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>

1 files changed, 8 insertions, 9 deletions

diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index c04c2a6da470..c8ef20747ee7 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -21,6 +21,7 @@
 #include <linux/io.h>
 
 #include <asm/cputype.h>
+#include <asm/delay.h>
 #include <asm/localtimer.h>
 #include <asm/arch_timer.h>
 #include <asm/system_info.h>
@@ -39,8 +40,7 @@ enum ppi_nr {
 static int arch_timer_ppi[MAX_TIMER_PPI];
 
 static struct clock_event_device __percpu **arch_timer_evt;
-
-extern void init_current_timer_delay(unsigned long freq);
+static struct delay_timer arch_delay_timer;
 
 static bool arch_timer_use_virtual = true;
 
@@ -325,12 +325,9 @@ static cycle_t arch_counter_read(struct clocksource *cs)
         return arch_counter_get_cntpct();
 }
 
-int read_current_timer(unsigned long *timer_val)
+static unsigned long arch_timer_read_current_timer(void)
 {
-        if (!arch_timer_rate)
-                return -ENXIO;
-        *timer_val = arch_counter_get_cntpct();
-        return 0;
+        return arch_counter_get_cntpct();
 }
 
 static cycle_t arch_counter_read_cc(const struct cyclecounter *cc)
@@ -441,11 +438,13 @@ static int __init arch_timer_register(void)
                 arch_timer_global_evt.cpumask = cpumask_of(0);
                 err = arch_timer_setup(&arch_timer_global_evt);
         }
-
         if (err)
                 goto out_free_irq;
 
-        init_current_timer_delay(arch_timer_rate);
+        /* Use the architected timer for the delay loop. */
+        arch_delay_timer.read_current_timer = &arch_timer_read_current_timer;
+        arch_delay_timer.freq = arch_timer_rate;
+        register_current_timer_delay(&arch_delay_timer);
         return 0;
 
 out_free_irq: