1 files changed, 354 insertions, 0 deletions
diff --git a/target/linux/olpc/files/arch/i386/kernel/mfgpt.c b/target/linux/olpc/files/arch/i386/kernel/mfgpt.c
new file mode 100644
index 0000000000..2e62a41e7f
--- /dev/null
+++ b/target/linux/olpc/files/arch/i386/kernel/mfgpt.c
@@ -0,0 +1,354 @@
+/* Driver/API for AMD Geode Multi-Function General Purpose Timers (MFGPT)
+ *
+ * Copyright (C) 2006, Advanced Micro Devices, Inc.
+ *
+ * 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.
+ */
+
+/* The MFPGT timers on the CS5536 provide us with suitable timers to use
+ * as clock event sources - not as good as a HPET or APIC, but certainly
+ * better then the PIT.  This isn't a general purpose MFGPT driver, but
+ * a simplified one designed specifically to act as a clock event source.
+ * For full details about the MFGPT, please consult the CS5536 data sheet.
+*/
+
+/* We are using the 32Khz input clock - its the only one that has the
+ * ranges we find desirable.  The following table lists the suitable
+ * divisors and the associated hz, minimum interval
+ * and the maximum interval:
+
+   Divisor   Hz      Min Delta (S) Max Delta (S)
+    1        32000     .0005          2.048
+    2        16000      .001          4.096
+    4         8000      .002          8.192
+    8         4000      .004         16.384
+    16        2000      .008         32.768
+    32        1000      .016         65.536
+    64         500      .032        131.072
+   128         250      .064        262.144
+   256         125      .128        524.288
+*/
+
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <asm/geode.h>
+
+#include "do_timer.h"
+
+#define MFGPT_MAX_TIMERS 8
+
+#define F_AVAIL    0x01
+
+static struct mfgpt_timer_t {
+	int flags;
+	struct module *owner;
+} mfgpt_timers[MFGPT_MAX_TIMERS];
+
+/* Selected from the table above */
+
+#define MFGPT_DIVISOR 16
+#define MFGPT_SCALE  4     /* divisor = 2^(scale) */
+#define MFGPT_HZ  (32000 / MFGPT_DIVISOR)
+#define MFGPT_PERIODIC (MFGPT_HZ / HZ)
+
+#ifdef CONFIG_GEODE_MFGPT_TIMER
+static int __init mfgpt_timer_setup(void);
+#else
+#define mfgpt_timer_setup() (0)
+#endif
+
+/* Allow for disabling of MFGPTs */
+static int disable = 0;
+static int __init mfgpt_disable(char *s)
+{
+	disable = 1;
+	return 1;
+}
+__setup("nomfgpt", mfgpt_disable);
+
+/*
+ * Check whether any MFGPTs are available for the kernel to use.  In most
+ * cases, firmware that uses AMD's VSA code will claim all timers during
+ * bootup; we certainly don't want to take them if they're already in use.
+ * In other cases (such as with VSAless OpenFirmware), the system firmware
+ * leaves timers available for us to use.
+ */
+int __init geode_mfgpt_detect(void)
+{
+	int count = 0, i;
+	u16 val;
+
+	if (disable) {
+		printk(KERN_INFO "geode-mfgpt:  Skipping MFGPT setup\n");
+		return 0;
+	}
+
+	for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
+		val = geode_mfgpt_read(i, MFGPT_REG_SETUP);
+		if (!(val & MFGPT_SETUP_SETUP)) {
+			mfgpt_timers[i].flags = F_AVAIL;
+			count++;
+		}
+	}
+
+	/* set up clock event device, if desired */
+	i = mfgpt_timer_setup();
+
+	return count;
+}
+
+int geode_mfgpt_toggle_event(int timer, int cmp, int event, int enable)
+{
+	u32 msr, mask, value, dummy;
+	int shift = (cmp == MFGPT_CMP1) ? 0 : 8;
+
+	if (timer < 0 || timer >= MFGPT_MAX_TIMERS)
+		return -EIO;
+
+	/*
+	 * The register maps for these are described in sections 6.17.1.x of
+	 * the AMD Geode CS5536 Companion Device Data Book.
+	 */
+	switch(event) {
+	case MFGPT_EVENT_RESET:
+		/* XXX: According to the docs, we cannot reset timers above
+		 * 6; that is, resets for 7 and 8 will be ignored.  Is this
+		 *  a problem? */
+		msr = MFGPT_NR_MSR;
+		mask = 1 << (timer + 24);
+		break;
+
+	case MFGPT_EVENT_NMI:
+		msr = MFGPT_NR_MSR;
+		mask = 1 << (timer + shift);
+		break;
+
+	case MFGPT_EVENT_IRQ:
+		msr = MFGPT_IRQ_MSR;
+		mask = 1 << (timer + shift);
+		break;
+
+	default:
+		return -EIO;
+	}
+
+	rdmsr(msr, value, dummy);
+
+	if (enable)
+		value |= mask;
+	else
+		value &= ~mask;
+
+	wrmsr(msr, value, dummy);
+	return 0;
+}
+EXPORT_SYMBOL(geode_mfgpt_toggle_event);
+
+int geode_mfgpt_set_irq(int timer, int cmp, int irq, int enable)
+{
+	u32 val, dummy;
+	int offset;
+
+	if (timer < 0 || timer >= MFGPT_MAX_TIMERS)
+		return -EIO;
+
+	if (geode_mfgpt_toggle_event(timer, cmp, MFGPT_EVENT_IRQ, enable))
+		return -EIO;
+
+	rdmsr(0x51400022, val, dummy);
+
+	offset = (timer % 4) * 4;
+
+	val &= ~((0xF << offset) | (0xF << (offset + 16)));
+
+	if (enable) {
+		val |= (irq & 0x0F) << (offset);
+		val |= (irq & 0x0F) << (offset + 16);
+	}
+
+	wrmsr(0x51400022, val, dummy);
+	return 0;
+}
+EXPORT_SYMBOL(geode_mfgpt_set_irq);
+
+static int mfgpt_get(int timer, struct module *owner)
+{
+	mfgpt_timers[timer].flags &= ~F_AVAIL;
+	mfgpt_timers[timer].owner = owner;
+	printk(KERN_INFO "geode-mfgpt:  Registered timer %d\n", timer);
+	return timer;
+}
+
+int geode_mfgpt_alloc_timer(int timer, int domain, struct module *owner)
+{
+	int i;
+
+	if (!geode_get_dev_base(GEODE_DEV_MFGPT))
+		return -ENODEV;
+	if (timer >= MFGPT_MAX_TIMERS)
+		return -EIO;
+
+	if (timer < 0) {
+		/* Try to find an available timer */
+		for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
+			if (mfgpt_timers[i].flags & F_AVAIL)
+				return mfgpt_get(i, owner);
+
+			if (i == 5 && domain == MFGPT_DOMAIN_WORKING)
+				break;
+		}
+	}
+	else {
+		/* If they requested a specific timer, try to honor that */
+		if (mfgpt_timers[timer].flags & F_AVAIL)
+			return mfgpt_get(timer, owner);
+	}
+
+	/* No timers available - too bad */
+	return -1;
+}
+EXPORT_SYMBOL(geode_mfgpt_alloc_timer);
+
+#ifdef CONFIG_GEODE_MFGPT_TIMER
+
+static unsigned int mfgpt_tick_mode = CLOCK_EVT_MODE_SHUTDOWN;
+static u16 mfgpt_event_clock;
+
+static int irq = 7;
+static int __init mfgpt_setup(char *str)
+{
+	get_option(&str, &irq);
+	return 1;
+}
+__setup("mfgpt_irq=", mfgpt_setup);
+
+static inline void mfgpt_disable_timer(u16 clock)
+{
+	u16 val = geode_mfgpt_read(clock, MFGPT_REG_SETUP);
+	geode_mfgpt_write(clock, MFGPT_REG_SETUP, val & ~MFGPT_SETUP_CNTEN);
+}
+
+static int mfgpt_next_event(unsigned long, struct clock_event_device *);
+static void mfgpt_set_mode(enum clock_event_mode, struct clock_event_device *);
+
+static struct clock_event_device mfgpt_clockevent = {
+	.name = "mfgpt-timer",
+	.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+	.set_mode = mfgpt_set_mode,
+	.set_next_event = mfgpt_next_event,
+	.rating = 250,
+	.cpumask = CPU_MASK_ALL,
+	.shift = 32
+};
+
+static inline void mfgpt_start_timer(u16 clock, u16 delta)
+{
+	geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_CMP2, (u16) delta);
+	geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_COUNTER, 0);
+
+	geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP,
+			  MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2);
+}
+
+static void mfgpt_set_mode(enum clock_event_mode mode,
+			   struct clock_event_device *evt)
+{
+	mfgpt_disable_timer(mfgpt_event_clock);
+
+	if (mode == CLOCK_EVT_MODE_PERIODIC)
+		mfgpt_start_timer(mfgpt_event_clock, MFGPT_PERIODIC);
+
+	mfgpt_tick_mode = mode;
+}
+
+static int mfgpt_next_event(unsigned long delta, struct clock_event_device *evt)
+{
+	mfgpt_start_timer(mfgpt_event_clock, delta);
+	return 0;
+}
+
+/* Assume (foolishly?), that this interrupt was due to our tick */
+
+static irqreturn_t mfgpt_tick(int irq, void *dev_id)
+{
+	if (mfgpt_tick_mode == CLOCK_EVT_MODE_SHUTDOWN)
+		return IRQ_HANDLED;
+
+	/* Turn off the clock */
+	mfgpt_disable_timer(mfgpt_event_clock);
+
+	/* Clear the counter */
+	geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_COUNTER, 0);
+
+	/* Restart the clock in periodic mode */
+
+	if (mfgpt_tick_mode == CLOCK_EVT_MODE_PERIODIC) {
+		geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP,
+				  MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2);
+	}
+
+	mfgpt_clockevent.event_handler(&mfgpt_clockevent);
+	return IRQ_HANDLED;
+}
+
+static struct irqaction mfgptirq  = {
+	.handler = mfgpt_tick,
+	.flags = IRQF_DISABLED | IRQF_NOBALANCING,
+	.mask = CPU_MASK_NONE,
+	.name = "mfgpt-timer"
+};
+
+static int __init mfgpt_timer_setup(void)
+{
+	int timer, ret;
+	u16 val;
+
+	timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING, THIS_MODULE);
+	if (timer < 0) {
+		printk(KERN_ERR "mfgpt-timer:  Could not allocate a MFPGT timer\n");
+		return -ENODEV;
+	}
+
+	mfgpt_event_clock = timer;
+	/* Set the clock scale and enable the event mode for CMP2 */
+	val = MFGPT_SCALE | (3 << 8);
+
+	geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP, val);
+
+	/* Set up the IRQ on the MFGPT side */
+	if (geode_mfgpt_setup_irq(mfgpt_event_clock, MFGPT_CMP2, irq)) {
+		printk(KERN_ERR "mfgpt-timer:  Could not set up IRQ %d\n", irq);
+		return -EIO;
+	}
+
+	/* And register it with the kernel */
+        ret = setup_irq(irq, &mfgptirq);
+
+	if (ret) {
+		printk(KERN_ERR "mfgpt-timer:  Unable to set up the interrupt.\n");
+		goto err;
+	}
+
+	/* Set up the clock event */
+	mfgpt_clockevent.mult = div_sc(MFGPT_HZ, NSEC_PER_SEC, 32);
+	mfgpt_clockevent.min_delta_ns = clockevent_delta2ns(0xF, &mfgpt_clockevent);
+	mfgpt_clockevent.max_delta_ns = clockevent_delta2ns(0xFFFE, &mfgpt_clockevent);
+
+	printk("mfgpt-timer:  registering the MFGT timer as a clock event.\n");
+	clockevents_register_device(&mfgpt_clockevent);
+
+	return 0;
+
+err:
+	geode_mfgpt_release_irq(mfgpt_event_clock, MFGPT_CMP2, irq);
+	printk(KERN_ERR "mfgpt-timer:  Unable to set up the MFGPT clock source\n");
+	return -EIO;
+}
+
+#endif