[POWERPC] Implement generic time of day clocksource for powerpc
authorTony Breeds <tony@bakeyournoodle.com>
Fri, 21 Sep 2007 21:35:52 +0000 (07:35 +1000)
committerPaul Mackerras <paulus@samba.org>
Wed, 3 Oct 2007 01:48:42 +0000 (11:48 +1000)
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
arch/powerpc/Kconfig
arch/powerpc/kernel/time.c

index 6468cd9..6819a94 100644 (file)
@@ -29,6 +29,12 @@ config MMU
 config GENERIC_CMOS_UPDATE
        def_bool y
 
+config GENERIC_TIME
+       def_bool y
+
+config GENERIC_TIME_VSYSCALL
+       def_bool y
+
 config GENERIC_HARDIRQS
        bool
        default y
index b94e4df..e71a0d8 100644 (file)
 #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);
 }