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1// SPDX-License-Identifier: GPL-2.0+2/*3 * Copyright 2012 Simon Arlott4 */5 6#include <linux/bitops.h>7#include <linux/clockchips.h>8#include <linux/clocksource.h>9#include <linux/interrupt.h>10#include <linux/irqreturn.h>11#include <linux/kernel.h>12#include <linux/module.h>13#include <linux/of.h>14#include <linux/of_address.h>15#include <linux/of_irq.h>16#include <linux/slab.h>17#include <linux/string.h>18#include <linux/sched_clock.h>19 20#include <asm/irq.h>21 22#define REG_CONTROL 0x0023#define REG_COUNTER_LO 0x0424#define REG_COUNTER_HI 0x0825#define REG_COMPARE(n) (0x0c + (n) * 4)26#define MAX_TIMER 327#define DEFAULT_TIMER 328 29struct bcm2835_timer {30 void __iomem *control;31 void __iomem *compare;32 int match_mask;33 struct clock_event_device evt;34};35 36static void __iomem *system_clock __read_mostly;37 38static u64 notrace bcm2835_sched_read(void)39{40 return readl_relaxed(system_clock);41}42 43static int bcm2835_time_set_next_event(unsigned long event,44 struct clock_event_device *evt_dev)45{46 struct bcm2835_timer *timer = container_of(evt_dev,47 struct bcm2835_timer, evt);48 writel_relaxed(readl_relaxed(system_clock) + event,49 timer->compare);50 return 0;51}52 53static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id)54{55 struct bcm2835_timer *timer = dev_id;56 void (*event_handler)(struct clock_event_device *);57 if (readl_relaxed(timer->control) & timer->match_mask) {58 writel_relaxed(timer->match_mask, timer->control);59 60 event_handler = READ_ONCE(timer->evt.event_handler);61 if (event_handler)62 event_handler(&timer->evt);63 return IRQ_HANDLED;64 } else {65 return IRQ_NONE;66 }67}68 69static int __init bcm2835_timer_init(struct device_node *node)70{71 void __iomem *base;72 u32 freq;73 int irq, ret;74 struct bcm2835_timer *timer;75 76 base = of_iomap(node, 0);77 if (!base) {78 pr_err("Can't remap registers\n");79 return -ENXIO;80 }81 82 ret = of_property_read_u32(node, "clock-frequency", &freq);83 if (ret) {84 pr_err("Can't read clock-frequency\n");85 goto err_iounmap;86 }87 88 system_clock = base + REG_COUNTER_LO;89 sched_clock_register(bcm2835_sched_read, 32, freq);90 91 clocksource_mmio_init(base + REG_COUNTER_LO, node->name,92 freq, 300, 32, clocksource_mmio_readl_up);93 94 irq = irq_of_parse_and_map(node, DEFAULT_TIMER);95 if (irq <= 0) {96 pr_err("Can't parse IRQ\n");97 ret = -EINVAL;98 goto err_iounmap;99 }100 101 timer = kzalloc(sizeof(*timer), GFP_KERNEL);102 if (!timer) {103 ret = -ENOMEM;104 goto err_iounmap;105 }106 107 timer->control = base + REG_CONTROL;108 timer->compare = base + REG_COMPARE(DEFAULT_TIMER);109 timer->match_mask = BIT(DEFAULT_TIMER);110 timer->evt.name = node->name;111 timer->evt.rating = 300;112 timer->evt.features = CLOCK_EVT_FEAT_ONESHOT;113 timer->evt.set_next_event = bcm2835_time_set_next_event;114 timer->evt.cpumask = cpumask_of(0);115 116 ret = request_irq(irq, bcm2835_time_interrupt, IRQF_TIMER | IRQF_SHARED,117 node->name, timer);118 if (ret) {119 pr_err("Can't set up timer IRQ\n");120 goto err_timer_free;121 }122 123 clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff);124 125 pr_info("bcm2835: system timer (irq = %d)\n", irq);126 127 return 0;128 129err_timer_free:130 kfree(timer);131 132err_iounmap:133 iounmap(base);134 return ret;135}136TIMER_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer",137 bcm2835_timer_init);138