diff options
Diffstat (limited to 'arch/arm/kernel/sched_clock.c')
-rw-r--r-- | arch/arm/kernel/sched_clock.c | 216 |
1 files changed, 0 insertions, 216 deletions
diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c deleted file mode 100644 index a781c59..0000000 --- a/arch/arm/kernel/sched_clock.c +++ /dev/null @@ -1,216 +0,0 @@ -/* - * sched_clock.c: support for extending counters to full 64-bit ns counter - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - */ -#include <linux/clocksource.h> -#include <linux/init.h> -#include <linux/jiffies.h> -#include <linux/kernel.h> -#include <linux/moduleparam.h> -#include <linux/sched.h> -#include <linux/syscore_ops.h> -#include <linux/timer.h> - -#include <asm/sched_clock.h> - -struct clock_data { - u64 epoch_ns; - u32 epoch_cyc; - u32 epoch_cyc_copy; - unsigned long rate; - u32 mult; - u32 shift; - bool suspended; -}; - -static void sched_clock_poll(unsigned long wrap_ticks); -static DEFINE_TIMER(sched_clock_timer, sched_clock_poll, 0, 0); -static int irqtime = -1; - -core_param(irqtime, irqtime, int, 0400); - -static struct clock_data cd = { - .mult = NSEC_PER_SEC / HZ, -}; - -static u32 __read_mostly sched_clock_mask = 0xffffffff; - -static u32 notrace jiffy_sched_clock_read(void) -{ - return (u32)(jiffies - INITIAL_JIFFIES); -} - -static u32 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read; - -static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift) -{ - return (cyc * mult) >> shift; -} - -static unsigned long long notrace cyc_to_sched_clock(u32 cyc, u32 mask) -{ - u64 epoch_ns; - u32 epoch_cyc; - - /* - * Load the epoch_cyc and epoch_ns atomically. We do this by - * ensuring that we always write epoch_cyc, epoch_ns and - * epoch_cyc_copy in strict order, and read them in strict order. - * If epoch_cyc and epoch_cyc_copy are not equal, then we're in - * the middle of an update, and we should repeat the load. - */ - do { - epoch_cyc = cd.epoch_cyc; - smp_rmb(); - epoch_ns = cd.epoch_ns; - smp_rmb(); - } while (epoch_cyc != cd.epoch_cyc_copy); - - return epoch_ns + cyc_to_ns((cyc - epoch_cyc) & mask, cd.mult, cd.shift); -} - -/* - * Atomically update the sched_clock epoch. - */ -static void notrace update_sched_clock(void) -{ - unsigned long flags; - u32 cyc; - u64 ns; - - cyc = read_sched_clock(); - ns = cd.epoch_ns + - cyc_to_ns((cyc - cd.epoch_cyc) & sched_clock_mask, - cd.mult, cd.shift); - /* - * Write epoch_cyc and epoch_ns in a way that the update is - * detectable in cyc_to_fixed_sched_clock(). - */ - raw_local_irq_save(flags); - cd.epoch_cyc_copy = cyc; - smp_wmb(); - cd.epoch_ns = ns; - smp_wmb(); - cd.epoch_cyc = cyc; - raw_local_irq_restore(flags); -} - -static void sched_clock_poll(unsigned long wrap_ticks) -{ - mod_timer(&sched_clock_timer, round_jiffies(jiffies + wrap_ticks)); - update_sched_clock(); -} - -void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) -{ - unsigned long r, w; - u64 res, wrap; - char r_unit; - - if (cd.rate > rate) - return; - - BUG_ON(bits > 32); - WARN_ON(!irqs_disabled()); - read_sched_clock = read; - sched_clock_mask = (1 << bits) - 1; - cd.rate = rate; - - /* calculate the mult/shift to convert counter ticks to ns. */ - clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 0); - - r = rate; - if (r >= 4000000) { - r /= 1000000; - r_unit = 'M'; - } else if (r >= 1000) { - r /= 1000; - r_unit = 'k'; - } else - r_unit = ' '; - - /* calculate how many ns until we wrap */ - wrap = cyc_to_ns((1ULL << bits) - 1, cd.mult, cd.shift); - do_div(wrap, NSEC_PER_MSEC); - w = wrap; - - /* calculate the ns resolution of this counter */ - res = cyc_to_ns(1ULL, cd.mult, cd.shift); - pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lums\n", - bits, r, r_unit, res, w); - - /* - * Start the timer to keep sched_clock() properly updated and - * sets the initial epoch. - */ - sched_clock_timer.data = msecs_to_jiffies(w - (w / 10)); - update_sched_clock(); - - /* - * Ensure that sched_clock() starts off at 0ns - */ - cd.epoch_ns = 0; - - /* Enable IRQ time accounting if we have a fast enough sched_clock */ - if (irqtime > 0 || (irqtime == -1 && rate >= 1000000)) - enable_sched_clock_irqtime(); - - pr_debug("Registered %pF as sched_clock source\n", read); -} - -static unsigned long long notrace sched_clock_32(void) -{ - u32 cyc = read_sched_clock(); - return cyc_to_sched_clock(cyc, sched_clock_mask); -} - -unsigned long long __read_mostly (*sched_clock_func)(void) = sched_clock_32; - -unsigned long long notrace sched_clock(void) -{ - if (cd.suspended) - return cd.epoch_ns; - - return sched_clock_func(); -} - -void __init sched_clock_postinit(void) -{ - /* - * If no sched_clock function has been provided at that point, - * make it the final one one. - */ - if (read_sched_clock == jiffy_sched_clock_read) - setup_sched_clock(jiffy_sched_clock_read, 32, HZ); - - sched_clock_poll(sched_clock_timer.data); -} - -static int sched_clock_suspend(void) -{ - sched_clock_poll(sched_clock_timer.data); - cd.suspended = true; - return 0; -} - -static void sched_clock_resume(void) -{ - cd.epoch_cyc = read_sched_clock(); - cd.epoch_cyc_copy = cd.epoch_cyc; - cd.suspended = false; -} - -static struct syscore_ops sched_clock_ops = { - .suspend = sched_clock_suspend, - .resume = sched_clock_resume, -}; - -static int __init sched_clock_syscore_init(void) -{ - register_syscore_ops(&sched_clock_ops); - return 0; -} -device_initcall(sched_clock_syscore_init); |