diff options
Diffstat (limited to 'drivers/clocksource/bcm2835_timer.c')
| -rw-r--r-- | drivers/clocksource/bcm2835_timer.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/drivers/clocksource/bcm2835_timer.c b/drivers/clocksource/bcm2835_timer.c new file mode 100644 index 000000000..26ed331b1 --- /dev/null +++ b/drivers/clocksource/bcm2835_timer.c @@ -0,0 +1,148 @@ +/* + * 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); |