mmtimer.c
/*
* Timer device implementation for SGI SN platforms.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (c) 2001-2006 Silicon Graphics, Inc. All rights reserved.
*
* This driver exports an API that should be supportable by any HPET or IA-PC
* multimedia timer. The code below is currently specific to the SGI Altix
* SHub RTC, however.
*
* 11/01/01 - jbarnes - initial revision
* 9/10/04 - Christoph Lameter - remove interrupt support for kernel inclusion
* 10/1/04 - Christoph Lameter - provide posix clock CLOCK_SGI_CYCLE
* 10/13/04 - Christoph Lameter, Dimitri Sivanich - provide timer interrupt
* support via the posix timer interface
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/ioctl.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/mmtimer.h>
#include <linux/miscdevice.h>
#include <linux/posix-timers.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <asm/sn/addrs.h>
#include <asm/sn/intr.h>
#include <asm/sn/shub_mmr.h>
#include <asm/sn/nodepda.h>
#include <asm/sn/shubio.h>
MODULE_AUTHOR("Jesse Barnes <jbarnes@sgi.com>");
MODULE_DESCRIPTION("SGI Altix RTC Timer");
MODULE_LICENSE("GPL");
/* name of the device, usually in /dev */
#define MMTIMER_NAME "mmtimer"
#define MMTIMER_DESC "SGI Altix RTC Timer"
#define MMTIMER_VERSION "2.1"
#define RTC_BITS 55 /* 55 bits for this implementation */
extern unsigned long sn_rtc_cycles_per_second;
#define RTC_COUNTER_ADDR ((long *)LOCAL_MMR_ADDR(SH_RTC))
#define rtc_time() (*RTC_COUNTER_ADDR)
static int mmtimer_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg);
static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
/*
* Period in femtoseconds (10^-15 s)
*/
static unsigned long mmtimer_femtoperiod = 0;
static const struct file_operations mmtimer_fops = {
.owner = THIS_MODULE,
.mmap = mmtimer_mmap,
.ioctl = mmtimer_ioctl,
};
/*
* We only have comparison registers RTC1-4 currently available per
* node. RTC0 is used by SAL.
*/
#define NUM_COMPARATORS 3
/* Check for an RTC interrupt pending */
static int inline mmtimer_int_pending(int comparator)
{
if (HUB_L((unsigned long *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED)) &
SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator)
return 1;
else
return 0;
}
/* Clear the RTC interrupt pending bit */
static void inline mmtimer_clr_int_pending(int comparator)
{
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED_ALIAS),
SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator);
}
/* Setup timer on comparator RTC1 */
static void inline mmtimer_setup_int_0(u64 expires)
{
u64 val;
/* Disable interrupt */
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 0UL);
/* Initialize comparator value */
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), -1L);
/* Clear pending bit */
mmtimer_clr_int_pending(0);
val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC1_INT_CONFIG_IDX_SHFT) |
((u64)cpu_physical_id(smp_processor_id()) <<
SH_RTC1_INT_CONFIG_PID_SHFT);
/* Set configuration */
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_CONFIG), val);
/* Enable RTC interrupts */
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 1UL);
/* Initialize comparator value */
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), expires);
}
/* Setup timer on comparator RTC2 */
static void inline mmtimer_setup_int_1(u64 expires)
{
u64 val;
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 0UL);
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), -1L);
mmtimer_clr_int_pending(1);
val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC2_INT_CONFIG_IDX_SHFT) |
((u64)cpu_physical_id(smp_processor_id()) <<
SH_RTC2_INT_CONFIG_PID_SHFT);
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_CONFIG), val);
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 1UL);
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), expires);
}
/* Setup timer on comparator RTC3 */
static void inline mmtimer_setup_int_2(u64 expires)
{
u64 val;
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 0UL);
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), -1L);
mmtimer_clr_int_pending(2);
val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC3_INT_CONFIG_IDX_SHFT) |
((u64)cpu_physical_id(smp_processor_id()) <<
SH_RTC3_INT_CONFIG_PID_SHFT);
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_CONFIG), val);
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 1UL);
HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), expires);
}
/*
* This function must be called with interrupts disabled and preemption off
* in order to insure that the setup succeeds in a deterministic time frame.
* It will check if the interrupt setup succeeded.
*/
static int inline mmtimer_setup(int comparator, unsigned long expires)
{
switch (comparator) {
case 0:
mmtimer_setup_int_0(expires);
break;
case 1:
mmtimer_setup_int_1(expires);
break;
case 2:
mmtimer_setup_int_2(expires);
break;
}
/* We might've missed our expiration time */
if (rtc_time() < expires)
return 1;
/*
* If an interrupt is already pending then its okay
* if not then we failed
*/
return mmtimer_int_pending(comparator);
}
static int inline mmtimer_disable_int(long nasid, int comparator)
{
switch (comparator) {
case 0:
nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE),
0UL) : REMOTE_HUB_S(nasid, SH_RTC1_INT_ENABLE, 0UL);
break;
case 1:
nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE),
0UL) : REMOTE_HUB_S(nasid, SH_RTC2_INT_ENABLE, 0UL);
break;
case 2:
nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE),
0UL) : REMOTE_HUB_S(nasid, SH_RTC3_INT_ENABLE, 0UL);
break;
default:
return -EFAULT;
}
return 0;
}
#define TIMER_OFF 0xbadcabLL
/* There is one of these for each comparator */
typedef struct mmtimer {
spinlock_t lock ____cacheline_aligned;
struct k_itimer *timer;
int i;
int cpu;
struct tasklet_struct tasklet;
} mmtimer_t;
static mmtimer_t ** timers;
/**
* mmtimer_ioctl - ioctl interface for /dev/mmtimer
* @inode: inode of the device
* @file: file structure for the device
* @cmd: command to execute
* @arg: optional argument to command
*
* Executes the command specified by @cmd. Returns 0 for success, < 0 for
* failure.
*
* Valid commands:
*
* %MMTIMER_GETOFFSET - Should return the offset (relative to the start
* of the page where the registers are mapped) for the counter in question.
*
* %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
* seconds
*
* %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
* specified by @arg
*
* %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
*
* %MMTIMER_MMAPAVAIL - Returns 1 if the registers can be mmap'd into userspace
*
* %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
* in the address specified by @arg.
*/
static int mmtimer_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
int ret = 0;
switch (cmd) {
case MMTIMER_GETOFFSET: /* offset of the counter */
/*
* SN RTC registers are on their own 64k page
*/
if(PAGE_SIZE <= (1 << 16))
ret = (((long)RTC_COUNTER_ADDR) & (PAGE_SIZE-1)) / 8;
else
ret = -ENOSYS;
break;
case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
if(copy_to_user((unsigned long __user *)arg,
&mmtimer_femtoperiod, sizeof(unsigned long)))
return -EFAULT;
break;
case MMTIMER_GETFREQ: /* frequency in Hz */
if(copy_to_user((unsigned long __user *)arg,
&sn_rtc_cycles_per_second,
sizeof(unsigned long)))
return -EFAULT;
ret = 0;
break;
case MMTIMER_GETBITS: /* number of bits in the clock */
ret = RTC_BITS;
break;
case MMTIMER_MMAPAVAIL: /* can we mmap the clock into userspace? */
ret = (PAGE_SIZE <= (1 << 16)) ? 1 : 0;
break;
case MMTIMER_GETCOUNTER:
if(copy_to_user((unsigned long __user *)arg,
RTC_COUNTER_ADDR, sizeof(unsigned long)))
return -EFAULT;
break;
default:
ret = -ENOSYS;
break;
}
return ret;
}
/**
* mmtimer_mmap - maps the clock's registers into userspace
* @file: file structure for the device
* @vma: VMA to map the registers into
*
* Calls remap_pfn_range() to map the clock's registers into
* the calling process' address space.
*/
static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
{
unsigned long mmtimer_addr;
if (vma->vm_end - vma->vm_start != PAGE_SIZE)
return -EINVAL;
if (vma->vm_flags & VM_WRITE)
return -EPERM;
if (PAGE_SIZE > (1 << 16))
return -ENOSYS;
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
mmtimer_addr = __pa(RTC_COUNTER_ADDR);
mmtimer_addr &= ~(PAGE_SIZE - 1);
mmtimer_addr &= 0xfffffffffffffffUL;
if (remap_pfn_range(vma, vma->vm_start, mmtimer_addr >> PAGE_SHIFT,
PAGE_SIZE, vma->vm_page_prot)) {
printk(KERN_ERR "remap_pfn_range failed in mmtimer.c\n");
return -EAGAIN;
}
return 0;
}
static struct miscdevice mmtimer_miscdev = {
SGI_MMTIMER,
MMTIMER_NAME,
&mmtimer_fops
};
static struct timespec sgi_clock_offset;
static int sgi_clock_period;
/*
* Posix Timer Interface
*/
static struct timespec sgi_clock_offset;
static int sgi_clock_period;
static int sgi_clock_get(clockid_t clockid, struct timespec *tp)
{
u64 nsec;
nsec = rtc_time() * sgi_clock_period
+ sgi_clock_offset.tv_nsec;
tp->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tp->tv_nsec)
+ sgi_clock_offset.tv_sec;
return 0;
};
static int sgi_clock_set(clockid_t clockid, struct timespec *tp)
{
u64 nsec;
u64 rem;
nsec = rtc_time() * sgi_clock_period;
sgi_clock_offset.tv_sec = tp->tv_sec - div_long_long_rem(nsec, NSEC_PER_SEC, &rem);
if (rem <= tp->tv_nsec)
sgi_clock_offset.tv_nsec = tp->tv_sec - rem;
else {
sgi_clock_offset.tv_nsec = tp->tv_sec + NSEC_PER_SEC - rem;
sgi_clock_offset.tv_sec--;
}
return 0;
}
/*
* Schedule the next periodic interrupt. This function will attempt
* to schedule a periodic interrupt later if necessary. If the scheduling
* of an interrupt fails then the time to skip is lengthened
* exponentially in order to ensure that the next interrupt
* can be properly scheduled..
*/
static int inline reschedule_periodic_timer(mmtimer_t *x)
{
int n;
struct k_itimer *t = x->timer;
t->it.mmtimer.clock = x->i;
t->it_overrun--;
n = 0;
do {
t->it.mmtimer.expires += t->it.mmtimer.incr << n;
t->it_overrun += 1 << n;
n++;
if (n > 20)
return 1;
} while (!mmtimer_setup(x->i, t->it.mmtimer.expires));
return 0;
}
/**
* mmtimer_interrupt - timer interrupt handler
* @irq: irq received
* @dev_id: device the irq came from
*
* Called when one of the comarators matches the counter, This
* routine will send signals to processes that have requested
* them.
*
* This interrupt is run in an interrupt context
* by the SHUB. It is therefore safe to locally access SHub
* registers.
*/
static irqreturn_t
mmtimer_interrupt(int irq, void *dev_id)
{
int i;
unsigned long expires = 0;
int result = IRQ_NONE;
unsigned indx = cpu_to_node(smp_processor_id());
/*
* Do this once for each comparison register
*/
for (i = 0; i < NUM_COMPARATORS; i++) {
mmtimer_t *base = timers[indx] + i;
/* Make sure this doesn't get reused before tasklet_sched */
spin_lock(&base->lock);
if (base->cpu == smp_processor_id()) {
if (base->timer)
expires = base->timer->it.mmtimer.expires;
/* expires test won't work with shared irqs */
if ((mmtimer_int_pending(i) > 0) ||
(expires && (expires < rtc_time()))) {
mmtimer_clr_int_pending(i);
tasklet_schedule(&base->tasklet);
result = IRQ_HANDLED;
}
}
spin_unlock(&base->lock);
expires = 0;
}
return result;
}
void mmtimer_tasklet(unsigned long data) {
mmtimer_t *x = (mmtimer_t *)data;
struct k_itimer *t = x->timer;
unsigned long flags;
if (t == NULL)
return;
/* Send signal and deal with periodic signals */
spin_lock_irqsave(&t->it_lock, flags);
spin_lock(&x->lock);
/* If timer was deleted between interrupt and here, leave */
if (t != x->timer)
goto out;
t->it_overrun = 0;
if (posix_timer_event(t, 0) != 0) {
// printk(KERN_WARNING "mmtimer: cannot deliver signal.\n");
t->it_overrun++;
}
if(t->it.mmtimer.incr) {
/* Periodic timer */
if (reschedule_periodic_timer(x)) {
printk(KERN_WARNING "mmtimer: unable to reschedule\n");
x->timer = NULL;
}
} else {
/* Ensure we don't false trigger in mmtimer_interrupt */
t->it.mmtimer.expires = 0;
}
t->it_overrun_last = t->it_overrun;
out:
spin_unlock(&x->lock);
spin_unlock_irqrestore(&t->it_lock, flags);
}
static int sgi_timer_create(struct k_itimer *timer)
{
/* Insure that a newly created timer is off */
timer->it.mmtimer.clock = TIMER_OFF;
return 0;
}
/* This does not really delete a timer. It just insures
* that the timer is not active
*
* Assumption: it_lock is already held with irq's disabled
*/
static int sgi_timer_del(struct k_itimer *timr)
{
int i = timr->it.mmtimer.clock;
cnodeid_t nodeid = timr->it.mmtimer.node;
mmtimer_t *t = timers[nodeid] + i;
unsigned long irqflags;
if (i != TIMER_OFF) {
spin_lock_irqsave(&t->lock, irqflags);
mmtimer_disable_int(cnodeid_to_nasid(nodeid),i);
t->timer = NULL;
timr->it.mmtimer.clock = TIMER_OFF;
timr->it.mmtimer.expires = 0;
spin_unlock_irqrestore(&t->lock, irqflags);
}
return 0;
}
#define timespec_to_ns(x) ((x).tv_nsec + (x).tv_sec * NSEC_PER_SEC)
#define ns_to_timespec(ts, nsec) (ts).tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &(ts).tv_nsec)
/* Assumption: it_lock is already held with irq's disabled */
static void sgi_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
{
if (timr->it.mmtimer.clock == TIMER_OFF) {
cur_setting->it_interval.tv_nsec = 0;
cur_setting->it_interval.tv_sec = 0;
cur_setting->it_value.tv_nsec = 0;
cur_setting->it_value.tv_sec =0;
return;
}
ns_to_timespec(cur_setting->it_interval, timr->it.mmtimer.incr * sgi_clock_period);
ns_to_timespec(cur_setting->it_value, (timr->it.mmtimer.expires - rtc_time())* sgi_clock_period);
return;
}
static int sgi_timer_set(struct k_itimer *timr, int flags,
struct itimerspec * new_setting,
struct itimerspec * old_setting)
{
int i;
unsigned long when, period, irqflags;
int err = 0;
cnodeid_t nodeid;
mmtimer_t *base;
if (old_setting)
sgi_timer_get(timr, old_setting);
sgi_timer_del(timr);
when = timespec_to_ns(new_setting->it_value);
period = timespec_to_ns(new_setting->it_interval);
if (when == 0)
/* Clear timer */
return 0;
if (flags & TIMER_ABSTIME) {
struct timespec n;
unsigned long now;
getnstimeofday(&n);
now = timespec_to_ns(n);
if (when > now)
when -= now;
else
/* Fire the timer immediately */
when = 0;
}
/*
* Convert to sgi clock period. Need to keep rtc_time() as near as possible
* to getnstimeofday() in order to be as faithful as possible to the time
* specified.
*/
when = (when + sgi_clock_period - 1) / sgi_clock_period + rtc_time();
period = (period + sgi_clock_period - 1) / sgi_clock_period;
/*
* We are allocating a local SHub comparator. If we would be moved to another
* cpu then another SHub may be local to us. Prohibit that by switching off
* preemption.
*/
preempt_disable();
nodeid = cpu_to_node(smp_processor_id());
retry:
/* Don't use an allocated timer, or a deleted one that's pending */
for(i = 0; i< NUM_COMPARATORS; i++) {
base = timers[nodeid] + i;
if (!base->timer && !base->tasklet.state) {
break;
}
}
if (i == NUM_COMPARATORS) {
preempt_enable();
return -EBUSY;
}
spin_lock_irqsave(&base->lock, irqflags);
if (base->timer || base->tasklet.state != 0) {
spin_unlock_irqrestore(&base->lock, irqflags);
goto retry;
}
base->timer = timr;
base->cpu = smp_processor_id();
timr->it.mmtimer.clock = i;
timr->it.mmtimer.node = nodeid;
timr->it.mmtimer.incr = period;
timr->it.mmtimer.expires = when;
if (period == 0) {
if (!mmtimer_setup(i, when)) {
mmtimer_disable_int(-1, i);
posix_timer_event(timr, 0);
timr->it.mmtimer.expires = 0;
}
} else {
timr->it.mmtimer.expires -= period;
if (reschedule_periodic_timer(base))
err = -EINVAL;
}
spin_unlock_irqrestore(&base->lock, irqflags);
preempt_enable();
return err;
}
static struct k_clock sgi_clock = {
.res = 0,
.clock_set = sgi_clock_set,
.clock_get = sgi_clock_get,
.timer_create = sgi_timer_create,
.nsleep = do_posix_clock_nonanosleep,
.timer_set = sgi_timer_set,
.timer_del = sgi_timer_del,
.timer_get = sgi_timer_get
};
/**
* mmtimer_init - device initialization routine
*
* Does initial setup for the mmtimer device.
*/
static int __init mmtimer_init(void)
{
unsigned i;
cnodeid_t node, maxn = -1;
if (!ia64_platform_is("sn2"))
return 0;
/*
* Sanity check the cycles/sec variable
*/
if (sn_rtc_cycles_per_second < 100000) {
printk(KERN_ERR "%s: unable to determine clock frequency\n",
MMTIMER_NAME);
goto out1;
}
mmtimer_femtoperiod = ((unsigned long)1E15 + sn_rtc_cycles_per_second /
2) / sn_rtc_cycles_per_second;
if (request_irq(SGI_MMTIMER_VECTOR, mmtimer_interrupt, IRQF_PERCPU, MMTIMER_NAME, NULL)) {
printk(KERN_WARNING "%s: unable to allocate interrupt.",
MMTIMER_NAME);
goto out1;
}
if (misc_register(&mmtimer_miscdev)) {
printk(KERN_ERR "%s: failed to register device\n",
MMTIMER_NAME);
goto out2;
}
/* Get max numbered node, calculate slots needed */
for_each_online_node(node) {
maxn = node;
}
maxn++;
/* Allocate list of node ptrs to mmtimer_t's */
timers = kzalloc(sizeof(mmtimer_t *)*maxn, GFP_KERNEL);
if (timers == NULL) {
printk(KERN_ERR "%s: failed to allocate memory for device\n",
MMTIMER_NAME);
goto out3;
}
/* Allocate mmtimer_t's for each online node */
for_each_online_node(node) {
timers[node] = kmalloc_node(sizeof(mmtimer_t)*NUM_COMPARATORS, GFP_KERNEL, node);
if (timers[node] == NULL) {
printk(KERN_ERR "%s: failed to allocate memory for device\n",
MMTIMER_NAME);
goto out4;
}
for (i=0; i< NUM_COMPARATORS; i++) {
mmtimer_t * base = timers[node] + i;
spin_lock_init(&base->lock);
base->timer = NULL;
base->cpu = 0;
base->i = i;
tasklet_init(&base->tasklet, mmtimer_tasklet,
(unsigned long) (base));
}
}
sgi_clock_period = sgi_clock.res = NSEC_PER_SEC / sn_rtc_cycles_per_second;
register_posix_clock(CLOCK_SGI_CYCLE, &sgi_clock);
printk(KERN_INFO "%s: v%s, %ld MHz\n", MMTIMER_DESC, MMTIMER_VERSION,
sn_rtc_cycles_per_second/(unsigned long)1E6);
return 0;
out4:
for_each_online_node(node) {
kfree(timers[node]);
}
out3:
misc_deregister(&mmtimer_miscdev);
out2:
free_irq(SGI_MMTIMER_VECTOR, NULL);
out1:
return -1;
}
module_init(mmtimer_init);
