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