diff options
Diffstat (limited to 'arch/hexagon/kernel/time.c')
| -rw-r--r-- | arch/hexagon/kernel/time.c | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/arch/hexagon/kernel/time.c b/arch/hexagon/kernel/time.c new file mode 100644 index 000000000000..6bee15c9c113 --- /dev/null +++ b/arch/hexagon/kernel/time.c @@ -0,0 +1,250 @@ +/* + * Time related functions for Hexagon architecture + * + * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 and + * only 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, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + */ + +#include <linux/init.h> +#include <linux/clockchips.h> +#include <linux/clocksource.h> +#include <linux/interrupt.h> +#include <linux/err.h> +#include <linux/platform_device.h> +#include <linux/ioport.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> + +#include <asm/timer-regs.h> +#include <asm/hexagon_vm.h> + +/* + * For the clocksource we need: + * pcycle frequency (600MHz) + * For the loops_per_jiffy we need: + * thread/cpu frequency (100MHz) + * And for the timer, we need: + * sleep clock rate + */ + +cycles_t pcycle_freq_mhz; +cycles_t thread_freq_mhz; +cycles_t sleep_clk_freq; + +static struct resource rtos_timer_resources[] = { + { + .start = RTOS_TIMER_REGS_ADDR, + .end = RTOS_TIMER_REGS_ADDR+PAGE_SIZE-1, + .flags = IORESOURCE_MEM, + }, +}; + +static struct platform_device rtos_timer_device = { + .name = "rtos_timer", + .id = -1, + .num_resources = ARRAY_SIZE(rtos_timer_resources), + .resource = rtos_timer_resources, +}; + +/* A lot of this stuff should move into a platform specific section. */ +struct adsp_hw_timer_struct { + u32 match; /* Match value */ + u32 count; + u32 enable; /* [1] - CLR_ON_MATCH_EN, [0] - EN */ + u32 clear; /* one-shot register that clears the count */ +}; + +/* Look for "TCX0" for related constants. */ +static __iomem struct adsp_hw_timer_struct *rtos_timer; + +static cycle_t timer_get_cycles(struct clocksource *cs) +{ + return (cycle_t) __vmgettime(); +} + +static struct clocksource hexagon_clocksource = { + .name = "pcycles", + .rating = 250, + .read = timer_get_cycles, + .mask = CLOCKSOURCE_MASK(64), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static int set_next_event(unsigned long delta, struct clock_event_device *evt) +{ + /* Assuming the timer will be disabled when we enter here. */ + + iowrite32(1, &rtos_timer->clear); + iowrite32(0, &rtos_timer->clear); + + iowrite32(delta, &rtos_timer->match); + iowrite32(1 << TIMER_ENABLE, &rtos_timer->enable); + return 0; +} + +/* + * Sets the mode (periodic, shutdown, oneshot, etc) of a timer. + */ +static void set_mode(enum clock_event_mode mode, + struct clock_event_device *evt) +{ + switch (mode) { + case CLOCK_EVT_MODE_SHUTDOWN: + /* XXX implement me */ + default: + break; + } +} + +#ifdef CONFIG_SMP +/* Broadcast mechanism */ +static void broadcast(const struct cpumask *mask) +{ + send_ipi(mask, IPI_TIMER); +} +#endif + +static struct clock_event_device hexagon_clockevent_dev = { + .name = "clockevent", + .features = CLOCK_EVT_FEAT_ONESHOT, + .rating = 400, + .irq = RTOS_TIMER_INT, + .set_next_event = set_next_event, + .set_mode = set_mode, +#ifdef CONFIG_SMP + .broadcast = broadcast, +#endif +}; + +#ifdef CONFIG_SMP +static DEFINE_PER_CPU(struct clock_event_device, clock_events); + +void setup_percpu_clockdev(void) +{ + int cpu = smp_processor_id(); + struct clock_event_device *ce_dev = &hexagon_clockevent_dev; + struct clock_event_device *dummy_clock_dev = + &per_cpu(clock_events, cpu); + + memcpy(dummy_clock_dev, ce_dev, sizeof(*dummy_clock_dev)); + INIT_LIST_HEAD(&dummy_clock_dev->list); + + dummy_clock_dev->features = CLOCK_EVT_FEAT_DUMMY; + dummy_clock_dev->cpumask = cpumask_of(cpu); + dummy_clock_dev->mode = CLOCK_EVT_MODE_UNUSED; + + clockevents_register_device(dummy_clock_dev); +} + +/* Called from smp.c for each CPU's timer ipi call */ +void ipi_timer(void) +{ + int cpu = smp_processor_id(); + struct clock_event_device *ce_dev = &per_cpu(clock_events, cpu); + + ce_dev->event_handler(ce_dev); +} +#endif /* CONFIG_SMP */ + +static irqreturn_t timer_interrupt(int irq, void *devid) +{ + struct clock_event_device *ce_dev = &hexagon_clockevent_dev; + + iowrite32(0, &rtos_timer->enable); + ce_dev->event_handler(ce_dev); + + return IRQ_HANDLED; +} + +/* This should also be pulled from devtree */ +static struct irqaction rtos_timer_intdesc = { + .handler = timer_interrupt, + .flags = IRQF_TIMER | IRQF_TRIGGER_RISING, + .name = "rtos_timer" +}; + +/* + * time_init_deferred - called by start_kernel to set up timer/clock source + * + * Install the IRQ handler for the clock, setup timers. + * This is done late, as that way, we can use ioremap(). + * + * This runs just before the delay loop is calibrated, and + * is used for delay calibration. + */ +void __init time_init_deferred(void) +{ + struct resource *resource = NULL; + struct clock_event_device *ce_dev = &hexagon_clockevent_dev; + struct device_node *dn; + struct resource r; + int err; + + ce_dev->cpumask = cpu_all_mask; + + if (!resource) + resource = rtos_timer_device.resource; + + /* ioremap here means this has to run later, after paging init */ + rtos_timer = ioremap(resource->start, resource->end + - resource->start + 1); + + if (!rtos_timer) { + release_mem_region(resource->start, resource->end + - resource->start + 1); + } + clocksource_register_khz(&hexagon_clocksource, pcycle_freq_mhz * 1000); + + /* Note: the sim generic RTOS clock is apparently really 18750Hz */ + + /* + * Last arg is some guaranteed seconds for which the conversion will + * work without overflow. + */ + clockevents_calc_mult_shift(ce_dev, sleep_clk_freq, 4); + + ce_dev->max_delta_ns = clockevent_delta2ns(0x7fffffff, ce_dev); + ce_dev->min_delta_ns = clockevent_delta2ns(0xf, ce_dev); + +#ifdef CONFIG_SMP + setup_percpu_clockdev(); +#endif + + clockevents_register_device(ce_dev); + setup_irq(ce_dev->irq, &rtos_timer_intdesc); +} + +void __init time_init(void) +{ + late_time_init = time_init_deferred; +} + +/* + * This could become parametric or perhaps even computed at run-time, + * but for now we take the observed simulator jitter. + */ +static long long fudgefactor = 350; /* Maybe lower if kernel optimized. */ + +void __udelay(unsigned long usecs) +{ + unsigned long long start = __vmgettime(); + unsigned long long finish = (pcycle_freq_mhz * usecs) - fudgefactor; + + while ((__vmgettime() - start) < finish) + cpu_relax(); /* not sure how this improves readability */ +} +EXPORT_SYMBOL(__udelay); |
