/*
* Driver for the CS5535/CS5536 Multi-Function General Purpose Timers (MFGPT)
*
* Copyright (C) 2006, Advanced Micro Devices, Inc.
* Copyright (C) 2007 Andres Salomon <dilinger@debian.org>
* Copyright (C) 2009 Andres Salomon <dilinger@collabora.co.uk>
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/cs5535.h>
#include <linux/slab.h>
#define DRV_NAME "cs5535-mfgpt"
static int mfgpt_reset_timers;
module_param_named(mfgptfix, mfgpt_reset_timers, int, 0644);
MODULE_PARM_DESC(mfgptfix, "Try to reset the MFGPT timers during init; "
"required by some broken BIOSes (ie, TinyBIOS < 0.99) or kexec "
"(1 = reset the MFGPT using an undocumented bit, "
"2 = perform a soft reset by unconfiguring all timers); "
"use what works best for you.");
struct cs5535_mfgpt_timer {
struct cs5535_mfgpt_chip *chip;
int nr;
};
static struct cs5535_mfgpt_chip {
DECLARE_BITMAP(avail, MFGPT_MAX_TIMERS);
resource_size_t base;
struct platform_device *pdev;
spinlock_t lock;
int initialized;
} cs5535_mfgpt_chip;
int cs5535_mfgpt_toggle_event(struct cs5535_mfgpt_timer *timer, int cmp,
int event, int enable)
{
uint32_t msr, mask, value, dummy;
int shift = (cmp == MFGPT_CMP1) ? 0 : 8;
if (!timer) {
WARN_ON(1);
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->nr + 24);
break;
case MFGPT_EVENT_NMI:
msr = MSR_MFGPT_NR;
mask = 1 << (timer->nr + shift);
break;
case MFGPT_EVENT_IRQ:
msr = MSR_MFGPT_IRQ;
mask = 1 << (timer->nr + 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(cs5535_mfgpt_toggle_event);
int cs5535_mfgpt_set_irq(struct cs5535_mfgpt_timer *timer, int cmp, int *irq,
int enable)
{
uint32_t zsel, lpc, dummy;
int shift;
if (!timer) {
WARN_ON(1);
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->nr % 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 = CONFIG_CS5535_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 (cs5535_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;
}
EXPORT_SYMBOL_GPL(cs5535_mfgpt_set_irq);
struct cs5535_mfgpt_timer *cs5535_mfgpt_alloc_timer(int timer_nr, int domain)
{
struct cs5535_mfgpt_chip *mfgpt = &cs5535_mfgpt_chip;
struct cs5535_mfgpt_timer *timer = NULL;
unsigned long flags;
int max;
if (!mfgpt->initialized)
goto done;
/* only allocate timers from the working domain if requested */
if (domain == MFGPT_DOMAIN_WORKING)
max = 6;
else
max = MFGPT_MAX_TIMERS;
if (timer_nr >= max) {
/* programmer error. silly programmers! */
WARN_ON(1);
goto done;
}
spin_lock_irqsave(&mfgpt->lock, flags);
if (timer_nr < 0) {
unsigned long t;
/* try to find any available timer */
t = find_first_bit(mfgpt->avail, max);
/* set timer_nr to -1 if no timers available */
timer_nr = t < max ? (int) t : -1;
} else {
/* check if the requested timer's available */
if (!test_bit(timer_nr, mfgpt->avail))
timer_nr = -1;
}
if (timer_nr >= 0)
/* if timer_nr is not -1, it's an available timer */
__clear_bit(timer_nr, mfgpt->avail);
spin_unlock_irqrestore(&mfgpt->lock, flags);
if (timer_nr < 0)
goto done;
timer = kmalloc(sizeof(*timer), GFP_KERNEL);
if (!timer) {
/* aw hell */
spin_lock_irqsave(&mfgpt->lock, flags);
__set_bit(timer_nr, mfgpt->avail);
spin_unlock_irqrestore(&mfgpt->lock, flags);
goto done;
}
timer->chip = mfgpt;
timer->nr = timer_nr;
dev_info(&mfgpt->pdev->dev, "registered timer %d\n", timer_nr);
done:
return timer;
}
EXPORT_SYMBOL_GPL(cs5535_mfgpt_alloc_timer);
/*
* XXX: This frees the timer memory, but never resets the actual hardware
* timer. The old geode_mfgpt code did this; it would be good to figure
* out a way to actually release the hardware timer. See comments below.
*/
void cs5535_mfgpt_free_timer(struct cs5535_mfgpt_timer *timer)
{
unsigned long flags;
uint16_t val;
/* timer can be made available again only if never set up */
val = cs5535_mfgpt_read(timer, MFGPT_REG_SETUP);
if (!(val & MFGPT_SETUP_SETUP)) {
spin_lock_irqsave(&timer->chip->lock, flags);
__set_bit(timer->nr, timer->chip->avail);
spin_unlock_irqrestore(&timer->chip->lock, flags);
}
kfree(timer);
}
EXPORT_SYMBOL_GPL(cs5535_mfgpt_free_timer);
uint16_t cs5535_mfgpt_read(struct cs5535_mfgpt_timer *timer, uint16_t reg)
{
return inw(timer->chip->base + reg + (timer->nr * 8));
}
EXPORT_SYMBOL_GPL(cs5535_mfgpt_read);
void cs5535_mfgpt_write(struct cs5535_mfgpt_timer *timer, uint16_t reg,
uint16_t value)
{
outw(value, timer->chip->base + reg + (timer->nr * 8));
}
EXPORT_SYMBOL_GPL(cs5535_mfgpt_write);
/*
* This is a sledgehammer that resets all MFGPT timers. This is required by
* some broken BIOSes which leave the system in an unstable state
* (TinyBIOS 0.98, for example; fixed in 0.99). It's uncertain as to
* whether or not this secret MSR can be used to release individual timers.
* Jordan tells me that he and Mitch once played w/ it, but it's unclear
* what the results of that were (and they experienced some instability).
*/
static void reset_all_timers(void)
{
uint32_t val, dummy;
/* The following undocumented bit resets the MFGPT timers */
val = 0xFF; dummy = 0;
wrmsr(MSR_MFGPT_SETUP, val, dummy);
}
/*
* This is another sledgehammer to reset all MFGPT timers.
* Instead of using the undocumented bit method it clears
* IRQ, NMI and RESET settings.
*/
static void soft_reset(void)
{
int i;
struct cs5535_mfgpt_timer t;
for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
t.nr = i;
cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_RESET, 0);
cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_RESET, 0);
cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_NMI, 0);
cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_NMI, 0);
cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_IRQ, 0);
cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_IRQ, 0);
}
}
/*
* 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 scan_timers(struct cs5535_mfgpt_chip *mfgpt)
{
struct cs5535_mfgpt_timer timer = { .chip = mfgpt };
unsigned long flags;
int timers = 0;
uint16_t val;
int i;
/* bios workaround */
if (mfgpt_reset_timers == 1)
reset_all_timers();
else if (mfgpt_reset_timers == 2)
soft_reset();
/* just to be safe, protect this section w/ lock */
spin_lock_irqsave(&mfgpt->lock, flags);
for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
timer.nr = i;
val = cs5535_mfgpt_read(&timer, MFGPT_REG_SETUP);
if (!(val & MFGPT_SETUP_SETUP) || mfgpt_reset_timers == 2) {
__set_bit(i, mfgpt->avail);
timers++;
}
}
spin_unlock_irqrestore(&mfgpt->lock, flags);
return timers;
}
static int cs5535_mfgpt_probe(struct platform_device *pdev)
{
struct resource *res;
int err = -EIO, t;
if (mfgpt_reset_timers < 0 || mfgpt_reset_timers > 2) {
dev_err(&pdev->dev, "Bad mfgpt_reset_timers value: %i\n",
mfgpt_reset_timers);
goto done;
}
/* There are two ways to get the MFGPT base address; one is by
* fetching it from MSR_LBAR_MFGPT, the other is by reading the
* PCI BAR info. The latter method is easier (especially across
* different architectures), so we'll stick with that for now. If
* it turns out to be unreliable in the face of crappy BIOSes, we
* can always go back to using MSRs.. */
res = platform_get_resource(pdev, IORESOURCE_IO, 0);
if (!res) {
dev_err(&pdev->dev, "can't fetch device resource info\n");
goto done;
}
if (!request_region(res->start, resource_size(res), pdev->name)) {
dev_err(&pdev->dev, "can't request region\n");
goto done;
}
/* set up the driver-specific struct */
cs5535_mfgpt_chip.base = res->start;
cs5535_mfgpt_chip.pdev = pdev;
spin_lock_init(&cs5535_mfgpt_chip.lock);
dev_info(&pdev->dev, "reserved resource region %pR\n", res);
/* detect the available timers */
t = scan_timers(&cs5535_mfgpt_chip);
dev_info(&pdev->dev, "%d MFGPT timers available\n", t);
cs5535_mfgpt_chip.initialized = 1;
return 0;
done:
return err;
}
static struct platform_driver cs5535_mfgpt_driver = {
.driver = {
.name = DRV_NAME,
},
.probe = cs5535_mfgpt_probe,
};
static int __init cs5535_mfgpt_init(void)
{
return platform_driver_register(&cs5535_mfgpt_driver);
}
module_init(cs5535_mfgpt_init);
MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
MODULE_DESCRIPTION("CS5535/CS5536 MFGPT timer driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);
