summaryrefslogtreecommitdiff
path: root/drivers/clocksource/bcm2835_timer.c
diff options
context:
space:
mode:
authorArnd Bergmann <arnd@arndb.de>2012-10-05 00:57:00 +0400
committerArnd Bergmann <arnd@arndb.de>2012-10-05 00:57:51 +0400
commitc37d6154c0b9163c27e53cc1d0be3867b4abd760 (patch)
tree7a24522c56d1cb284dff1d3c225bbdaba0901bb5 /drivers/clocksource/bcm2835_timer.c
parente7a570ff7dff9af6e54ff5e580a61ec7652137a0 (diff)
parent8a1ab3155c2ac7fbe5f2038d6e26efeb607a1498 (diff)
downloadlinux-c37d6154c0b9163c27e53cc1d0be3867b4abd760.tar.xz
Merge branch 'disintegrate-asm-generic' of git://git.infradead.org/users/dhowells/linux-headers into asm-generic
Patches from David Howells <dhowells@redhat.com>: This is to complete part of the UAPI disintegration for which the preparatory patches were pulled recently. Note that there are some fixup patches which are at the base of the branch aimed at you, plus all arches get the asm-generic branch merged in too. * 'disintegrate-asm-generic' of git://git.infradead.org/users/dhowells/linux-headers: UAPI: (Scripted) Disintegrate include/asm-generic UAPI: Fix conditional header installation handling (notably kvm_para.h on m68k) c6x: remove c6x signal.h UAPI: Split compound conditionals containing __KERNEL__ in Arm64 UAPI: Fix the guards on various asm/unistd.h files Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'drivers/clocksource/bcm2835_timer.c')
-rw-r--r--drivers/clocksource/bcm2835_timer.c161
1 files changed, 161 insertions, 0 deletions
diff --git a/drivers/clocksource/bcm2835_timer.c b/drivers/clocksource/bcm2835_timer.c
new file mode 100644
index 000000000000..bc19f12c20ce
--- /dev/null
+++ b/drivers/clocksource/bcm2835_timer.c
@@ -0,0 +1,161 @@
+/*
+ * 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,
+};