diff options
author | Jonathan Austin <Jonathan.Austin@arm.com> | 2012-09-21 21:51:44 +0400 |
---|---|---|
committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2012-09-27 01:57:52 +0400 |
commit | 56942fec06efa0e17df0f4c3b438332c923b9014 (patch) | |
tree | 89b604c987b7f6a0eaaa16af7a9d8f45711349a7 /arch/arm | |
parent | a1b2dde70419ae947fd7c9c8fcad7da005dc600e (diff) | |
download | linux-56942fec06efa0e17df0f4c3b438332c923b9014.tar.xz |
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')
-rw-r--r-- | arch/arm/include/asm/arch_timer.h | 1 | ||||
-rw-r--r-- | arch/arm/include/asm/delay.h | 9 | ||||
-rw-r--r-- | arch/arm/include/asm/timex.h | 6 | ||||
-rw-r--r-- | arch/arm/kernel/arch_timer.c | 17 | ||||
-rw-r--r-- | arch/arm/lib/delay.c | 34 |
5 files changed, 43 insertions, 24 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 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: 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 |