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Diffstat (limited to 'arch/x86/kernel/mfgpt_32.c')
-rw-r--r--arch/x86/kernel/mfgpt_32.c362
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diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c
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+++ b/arch/x86/kernel/mfgpt_32.c
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+/*
+ * Driver/API for AMD Geode Multi-Function General Purpose Timers (MFGPT)
+ *
+ * Copyright (C) 2006, Advanced Micro Devices, Inc.
+ * Copyright (C) 2007, Andres Salomon <dilinger@debian.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ *
+ * The MFGPTs are documented in AMD Geode CS5536 Companion Device Data Book.
+ */
+
+/*
+ * 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 <asm/geode.h>
+
+#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;
+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? -dilinger
+ */
+ 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;
+}
+
+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(MSR_PIC_ZSEL_LOW, val, dummy);
+
+ offset = (timer % 4) * 4;
+
+ val &= ~((0xF << offset) | (0xF << (offset + 16)));
+
+ if (enable) {
+ val |= (irq & 0x0F) << (offset);
+ val |= (irq & 0x0F) << (offset + 16);
+ }
+
+ wrmsr(MSR_PIC_ZSEL_LOW, val, dummy);
+ return 0;
+}
+
+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;
+}
+
+
+#ifdef CONFIG_GEODE_MFGPT_TIMER
+
+/*
+ * 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.
+ */
+
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+
+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(KERN_INFO
+ "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
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