/* * Copyright 2012 Simon Arlott * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */ #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;	struct irqaction act;}; 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 = ACCESS_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) {		pr_err("Can't allocate timer struct\n");		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);	timer->act.name = node->name;	timer->act.flags = IRQF_TIMER | IRQF_SHARED;	timer->act.dev_id = timer;	timer->act.handler = bcm2835_time_interrupt; 	ret = setup_irq(irq, &timer->act);	if (ret) {		pr_err("Can't set up timer IRQ\n");		goto err_iounmap;	} 	clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff); 	pr_info("bcm2835: system timer (irq = %d)\n", irq); 	return 0; err_iounmap:	iounmap(base);	return ret;}TIMER_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer",			bcm2835_timer_init);