/* * 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 void bcm2835_time_set_mode(enum clock_event_mode mode, struct clock_event_device *evt_dev) { switch (mode) { case CLOCK_EVT_MODE_ONESHOT: case CLOCK_EVT_MODE_UNUSED: case CLOCK_EVT_MODE_SHUTDOWN: case CLOCK_EVT_MODE_RESUME: break; default: WARN(1, "%s: unhandled event mode %d\n", __func__, mode); break; } } 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 void __init bcm2835_timer_init(struct device_node *node) { void __iomem *base; u32 freq; int irq; struct bcm2835_timer *timer; base = of_iomap(node, 0); if (!base) panic("Can't remap registers"); if (of_property_read_u32(node, "clock-frequency", &freq)) panic("Can't read clock-frequency"); 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) panic("Can't parse IRQ"); timer = kzalloc(sizeof(*timer), GFP_KERNEL); if (!timer) panic("Can't allocate timer struct\n"); 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_mode = bcm2835_time_set_mode; 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; if (setup_irq(irq, &timer->act)) panic("Can't set up timer IRQ\n"); clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff); pr_info("bcm2835: system timer (irq = %d)\n", irq); } CLOCKSOURCE_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer", bcm2835_timer_init);