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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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3.2 kB · 137 lines
C
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138// SPDX-License-Identifier: GPL-2.0+/* * Copyright 2012 Simon Arlott */
#include <linux/bitops.h>#include <linux/clockchips.h>#include <linux/clocksource.h>#include <linux/interrupt.h>#include <linux/irqreturn.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/of.h>#include <linux/of_address.h>#include <linux/of_irq.h>#include <linux/slab.h>#include <linux/string.h>#include <linux/sched_clock.h>
#include <asm/irq.h>
#define REG_CONTROL 0x00#define REG_COUNTER_LO 0x04#define REG_COUNTER_HI 0x08#define REG_COMPARE(n) (0x0c + (n) * 4)#define MAX_TIMER 3#define DEFAULT_TIMER 3
struct bcm2835_timer { void __iomem *control; void __iomem *compare; int match_mask; struct clock_event_device evt;};
static void __iomem *system_clock __read_mostly;
static u64 notrace bcm2835_sched_read(void){ return readl_relaxed(system_clock);}
static int bcm2835_time_set_next_event(unsigned long event, struct clock_event_device *evt_dev){ struct bcm2835_timer *timer = container_of(evt_dev, struct bcm2835_timer, evt); writel_relaxed(readl_relaxed(system_clock) + event, timer->compare); return 0;}
static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id){ struct bcm2835_timer *timer = dev_id; void (*event_handler)(struct clock_event_device *); if (readl_relaxed(timer->control) & timer->match_mask) { writel_relaxed(timer->match_mask, timer->control);
event_handler = READ_ONCE(timer->evt.event_handler); if (event_handler) event_handler(&timer->evt); return IRQ_HANDLED; } else { return IRQ_NONE; }}
static int __init bcm2835_timer_init(struct device_node *node){ void __iomem *base; u32 freq; int irq, ret; struct bcm2835_timer *timer;
base = of_iomap(node, 0); if (!base) { pr_err("Can't remap registers\n"); return -ENXIO; }
ret = of_property_read_u32(node, "clock-frequency", &freq); if (ret) { pr_err("Can't read clock-frequency\n"); goto err_iounmap; }
system_clock = base + REG_COUNTER_LO; sched_clock_register(bcm2835_sched_read, 32, freq);
clocksource_mmio_init(base + REG_COUNTER_LO, node->name, freq, 300, 32, clocksource_mmio_readl_up);
irq = irq_of_parse_and_map(node, DEFAULT_TIMER); if (irq <= 0) { pr_err("Can't parse IRQ\n"); ret = -EINVAL; goto err_iounmap; }
timer = kzalloc_obj(*timer); if (!timer) { ret = -ENOMEM; goto err_iounmap; }
timer->control = base + REG_CONTROL; timer->compare = base + REG_COMPARE(DEFAULT_TIMER); timer->match_mask = BIT(DEFAULT_TIMER); timer->evt.name = node->name; timer->evt.rating = 300; timer->evt.features = CLOCK_EVT_FEAT_ONESHOT; timer->evt.set_next_event = bcm2835_time_set_next_event; timer->evt.cpumask = cpumask_of(0);
ret = request_irq(irq, bcm2835_time_interrupt, IRQF_TIMER | IRQF_SHARED, node->name, timer); if (ret) { pr_err("Can't set up timer IRQ\n"); goto err_timer_free; }
clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff);
pr_info("bcm2835: system timer (irq = %d)\n", irq);
return 0;
err_timer_free: kfree(timer);
err_iounmap: iounmap(base); return ret;}TIMER_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer", bcm2835_timer_init);