timers: Add CLOCK_BOOTTIME hrtimer base

CLOCK_MONOTONIC stops while the system is in suspend. This is because
to applications system suspend is invisible. However, there is a
growing set of applications that are wanting to be suspend-aware,
but do not want to deal with the complications of CLOCK_REALTIME
(which might jump around if settimeofday is called).

For these applications, I propose a new clockid: CLOCK_BOOTTIME.
CLOCK_BOOTTIME is idential to CLOCK_MONOTONIC, except it also
includes any time spent in suspend.

This patch add hrtimer base for CLOCK_BOOTTIME, using
get_monotonic_boottime/ktime_get_boottime, to allow
in kernel users to set timers against.

CC: Jamie Lokier <jamie@shareable.org>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Alexander Shishkin <virtuoso@slind.org>
CC: Arve Hjønnevåg <arve@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 12 insertions, 4 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index e8bf3ad99063..4c53af18734b 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -73,6 +73,11 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
                         .get_time = &ktime_get,
                         .resolution = KTIME_LOW_RES,
                 },
+                {
+                        .index = CLOCK_BOOTTIME,
+                        .get_time = &ktime_get_boottime,
+                        .resolution = KTIME_LOW_RES,
+                },
         }
 };
 
@@ -90,16 +95,17 @@ static inline int hrtimer_clockid_to_base(clockid_t clock_id)
  */
 static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)
 {
-        ktime_t xtim, tomono;
+        ktime_t xtim, mono, boot;
         struct timespec xts, tom, slp;
 
         get_xtime_and_monotonic_and_sleep_offset(&xts, &tom, &slp);
 
         xtim = timespec_to_ktime(xts);
-        tomono = timespec_to_ktime(tom);
+        mono = ktime_add(xtim, timespec_to_ktime(tom));
+        boot = ktime_add(mono, timespec_to_ktime(slp));
         base->clock_base[HRTIMER_BASE_REALTIME].softirq_time = xtim;
-        base->clock_base[HRTIMER_BASE_MONOTONIC].softirq_time =
-                ktime_add(xtim, tomono);
+        base->clock_base[HRTIMER_BASE_MONOTONIC].softirq_time = mono;
+        base->clock_base[HRTIMER_BASE_BOOTTIME].softirq_time = boot;
 }
 
 /*
@@ -727,6 +733,7 @@ static int hrtimer_switch_to_hres(void)
         base->hres_active = 1;
         base->clock_base[HRTIMER_BASE_REALTIME].resolution = KTIME_HIGH_RES;
         base->clock_base[HRTIMER_BASE_MONOTONIC].resolution = KTIME_HIGH_RES;
+        base->clock_base[HRTIMER_BASE_BOOTTIME].resolution = KTIME_HIGH_RES;
 
         tick_setup_sched_timer();
 
@@ -1719,6 +1726,7 @@ void __init hrtimers_init(void)
 {
         hrtimer_clock_to_base_table[CLOCK_REALTIME] = HRTIMER_BASE_REALTIME;
         hrtimer_clock_to_base_table[CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC;
+        hrtimer_clock_to_base_table[CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME;
 
         hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
                           (void *)(long)smp_processor_id());