[PATCH] ARM: move read_{boot, persistent}_clock to the architecture level

[PATCH] ARM: move read_{boot, persistent}_clock to the architecture level

[Marc Zyngier]

At the moment, read_persistent_clock is implemented at the
platform level, which makes it impossible to compile these
platforms in a single kernel.

Implement these two functions at the architecture level, and
provide a thin registration interface for both read_boot_clock
and read_persistent_clock. The two affected platforms (OMAP and
Tegra) are converted at the same time.

Compile tested only.

Reported-by: Jeff Ohlstein <johlstei@codeaurora.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm/include/asm/mach/time.h |    5 +++++
 arch/arm/kernel/time.c           |   36 ++++++++++++++++++++++++++++++++++++
 arch/arm/mach-tegra/timer.c      |    5 +++--
 arch/arm/plat-omap/counter_32k.c |    6 ++++--
 4 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/arch/arm/include/asm/mach/time.h b/arch/arm/include/asm/mach/time.h
index f73c908..6ca945f 100644
--- a/arch/arm/include/asm/mach/time.h
+++ b/arch/arm/include/asm/mach/time.h
@@ -42,4 +42,9 @@ struct sys_timer {
 
 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 fe31b22..af2afb0 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -110,6 +110,42 @@ 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;
+}
+
 #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS)
 static int timer_suspend(void)
 {
diff --git a/arch/arm/mach-tegra/timer.c b/arch/arm/mach-tegra/timer.c
index 1eed8d4..315672c 100644
--- a/arch/arm/mach-tegra/timer.c
+++ b/arch/arm/mach-tegra/timer.c
@@ -124,7 +124,7 @@ static u64 tegra_rtc_read_ms(void)
 }
 
 /*
- * read_persistent_clock -  Return time from a persistent clock.
+ * tegra_read_persistent_clock -  Return time from a persistent clock.
  *
  * Reads the time from a source which isn't disabled during PM, the
  * 32k sync timer.  Convert the cycles elapsed since last read into
@@ -133,7 +133,7 @@ static u64 tegra_rtc_read_ms(void)
  * tegra_rtc driver could be executing to avoid race conditions
  * on the RTC shadow register
  */
-void read_persistent_clock(struct timespec *ts)
+static void tegra_read_persistent_clock(struct timespec *ts)
 {
 	u64 delta;
 	struct timespec *tsp = &persistent_ts;
@@ -243,6 +243,7 @@ static void __init tegra_init_timer(void)
 	tegra_clockevent.irq = tegra_timer_irq.irq;
 	clockevents_register_device(&tegra_clockevent);
 	tegra_twd_init();
+	register_persistent_clock(NULL, tegra_read_persistent_clock);
 }
 
 struct sys_timer tegra_timer = {
diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
index 5068fe5..44ae077 100644
--- a/arch/arm/plat-omap/counter_32k.c
+++ b/arch/arm/plat-omap/counter_32k.c
@@ -19,6 +19,7 @@
 #include <linux/io.h>
 #include <linux/clocksource.h>
 
+#include <asm/mach/time.h>
 #include <asm/sched_clock.h>
 
 #include <plat/hardware.h>
@@ -43,7 +44,7 @@ static u32 notrace omap_32k_read_sched_clock(void)
 }
 
 /**
- * read_persistent_clock -  Return time from a persistent clock.
+ * omap_read_persistent_clock -  Return time from a persistent clock.
  *
  * Reads the time from a source which isn't disabled during PM, the
  * 32k sync timer.  Convert the cycles elapsed since last read into
@@ -52,7 +53,7 @@ static u32 notrace omap_32k_read_sched_clock(void)
 static struct timespec persistent_ts;
 static cycles_t cycles, last_cycles;
 static unsigned int persistent_mult, persistent_shift;
-void read_persistent_clock(struct timespec *ts)
+static void omap_read_persistent_clock(struct timespec *ts)
 {
 	unsigned long long nsecs;
 	cycles_t delta;
@@ -116,6 +117,7 @@ int __init omap_init_clocksource_32k(void)
 			printk(err, "32k_counter");
 
 		setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);
+		register_persistent_clock(NULL, omap_read_persistent_clock);
 	}
 	return 0;
 }
-- 
1.7.10

[PATCH] ARM: move read_{boot, persistent}_clock to the architecture level

[Stephen Warren]

On 04/28/2012 06:45 AM, Marc Zyngier wrote:
> At the moment, read_persistent_clock is implemented at the
> platform level, which makes it impossible to compile these
> platforms in a single kernel.
> 
> Implement these two functions at the architecture level, and
> provide a thin registration interface for both read_boot_clock
> and read_persistent_clock. The two affected platforms (OMAP and
> Tegra) are converted at the same time.
> 
> Compile tested only.
> 
> Reported-by: Jeff Ohlstein <johlstei@codeaurora.org>
> Cc: Stephen Warren <swarren@wwwdotorg.org>
> Cc: Tony Lindgren <tony@atomide.com>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Tested-by: Stephen Warren <swarren@wwwdotorg.org>

I'm not sure exactly how to fully exercise this, but Tegra still boots
without issue or obvious error messages with this patch applied.

[PATCH] ARM: move read_{boot,persistent}_clock to the architecture level

[Tony Lindgren]

* Marc Zyngier <marc.zyngier@arm.com> [120428 05:49]:
> At the moment, read_persistent_clock is implemented at the
> platform level, which makes it impossible to compile these
> platforms in a single kernel.
> 
> Implement these two functions at the architecture level, and
> provide a thin registration interface for both read_boot_clock
> and read_persistent_clock. The two affected platforms (OMAP and
> Tegra) are converted at the same time.
> 
> Compile tested only.

Sorry I'm a bit behind with emails again..

Boot tested on omap1 and omap2/3/4:

Tested-by: Tony Lindgren <tony@atomide.com>

[PATCH] ARM: move read_{boot, persistent}_clock to the architecture level

[Russell King - ARM Linux]

On Sat, Apr 28, 2012 at 01:45:45PM +0100, Marc Zyngier wrote:
> At the moment, read_persistent_clock is implemented at the
> platform level, which makes it impossible to compile these
> platforms in a single kernel.
> 
> Implement these two functions at the architecture level, and
> provide a thin registration interface for both read_boot_clock
> and read_persistent_clock. The two affected platforms (OMAP and
> Tegra) are converted at the same time.
> 
> Compile tested only.

As this now has tested-bys for OMAP and Tegra, I guess it's ready.  Who's
planning to take this?

[PATCH] ARM: move read_{boot, persistent}_clock to the architecture level

[Marc Zyngier]

On Sat, 5 May 2012 17:47:53 +0100, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Sat, Apr 28, 2012 at 01:45:45PM +0100, Marc Zyngier wrote:
>> At the moment, read_persistent_clock is implemented at the
>> platform level, which makes it impossible to compile these
>> platforms in a single kernel.
>> 
>> Implement these two functions at the architecture level, and
>> provide a thin registration interface for both read_boot_clock
>> and read_persistent_clock. The two affected platforms (OMAP and
>> Tegra) are converted at the same time.
>> 
>> Compile tested only.
> 
> As this now has tested-bys for OMAP and Tegra, I guess it's ready. 
Who's
> planning to take this?

If you're happy to take it, and unless someone objects to it, I'll put it
in the patch system.

Thanks Stephen and Tony for testing it.

        M.
-- 
Fast, cheap, reliable. Pick two.

[PATCH] ARM: move read_{boot, persistent}_clock to the architecture level

[Russell King - ARM Linux]

On Sat, May 05, 2012 at 07:16:50PM +0200, Marc Zyngier wrote:
> On Sat, 5 May 2012 17:47:53 +0100, Russell King - ARM Linux
> <linux@arm.linux.org.uk> wrote:
> > On Sat, Apr 28, 2012 at 01:45:45PM +0100, Marc Zyngier wrote:
> >> At the moment, read_persistent_clock is implemented at the
> >> platform level, which makes it impossible to compile these
> >> platforms in a single kernel.
> >> 
> >> Implement these two functions at the architecture level, and
> >> provide a thin registration interface for both read_boot_clock
> >> and read_persistent_clock. The two affected platforms (OMAP and
> >> Tegra) are converted at the same time.
> >> 
> >> Compile tested only.
> > 
> > As this now has tested-bys for OMAP and Tegra, I guess it's ready. 
> Who's
> > planning to take this?
> 
> If you're happy to take it, and unless someone objects to it, I'll put it
> in the patch system.

Sure.