ARM timekeeping functionality allows to register persistent/boot clock
dynamically.
This code is arch-independent and can be useful on other plaforms as well.
As a byproduct of this change, tegra20_timer becomes ARM64 compatible.
Tested: backported the change to chromeos-3.14 kernel ran on tegra 64bit
board, made sure high-resolution clock works.
Signed-off-by: Anatol Pomozov <anatol.pomo...@gmail.com>
---
arch/arm/include/asm/mach/time.h | 5 -----
arch/arm/kernel/time.c | 36 -------------------------------
arch/arm/plat-omap/counter_32k.c | 9 +++++---
drivers/clocksource/tegra20_timer.c | 10 +++++----
include/linux/timekeeping.h | 11 ++++++++++
kernel/time/timekeeping.c | 43 +++++++++++++++++++++++++++++++++----
6 files changed, 62 insertions(+), 52 deletions(-)
diff --git a/arch/arm/include/asm/mach/time.h b/arch/arm/include/asm/mach/time.h
index 90c12e1..3cbcafc 100644
--- a/arch/arm/include/asm/mach/time.h
+++ b/arch/arm/include/asm/mach/time.h
@@ -12,9 +12,4 @@
extern void timer_tick(void);
-struct timespec;
-typedef void (*clock_access_fn)(struct timespec *);
-extern int register_persistent_clock(clock_access_fn read_boot,
- clock_access_fn read_persistent);
-
#endif
diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c
index 0cc7e58..0aa1dcd 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -76,42 +76,6 @@ void timer_tick(void)
}
#endif
-static void dummy_clock_access(struct timespec *ts)
-{
- ts->tv_sec = 0;
- ts->tv_nsec = 0;
-}
-
-static clock_access_fn __read_persistent_clock = dummy_clock_access;
-static clock_access_fn __read_boot_clock = dummy_clock_access;;
-
-void read_persistent_clock(struct timespec *ts)
-{
- __read_persistent_clock(ts);
-}
-
-void read_boot_clock(struct timespec *ts)
-{
- __read_boot_clock(ts);
-}
-
-int __init register_persistent_clock(clock_access_fn read_boot,
- clock_access_fn read_persistent)
-{
- /* Only allow the clockaccess functions to be registered once */
- if (__read_persistent_clock == dummy_clock_access &&
- __read_boot_clock == dummy_clock_access) {
- if (read_boot)
- __read_boot_clock = read_boot;
- if (read_persistent)
- __read_persistent_clock = read_persistent;
-
- return 0;
- }
-
- return -EINVAL;
-}
-
void __init time_init(void)
{
if (machine_desc->init_time) {
diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
index 61b4d70..0dbfffd 100644
--- a/arch/arm/plat-omap/counter_32k.c
+++ b/arch/arm/plat-omap/counter_32k.c
@@ -18,10 +18,9 @@
#include <linux/err.h>
#include <linux/io.h>
#include <linux/clocksource.h>
+#include <linux/time.h>
#include <linux/sched_clock.h>
-#include <asm/mach/time.h>
-
#include <plat/counter-32k.h>
/* OMAP2_32KSYNCNT_CR_OFF: offset of 32ksync counter register */
@@ -76,6 +75,10 @@ static void omap_read_persistent_clock(struct timespec *ts)
spin_unlock_irqrestore(&read_persistent_clock_lock, flags);
}
+static const struct persistent_clock_ops omap_persistent_clock = {
+ .read = omap_read_persistent_clock
+};
+
/**
* omap_init_clocksource_32k - setup and register counter 32k as a
* kernel clocksource
@@ -116,7 +119,7 @@ int __init omap_init_clocksource_32k(void __iomem *vbase)
}
sched_clock_register(omap_32k_read_sched_clock, 32, 32768);
- register_persistent_clock(NULL, omap_read_persistent_clock);
+ register_persistent_clock(&omap_persistent_clock);
pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n");
return 0;
diff --git a/drivers/clocksource/tegra20_timer.c
b/drivers/clocksource/tegra20_timer.c
index d2616ef..210130e 100644
--- a/drivers/clocksource/tegra20_timer.c
+++ b/drivers/clocksource/tegra20_timer.c
@@ -28,9 +28,7 @@
#include <linux/of_irq.h>
#include <linux/sched_clock.h>
#include <linux/delay.h>
-
-#include <asm/mach/time.h>
-#include <asm/smp_twd.h>
+#include <linux/timekeeping.h>
#define RTC_SECONDS 0x08
#define RTC_SHADOW_SECONDS 0x0c
@@ -142,6 +140,10 @@ static void tegra_read_persistent_clock(struct timespec
*ts)
*ts = *tsp;
}
+static const struct persistent_clock_ops tegra_persistent_clock = {
+ .read = tegra_read_persistent_clock
+};
+
static unsigned long tegra_delay_timer_read_counter_long(void)
{
return readl(timer_reg_base + TIMERUS_CNTR_1US);
@@ -252,7 +254,7 @@ static void __init tegra20_init_rtc(struct device_node *np)
else
clk_prepare_enable(clk);
- register_persistent_clock(NULL, tegra_read_persistent_clock);
+ register_persistent_clock(&tegra_persistent_clock);
}
CLOCKSOURCE_OF_DECLARE(tegra20_rtc, "nvidia,tegra20-rtc", tegra20_init_rtc);
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 1caa6b0..02023f7 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -201,6 +201,17 @@ static inline bool has_persistent_clock(void)
return persistent_clock_exist;
}
+struct persistent_clock_ops {
+ void (*read)(struct timespec *ts);
+ int (*update)(const struct timespec ts);
+};
+
+struct boot_clock_ops {
+ void (*read)(struct timespec *ts);
+};
+
+extern void register_persistent_clock(const struct persistent_clock_ops
*clock);
+extern void register_boot_clock(const struct boot_clock_ops *clock);
extern void read_persistent_clock(struct timespec *ts);
extern void read_boot_clock(struct timespec *ts);
extern int update_persistent_clock(struct timespec now);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index fb4a9c2..414c172 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -66,6 +66,9 @@ int __read_mostly timekeeping_suspended;
/* Flag for if there is a persistent clock on this platform */
bool __read_mostly persistent_clock_exist = false;
+const struct persistent_clock_ops __read_mostly *persistent_clock = NULL;
+const struct boot_clock_ops __read_mostly *boot_clock = NULL;
+
static inline void tk_normalize_xtime(struct timekeeper *tk)
{
while (tk->tkr.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr.shift)) {
@@ -956,6 +959,30 @@ u64 timekeeping_max_deferment(void)
return ret;
}
+extern void register_persistent_clock(const struct persistent_clock_ops *clock)
+{
+ BUG_ON(!clock);
+ BUG_ON(!clock->read);
+
+ if (persistent_clock) {
+ pr_warn("Ignore extra persistent clock registration");
+ return;
+ }
+ persistent_clock = clock;
+}
+
+extern void register_boot_clock(const struct boot_clock_ops *clock)
+{
+ BUG_ON(!clock);
+ BUG_ON(!clock->read);
+
+ if (boot_clock) {
+ pr_warn("Ignore extra boot clock registration");
+ return;
+ }
+ boot_clock = clock;
+}
+
/**
* read_persistent_clock - Return time from the persistent clock.
*
@@ -967,8 +994,12 @@ u64 timekeeping_max_deferment(void)
*/
void __weak read_persistent_clock(struct timespec *ts)
{
- ts->tv_sec = 0;
- ts->tv_nsec = 0;
+ if (persistent_clock) {
+ persistent_clock->read(ts);
+ } else {
+ ts->tv_sec = 0;
+ ts->tv_nsec = 0;
+ }
}
/**
@@ -982,8 +1013,12 @@ void __weak read_persistent_clock(struct timespec *ts)
*/
void __weak read_boot_clock(struct timespec *ts)
{
- ts->tv_sec = 0;
- ts->tv_nsec = 0;
+ if (boot_clock) {
+ boot_clock->read(ts);
+ } else {
+ ts->tv_sec = 0;
+ ts->tv_nsec = 0;
+ }
}
/*
--
2.1.0.rc2.206.gedb03e5
--
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