1 files changed, 218 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
new file mode 100644
index 000000000..378186b5e
--- /dev/null
+++ b/arch/xtensa/kernel/time.c
@@ -0,0 +1,218 @@
+/*
+ * arch/xtensa/kernel/time.c
+ *
+ * Timer and clock support.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2005 Tensilica Inc.
+ *
+ * Chris Zankel <chris@zankel.net>
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/profile.h>
+#include <linux/delay.h>
+#include <linux/irqdomain.h>
+#include <linux/sched_clock.h>
+
+#include <asm/timex.h>
+#include <asm/platform.h>
+
+unsigned long ccount_freq;		/* ccount Hz */
+EXPORT_SYMBOL(ccount_freq);
+
+static u64 ccount_read(struct clocksource *cs)
+{
+	return (u64)get_ccount();
+}
+
+static u64 notrace ccount_sched_clock_read(void)
+{
+	return get_ccount();
+}
+
+static struct clocksource ccount_clocksource = {
+	.name = "ccount",
+	.rating = 200,
+	.read = ccount_read,
+	.mask = CLOCKSOURCE_MASK(32),
+	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int ccount_timer_set_next_event(unsigned long delta,
+		struct clock_event_device *dev);
+struct ccount_timer {
+	struct clock_event_device evt;
+	int irq_enabled;
+	char name[24];
+};
+static DEFINE_PER_CPU(struct ccount_timer, ccount_timer);
+
+static int ccount_timer_set_next_event(unsigned long delta,
+		struct clock_event_device *dev)
+{
+	unsigned long flags, next;
+	int ret = 0;
+
+	local_irq_save(flags);
+	next = get_ccount() + delta;
+	set_linux_timer(next);
+	if (next - get_ccount() > delta)
+		ret = -ETIME;
+	local_irq_restore(flags);
+
+	return ret;
+}
+
+/*
+ * There is no way to disable the timer interrupt at the device level,
+ * only at the intenable register itself. Since enable_irq/disable_irq
+ * calls are nested, we need to make sure that these calls are
+ * balanced.
+ */
+static int ccount_timer_shutdown(struct clock_event_device *evt)
+{
+	struct ccount_timer *timer =
+		container_of(evt, struct ccount_timer, evt);
+
+	if (timer->irq_enabled) {
+		disable_irq_nosync(evt->irq);
+		timer->irq_enabled = 0;
+	}
+	return 0;
+}
+
+static int ccount_timer_set_oneshot(struct clock_event_device *evt)
+{
+	struct ccount_timer *timer =
+		container_of(evt, struct ccount_timer, evt);
+
+	if (!timer->irq_enabled) {
+		enable_irq(evt->irq);
+		timer->irq_enabled = 1;
+	}
+	return 0;
+}
+
+static irqreturn_t timer_interrupt(int irq, void *dev_id);
+static struct irqaction timer_irqaction = {
+	.handler =	timer_interrupt,
+	.flags =	IRQF_TIMER,
+	.name =		"timer",
+};
+
+void local_timer_setup(unsigned cpu)
+{
+	struct ccount_timer *timer = &per_cpu(ccount_timer, cpu);
+	struct clock_event_device *clockevent = &timer->evt;
+
+	timer->irq_enabled = 1;
+	clockevent->name = timer->name;
+	snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu);
+	clockevent->features = CLOCK_EVT_FEAT_ONESHOT;
+	clockevent->rating = 300;
+	clockevent->set_next_event = ccount_timer_set_next_event;
+	clockevent->set_state_shutdown = ccount_timer_shutdown;
+	clockevent->set_state_oneshot = ccount_timer_set_oneshot;
+	clockevent->tick_resume = ccount_timer_set_oneshot;
+	clockevent->cpumask = cpumask_of(cpu);
+	clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
+	if (WARN(!clockevent->irq, "error: can't map timer irq"))
+		return;
+	clockevents_config_and_register(clockevent, ccount_freq,
+					0xf, 0xffffffff);
+}
+
+#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
+#ifdef CONFIG_OF
+static void __init calibrate_ccount(void)
+{
+	struct device_node *cpu;
+	struct clk *clk;
+
+	cpu = of_find_compatible_node(NULL, NULL, "cdns,xtensa-cpu");
+	if (cpu) {
+		clk = of_clk_get(cpu, 0);
+		if (!IS_ERR(clk)) {
+			ccount_freq = clk_get_rate(clk);
+			return;
+		} else {
+			pr_warn("%s: CPU input clock not found\n",
+				__func__);
+		}
+	} else {
+		pr_warn("%s: CPU node not found in the device tree\n",
+			__func__);
+	}
+
+	platform_calibrate_ccount();
+}
+#else
+static inline void calibrate_ccount(void)
+{
+	platform_calibrate_ccount();
+}
+#endif
+#endif
+
+void __init time_init(void)
+{
+	of_clk_init(NULL);
+#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
+	pr_info("Calibrating CPU frequency ");
+	calibrate_ccount();
+	pr_cont("%d.%02d MHz\n",
+		(int)ccount_freq / 1000000,
+		(int)(ccount_freq / 10000) % 100);
+#else
+	ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL;
+#endif
+	WARN(!ccount_freq,
+	     "%s: CPU clock frequency is not set up correctly\n",
+	     __func__);
+	clocksource_register_hz(&ccount_clocksource, ccount_freq);
+	local_timer_setup(0);
+	setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction);
+	sched_clock_register(ccount_sched_clock_read, 32, ccount_freq);
+	timer_probe();
+}
+
+/*
+ * The timer interrupt is called HZ times per second.
+ */
+
+irqreturn_t timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt;
+
+	set_linux_timer(get_linux_timer());
+	evt->event_handler(evt);
+
+	/* Allow platform to do something useful (Wdog). */
+	platform_heartbeat();
+
+	return IRQ_HANDLED;
+}
+
+#ifndef CONFIG_GENERIC_CALIBRATE_DELAY
+void calibrate_delay(void)
+{
+	loops_per_jiffy = ccount_freq / HZ;
+	pr_info("Calibrating delay loop (skipped)... %lu.%02lu BogoMIPS preset\n",
+		loops_per_jiffy / (1000000 / HZ),
+		(loops_per_jiffy / (10000 / HZ)) % 100);
+}
+#endif