mirror of https://gitee.com/openkylin/linux.git
138 lines
3.1 KiB
C
138 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright 2012 Simon Arlott
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*/
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#include <linux/bitops.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/irqreturn.h>
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#include <linux/kernel.h>
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#include <linux/module.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/of_platform.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/sched_clock.h>
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#include <asm/irq.h>
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#define REG_CONTROL 0x00
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#define REG_COUNTER_LO 0x04
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#define REG_COUNTER_HI 0x08
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#define REG_COMPARE(n) (0x0c + (n) * 4)
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#define MAX_TIMER 3
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#define DEFAULT_TIMER 3
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struct bcm2835_timer {
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void __iomem *control;
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void __iomem *compare;
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int match_mask;
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struct clock_event_device evt;
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};
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static void __iomem *system_clock __read_mostly;
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static u64 notrace bcm2835_sched_read(void)
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{
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return readl_relaxed(system_clock);
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}
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static int bcm2835_time_set_next_event(unsigned long event,
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struct clock_event_device *evt_dev)
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{
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struct bcm2835_timer *timer = container_of(evt_dev,
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struct bcm2835_timer, evt);
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writel_relaxed(readl_relaxed(system_clock) + event,
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timer->compare);
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return 0;
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}
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static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id)
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{
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struct bcm2835_timer *timer = dev_id;
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void (*event_handler)(struct clock_event_device *);
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if (readl_relaxed(timer->control) & timer->match_mask) {
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writel_relaxed(timer->match_mask, timer->control);
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event_handler = READ_ONCE(timer->evt.event_handler);
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if (event_handler)
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event_handler(&timer->evt);
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return IRQ_HANDLED;
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} else {
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return IRQ_NONE;
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}
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}
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static int __init bcm2835_timer_init(struct device_node *node)
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{
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void __iomem *base;
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u32 freq;
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int irq, ret;
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struct bcm2835_timer *timer;
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base = of_iomap(node, 0);
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if (!base) {
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pr_err("Can't remap registers\n");
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return -ENXIO;
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}
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ret = of_property_read_u32(node, "clock-frequency", &freq);
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if (ret) {
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pr_err("Can't read clock-frequency\n");
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goto err_iounmap;
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}
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system_clock = base + REG_COUNTER_LO;
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sched_clock_register(bcm2835_sched_read, 32, freq);
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clocksource_mmio_init(base + REG_COUNTER_LO, node->name,
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freq, 300, 32, clocksource_mmio_readl_up);
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irq = irq_of_parse_and_map(node, DEFAULT_TIMER);
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if (irq <= 0) {
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pr_err("Can't parse IRQ\n");
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ret = -EINVAL;
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goto err_iounmap;
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}
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timer = kzalloc(sizeof(*timer), GFP_KERNEL);
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if (!timer) {
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ret = -ENOMEM;
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goto err_iounmap;
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}
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timer->control = base + REG_CONTROL;
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timer->compare = base + REG_COMPARE(DEFAULT_TIMER);
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timer->match_mask = BIT(DEFAULT_TIMER);
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timer->evt.name = node->name;
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timer->evt.rating = 300;
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timer->evt.features = CLOCK_EVT_FEAT_ONESHOT;
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timer->evt.set_next_event = bcm2835_time_set_next_event;
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timer->evt.cpumask = cpumask_of(0);
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ret = request_irq(irq, bcm2835_time_interrupt, IRQF_TIMER | IRQF_SHARED,
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node->name, timer);
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if (ret) {
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pr_err("Can't set up timer IRQ\n");
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goto err_timer_free;
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}
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clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff);
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pr_info("bcm2835: system timer (irq = %d)\n", irq);
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return 0;
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err_timer_free:
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kfree(timer);
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err_iounmap:
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iounmap(base);
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return ret;
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}
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TIMER_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer",
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bcm2835_timer_init);
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