/*
* 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
