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authorAtsushi Nemoto <anemo@mba.ocn.ne.jp>2006-10-24 00:21:27 +0900
committerRalf Baechle <ralf@linux-mips.org>2006-10-31 20:13:23 +0000
commit16b7b2ac0148e839da86af8747b6fa4aad43a9b7 (patch)
tree93912ae2e9c64f71a8cca028677fd918b9edf0fa /arch/mips/kernel/time.c
parent70e46f48cb5933119712ee27945309a4bfc98282 (diff)
[MIPS] Fixup migration to GENERIC_TIME
Since we already moved to GENERIC_TIME, we should implement alternatives of old do_gettimeoffset routines to get sub-jiffies resolution from gettimeofday(). This patch includes: * MIPS clocksource support (based on works by Manish Lachwani). * remove unused gettimeoffset routines and related codes. * remove unised 64bit do_div64_32(). * simplify mips_hpt_init. (no argument needed, __init tag) * simplify c0_hpt_timer_init. (no need to write to c0_count) * remove some hpt_init routines. * mips_hpt_mask variable to specify bitmask of hpt value. * convert jmr3927_do_gettimeoffset to jmr3927_hpt_read. * convert ip27_do_gettimeoffset to ip27_hpt_read. * convert bcm1480_do_gettimeoffset to bcm1480_hpt_read. * simplify sb1250 hpt functions. (no need to subtract and shift) Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/time.c')
-rw-r--r--arch/mips/kernel/time.c319
1 files changed, 53 insertions, 266 deletions
diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c
index debe86c2f691..e535f86efa2f 100644
--- a/arch/mips/kernel/time.c
+++ b/arch/mips/kernel/time.c
@@ -11,6 +11,7 @@
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
+#include <linux/clocksource.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
@@ -67,15 +68,9 @@ int (*rtc_mips_set_time)(unsigned long) = null_rtc_set_time;
int (*rtc_mips_set_mmss)(unsigned long);
-/* usecs per counter cycle, shifted to left by 32 bits */
-static unsigned int sll32_usecs_per_cycle;
-
/* how many counter cycles in a jiffy */
static unsigned long cycles_per_jiffy __read_mostly;
-/* Cycle counter value at the previous timer interrupt.. */
-static unsigned int timerhi, timerlo;
-
/* expirelo is the count value for next CPU timer interrupt */
static unsigned int expirelo;
@@ -93,7 +88,7 @@ static unsigned int null_hpt_read(void)
return 0;
}
-static void null_hpt_init(unsigned int count)
+static void __init null_hpt_init(void)
{
/* nothing */
}
@@ -128,186 +123,18 @@ static unsigned int c0_hpt_read(void)
return read_c0_count();
}
-/* For use solely as a high precision timer. */
-static void c0_hpt_init(unsigned int count)
-{
- write_c0_count(read_c0_count() - count);
-}
-
/* For use both as a high precision timer and an interrupt source. */
-static void c0_hpt_timer_init(unsigned int count)
+static void __init c0_hpt_timer_init(void)
{
- count = read_c0_count() - count;
- expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
- write_c0_count(expirelo - cycles_per_jiffy);
+ expirelo = read_c0_count() + cycles_per_jiffy;
write_c0_compare(expirelo);
- write_c0_count(count);
}
int (*mips_timer_state)(void);
void (*mips_timer_ack)(void);
unsigned int (*mips_hpt_read)(void);
-void (*mips_hpt_init)(unsigned int);
-
-/*
- * Gettimeoffset routines. These routines returns the time duration
- * since last timer interrupt in usecs.
- *
- * If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
- * Otherwise use calibrate_gettimeoffset()
- *
- * If the CPU does not have the counter register, you can either supply
- * your own gettimeoffset() routine, or use null_gettimeoffset(), which
- * gives the same resolution as HZ.
- */
-
-static unsigned long null_gettimeoffset(void)
-{
- return 0;
-}
-
-
-/* The function pointer to one of the gettimeoffset funcs. */
-unsigned long (*do_gettimeoffset)(void) = null_gettimeoffset;
-
-
-static unsigned long fixed_rate_gettimeoffset(void)
-{
- u32 count;
- unsigned long res;
-
- /* Get last timer tick in absolute kernel time */
- count = mips_hpt_read();
-
- /* .. relative to previous jiffy (32 bits is enough) */
- count -= timerlo;
-
- __asm__("multu %1,%2"
- : "=h" (res)
- : "r" (count), "r" (sll32_usecs_per_cycle)
- : "lo", GCC_REG_ACCUM);
-
- /*
- * Due to possible jiffies inconsistencies, we need to check
- * the result so that we'll get a timer that is monotonic.
- */
- if (res >= USECS_PER_JIFFY)
- res = USECS_PER_JIFFY - 1;
-
- return res;
-}
-
-
-/*
- * Cached "1/(clocks per usec) * 2^32" value.
- * It has to be recalculated once each jiffy.
- */
-static unsigned long cached_quotient;
-
-/* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
-static unsigned long last_jiffies;
-
-/*
- * This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
- */
-static unsigned long calibrate_div32_gettimeoffset(void)
-{
- u32 count;
- unsigned long res, tmp;
- unsigned long quotient;
-
- tmp = jiffies;
-
- quotient = cached_quotient;
-
- if (last_jiffies != tmp) {
- last_jiffies = tmp;
- if (last_jiffies != 0) {
- unsigned long r0;
- do_div64_32(r0, timerhi, timerlo, tmp);
- do_div64_32(quotient, USECS_PER_JIFFY,
- USECS_PER_JIFFY_FRAC, r0);
- cached_quotient = quotient;
- }
- }
-
- /* Get last timer tick in absolute kernel time */
- count = mips_hpt_read();
-
- /* .. relative to previous jiffy (32 bits is enough) */
- count -= timerlo;
-
- __asm__("multu %1,%2"
- : "=h" (res)
- : "r" (count), "r" (quotient)
- : "lo", GCC_REG_ACCUM);
-
- /*
- * Due to possible jiffies inconsistencies, we need to check
- * the result so that we'll get a timer that is monotonic.
- */
- if (res >= USECS_PER_JIFFY)
- res = USECS_PER_JIFFY - 1;
-
- return res;
-}
-
-static unsigned long calibrate_div64_gettimeoffset(void)
-{
- u32 count;
- unsigned long res, tmp;
- unsigned long quotient;
-
- tmp = jiffies;
-
- quotient = cached_quotient;
-
- if (last_jiffies != tmp) {
- last_jiffies = tmp;
- if (last_jiffies) {
- unsigned long r0;
- __asm__(".set push\n\t"
- ".set mips3\n\t"
- "lwu %0,%3\n\t"
- "dsll32 %1,%2,0\n\t"
- "or %1,%1,%0\n\t"
- "ddivu $0,%1,%4\n\t"
- "mflo %1\n\t"
- "dsll32 %0,%5,0\n\t"
- "or %0,%0,%6\n\t"
- "ddivu $0,%0,%1\n\t"
- "mflo %0\n\t"
- ".set pop"
- : "=&r" (quotient), "=&r" (r0)
- : "r" (timerhi), "m" (timerlo),
- "r" (tmp), "r" (USECS_PER_JIFFY),
- "r" (USECS_PER_JIFFY_FRAC)
- : "hi", "lo", GCC_REG_ACCUM);
- cached_quotient = quotient;
- }
- }
-
- /* Get last timer tick in absolute kernel time */
- count = mips_hpt_read();
-
- /* .. relative to previous jiffy (32 bits is enough) */
- count -= timerlo;
-
- __asm__("multu %1,%2"
- : "=h" (res)
- : "r" (count), "r" (quotient)
- : "lo", GCC_REG_ACCUM);
-
- /*
- * Due to possible jiffies inconsistencies, we need to check
- * the result so that we'll get a timer that is monotonic.
- */
- if (res >= USECS_PER_JIFFY)
- res = USECS_PER_JIFFY - 1;
-
- return res;
-}
-
+void (*mips_hpt_init)(void) __initdata = null_hpt_init;
+unsigned int mips_hpt_mask = 0xffffffff;
/* last time when xtime and rtc are sync'ed up */
static long last_rtc_update;
@@ -334,18 +161,10 @@ void local_timer_interrupt(int irq, void *dev_id)
*/
irqreturn_t timer_interrupt(int irq, void *dev_id)
{
- unsigned long j;
- unsigned int count;
-
write_seqlock(&xtime_lock);
- count = mips_hpt_read();
mips_timer_ack();
- /* Update timerhi/timerlo for intra-jiffy calibration. */
- timerhi += count < timerlo; /* Wrap around */
- timerlo = count;
-
/*
* call the generic timer interrupt handling
*/
@@ -368,47 +187,6 @@ irqreturn_t timer_interrupt(int irq, void *dev_id)
}
}
- /*
- * If jiffies has overflown in this timer_interrupt, we must
- * update the timer[hi]/[lo] to make fast gettimeoffset funcs
- * quotient calc still valid. -arca
- *
- * The first timer interrupt comes late as interrupts are
- * enabled long after timers are initialized. Therefore the
- * high precision timer is fast, leading to wrong gettimeoffset()
- * calculations. We deal with it by setting it based on the
- * number of its ticks between the second and the third interrupt.
- * That is still somewhat imprecise, but it's a good estimate.
- * --macro
- */
- j = jiffies;
- if (j < 4) {
- static unsigned int prev_count;
- static int hpt_initialized;
-
- switch (j) {
- case 0:
- timerhi = timerlo = 0;
- mips_hpt_init(count);
- break;
- case 2:
- prev_count = count;
- break;
- case 3:
- if (!hpt_initialized) {
- unsigned int c3 = 3 * (count - prev_count);
-
- timerhi = 0;
- timerlo = c3;
- mips_hpt_init(count - c3);
- hpt_initialized = 1;
- }
- break;
- default:
- break;
- }
- }
-
write_sequnlock(&xtime_lock);
/*
@@ -476,12 +254,11 @@ asmlinkage void ll_local_timer_interrupt(int irq)
* 1) board_time_init() -
* a) (optional) set up RTC routines,
* b) (optional) calibrate and set the mips_hpt_frequency
- * (only needed if you intended to use fixed_rate_gettimeoffset
- * or use cpu counter as timer interrupt source)
+ * (only needed if you intended to use cpu counter as timer interrupt
+ * source)
* 2) setup xtime based on rtc_mips_get_time().
- * 3) choose a appropriate gettimeoffset routine.
- * 4) calculate a couple of cached variables for later usage
- * 5) plat_timer_setup() -
+ * 3) calculate a couple of cached variables for later usage
+ * 4) plat_timer_setup() -
* a) (optional) over-write any choices made above by time_init().
* b) machine specific code should setup the timer irqaction.
* c) enable the timer interrupt
@@ -533,13 +310,48 @@ static unsigned int __init calibrate_hpt(void)
} while (--i);
hpt_end = mips_hpt_read();
- hpt_count = hpt_end - hpt_start;
+ hpt_count = (hpt_end - hpt_start) & mips_hpt_mask;
hz = HZ;
frequency = (u64)hpt_count * (u64)hz;
return frequency >> log_2_loops;
}
+static cycle_t read_mips_hpt(void)
+{
+ return (cycle_t)mips_hpt_read();
+}
+
+static struct clocksource clocksource_mips = {
+ .name = "MIPS",
+ .read = read_mips_hpt,
+ .is_continuous = 1,
+};
+
+static void __init init_mips_clocksource(void)
+{
+ u64 temp;
+ u32 shift;
+
+ if (!mips_hpt_frequency || mips_hpt_read == null_hpt_read)
+ return;
+
+ /* Calclate a somewhat reasonable rating value */
+ clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
+ /* Find a shift value */
+ for (shift = 32; shift > 0; shift--) {
+ temp = (u64) NSEC_PER_SEC << shift;
+ do_div(temp, mips_hpt_frequency);
+ if ((temp >> 32) == 0)
+ break;
+ }
+ clocksource_mips.shift = shift;
+ clocksource_mips.mult = (u32)temp;
+ clocksource_mips.mask = mips_hpt_mask;
+
+ clocksource_register(&clocksource_mips);
+}
+
void __init time_init(void)
{
if (board_time_init)
@@ -555,41 +367,21 @@ void __init time_init(void)
-xtime.tv_sec, -xtime.tv_nsec);
/* Choose appropriate high precision timer routines. */
- if (!cpu_has_counter && !mips_hpt_read) {
+ if (!cpu_has_counter && !mips_hpt_read)
/* No high precision timer -- sorry. */
mips_hpt_read = null_hpt_read;
- mips_hpt_init = null_hpt_init;
- } else if (!mips_hpt_frequency && !mips_timer_state) {
+ else if (!mips_hpt_frequency && !mips_timer_state) {
/* A high precision timer of unknown frequency. */
- if (!mips_hpt_read) {
+ if (!mips_hpt_read)
/* No external high precision timer -- use R4k. */
mips_hpt_read = c0_hpt_read;
- mips_hpt_init = c0_hpt_init;
- }
-
- if (cpu_has_mips32r1 || cpu_has_mips32r2 ||
- (current_cpu_data.isa_level == MIPS_CPU_ISA_I) ||
- (current_cpu_data.isa_level == MIPS_CPU_ISA_II))
- /*
- * We need to calibrate the counter but we don't have
- * 64-bit division.
- */
- do_gettimeoffset = calibrate_div32_gettimeoffset;
- else
- /*
- * We need to calibrate the counter but we *do* have
- * 64-bit division.
- */
- do_gettimeoffset = calibrate_div64_gettimeoffset;
} else {
/* We know counter frequency. Or we can get it. */
if (!mips_hpt_read) {
/* No external high precision timer -- use R4k. */
mips_hpt_read = c0_hpt_read;
- if (mips_timer_state)
- mips_hpt_init = c0_hpt_init;
- else {
+ if (!mips_timer_state) {
/* No external timer interrupt -- use R4k. */
mips_hpt_init = c0_hpt_timer_init;
mips_timer_ack = c0_timer_ack;
@@ -598,16 +390,9 @@ void __init time_init(void)
if (!mips_hpt_frequency)
mips_hpt_frequency = calibrate_hpt();
- do_gettimeoffset = fixed_rate_gettimeoffset;
-
/* Calculate cache parameters. */
cycles_per_jiffy = (mips_hpt_frequency + HZ / 2) / HZ;
- /* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq */
- do_div64_32(sll32_usecs_per_cycle,
- 1000000, mips_hpt_frequency / 2,
- mips_hpt_frequency);
-
/* Report the high precision timer rate for a reference. */
printk("Using %u.%03u MHz high precision timer.\n",
((mips_hpt_frequency + 500) / 1000) / 1000,
@@ -619,7 +404,7 @@ void __init time_init(void)
mips_timer_ack = null_timer_ack;
/* This sets up the high precision timer for the first interrupt. */
- mips_hpt_init(mips_hpt_read());
+ mips_hpt_init();
/*
* Call board specific timer interrupt setup.
@@ -633,6 +418,8 @@ void __init time_init(void)
* is not invoked accidentally.
*/
plat_timer_setup(&timer_irqaction);
+
+ init_mips_clocksource();
}
#define FEBRUARY 2

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