--- /dev/null
+/*
+ * 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/bcm2835_timer.h>
+#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 <asm/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 u32 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 struct of_device_id bcm2835_time_match[] __initconst = {
+ { .compatible = "brcm,bcm2835-system-timer" },
+ {}
+};
+
+static void __init bcm2835_time_init(void)
+{
+ struct device_node *node;
+ void __iomem *base;
+ u32 freq;
+ int irq;
+ struct bcm2835_timer *timer;
+
+ node = of_find_matching_node(NULL, bcm2835_time_match);
+ if (!node)
+ panic("No bcm2835 timer node");
+
+ 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;
+ setup_sched_clock(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);
+}
+
+struct sys_timer bcm2835_timer = {
+ .init = bcm2835_time_init,
+};
projects / linux-drm-fsl-dcu.git / commitdiff