diff options
Diffstat (limited to 'arch/mips/kernel/time.c')
| -rw-r--r-- | arch/mips/kernel/time.c | 319 |
1 files changed, 53 insertions, 266 deletions
diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c index debe86c2f69..e535f86efa2 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 |