1 files changed, 207 insertions, 0 deletions
diff --git a/arch/mips/loongson2ef/common/cs5536/cs5536_mfgpt.c b/arch/mips/loongson2ef/common/cs5536/cs5536_mfgpt.c
new file mode 100644
index 000000000000..30af1b7c7529
--- /dev/null
+++ b/arch/mips/loongson2ef/common/cs5536/cs5536_mfgpt.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * CS5536 General timer functions
+ *
+ * Copyright (C) 2007 Lemote Inc. & Institute of Computing Technology
+ * Author: Yanhua, yanh@lemote.com
+ *
+ * Copyright (C) 2009 Lemote Inc.
+ * Author: Wu zhangjin, wuzhangjin@gmail.com
+ *
+ * Reference: AMD Geode(TM) CS5536 Companion Device Data Book
+ */
+
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/jiffies.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/clockchips.h>
+
+#include <asm/time.h>
+
+#include <cs5536/cs5536_mfgpt.h>
+
+static DEFINE_RAW_SPINLOCK(mfgpt_lock);
+
+static u32 mfgpt_base;
+
+/*
+ * Initialize the MFGPT timer.
+ *
+ * This is also called after resume to bring the MFGPT into operation again.
+ */
+
+/* disable counter */
+void disable_mfgpt0_counter(void)
+{
+	outw(inw(MFGPT0_SETUP) & 0x7fff, MFGPT0_SETUP);
+}
+EXPORT_SYMBOL(disable_mfgpt0_counter);
+
+/* enable counter, comparator2 to event mode, 14.318MHz clock */
+void enable_mfgpt0_counter(void)
+{
+	outw(0xe310, MFGPT0_SETUP);
+}
+EXPORT_SYMBOL(enable_mfgpt0_counter);
+
+static int mfgpt_timer_set_periodic(struct clock_event_device *evt)
+{
+	raw_spin_lock(&mfgpt_lock);
+
+	outw(COMPARE, MFGPT0_CMP2);	/* set comparator2 */
+	outw(0, MFGPT0_CNT);		/* set counter to 0 */
+	enable_mfgpt0_counter();
+
+	raw_spin_unlock(&mfgpt_lock);
+	return 0;
+}
+
+static int mfgpt_timer_shutdown(struct clock_event_device *evt)
+{
+	if (clockevent_state_periodic(evt) || clockevent_state_oneshot(evt)) {
+		raw_spin_lock(&mfgpt_lock);
+		disable_mfgpt0_counter();
+		raw_spin_unlock(&mfgpt_lock);
+	}
+
+	return 0;
+}
+
+static struct clock_event_device mfgpt_clockevent = {
+	.name = "mfgpt",
+	.features = CLOCK_EVT_FEAT_PERIODIC,
+
+	/* The oneshot mode have very high deviation, don't use it! */
+	.set_state_shutdown = mfgpt_timer_shutdown,
+	.set_state_periodic = mfgpt_timer_set_periodic,
+	.irq = CS5536_MFGPT_INTR,
+};
+
+static irqreturn_t timer_interrupt(int irq, void *dev_id)
+{
+	u32 basehi;
+
+	/*
+	 * get MFGPT base address
+	 *
+	 * NOTE: do not remove me, it's need for the value of mfgpt_base is
+	 * variable
+	 */
+	_rdmsr(DIVIL_MSR_REG(DIVIL_LBAR_MFGPT), &basehi, &mfgpt_base);
+
+	/* ack */
+	outw(inw(MFGPT0_SETUP) | 0x4000, MFGPT0_SETUP);
+
+	mfgpt_clockevent.event_handler(&mfgpt_clockevent);
+
+	return IRQ_HANDLED;
+}
+
+static struct irqaction irq5 = {
+	.handler = timer_interrupt,
+	.flags = IRQF_NOBALANCING | IRQF_TIMER,
+	.name = "timer"
+};
+
+/*
+ * Initialize the conversion factor and the min/max deltas of the clock event
+ * structure and register the clock event source with the framework.
+ */
+void __init setup_mfgpt0_timer(void)
+{
+	u32 basehi;
+	struct clock_event_device *cd = &mfgpt_clockevent;
+	unsigned int cpu = smp_processor_id();
+
+	cd->cpumask = cpumask_of(cpu);
+	clockevent_set_clock(cd, MFGPT_TICK_RATE);
+	cd->max_delta_ns = clockevent_delta2ns(0xffff, cd);
+	cd->max_delta_ticks = 0xffff;
+	cd->min_delta_ns = clockevent_delta2ns(0xf, cd);
+	cd->min_delta_ticks = 0xf;
+
+	/* Enable MFGPT0 Comparator 2 Output to the Interrupt Mapper */
+	_wrmsr(DIVIL_MSR_REG(MFGPT_IRQ), 0, 0x100);
+
+	/* Enable Interrupt Gate 5 */
+	_wrmsr(DIVIL_MSR_REG(PIC_ZSEL_LOW), 0, 0x50000);
+
+	/* get MFGPT base address */
+	_rdmsr(DIVIL_MSR_REG(DIVIL_LBAR_MFGPT), &basehi, &mfgpt_base);
+
+	clockevents_register_device(cd);
+
+	setup_irq(CS5536_MFGPT_INTR, &irq5);
+}
+
+/*
+ * Since the MFGPT overflows every tick, its not very useful
+ * to just read by itself. So use jiffies to emulate a free
+ * running counter:
+ */
+static u64 mfgpt_read(struct clocksource *cs)
+{
+	unsigned long flags;
+	int count;
+	u32 jifs;
+	static int old_count;
+	static u32 old_jifs;
+
+	raw_spin_lock_irqsave(&mfgpt_lock, flags);
+	/*
+	 * Although our caller may have the read side of xtime_lock,
+	 * this is now a seqlock, and we are cheating in this routine
+	 * by having side effects on state that we cannot undo if
+	 * there is a collision on the seqlock and our caller has to
+	 * retry.  (Namely, old_jifs and old_count.)  So we must treat
+	 * jiffies as volatile despite the lock.  We read jiffies
+	 * before latching the timer count to guarantee that although
+	 * the jiffies value might be older than the count (that is,
+	 * the counter may underflow between the last point where
+	 * jiffies was incremented and the point where we latch the
+	 * count), it cannot be newer.
+	 */
+	jifs = jiffies;
+	/* read the count */
+	count = inw(MFGPT0_CNT);
+
+	/*
+	 * It's possible for count to appear to go the wrong way for this
+	 * reason:
+	 *
+	 *  The timer counter underflows, but we haven't handled the resulting
+	 *  interrupt and incremented jiffies yet.
+	 *
+	 * Previous attempts to handle these cases intelligently were buggy, so
+	 * we just do the simple thing now.
+	 */
+	if (count < old_count && jifs == old_jifs)
+		count = old_count;
+
+	old_count = count;
+	old_jifs = jifs;
+
+	raw_spin_unlock_irqrestore(&mfgpt_lock, flags);
+
+	return (u64) (jifs * COMPARE) + count;
+}
+
+static struct clocksource clocksource_mfgpt = {
+	.name = "mfgpt",
+	.rating = 120, /* Functional for real use, but not desired */
+	.read = mfgpt_read,
+	.mask = CLOCKSOURCE_MASK(32),
+};
+
+int __init init_mfgpt_clocksource(void)
+{
+	if (num_possible_cpus() > 1)	/* MFGPT does not scale! */
+		return 0;
+
+	return clocksource_register_hz(&clocksource_mfgpt, MFGPT_TICK_RATE);
+}
+
+arch_initcall(init_mfgpt_clocksource);