diff options
| -rw-r--r-- | arch/arm/lib/delay.c | 26 | ||||
| -rw-r--r-- | drivers/clocksource/tegra20_timer.c | 13 | ||||
| -rw-r--r-- | init/calibrate.c | 11 |
3 files changed, 46 insertions, 4 deletions
diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c index 5306de350133..312d43eb686a 100644 --- a/arch/arm/lib/delay.c +++ b/arch/arm/lib/delay.c @@ -19,6 +19,7 @@ * Author: Will Deacon <will.deacon@arm.com> */ +#include <linux/clocksource.h> #include <linux/delay.h> #include <linux/init.h> #include <linux/kernel.h> @@ -36,6 +37,7 @@ struct arm_delay_ops arm_delay_ops = { static const struct delay_timer *delay_timer; static bool delay_calibrated; +static u64 delay_res; int read_current_timer(unsigned long *timer_val) { @@ -47,6 +49,11 @@ int read_current_timer(unsigned long *timer_val) } EXPORT_SYMBOL_GPL(read_current_timer); +static inline u64 cyc_to_ns(u64 cyc, u32 mult, u32 shift) +{ + return (cyc * mult) >> shift; +} + static void __timer_delay(unsigned long cycles) { cycles_t start = get_cycles(); @@ -69,18 +76,24 @@ static void __timer_udelay(unsigned long usecs) void __init register_current_timer_delay(const struct delay_timer *timer) { - if (!delay_calibrated) { - pr_info("Switching to timer-based delay loop\n"); + u32 new_mult, new_shift; + u64 res; + + clocks_calc_mult_shift(&new_mult, &new_shift, timer->freq, + NSEC_PER_SEC, 3600); + res = cyc_to_ns(1ULL, new_mult, new_shift); + + if (!delay_calibrated && (!delay_res || (res < delay_res))) { + pr_info("Switching to timer-based delay loop, resolution %lluns\n", res); delay_timer = timer; lpj_fine = timer->freq / HZ; + delay_res = res; /* cpufreq may scale loops_per_jiffy, so keep a private copy */ arm_delay_ops.ticks_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"); } @@ -91,3 +104,8 @@ unsigned long calibrate_delay_is_known(void) delay_calibrated = true; return lpj_fine; } + +void calibration_delay_done(void) +{ + delay_calibrated = true; +} diff --git a/drivers/clocksource/tegra20_timer.c b/drivers/clocksource/tegra20_timer.c index d1869f02051c..d2616ef16770 100644 --- a/drivers/clocksource/tegra20_timer.c +++ b/drivers/clocksource/tegra20_timer.c @@ -27,6 +27,7 @@ #include <linux/of_address.h> #include <linux/of_irq.h> #include <linux/sched_clock.h> +#include <linux/delay.h> #include <asm/mach/time.h> #include <asm/smp_twd.h> @@ -53,6 +54,8 @@ static void __iomem *rtc_base; static struct timespec persistent_ts; static u64 persistent_ms, last_persistent_ms; +static struct delay_timer tegra_delay_timer; + #define timer_writel(value, reg) \ __raw_writel(value, timer_reg_base + (reg)) #define timer_readl(reg) \ @@ -139,6 +142,11 @@ static void tegra_read_persistent_clock(struct timespec *ts) *ts = *tsp; } +static unsigned long tegra_delay_timer_read_counter_long(void) +{ + return readl(timer_reg_base + TIMERUS_CNTR_1US); +} + static irqreturn_t tegra_timer_interrupt(int irq, void *dev_id) { struct clock_event_device *evt = (struct clock_event_device *)dev_id; @@ -206,6 +214,11 @@ static void __init tegra20_init_timer(struct device_node *np) BUG(); } + tegra_delay_timer.read_current_timer = + tegra_delay_timer_read_counter_long; + tegra_delay_timer.freq = 1000000; + register_current_timer_delay(&tegra_delay_timer); + ret = setup_irq(tegra_timer_irq.irq, &tegra_timer_irq); if (ret) { pr_err("Failed to register timer IRQ: %d\n", ret); diff --git a/init/calibrate.c b/init/calibrate.c index 520702db9acc..ce635dccf3d9 100644 --- a/init/calibrate.c +++ b/init/calibrate.c @@ -262,6 +262,15 @@ unsigned long __attribute__((weak)) calibrate_delay_is_known(void) return 0; } +/* + * Indicate the cpu delay calibration is done. This can be used by + * architectures to stop accepting delay timer registrations after this point. + */ + +void __attribute__((weak)) calibration_delay_done(void) +{ +} + void calibrate_delay(void) { unsigned long lpj; @@ -301,4 +310,6 @@ void calibrate_delay(void) loops_per_jiffy = lpj; printed = true; + + calibration_delay_done(); } |