ARM: 7538/1: delay: add registration mechanism for delay timer sources

The current timer-based delay loop relies on the architected timer to
initiate the switch away from the polling-based implementation. This is
unfortunate for platforms without the architected timers but with a
suitable delay source (that is, constant frequency, always powered-up
and ticking as long as the CPUs are online).

This patch introduces a registration mechanism for the delay timer
(which provides an unconditional read_current_timer implementation) and
updates the architected timer code to use the new interface.

Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Jonathan Austin <jonathan.austin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 9 insertions, 7 deletions

diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index ad9b155c8262..d40229d9a1c9 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -5,7 +5,6 @@
 #include <linux/clocksource.h>
 
 #ifdef CONFIG_ARM_ARCH_TIMER
-#define ARCH_HAS_READ_CURRENT_TIMER
 int arch_timer_of_register(void);
 int arch_timer_sched_clock_init(void);
 struct timecounter *arch_timer_get_timecounter(void);
diff --git a/arch/arm/include/asm/delay.h b/arch/arm/include/asm/delay.h
index dc6145120de3..ab98fdd083bd 100644
--- a/arch/arm/include/asm/delay.h
+++ b/arch/arm/include/asm/delay.h
@@ -15,6 +15,11 @@
 
 #ifndef __ASSEMBLY__
 
+struct delay_timer {
+        unsigned long (*read_current_timer)(void);
+        unsigned long freq;
+};
+
 extern struct arm_delay_ops {
         void (*delay)(unsigned long);
         void (*const_udelay)(unsigned long);
@@ -56,6 +61,10 @@ extern void __loop_delay(unsigned long loops);
 extern void __loop_udelay(unsigned long usecs);
 extern void __loop_const_udelay(unsigned long);
 
+/* Delay-loop timer registration. */
+#define ARCH_HAS_READ_CURRENT_TIMER
+extern void register_current_timer_delay(const struct delay_timer *timer);
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* defined(_ARM_DELAY_H) */
diff --git a/arch/arm/include/asm/timex.h b/arch/arm/include/asm/timex.h
index ce119442277c..9acc135dad94 100644
--- a/arch/arm/include/asm/timex.h
+++ b/arch/arm/include/asm/timex.h
@@ -12,15 +12,9 @@
 #ifndef _ASMARM_TIMEX_H
 #define _ASMARM_TIMEX_H
 
-#include <asm/arch_timer.h>
 #include <mach/timex.h>
 
 typedef unsigned long cycles_t;
-
-#ifdef ARCH_HAS_READ_CURRENT_TIMER
 #define get_cycles()    ({ cycles_t c; read_current_timer(&c) ? 0 : c; })
-#else
-#define get_cycles()    (0)
-#endif
 
 #endif