--- /dev/null
+/*
+ * CS5536 General timer functions
+ *
+ * Copyright (C) 2007 Lemote Inc. & Insititute of Computing Technology
+ * Author: Yanhua, yanh@lemote.com
+ *
+ * Copyright (C) 2009 Lemote Inc.
+ * Author: Wu zhangjin, wuzj@lemote.com
+ *
+ * Reference: AMD Geode(TM) CS5536 Companion Device Data Book
+ *
+ * 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.
+ */
+
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/module.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>
+
+DEFINE_SPINLOCK(mfgpt_lock);
+EXPORT_SYMBOL(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 void init_mfgpt_timer(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ spin_lock(&mfgpt_lock);
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ outw(COMPARE, MFGPT0_CMP2); /* set comparator2 */
+ outw(0, MFGPT0_CNT); /* set counter to 0 */
+ enable_mfgpt0_counter();
+ break;
+
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ case CLOCK_EVT_MODE_UNUSED:
+ if (evt->mode == CLOCK_EVT_MODE_PERIODIC ||
+ evt->mode == CLOCK_EVT_MODE_ONESHOT)
+ disable_mfgpt0_counter();
+ break;
+
+ case CLOCK_EVT_MODE_ONESHOT:
+ /* The oneshot mode have very high deviation, Not use it! */
+ break;
+
+ case CLOCK_EVT_MODE_RESUME:
+ /* Nothing to do here */
+ break;
+ }
+ spin_unlock(&mfgpt_lock);
+}
+
+static struct clock_event_device mfgpt_clockevent = {
+ .name = "mfgpt",
+ .features = CLOCK_EVT_FEAT_PERIODIC,
+ .set_mode = init_mfgpt_timer,
+ .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_DISABLED | 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->min_delta_ns = clockevent_delta2ns(0xf, cd);
+
+ /* 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 cycle_t mfgpt_read(struct clocksource *cs)
+{
+ unsigned long flags;
+ int count;
+ u32 jifs;
+ static int old_count;
+ static u32 old_jifs;
+
+ 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;
+
+ spin_unlock_irqrestore(&mfgpt_lock, flags);
+
+ return (cycle_t) (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),
+ .mult = 0,
+ .shift = 22,
+};
+
+int __init init_mfgpt_clocksource(void)
+{
+ if (num_possible_cpus() > 1) /* MFGPT does not scale! */
+ return 0;
+
+ clocksource_mfgpt.mult = clocksource_hz2mult(MFGPT_TICK_RATE, 22);
+ return clocksource_register(&clocksource_mfgpt);
+}
+
+arch_initcall(init_mfgpt_clocksource);
git.openpandora.org / pandora-kernel.git / commitdiff