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@@ -11,6 +11,7 @@
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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+#include <linux/clocksource.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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@@ -67,15 +68,9 @@ int (*rtc_mips_set_time)(unsigned long) = null_rtc_set_time;
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int (*rtc_mips_set_mmss)(unsigned long);
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-/* usecs per counter cycle, shifted to left by 32 bits */
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-static unsigned int sll32_usecs_per_cycle;
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-
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/* how many counter cycles in a jiffy */
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static unsigned long cycles_per_jiffy __read_mostly;
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-/* Cycle counter value at the previous timer interrupt.. */
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-static unsigned int timerhi, timerlo;
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-
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/* expirelo is the count value for next CPU timer interrupt */
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static unsigned int expirelo;
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@@ -93,7 +88,7 @@ static unsigned int null_hpt_read(void)
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return 0;
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}
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-static void null_hpt_init(unsigned int count)
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+static void __init null_hpt_init(void)
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{
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/* nothing */
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}
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@@ -128,186 +123,18 @@ static unsigned int c0_hpt_read(void)
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return read_c0_count();
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}
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-/* For use solely as a high precision timer. */
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-static void c0_hpt_init(unsigned int count)
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-{
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- write_c0_count(read_c0_count() - count);
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-}
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-
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/* For use both as a high precision timer and an interrupt source. */
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-static void c0_hpt_timer_init(unsigned int count)
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+static void __init c0_hpt_timer_init(void)
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{
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- count = read_c0_count() - count;
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- expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
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- write_c0_count(expirelo - cycles_per_jiffy);
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+ expirelo = read_c0_count() + cycles_per_jiffy;
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write_c0_compare(expirelo);
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- write_c0_count(count);
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}
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int (*mips_timer_state)(void);
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void (*mips_timer_ack)(void);
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unsigned int (*mips_hpt_read)(void);
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-void (*mips_hpt_init)(unsigned int);
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-
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-/*
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- * Gettimeoffset routines. These routines returns the time duration
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- * since last timer interrupt in usecs.
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- *
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- * If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
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- * Otherwise use calibrate_gettimeoffset()
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- *
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- * If the CPU does not have the counter register, you can either supply
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- * your own gettimeoffset() routine, or use null_gettimeoffset(), which
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- * gives the same resolution as HZ.
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- */
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-
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-static unsigned long null_gettimeoffset(void)
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-{
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- return 0;
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-}
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-
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-
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-/* The function pointer to one of the gettimeoffset funcs. */
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-unsigned long (*do_gettimeoffset)(void) = null_gettimeoffset;
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-
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-
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-static unsigned long fixed_rate_gettimeoffset(void)
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-{
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- u32 count;
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- unsigned long res;
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-
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- /* Get last timer tick in absolute kernel time */
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- count = mips_hpt_read();
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-
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- /* .. relative to previous jiffy (32 bits is enough) */
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- count -= timerlo;
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-
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- __asm__("multu %1,%2"
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- : "=h" (res)
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- : "r" (count), "r" (sll32_usecs_per_cycle)
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- : "lo", GCC_REG_ACCUM);
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-
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- /*
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- * Due to possible jiffies inconsistencies, we need to check
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- * the result so that we'll get a timer that is monotonic.
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- */
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- if (res >= USECS_PER_JIFFY)
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- res = USECS_PER_JIFFY - 1;
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-
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- return res;
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-}
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-
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-
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-/*
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- * Cached "1/(clocks per usec) * 2^32" value.
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- * It has to be recalculated once each jiffy.
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- */
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-static unsigned long cached_quotient;
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-
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-/* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
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-static unsigned long last_jiffies;
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-
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-/*
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- * This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
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- */
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-static unsigned long calibrate_div32_gettimeoffset(void)
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-{
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- u32 count;
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- unsigned long res, tmp;
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- unsigned long quotient;
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-
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- tmp = jiffies;
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-
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- quotient = cached_quotient;
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-
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- if (last_jiffies != tmp) {
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- last_jiffies = tmp;
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- if (last_jiffies != 0) {
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- unsigned long r0;
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- do_div64_32(r0, timerhi, timerlo, tmp);
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- do_div64_32(quotient, USECS_PER_JIFFY,
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- USECS_PER_JIFFY_FRAC, r0);
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- cached_quotient = quotient;
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- }
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- }
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-
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- /* Get last timer tick in absolute kernel time */
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- count = mips_hpt_read();
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-
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- /* .. relative to previous jiffy (32 bits is enough) */
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- count -= timerlo;
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-
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- __asm__("multu %1,%2"
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- : "=h" (res)
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- : "r" (count), "r" (quotient)
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- : "lo", GCC_REG_ACCUM);
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-
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- /*
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- * Due to possible jiffies inconsistencies, we need to check
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- * the result so that we'll get a timer that is monotonic.
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- */
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- if (res >= USECS_PER_JIFFY)
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- res = USECS_PER_JIFFY - 1;
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-
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- return res;
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-}
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-
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-static unsigned long calibrate_div64_gettimeoffset(void)
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-{
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- u32 count;
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- unsigned long res, tmp;
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- unsigned long quotient;
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-
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- tmp = jiffies;
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-
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- quotient = cached_quotient;
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-
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- if (last_jiffies != tmp) {
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- last_jiffies = tmp;
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- if (last_jiffies) {
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- unsigned long r0;
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- __asm__(".set push\n\t"
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- ".set mips3\n\t"
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- "lwu %0,%3\n\t"
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- "dsll32 %1,%2,0\n\t"
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- "or %1,%1,%0\n\t"
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- "ddivu $0,%1,%4\n\t"
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- "mflo %1\n\t"
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- "dsll32 %0,%5,0\n\t"
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- "or %0,%0,%6\n\t"
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- "ddivu $0,%0,%1\n\t"
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- "mflo %0\n\t"
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- ".set pop"
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- : "=&r" (quotient), "=&r" (r0)
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- : "r" (timerhi), "m" (timerlo),
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- "r" (tmp), "r" (USECS_PER_JIFFY),
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- "r" (USECS_PER_JIFFY_FRAC)
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- : "hi", "lo", GCC_REG_ACCUM);
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- cached_quotient = quotient;
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- }
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- }
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-
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- /* Get last timer tick in absolute kernel time */
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- count = mips_hpt_read();
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-
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- /* .. relative to previous jiffy (32 bits is enough) */
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- count -= timerlo;
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-
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- __asm__("multu %1,%2"
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- : "=h" (res)
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- : "r" (count), "r" (quotient)
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- : "lo", GCC_REG_ACCUM);
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-
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- /*
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- * Due to possible jiffies inconsistencies, we need to check
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- * the result so that we'll get a timer that is monotonic.
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- */
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- if (res >= USECS_PER_JIFFY)
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- res = USECS_PER_JIFFY - 1;
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-
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- return res;
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-}
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-
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+void (*mips_hpt_init)(void) __initdata = null_hpt_init;
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+unsigned int mips_hpt_mask = 0xffffffff;
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/* last time when xtime and rtc are sync'ed up */
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static long last_rtc_update;
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@@ -334,18 +161,10 @@ void local_timer_interrupt(int irq, void *dev_id)
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*/
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irqreturn_t timer_interrupt(int irq, void *dev_id)
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{
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- unsigned long j;
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- unsigned int count;
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-
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write_seqlock(&xtime_lock);
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- count = mips_hpt_read();
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mips_timer_ack();
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- /* Update timerhi/timerlo for intra-jiffy calibration. */
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- timerhi += count < timerlo; /* Wrap around */
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- timerlo = count;
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-
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/*
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* call the generic timer interrupt handling
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*/
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@@ -368,47 +187,6 @@ irqreturn_t timer_interrupt(int irq, void *dev_id)
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}
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}
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- /*
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- * If jiffies has overflown in this timer_interrupt, we must
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- * update the timer[hi]/[lo] to make fast gettimeoffset funcs
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- * quotient calc still valid. -arca
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- *
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- * The first timer interrupt comes late as interrupts are
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- * enabled long after timers are initialized. Therefore the
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- * high precision timer is fast, leading to wrong gettimeoffset()
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- * calculations. We deal with it by setting it based on the
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- * number of its ticks between the second and the third interrupt.
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- * That is still somewhat imprecise, but it's a good estimate.
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- * --macro
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- */
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- j = jiffies;
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- if (j < 4) {
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- static unsigned int prev_count;
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- static int hpt_initialized;
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-
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- switch (j) {
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- case 0:
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- timerhi = timerlo = 0;
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- mips_hpt_init(count);
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- break;
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- case 2:
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- prev_count = count;
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- break;
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- case 3:
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- if (!hpt_initialized) {
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- unsigned int c3 = 3 * (count - prev_count);
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-
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- timerhi = 0;
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- timerlo = c3;
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- mips_hpt_init(count - c3);
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- hpt_initialized = 1;
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- }
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- break;
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- default:
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- break;
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- }
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- }
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-
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write_sequnlock(&xtime_lock);
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/*
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@@ -476,12 +254,11 @@ asmlinkage void ll_local_timer_interrupt(int irq)
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* 1) board_time_init() -
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* a) (optional) set up RTC routines,
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* b) (optional) calibrate and set the mips_hpt_frequency
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- * (only needed if you intended to use fixed_rate_gettimeoffset
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- * or use cpu counter as timer interrupt source)
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+ * (only needed if you intended to use cpu counter as timer interrupt
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+ * source)
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* 2) setup xtime based on rtc_mips_get_time().
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- * 3) choose a appropriate gettimeoffset routine.
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- * 4) calculate a couple of cached variables for later usage
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- * 5) plat_timer_setup() -
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+ * 3) calculate a couple of cached variables for later usage
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+ * 4) plat_timer_setup() -
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* a) (optional) over-write any choices made above by time_init().
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* b) machine specific code should setup the timer irqaction.
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* c) enable the timer interrupt
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@@ -533,13 +310,48 @@ static unsigned int __init calibrate_hpt(void)
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} while (--i);
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hpt_end = mips_hpt_read();
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- hpt_count = hpt_end - hpt_start;
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+ hpt_count = (hpt_end - hpt_start) & mips_hpt_mask;
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hz = HZ;
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frequency = (u64)hpt_count * (u64)hz;
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return frequency >> log_2_loops;
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}
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+static cycle_t read_mips_hpt(void)
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+{
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+ return (cycle_t)mips_hpt_read();
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+}
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+
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+static struct clocksource clocksource_mips = {
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+ .name = "MIPS",
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+ .read = read_mips_hpt,
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+ .is_continuous = 1,
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+};
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+
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+static void __init init_mips_clocksource(void)
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+{
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+ u64 temp;
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+ u32 shift;
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+
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+ if (!mips_hpt_frequency || mips_hpt_read == null_hpt_read)
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+ return;
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+
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+ /* Calclate a somewhat reasonable rating value */
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+ clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
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+ /* Find a shift value */
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+ for (shift = 32; shift > 0; shift--) {
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+ temp = (u64) NSEC_PER_SEC << shift;
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+ do_div(temp, mips_hpt_frequency);
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+ if ((temp >> 32) == 0)
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+ break;
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+ }
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+ clocksource_mips.shift = shift;
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+ clocksource_mips.mult = (u32)temp;
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+ clocksource_mips.mask = mips_hpt_mask;
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+
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+ clocksource_register(&clocksource_mips);
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+}
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+
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void __init time_init(void)
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{
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if (board_time_init)
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@@ -555,41 +367,21 @@ void __init time_init(void)
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-xtime.tv_sec, -xtime.tv_nsec);
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/* Choose appropriate high precision timer routines. */
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- if (!cpu_has_counter && !mips_hpt_read) {
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+ if (!cpu_has_counter && !mips_hpt_read)
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/* No high precision timer -- sorry. */
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mips_hpt_read = null_hpt_read;
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- mips_hpt_init = null_hpt_init;
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- } else if (!mips_hpt_frequency && !mips_timer_state) {
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+ else if (!mips_hpt_frequency && !mips_timer_state) {
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/* A high precision timer of unknown frequency. */
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- if (!mips_hpt_read) {
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+ if (!mips_hpt_read)
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/* No external high precision timer -- use R4k. */
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mips_hpt_read = c0_hpt_read;
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- mips_hpt_init = c0_hpt_init;
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- }
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-
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- if (cpu_has_mips32r1 || cpu_has_mips32r2 ||
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- (current_cpu_data.isa_level == MIPS_CPU_ISA_I) ||
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- (current_cpu_data.isa_level == MIPS_CPU_ISA_II))
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- /*
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- * We need to calibrate the counter but we don't have
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- * 64-bit division.
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- */
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- do_gettimeoffset = calibrate_div32_gettimeoffset;
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- else
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- /*
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- * We need to calibrate the counter but we *do* have
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- * 64-bit division.
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- */
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- do_gettimeoffset = calibrate_div64_gettimeoffset;
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} else {
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/* We know counter frequency. Or we can get it. */
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if (!mips_hpt_read) {
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/* No external high precision timer -- use R4k. */
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mips_hpt_read = c0_hpt_read;
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- if (mips_timer_state)
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- mips_hpt_init = c0_hpt_init;
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- else {
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+ if (!mips_timer_state) {
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/* No external timer interrupt -- use R4k. */
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mips_hpt_init = c0_hpt_timer_init;
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mips_timer_ack = c0_timer_ack;
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@@ -598,16 +390,9 @@ void __init time_init(void)
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if (!mips_hpt_frequency)
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mips_hpt_frequency = calibrate_hpt();
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- do_gettimeoffset = fixed_rate_gettimeoffset;
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-
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/* Calculate cache parameters. */
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cycles_per_jiffy = (mips_hpt_frequency + HZ / 2) / HZ;
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- /* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq */
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- do_div64_32(sll32_usecs_per_cycle,
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- 1000000, mips_hpt_frequency / 2,
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- mips_hpt_frequency);
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-
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/* Report the high precision timer rate for a reference. */
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printk("Using %u.%03u MHz high precision timer.\n",
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((mips_hpt_frequency + 500) / 1000) / 1000,
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@@ -619,7 +404,7 @@ void __init time_init(void)
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mips_timer_ack = null_timer_ack;
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/* This sets up the high precision timer for the first interrupt. */
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- mips_hpt_init(mips_hpt_read());
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+ mips_hpt_init();
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/*
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* Call board specific timer interrupt setup.
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@@ -633,6 +418,8 @@ void __init time_init(void)
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* is not invoked accidentally.
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*/
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plat_timer_setup(&timer_irqaction);
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+
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+ init_mips_clocksource();
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}
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#define FEBRUARY 2
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Atsushi Nemoto