diff options
Diffstat (limited to 'drivers/clocksource/mips-gic-timer.c')
| -rw-r--r-- | drivers/clocksource/mips-gic-timer.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/drivers/clocksource/mips-gic-timer.c b/drivers/clocksource/mips-gic-timer.c new file mode 100644 index 00000000000..3bd31b1321f --- /dev/null +++ b/drivers/clocksource/mips-gic-timer.c @@ -0,0 +1,166 @@ +/* + * 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) 2012 MIPS Technologies, Inc. All rights reserved. + */ +#include <linux/clockchips.h> +#include <linux/cpu.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/irqchip/mips-gic.h> +#include <linux/notifier.h> +#include <linux/of_irq.h> +#include <linux/percpu.h> +#include <linux/smp.h> +#include <linux/time.h> + +static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device); +static int gic_timer_irq; +static unsigned int gic_frequency; + +static int gic_next_event(unsigned long delta, struct clock_event_device *evt) +{ + u64 cnt; + int res; + + cnt = gic_read_count(); + cnt += (u64)delta; + gic_write_cpu_compare(cnt, cpumask_first(evt->cpumask)); + res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0; + return res; +} + +static void gic_set_clock_mode(enum clock_event_mode mode, + struct clock_event_device *evt) +{ + /* Nothing to do ... */ +} + +static irqreturn_t gic_compare_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *cd = dev_id; + + gic_write_compare(gic_read_compare()); + cd->event_handler(cd); + return IRQ_HANDLED; +} + +struct irqaction gic_compare_irqaction = { + .handler = gic_compare_interrupt, + .percpu_dev_id = &gic_clockevent_device, + .flags = IRQF_PERCPU | IRQF_TIMER, + .name = "timer", +}; + +static void gic_clockevent_cpu_init(struct clock_event_device *cd) +{ + unsigned int cpu = smp_processor_id(); + + cd->name = "MIPS GIC"; + cd->features = CLOCK_EVT_FEAT_ONESHOT | + CLOCK_EVT_FEAT_C3STOP; + + cd->rating = 350; + cd->irq = gic_timer_irq; + cd->cpumask = cpumask_of(cpu); + cd->set_next_event = gic_next_event; + cd->set_mode = gic_set_clock_mode; + + clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff); + + enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE); +} + +static void gic_clockevent_cpu_exit(struct clock_event_device *cd) +{ + disable_percpu_irq(gic_timer_irq); +} + +static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action, + void *data) +{ + switch (action & ~CPU_TASKS_FROZEN) { + case CPU_STARTING: + gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device)); + break; + case CPU_DYING: + gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device)); + break; + } + + return NOTIFY_OK; +} + +static struct notifier_block gic_cpu_nb = { + .notifier_call = gic_cpu_notifier, +}; + +static int gic_clockevent_init(void) +{ + if (!cpu_has_counter || !gic_frequency) + return -ENXIO; + + setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction); + + register_cpu_notifier(&gic_cpu_nb); + + gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device)); + + return 0; +} + +static cycle_t gic_hpt_read(struct clocksource *cs) +{ + return gic_read_count(); +} + +static struct clocksource gic_clocksource = { + .name = "GIC", + .read = gic_hpt_read, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static void __init __gic_clocksource_init(void) +{ + /* Set clocksource mask. */ + gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width()); + + /* Calculate a somewhat reasonable rating value. */ + gic_clocksource.rating = 200 + gic_frequency / 10000000; + + clocksource_register_hz(&gic_clocksource, gic_frequency); + + gic_clockevent_init(); +} + +void __init gic_clocksource_init(unsigned int frequency) +{ + gic_frequency = frequency; + gic_timer_irq = MIPS_GIC_IRQ_BASE + + GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE); + + __gic_clocksource_init(); +} + +static void __init gic_clocksource_of_init(struct device_node *node) +{ + if (WARN_ON(!gic_present || !node->parent || + !of_device_is_compatible(node->parent, "mti,gic"))) + return; + + if (of_property_read_u32(node, "clock-frequency", &gic_frequency)) { + pr_err("GIC frequency not specified.\n"); + return; + } + gic_timer_irq = irq_of_parse_and_map(node, 0); + if (!gic_timer_irq) { + pr_err("GIC timer IRQ not specified.\n"); + return; + } + + __gic_clocksource_init(); +} +CLOCKSOURCE_OF_DECLARE(mips_gic_timer, "mti,gic-timer", + gic_clocksource_of_init); |