summaryrefslogtreecommitdiffstats
path: root/drivers/clocksource/timer-vt8500.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/clocksource/timer-vt8500.c')
-rw-r--r--drivers/clocksource/timer-vt8500.c168
1 files changed, 168 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-vt8500.c b/drivers/clocksource/timer-vt8500.c
new file mode 100644
index 000000000000..e0f7489cfc8e
--- /dev/null
+++ b/drivers/clocksource/timer-vt8500.c
@@ -0,0 +1,168 @@
+/*
+ * arch/arm/mach-vt8500/timer.c
+ *
+ * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
+ * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
+ *
+ * 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
+ */
+
+/*
+ * This file is copied and modified from the original timer.c provided by
+ * Alexey Charkov. Minor changes have been made for Device Tree Support.
+ */
+
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/delay.h>
+
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#define VT8500_TIMER_OFFSET 0x0100
+#define VT8500_TIMER_HZ 3000000
+#define TIMER_MATCH_VAL 0x0000
+#define TIMER_COUNT_VAL 0x0010
+#define TIMER_STATUS_VAL 0x0014
+#define TIMER_IER_VAL 0x001c /* interrupt enable */
+#define TIMER_CTRL_VAL 0x0020
+#define TIMER_AS_VAL 0x0024 /* access status */
+#define TIMER_COUNT_R_ACTIVE (1 << 5) /* not ready for read */
+#define TIMER_COUNT_W_ACTIVE (1 << 4) /* not ready for write */
+#define TIMER_MATCH_W_ACTIVE (1 << 0) /* not ready for write */
+
+#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
+
+#define MIN_OSCR_DELTA 16
+
+static void __iomem *regbase;
+
+static u64 vt8500_timer_read(struct clocksource *cs)
+{
+ int loops = msecs_to_loops(10);
+ writel(3, regbase + TIMER_CTRL_VAL);
+ while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE)
+ && --loops)
+ cpu_relax();
+ return readl(regbase + TIMER_COUNT_VAL);
+}
+
+static struct clocksource clocksource = {
+ .name = "vt8500_timer",
+ .rating = 200,
+ .read = vt8500_timer_read,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int vt8500_timer_set_next_event(unsigned long cycles,
+ struct clock_event_device *evt)
+{
+ int loops = msecs_to_loops(10);
+ u64 alarm = clocksource.read(&clocksource) + cycles;
+ while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE)
+ && --loops)
+ cpu_relax();
+ writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL);
+
+ if ((signed)(alarm - clocksource.read(&clocksource)) <= MIN_OSCR_DELTA)
+ return -ETIME;
+
+ writel(1, regbase + TIMER_IER_VAL);
+
+ return 0;
+}
+
+static int vt8500_shutdown(struct clock_event_device *evt)
+{
+ writel(readl(regbase + TIMER_CTRL_VAL) | 1, regbase + TIMER_CTRL_VAL);
+ writel(0, regbase + TIMER_IER_VAL);
+ return 0;
+}
+
+static struct clock_event_device clockevent = {
+ .name = "vt8500_timer",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .rating = 200,
+ .set_next_event = vt8500_timer_set_next_event,
+ .set_state_shutdown = vt8500_shutdown,
+ .set_state_oneshot = vt8500_shutdown,
+};
+
+static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = dev_id;
+ writel(0xf, regbase + TIMER_STATUS_VAL);
+ evt->event_handler(evt);
+
+ return IRQ_HANDLED;
+}
+
+static struct irqaction irq = {
+ .name = "vt8500_timer",
+ .flags = IRQF_TIMER | IRQF_IRQPOLL,
+ .handler = vt8500_timer_interrupt,
+ .dev_id = &clockevent,
+};
+
+static int __init vt8500_timer_init(struct device_node *np)
+{
+ int timer_irq, ret;
+
+ regbase = of_iomap(np, 0);
+ if (!regbase) {
+ pr_err("%s: Missing iobase description in Device Tree\n",
+ __func__);
+ return -ENXIO;
+ }
+
+ timer_irq = irq_of_parse_and_map(np, 0);
+ if (!timer_irq) {
+ pr_err("%s: Missing irq description in Device Tree\n",
+ __func__);
+ return -EINVAL;
+ }
+
+ writel(1, regbase + TIMER_CTRL_VAL);
+ writel(0xf, regbase + TIMER_STATUS_VAL);
+ writel(~0, regbase + TIMER_MATCH_VAL);
+
+ ret = clocksource_register_hz(&clocksource, VT8500_TIMER_HZ);
+ if (ret) {
+ pr_err("%s: vt8500_timer_init: clocksource_register failed for %s\n",
+ __func__, clocksource.name);
+ return ret;
+ }
+
+ clockevent.cpumask = cpumask_of(0);
+
+ ret = setup_irq(timer_irq, &irq);
+ if (ret) {
+ pr_err("%s: setup_irq failed for %s\n", __func__,
+ clockevent.name);
+ return ret;
+ }
+
+ clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ,
+ MIN_OSCR_DELTA * 2, 0xf0000000);
+
+ return 0;
+}
+
+TIMER_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init);