
-         * These calculations are faster (gets rid of divides)
-         * if done in units of 1/2^20 rather than microseconds.
-         * The conversion to microseconds at the end is done
-         * without a divide (and in fact, without a multiply)
-         */
-        temp_varp = do_gtod.varp;
-
-        /* Sampling the time base must be done after loading
-         * do_gtod.varp in order to avoid racing with update_gtod.
-         */
-        data_barrier(temp_varp);
-        tb_ticks = get_tb() - temp_varp->tb_orig_stamp;
-        temp_tb_to_xs = temp_varp->tb_to_xs;
-        temp_stamp_xsec = temp_varp->stamp_xsec;
-        xsec = temp_stamp_xsec + mulhdu(tb_ticks, temp_tb_to_xs);
-        sec = xsec / XSEC_PER_SEC;
-        usec = (unsigned long)xsec & (XSEC_PER_SEC - 1);
-        usec = SCALE_XSEC(usec, 1000000);
-
-        tv->tv_sec = sec;
-        tv->tv_usec = usec;
-}
-
-void do_gettimeofday(struct timeval *tv)
-{
-        if (__USE_RTC()) {
-                /* do this the old way */
-                unsigned long flags, seq;
-                unsigned int sec, nsec, usec;
-
-                do {
-                        seq = read_seqbegin_irqsave(&xtime_lock, flags);
-                        sec = xtime.tv_sec;
-                        nsec = xtime.tv_nsec + tb_ticks_since(tb_last_jiffy);
-                } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
-                usec = nsec / 1000;
-                while (usec >= 1000000) {
-                        usec -= 1000000;
-                        ++sec;
-                }
-                tv->tv_sec = sec;
-                tv->tv_usec = usec;
-                return;
-        }
-        __do_gettimeofday(tv);
-}
-
-EXPORT_SYMBOL(do_gettimeofday);
 
 /*
  * There are two copies of tb_to_xs and stamp_xsec so that no
@@ -447,56 +415,6 @@ static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
         ++(vdso_data->tb_update_count);
 }
 
-/*
- * When the timebase - tb_orig_stamp gets too big, we do a manipulation
- * between tb_orig_stamp and stamp_xsec. The goal here is to keep the
- * difference tb - tb_orig_stamp small enough to always fit inside a
- * 32 bits number. This is a requirement of our fast 32 bits userland
- * implementation in the vdso. If we "miss" a call to this function
- * (interrupt latency, CPU locked in a spinlock, ...) and we end up
- * with a too big difference, then the vdso will fallback to calling
- * the syscall
- */
-static __inline__ void timer_recalc_offset(u64 cur_tb)
-{
-        unsigned long offset;
-        u64 new_stamp_xsec;
-        u64 tlen, t2x;
-        u64 tb, xsec_old, xsec_new;
-        struct gettimeofday_vars *varp;
-
-        if (__USE_RTC())
-                return;
-        tlen = current_tick_length();
-        offset = cur_tb - do_gtod.varp->tb_orig_stamp;
-        if (tlen == last_tick_len && offset < 0x80000000u)
-                return;
-        if (tlen != last_tick_len) {
-                t2x = mulhdu(tlen << TICKLEN_SHIFT, ticklen_to_xs);
-                last_tick_len = tlen;
-        } else
-                t2x = do_gtod.varp->tb_to_xs;
-        new_stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
-        do_div(new_stamp_xsec, 1000000000);
-        new_stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
-
-        ++vdso_data->tb_update_count;
-        smp_mb();
-
-        /*
-         * Make sure time doesn't go backwards for userspace gettimeofday.
-         */
-        tb = get_tb();
-        varp = do_gtod.varp;
-        xsec_old = mulhdu(tb - varp->tb_orig_stamp, varp->tb_to_xs)
-                + varp->stamp_xsec;
-        xsec_new = mulhdu(tb - cur_tb, t2x) + new_stamp_xsec;
-        if (xsec_new < xsec_old)
-                new_stamp_xsec += xsec_old - xsec_new;
-
-        update_gtod(cur_tb, new_stamp_xsec, t2x);
-}
-
 #ifdef CONFIG_SMP
 unsigned long profile_pc(struct pt_regs *regs)
 {
@@ -568,6 +486,8 @@ static int __init iSeries_tb_recal(void)
         iSeries_recal_titan = titan;
         iSeries_recal_tb = tb;
 
+        /* Called here as now we know accurate values for the timebase */
+        clocksource_init();
         return 0;
 }
 late_initcall(iSeries_tb_recal);
@@ -650,7 +570,6 @@ void timer_interrupt(struct pt_regs * regs)
                 if (per_cpu(last_jiffy, cpu) >= tb_next_jiffy) {
                         tb_last_jiffy = tb_next_jiffy;
                         do_timer(1);
-                        timer_recalc_offset(tb_last_jiffy);
                 }
                 write_sequnlock(&xtime_lock);
         }
@@ -722,66 +641,6 @@ unsigned long long sched_clock(void)
         return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
 }
 
-int do_settimeofday(struct timespec *tv)
-{
-        time_t wtm_sec, new_sec = tv->tv_sec;
-        long wtm_nsec, new_nsec = tv->tv_nsec;
-        unsigned long flags;
-        u64 new_xsec;
-        unsigned long tb_delta;
-
-        if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
-                return -EINVAL;
-
-        write_seqlock_irqsave(&xtime_lock, flags);
-
-        /*
-         * Updating the RTC is not the job of this code. If the time is
-         * stepped under NTP, the RTC will be updated after STA_UNSYNC
-         * is cleared.  Tools like clock/hwclock either copy the RTC
-         * to the system time, in which case there is no point in writing
-         * to the RTC again, or write to the RTC but then they don't call
-         * settimeofday to perform this operation.
-         */
-
-        /* Make userspace gettimeofday spin until we're done. */
-        ++vdso_data->tb_update_count;
-        smp_mb();
-
-        /*
-         * Subtract off the number of nanoseconds since the
-         * beginning of the last tick.
-         */
-        tb_delta = tb_ticks_since(tb_last_jiffy);
-        tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */
-        new_nsec -= SCALE_XSEC(tb_delta, 1000000000);
-
-        wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);
-        wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
-
-        set_normalized_timespec(&xtime, new_sec, new_nsec);
-        set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
-
-        ntp_clear();
-
-        new_xsec = xtime.tv_nsec;
-        if (new_xsec != 0) {
-                new_xsec *= XSEC_PER_SEC;
-                do_div(new_xsec, NSEC_PER_SEC);
-        }
-        new_xsec += (u64)xtime.tv_sec * XSEC_PER_SEC;
-        update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs);
-
-        vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
-        vdso_data->tz_dsttime = sys_tz.tz_dsttime;
-
-        write_sequnlock_irqrestore(&xtime_lock, flags);
-        clock_was_set();
-        return 0;
-}
-
-EXPORT_SYMBOL(do_settimeofday);
-
 static int __init get_freq(char *name, int cells, unsigned long *val)
 {
         struct device_node *cpu;
@@ -873,6 +732,69 @@ unsigned long read_persistent_clock(void)
                       tm.tm_hour, tm.tm_min, tm.tm_sec);
 }
 
+/* clocksource code */
+static cycle_t rtc_read(void)
+{
+        return (cycle_t)get_rtc();
+}
+
+static cycle_t timebase_read(void)
+{
+        return (cycle_t)get_tb();
+}
+
+void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
+{
+        u64 t2x, stamp_xsec;
+
+        if (clock != &clocksource_timebase)
+                return;
+
+        /* Make userspace gettimeofday spin until we're done. */
+        ++vdso_data->tb_update_count;
+        smp_mb();
+
+        /* XXX this assumes clock->shift == 22 */
+        /* 4611686018 ~= 2^(20+64-22) / 1e9 */
+        t2x = (u64) clock->mult * 4611686018ULL;
+        stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
+        do_div(stamp_xsec, 1000000000);
+        stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
+        update_gtod(clock->cycle_last, stamp_xsec, t2x);
+}
+
+void update_vsyscall_tz(void)
+{
+        /* Make userspace gettimeofday spin until we're done. */
+        ++vdso_data->tb_update_count;
+        smp_mb();
+        vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
+        vdso_data->tz_dsttime = sys_tz.tz_dsttime;
+        smp_mb();
+        ++vdso_data->tb_update_count;
+}
+
+void __init clocksource_init(void)
+{
+        struct clocksource *clock;
+
+        if (__USE_RTC())
+                clock = &clocksource_rtc;
+        else
+                clock = &clocksource_timebase;
+
+        clock->mult = clocksource_hz2mult(tb_ticks_per_sec, clock->shift);
+
+        if (clocksource_register(clock)) {
+                printk(KERN_ERR "clocksource: %s is already registered\n",
+                       clock->name);
+                return;
+        }
+
+        printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
+               clock->name, clock->mult, clock->shift);
+}
+
 /* This function is only called on the boot processor */
 void __init time_init(void)
 {
@@ -982,6 +904,10 @@ void __init time_init(void)
 
         write_sequnlock_irqrestore(&xtime_lock, flags);
 
+        /* Register the clocksource, if we're not running on iSeries */
+        if (!firmware_has_feature(FW_FEATURE_ISERIES))
+                clocksource_init();
+
         /* Not exact, but the timer interrupt takes care of this */
         set_dec(tb_ticks_per_jiffy);
 }