138 lines
3.1 KiB
C
138 lines
3.1 KiB
C
// 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_address.h>
|
|
#include <linux/of_irq.h>
|
|
#include <linux/of_platform.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(sizeof(*timer), GFP_KERNEL);
|
|
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);
|