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/*

 * 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)) {