1 files changed, 132 insertions, 0 deletions

diff --git a/arch/v850/kernel/highres_timer.c b/arch/v850/kernel/highres_timer.c
new file mode 100644
index 000000000000..b16ad1eaf966
--- /dev/null
+++ b/arch/v850/kernel/highres_timer.c
@@ -0,0 +1,132 @@
+/*
+ * arch/v850/kernel/highres_timer.c -- High resolution timing routines
+ *
+ *  Copyright (C) 2001,02,03  NEC Electronics Corporation
+ *  Copyright (C) 2001,02,03  Miles Bader <miles@gnu.org>
+ *
+ * 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.
+ *
+ * Written by Miles Bader <miles@gnu.org>
+ */
+
+#include <asm/system.h>
+#include <asm/v850e_timer_d.h>
+#include <asm/highres_timer.h>
+
+#define HIGHRES_TIMER_USEC_SHIFT   12
+
+/* Pre-calculated constant used for converting ticks to real time
+   units.  We initialize it to prevent it being put into BSS.  */
+static u32 highres_timer_usec_prescale = 1;
+
+void highres_timer_slow_tick_irq (void) __attribute__ ((noreturn));
+void highres_timer_slow_tick_irq (void)
+{
+        /* This is an interrupt handler, so it must be very careful to
+           not to trash any registers.  At this point, the stack-pointer
+           (r3) has been saved in the chip ram location ENTRY_SP by the
+           interrupt vector, so we can use it as a scratch register; we
+           must also restore it before returning.  */
+        asm ("ld.w      %0[r0], sp;"
+             "add       1, sp;"
+             "st.w      sp, %0[r0];"
+             "ld.w      %1[r0], sp;" /* restore pre-irq stack-pointer */
+             "reti"
+             ::
+              "i" (HIGHRES_TIMER_SLOW_TICKS_ADDR),
+              "i" (ENTRY_SP_ADDR)
+             : "memory");
+}
+
+void highres_timer_reset (void)
+{
+        V850E_TIMER_D_TMD (HIGHRES_TIMER_TIMER_D_UNIT) = 0;
+        HIGHRES_TIMER_SLOW_TICKS = 0;
+}
+
+void highres_timer_start (void)
+{
+        u32 fast_tick_rate;
+
+        /* Start hardware timer.  */
+        v850e_timer_d_configure (HIGHRES_TIMER_TIMER_D_UNIT,
+                                 HIGHRES_TIMER_SLOW_TICK_RATE);
+
+        fast_tick_rate =
+                (V850E_TIMER_D_BASE_FREQ
+                 >> V850E_TIMER_D_DIVLOG2 (HIGHRES_TIMER_TIMER_D_UNIT));
+
+        /* The obvious way of calculating microseconds from fast ticks
+           is to do:
+
+             usec = fast_ticks * 10^6 / fast_tick_rate
+
+           However, divisions are much slower than multiplications, and
+           the above calculation can overflow, so we do this instead:
+
+             usec = fast_ticks * (10^6 * 2^12 / fast_tick_rate) / 2^12
+
+           since we can pre-calculate (10^6 * (2^12 / fast_tick_rate))
+           and use a shift for dividing by 2^12, this avoids division,
+           and is almost as accurate (it differs by about 2 microseconds
+           at the extreme value of the fast-tick counter's ranger).  */
+        highres_timer_usec_prescale = ((1000000 << HIGHRES_TIMER_USEC_SHIFT)
+                                       / fast_tick_rate);
+
+        /* Enable the interrupt (which is hardwired to this use), and
+           give it the highest priority.  */
+        V850E_INTC_IC (IRQ_INTCMD (HIGHRES_TIMER_TIMER_D_UNIT)) = 0;
+}
+
+void highres_timer_stop (void)
+{
+        /* Stop the timer.  */
+        V850E_TIMER_D_TMCD (HIGHRES_TIMER_TIMER_D_UNIT) =
+                V850E_TIMER_D_TMCD_CAE;
+        /* Disable its interrupt, just in case.  */
+        v850e_intc_disable_irq (IRQ_INTCMD (HIGHRES_TIMER_TIMER_D_UNIT));
+}
+
+inline void highres_timer_read_ticks (u32 *slow_ticks, u32 *fast_ticks)
+{
+        int flags;
+        u32 fast_ticks_1, fast_ticks_2, _slow_ticks;
+
+        local_irq_save (flags);
+        fast_ticks_1 = V850E_TIMER_D_TMD (HIGHRES_TIMER_TIMER_D_UNIT);
+        _slow_ticks = HIGHRES_TIMER_SLOW_TICKS;
+        fast_ticks_2 = V850E_TIMER_D_TMD (HIGHRES_TIMER_TIMER_D_UNIT);
+        local_irq_restore (flags);
+
+        if (fast_ticks_2 < fast_ticks_1)
+                _slow_ticks++;
+
+        *slow_ticks = _slow_ticks;
+        *fast_ticks = fast_ticks_2;
+}
+
+inline void highres_timer_ticks_to_timeval (u32 slow_ticks, u32 fast_ticks,
+                                            struct timeval *tv)
+{
+        unsigned long sec, sec_rem, usec;
+
+        usec = ((fast_ticks * highres_timer_usec_prescale)
+                >> HIGHRES_TIMER_USEC_SHIFT);
+
+        sec = slow_ticks / HIGHRES_TIMER_SLOW_TICK_RATE;
+        sec_rem = slow_ticks % HIGHRES_TIMER_SLOW_TICK_RATE;
+
+        usec += sec_rem * (1000000 / HIGHRES_TIMER_SLOW_TICK_RATE);
+
+        tv->tv_sec = sec;
+        tv->tv_usec = usec;
+}
+
+void highres_timer_read (struct timeval *tv)
+{
+        u32 fast_ticks, slow_ticks;
+        highres_timer_read_ticks (&slow_ticks, &fast_ticks);
+        highres_timer_ticks_to_timeval (slow_ticks, fast_ticks, tv);
+}