/*
* 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)
/* 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++;
}
}
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;
}
