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Diffstat (limited to 'arch/xtensa/kernel/time.c')
| -rw-r--r-- | arch/xtensa/kernel/time.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c new file mode 100644 index 000000000..1c3dfea84 --- /dev/null +++ b/arch/xtensa/kernel/time.c @@ -0,0 +1,210 @@ +/* + * arch/xtensa/kernel/time.c + * + * Timer and clock support. + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 2005 Tensilica Inc. + * + * Chris Zankel <chris@zankel.net> + */ + +#include <linux/clk.h> +#include <linux/of_clk.h> +#include <linux/errno.h> +#include <linux/sched.h> +#include <linux/time.h> +#include <linux/clocksource.h> +#include <linux/clockchips.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/irq.h> +#include <linux/profile.h> +#include <linux/delay.h> +#include <linux/irqdomain.h> +#include <linux/sched_clock.h> + +#include <asm/timex.h> +#include <asm/platform.h> + +unsigned long ccount_freq; /* ccount Hz */ +EXPORT_SYMBOL(ccount_freq); + +static u64 ccount_read(struct clocksource *cs) +{ + return (u64)get_ccount(); +} + +static u64 notrace ccount_sched_clock_read(void) +{ + return get_ccount(); +} + +static struct clocksource ccount_clocksource = { + .name = "ccount", + .rating = 200, + .read = ccount_read, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +struct ccount_timer { + struct clock_event_device evt; + int irq_enabled; + char name[24]; +}; + +static int ccount_timer_set_next_event(unsigned long delta, + struct clock_event_device *dev) +{ + unsigned long flags, next; + int ret = 0; + + local_irq_save(flags); + next = get_ccount() + delta; + set_linux_timer(next); + if (next - get_ccount() > delta) + ret = -ETIME; + local_irq_restore(flags); + + return ret; +} + +/* + * There is no way to disable the timer interrupt at the device level, + * only at the intenable register itself. Since enable_irq/disable_irq + * calls are nested, we need to make sure that these calls are + * balanced. + */ +static int ccount_timer_shutdown(struct clock_event_device *evt) +{ + struct ccount_timer *timer = + container_of(evt, struct ccount_timer, evt); + + if (timer->irq_enabled) { + disable_irq_nosync(evt->irq); + timer->irq_enabled = 0; + } + return 0; +} + +static int ccount_timer_set_oneshot(struct clock_event_device *evt) +{ + struct ccount_timer *timer = + container_of(evt, struct ccount_timer, evt); + + if (!timer->irq_enabled) { + enable_irq(evt->irq); + timer->irq_enabled = 1; + } + return 0; +} + +static DEFINE_PER_CPU(struct ccount_timer, ccount_timer) = { + .evt = { + .features = CLOCK_EVT_FEAT_ONESHOT, + .rating = 300, + .set_next_event = ccount_timer_set_next_event, + .set_state_shutdown = ccount_timer_shutdown, + .set_state_oneshot = ccount_timer_set_oneshot, + .tick_resume = ccount_timer_set_oneshot, + }, +}; + +static irqreturn_t timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt; + + set_linux_timer(get_linux_timer()); + evt->event_handler(evt); + return IRQ_HANDLED; +} + +void local_timer_setup(unsigned cpu) +{ + struct ccount_timer *timer = &per_cpu(ccount_timer, cpu); + struct clock_event_device *clockevent = &timer->evt; + + timer->irq_enabled = 1; + snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu); + clockevent->name = timer->name; + clockevent->cpumask = cpumask_of(cpu); + clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT); + if (WARN(!clockevent->irq, "error: can't map timer irq")) + return; + clockevents_config_and_register(clockevent, ccount_freq, + 0xf, 0xffffffff); +} + +#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT +#ifdef CONFIG_OF +static void __init calibrate_ccount(void) +{ + struct device_node *cpu; + struct clk *clk; + + cpu = of_find_compatible_node(NULL, NULL, "cdns,xtensa-cpu"); + if (cpu) { + clk = of_clk_get(cpu, 0); + of_node_put(cpu); + if (!IS_ERR(clk)) { + ccount_freq = clk_get_rate(clk); + return; + } else { + pr_warn("%s: CPU input clock not found\n", + __func__); + } + } else { + pr_warn("%s: CPU node not found in the device tree\n", + __func__); + } + + platform_calibrate_ccount(); +} +#else +static inline void calibrate_ccount(void) +{ + platform_calibrate_ccount(); +} +#endif +#endif + +void __init time_init(void) +{ + int irq; + + of_clk_init(NULL); +#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT + pr_info("Calibrating CPU frequency "); + calibrate_ccount(); + pr_cont("%d.%02d MHz\n", + (int)ccount_freq / 1000000, + (int)(ccount_freq / 10000) % 100); +#else + ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL; +#endif + WARN(!ccount_freq, + "%s: CPU clock frequency is not set up correctly\n", + __func__); + clocksource_register_hz(&ccount_clocksource, ccount_freq); + local_timer_setup(0); + irq = this_cpu_ptr(&ccount_timer)->evt.irq; + if (request_irq(irq, timer_interrupt, IRQF_TIMER, "timer", NULL)) + pr_err("Failed to request irq %d (timer)\n", irq); + sched_clock_register(ccount_sched_clock_read, 32, ccount_freq); + timer_probe(); +} + +#ifndef CONFIG_GENERIC_CALIBRATE_DELAY +void calibrate_delay(void) +{ + loops_per_jiffy = ccount_freq / HZ; + pr_info("Calibrating delay loop (skipped)... %lu.%02lu BogoMIPS preset\n", + loops_per_jiffy / (1000000 / HZ), + (loops_per_jiffy / (10000 / HZ)) % 100); +} +#endif |