411 строки
10 KiB
C
411 строки
10 KiB
C
/*
|
|
* 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 32.768kHz input clock - it's 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 32768 .00048828125 2.000
|
|
* 2 16384 .0009765625 4.000
|
|
* 4 8192 .001953125 8.000
|
|
* 8 4096 .00390625 16.000
|
|
* 16 2048 .0078125 32.000
|
|
* 32 1024 .015625 64.000
|
|
* 64 512 .03125 128.000
|
|
* 128 256 .0625 256.000
|
|
* 256 128 .125 512.000
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/module.h>
|
|
#include <asm/geode.h>
|
|
|
|
#define MFGPT_DEFAULT_IRQ 7
|
|
|
|
static struct mfgpt_timer_t {
|
|
unsigned int avail:1;
|
|
} mfgpt_timers[MFGPT_MAX_TIMERS];
|
|
|
|
/* Selected from the table above */
|
|
|
|
#define MFGPT_DIVISOR 16
|
|
#define MFGPT_SCALE 4 /* divisor = 2^(scale) */
|
|
#define MFGPT_HZ (32768 / MFGPT_DIVISOR)
|
|
#define MFGPT_PERIODIC (MFGPT_HZ / HZ)
|
|
|
|
/* Allow for disabling of MFGPTs */
|
|
static int disable;
|
|
static int __init mfgpt_disable(char *s)
|
|
{
|
|
disable = 1;
|
|
return 1;
|
|
}
|
|
__setup("nomfgpt", mfgpt_disable);
|
|
|
|
/* Reset the MFGPT timers. This is required by some broken BIOSes which already
|
|
* do the same and leave the system in an unstable state. TinyBIOS 0.98 is
|
|
* affected at least (0.99 is OK with MFGPT workaround left to off).
|
|
*/
|
|
static int __init mfgpt_fix(char *s)
|
|
{
|
|
u32 val, dummy;
|
|
|
|
/* The following udocumented bit resets the MFGPT timers */
|
|
val = 0xFF; dummy = 0;
|
|
wrmsr(MSR_MFGPT_SETUP, val, dummy);
|
|
return 1;
|
|
}
|
|
__setup("mfgptfix", mfgpt_fix);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
|
|
static int timers = -1;
|
|
|
|
static void geode_mfgpt_detect(void)
|
|
{
|
|
int i;
|
|
u16 val;
|
|
|
|
timers = 0;
|
|
|
|
if (disable) {
|
|
printk(KERN_INFO "geode-mfgpt: MFGPT support is disabled\n");
|
|
goto done;
|
|
}
|
|
|
|
if (!geode_get_dev_base(GEODE_DEV_MFGPT)) {
|
|
printk(KERN_INFO "geode-mfgpt: MFGPT LBAR is not set up\n");
|
|
goto done;
|
|
}
|
|
|
|
for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
|
|
val = geode_mfgpt_read(i, MFGPT_REG_SETUP);
|
|
if (!(val & MFGPT_SETUP_SETUP)) {
|
|
mfgpt_timers[i].avail = 1;
|
|
timers++;
|
|
}
|
|
}
|
|
|
|
done:
|
|
printk(KERN_INFO "geode-mfgpt: %d MFGPT timers available.\n", timers);
|
|
}
|
|
|
|
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 = MSR_MFGPT_NR;
|
|
mask = 1 << (timer + 24);
|
|
break;
|
|
|
|
case MFGPT_EVENT_NMI:
|
|
msr = MSR_MFGPT_NR;
|
|
mask = 1 << (timer + shift);
|
|
break;
|
|
|
|
case MFGPT_EVENT_IRQ:
|
|
msr = MSR_MFGPT_IRQ;
|
|
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_GPL(geode_mfgpt_toggle_event);
|
|
|
|
int geode_mfgpt_set_irq(int timer, int cmp, int *irq, int enable)
|
|
{
|
|
u32 zsel, lpc, dummy;
|
|
int shift;
|
|
|
|
if (timer < 0 || timer >= MFGPT_MAX_TIMERS)
|
|
return -EIO;
|
|
|
|
/*
|
|
* Unfortunately, MFGPTs come in pairs sharing their IRQ lines. If VSA
|
|
* is using the same CMP of the timer's Siamese twin, the IRQ is set to
|
|
* 2, and we mustn't use nor change it.
|
|
* XXX: Likewise, 2 Linux drivers might clash if the 2nd overwrites the
|
|
* IRQ of the 1st. This can only happen if forcing an IRQ, calling this
|
|
* with *irq==0 is safe. Currently there _are_ no 2 drivers.
|
|
*/
|
|
rdmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
|
|
shift = ((cmp == MFGPT_CMP1 ? 0 : 4) + timer % 4) * 4;
|
|
if (((zsel >> shift) & 0xF) == 2)
|
|
return -EIO;
|
|
|
|
/* Choose IRQ: if none supplied, keep IRQ already set or use default */
|
|
if (!*irq)
|
|
*irq = (zsel >> shift) & 0xF;
|
|
if (!*irq)
|
|
*irq = MFGPT_DEFAULT_IRQ;
|
|
|
|
/* Can't use IRQ if it's 0 (=disabled), 2, or routed to LPC */
|
|
if (*irq < 1 || *irq == 2 || *irq > 15)
|
|
return -EIO;
|
|
rdmsr(MSR_PIC_IRQM_LPC, lpc, dummy);
|
|
if (lpc & (1 << *irq))
|
|
return -EIO;
|
|
|
|
/* All chosen and checked - go for it */
|
|
if (geode_mfgpt_toggle_event(timer, cmp, MFGPT_EVENT_IRQ, enable))
|
|
return -EIO;
|
|
if (enable) {
|
|
zsel = (zsel & ~(0xF << shift)) | (*irq << shift);
|
|
wrmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int mfgpt_get(int timer)
|
|
{
|
|
mfgpt_timers[timer].avail = 0;
|
|
printk(KERN_INFO "geode-mfgpt: Registered timer %d\n", timer);
|
|
return timer;
|
|
}
|
|
|
|
int geode_mfgpt_alloc_timer(int timer, int domain)
|
|
{
|
|
int i;
|
|
|
|
if (timers == -1) {
|
|
/* timers haven't been detected yet */
|
|
geode_mfgpt_detect();
|
|
}
|
|
|
|
if (!timers)
|
|
return -1;
|
|
|
|
if (timer >= MFGPT_MAX_TIMERS)
|
|
return -1;
|
|
|
|
if (timer < 0) {
|
|
/* Try to find an available timer */
|
|
for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
|
|
if (mfgpt_timers[i].avail)
|
|
return mfgpt_get(i);
|
|
|
|
if (i == 5 && domain == MFGPT_DOMAIN_WORKING)
|
|
break;
|
|
}
|
|
} else {
|
|
/* If they requested a specific timer, try to honor that */
|
|
if (mfgpt_timers[timer].avail)
|
|
return mfgpt_get(timer);
|
|
}
|
|
|
|
/* No timers available - too bad */
|
|
return -1;
|
|
}
|
|
EXPORT_SYMBOL_GPL(geode_mfgpt_alloc_timer);
|
|
|
|
|
|
#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 than 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;
|
|
static int __init mfgpt_setup(char *str)
|
|
{
|
|
get_option(&str, &irq);
|
|
return 1;
|
|
}
|
|
__setup("mfgpt_irq=", mfgpt_setup);
|
|
|
|
static void mfgpt_disable_timer(u16 clock)
|
|
{
|
|
/* avoid races by clearing CMP1 and CMP2 unconditionally */
|
|
geode_mfgpt_write(clock, MFGPT_REG_SETUP, (u16) ~MFGPT_SETUP_CNTEN |
|
|
MFGPT_SETUP_CMP1 | MFGPT_SETUP_CMP2);
|
|
}
|
|
|
|
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_all_mask,
|
|
.shift = 32
|
|
};
|
|
|
|
static void mfgpt_start_timer(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_PERIODIC);
|
|
|
|
mfgpt_tick_mode = mode;
|
|
}
|
|
|
|
static int mfgpt_next_event(unsigned long delta, struct clock_event_device *evt)
|
|
{
|
|
mfgpt_start_timer(delta);
|
|
return 0;
|
|
}
|
|
|
|
static irqreturn_t mfgpt_tick(int irq, void *dev_id)
|
|
{
|
|
u16 val = geode_mfgpt_read(mfgpt_event_clock, MFGPT_REG_SETUP);
|
|
|
|
/* See if the interrupt was for us */
|
|
if (!(val & (MFGPT_SETUP_SETUP | MFGPT_SETUP_CMP2 | MFGPT_SETUP_CMP1)))
|
|
return IRQ_NONE;
|
|
|
|
/* Turn off the clock (and clear the event) */
|
|
mfgpt_disable_timer(mfgpt_event_clock);
|
|
|
|
if (mfgpt_tick_mode == CLOCK_EVT_MODE_SHUTDOWN)
|
|
return IRQ_HANDLED;
|
|
|
|
/* 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,
|
|
.name = "mfgpt-timer"
|
|
};
|
|
|
|
int __init mfgpt_timer_setup(void)
|
|
{
|
|
int timer, ret;
|
|
u16 val;
|
|
|
|
timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
|
|
if (timer < 0) {
|
|
printk(KERN_ERR
|
|
"mfgpt-timer: Could not allocate a MFPGT timer\n");
|
|
return -ENODEV;
|
|
}
|
|
|
|
mfgpt_event_clock = timer;
|
|
|
|
/* 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 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 clock event */
|
|
mfgpt_clockevent.mult = div_sc(MFGPT_HZ, NSEC_PER_SEC,
|
|
mfgpt_clockevent.shift);
|
|
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 MFGPT timer %d as a clock event, using IRQ %d\n",
|
|
timer, irq);
|
|
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
|