diff options
Diffstat (limited to 'drivers/clocksource')
| -rw-r--r-- | drivers/clocksource/Kconfig | 5 | ||||
| -rw-r--r-- | drivers/clocksource/Makefile | 2 | ||||
| -rw-r--r-- | drivers/clocksource/arm_generic.c | 232 |
3 files changed, 239 insertions, 0 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index d53cd0afc200..6a78073c3808 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -35,3 +35,8 @@ config CLKSRC_DBX500_PRCMU_SCHED_CLOCK default y help Use the always on PRCMU Timer as sched_clock + +config CLKSRC_ARM_GENERIC + def_bool y if ARM64 + help + This option enables support for the ARM generic timer. diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile index d496a55f6bb0..603be366f762 100644 --- a/drivers/clocksource/Makefile +++ b/drivers/clocksource/Makefile @@ -14,3 +14,5 @@ obj-$(CONFIG_DW_APB_TIMER_OF) += dw_apb_timer_of.o obj-$(CONFIG_CLKSRC_DBX500_PRCMU) += clksrc-dbx500-prcmu.o obj-$(CONFIG_ARMADA_370_XP_TIMER) += time-armada-370-xp.o obj-$(CONFIG_ARCH_BCM2835) += bcm2835_timer.o + +obj-$(CONFIG_CLKSRC_ARM_GENERIC) += arm_generic.o diff --git a/drivers/clocksource/arm_generic.c b/drivers/clocksource/arm_generic.c new file mode 100644 index 000000000000..c4d9f9566c64 --- /dev/null +++ b/drivers/clocksource/arm_generic.c @@ -0,0 +1,232 @@ +/* + * Generic timers support + * + * Copyright (C) 2012 ARM Ltd. + * Author: Marc Zyngier <marc.zyngier@arm.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/smp.h> +#include <linux/cpu.h> +#include <linux/jiffies.h> +#include <linux/interrupt.h> +#include <linux/clockchips.h> +#include <linux/of_irq.h> +#include <linux/io.h> + +#include <clocksource/arm_generic.h> + +#include <asm/arm_generic.h> + +static u32 arch_timer_rate; +static u64 sched_clock_mult __read_mostly; +static DEFINE_PER_CPU(struct clock_event_device, arch_timer_evt); +static int arch_timer_ppi; + +static irqreturn_t arch_timer_handle_irq(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + unsigned long ctrl; + + ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL); + if (ctrl & ARCH_TIMER_CTRL_ISTATUS) { + ctrl |= ARCH_TIMER_CTRL_IMASK; + arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl); + evt->event_handler(evt); + return IRQ_HANDLED; + } + + return IRQ_NONE; +} + +static void arch_timer_stop(void) +{ + unsigned long ctrl; + + ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL); + ctrl &= ~ARCH_TIMER_CTRL_ENABLE; + arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl); +} + +static void arch_timer_set_mode(enum clock_event_mode mode, + struct clock_event_device *clk) +{ + switch (mode) { + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + arch_timer_stop(); + break; + default: + break; + } +} + +static int arch_timer_set_next_event(unsigned long evt, + struct clock_event_device *unused) +{ + unsigned long ctrl; + + ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL); + ctrl |= ARCH_TIMER_CTRL_ENABLE; + ctrl &= ~ARCH_TIMER_CTRL_IMASK; + + arch_timer_reg_write(ARCH_TIMER_REG_TVAL, evt); + arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl); + + return 0; +} + +static void __cpuinit arch_timer_setup(struct clock_event_device *clk) +{ + /* Let's make sure the timer is off before doing anything else */ + arch_timer_stop(); + + clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP; + clk->name = "arch_sys_timer"; + clk->rating = 400; + clk->set_mode = arch_timer_set_mode; + clk->set_next_event = arch_timer_set_next_event; + clk->irq = arch_timer_ppi; + clk->cpumask = cpumask_of(smp_processor_id()); + + clockevents_config_and_register(clk, arch_timer_rate, + 0xf, 0x7fffffff); + + enable_percpu_irq(clk->irq, 0); + + /* Ensure the physical counter is visible to userspace for the vDSO. */ + arch_counter_enable_user_access(); +} + +static void __init arch_timer_calibrate(void) +{ + if (arch_timer_rate == 0) { + arch_timer_reg_write(ARCH_TIMER_REG_CTRL, 0); + arch_timer_rate = arch_timer_reg_read(ARCH_TIMER_REG_FREQ); + + /* Check the timer frequency. */ + if (arch_timer_rate == 0) + panic("Architected timer frequency is set to zero.\n" + "You must set this in your .dts file\n"); + } + + /* Cache the sched_clock multiplier to save a divide in the hot path. */ + + sched_clock_mult = NSEC_PER_SEC / arch_timer_rate; + + pr_info("Architected local timer running at %u.%02uMHz.\n", + arch_timer_rate / 1000000, (arch_timer_rate / 10000) % 100); +} + +static cycle_t arch_counter_read(struct clocksource *cs) +{ + return arch_counter_get_cntpct(); +} + +static struct clocksource clocksource_counter = { + .name = "arch_sys_counter", + .rating = 400, + .read = arch_counter_read, + .mask = CLOCKSOURCE_MASK(56), + .flags = (CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_VALID_FOR_HRES), +}; + +int read_current_timer(unsigned long *timer_value) +{ + *timer_value = arch_counter_get_cntpct(); + return 0; +} + +unsigned long long notrace sched_clock(void) +{ + return arch_counter_get_cntvct() * sched_clock_mult; +} + +static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + int cpu = (long)hcpu; + struct clock_event_device *clk = per_cpu_ptr(&arch_timer_evt, cpu); + + switch(action) { + case CPU_STARTING: + case CPU_STARTING_FROZEN: + arch_timer_setup(clk); + break; + + case CPU_DYING: + case CPU_DYING_FROZEN: + pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n", + clk->irq, cpu); + disable_percpu_irq(clk->irq); + arch_timer_set_mode(CLOCK_EVT_MODE_UNUSED, clk); + break; + } + + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata arch_timer_cpu_nb = { + .notifier_call = arch_timer_cpu_notify, +}; + +static const struct of_device_id arch_timer_of_match[] __initconst = { + { .compatible = "arm,armv8-timer" }, + {}, +}; + +int __init arm_generic_timer_init(void) +{ + struct device_node *np; + int err; + u32 freq; + + np = of_find_matching_node(NULL, arch_timer_of_match); + if (!np) { + pr_err("arch_timer: can't find DT node\n"); + return -ENODEV; + } + + /* Try to determine the frequency from the device tree or CNTFRQ */ + if (!of_property_read_u32(np, "clock-frequency", &freq)) + arch_timer_rate = freq; + arch_timer_calibrate(); + + arch_timer_ppi = irq_of_parse_and_map(np, 0); + pr_info("arch_timer: found %s irq %d\n", np->name, arch_timer_ppi); + + err = request_percpu_irq(arch_timer_ppi, arch_timer_handle_irq, + np->name, &arch_timer_evt); + if (err) { + pr_err("arch_timer: can't register interrupt %d (%d)\n", + arch_timer_ppi, err); + return err; + } + + clocksource_register_hz(&clocksource_counter, arch_timer_rate); + + /* Calibrate the delay loop directly */ + lpj_fine = arch_timer_rate / HZ; + + /* Immediately configure the timer on the boot CPU */ + arch_timer_setup(per_cpu_ptr(&arch_timer_evt, smp_processor_id())); + + register_cpu_notifier(&arch_timer_cpu_nb); + + return 0; +} |