aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/lib
diff options
context:
space:
mode:
authorJonathan Austin <Jonathan.Austin@arm.com>2012-09-21 18:51:44 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2012-09-26 22:57:52 +0100
commit56942fec06efa0e17df0f4c3b438332c923b9014 (patch)
tree89b604c987b7f6a0eaaa16af7a9d8f45711349a7 /arch/arm/lib
parenta1b2dde70419ae947fd7c9c8fcad7da005dc600e (diff)
downloadlinux-linaro-stable-56942fec06efa0e17df0f4c3b438332c923b9014.tar.gz
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>
Diffstat (limited to 'arch/arm/lib')
-rw-r--r--arch/arm/lib/delay.c34
1 files changed, 26 insertions, 8 deletions
diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c
index d6dacc69254e..9d0a30032d7f 100644
--- a/arch/arm/lib/delay.c
+++ b/arch/arm/lib/delay.c
@@ -34,7 +34,18 @@ struct arm_delay_ops arm_delay_ops = {
.udelay = __loop_udelay,
};
-#ifdef ARCH_HAS_READ_CURRENT_TIMER
+static const struct delay_timer *delay_timer;
+static bool delay_calibrated;
+
+int read_current_timer(unsigned long *timer_val)
+{
+ if (!delay_timer)
+ return -ENXIO;
+
+ *timer_val = delay_timer->read_current_timer();
+ return 0;
+}
+
static void __timer_delay(unsigned long cycles)
{
cycles_t start = get_cycles();
@@ -55,17 +66,24 @@ static void __timer_udelay(unsigned long usecs)
__timer_const_udelay(usecs * UDELAY_MULT);
}
-void __init init_current_timer_delay(unsigned long freq)
+void __init register_current_timer_delay(const struct delay_timer *timer)
{
- pr_info("Switching to timer-based delay loop\n");
- lpj_fine = freq / HZ;
- arm_delay_ops.delay = __timer_delay;
- arm_delay_ops.const_udelay = __timer_const_udelay;
- arm_delay_ops.udelay = __timer_udelay;
+ if (!delay_calibrated) {
+ pr_info("Switching to timer-based delay loop\n");
+ delay_timer = timer;
+ lpj_fine = timer->freq / HZ;
+ loops_per_jiffy = lpj_fine;
+ arm_delay_ops.delay = __timer_delay;
+ arm_delay_ops.const_udelay = __timer_const_udelay;
+ arm_delay_ops.udelay = __timer_udelay;
+ delay_calibrated = true;
+ } else {
+ pr_info("Ignoring duplicate/late registration of read_current_timer delay\n");
+ }
}
unsigned long __cpuinit calibrate_delay_is_known(void)
{
+ delay_calibrated = true;
return lpj_fine;
}
-#endif