snsc.c

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/*
 * SN Platform system controller communication support
 *
 * 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) 2004, 2006 Silicon Graphics, Inc. All rights reserved.
 */

/*
 * System controller communication driver
 *
 * This driver allows a user process to communicate with the system
 * controller (a.k.a. "IRouter") network in an SGI SN system.
 */

#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/poll.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <asm/sn/io.h>
#include <asm/sn/sn_sal.h>
#include <asm/sn/module.h>
#include <asm/sn/geo.h>
#include <asm/sn/nodepda.h>
#include "snsc.h"

#define SYSCTL_BASENAME "snsc"

#define SCDRV_BUFSZ 2048
#define SCDRV_TIMEOUT   1000

static DEFINE_MUTEX(scdrv_mutex);
static irqreturn_t
scdrv_interrupt(int irq, void *subch_data)
{
    struct subch_data_s *sd = subch_data;
    unsigned long flags;
    int status;

    spin_lock_irqsave(&sd->sd_rlock, flags);
    spin_lock(&sd->sd_wlock);
    status = ia64_sn_irtr_intr(sd->sd_nasid, sd->sd_subch);

    if (status > 0) {
        if (status & SAL_IROUTER_INTR_RECV) {
            wake_up(&sd->sd_rq);
        }
        if (status & SAL_IROUTER_INTR_XMIT) {
            ia64_sn_irtr_intr_disable
                (sd->sd_nasid, sd->sd_subch,
                 SAL_IROUTER_INTR_XMIT);
            wake_up(&sd->sd_wq);
        }
    }
    spin_unlock(&sd->sd_wlock);
    spin_unlock_irqrestore(&sd->sd_rlock, flags);
    return IRQ_HANDLED;
}

/*
 * scdrv_open
 *
 * Reserve a subchannel for system controller communication.
 */

static int
scdrv_open(struct inode *inode, struct file *file)
{
    struct sysctl_data_s *scd;
    struct subch_data_s *sd;
    int rv;

    /* look up device info for this device file */
    scd = container_of(inode->i_cdev, struct sysctl_data_s, scd_cdev);

    /* allocate memory for subchannel data */
    sd = kzalloc(sizeof (struct subch_data_s), GFP_KERNEL);
    if (sd == NULL) {
        printk("%s: couldn't allocate subchannel data\n",
               __func__);
        return -ENOMEM;
    }

    /* initialize subch_data_s fields */
    sd->sd_nasid = scd->scd_nasid;
    sd->sd_subch = ia64_sn_irtr_open(scd->scd_nasid);

    if (sd->sd_subch < 0) {
        kfree(sd);
        printk("%s: couldn't allocate subchannel\n", __func__);
        return -EBUSY;
    }

    spin_lock_init(&sd->sd_rlock);
    spin_lock_init(&sd->sd_wlock);
    init_waitqueue_head(&sd->sd_rq);
    init_waitqueue_head(&sd->sd_wq);
    sema_init(&sd->sd_rbs, 1);
    sema_init(&sd->sd_wbs, 1);

    file->private_data = sd;

    /* hook this subchannel up to the system controller interrupt */
    mutex_lock(&scdrv_mutex);
    rv = request_irq(SGI_UART_VECTOR, scdrv_interrupt,
             IRQF_SHARED | IRQF_DISABLED,
             SYSCTL_BASENAME, sd);
    if (rv) {
        ia64_sn_irtr_close(sd->sd_nasid, sd->sd_subch);
        kfree(sd);
        printk("%s: irq request failed (%d)\n", __func__, rv);
        mutex_unlock(&scdrv_mutex);
        return -EBUSY;
    }
    mutex_unlock(&scdrv_mutex);
    return 0;
}

/*
 * scdrv_release
 *
 * Release a previously-reserved subchannel.
 */

static int
scdrv_release(struct inode *inode, struct file *file)
{
    struct subch_data_s *sd = (struct subch_data_s *) file->private_data;
    int rv;

    /* free the interrupt */
    free_irq(SGI_UART_VECTOR, sd);

    /* ask SAL to close the subchannel */
    rv = ia64_sn_irtr_close(sd->sd_nasid, sd->sd_subch);

    kfree(sd);
    return rv;
}

/*
 * scdrv_read
 *
 * Called to read bytes from the open IRouter pipe.
 *
 */

static inline int
read_status_check(struct subch_data_s *sd, int *len)
{
    return ia64_sn_irtr_recv(sd->sd_nasid, sd->sd_subch, sd->sd_rb, len);
}

static ssize_t
scdrv_read(struct file *file, char __user *buf, size_t count, loff_t *f_pos)
{
    int status;
    int len;
    unsigned long flags;
    struct subch_data_s *sd = (struct subch_data_s *) file->private_data;

    /* try to get control of the read buffer */
    if (down_trylock(&sd->sd_rbs)) {
        /* somebody else has it now;
         * if we're non-blocking, then exit...
         */
        if (file->f_flags & O_NONBLOCK) {
            return -EAGAIN;
        }
        /* ...or if we want to block, then do so here */
        if (down_interruptible(&sd->sd_rbs)) {
            /* something went wrong with wait */
            return -ERESTARTSYS;
        }
    }

    /* anything to read? */
    len = CHUNKSIZE;
    spin_lock_irqsave(&sd->sd_rlock, flags);
    status = read_status_check(sd, &len);

    /* if not, and we're blocking I/O, loop */
    while (status < 0) {
        DECLARE_WAITQUEUE(wait, current);

        if (file->f_flags & O_NONBLOCK) {
            spin_unlock_irqrestore(&sd->sd_rlock, flags);
            up(&sd->sd_rbs);
            return -EAGAIN;
        }

        len = CHUNKSIZE;
        set_current_state(TASK_INTERRUPTIBLE);
        add_wait_queue(&sd->sd_rq, &wait);
        spin_unlock_irqrestore(&sd->sd_rlock, flags);

        schedule_timeout(SCDRV_TIMEOUT);

        remove_wait_queue(&sd->sd_rq, &wait);
        if (signal_pending(current)) {
            /* wait was interrupted */
            up(&sd->sd_rbs);
            return -ERESTARTSYS;
        }

        spin_lock_irqsave(&sd->sd_rlock, flags);
        status = read_status_check(sd, &len);
    }
    spin_unlock_irqrestore(&sd->sd_rlock, flags);

    if (len > 0) {
        /* we read something in the last read_status_check(); copy
         * it out to user space
         */
        if (count < len) {
            pr_debug("%s: only accepting %d of %d bytes\n",
                 __func__, (int) count, len);
        }
        len = min((int) count, len);
        if (copy_to_user(buf, sd->sd_rb, len))
            len = -EFAULT;
    }

    /* release the read buffer and wake anyone who might be
     * waiting for it
     */
    up(&sd->sd_rbs);

    /* return the number of characters read in */
    return len;
}

/*
 * scdrv_write
 *
 * Writes a chunk of an IRouter packet (or other system controller data)
 * to the system controller.
 *
 */
static inline int
write_status_check(struct subch_data_s *sd, int count)
{
    return ia64_sn_irtr_send(sd->sd_nasid, sd->sd_subch, sd->sd_wb, count);
}

static ssize_t
scdrv_write(struct file *file, const char __user *buf,
        size_t count, loff_t *f_pos)
{
    unsigned long flags;
    int status;
    struct subch_data_s *sd = (struct subch_data_s *) file->private_data;

    /* try to get control of the write buffer */
    if (down_trylock(&sd->sd_wbs)) {
        /* somebody else has it now;
         * if we're non-blocking, then exit...
         */
        if (file->f_flags & O_NONBLOCK) {
            return -EAGAIN;
        }
        /* ...or if we want to block, then do so here */
        if (down_interruptible(&sd->sd_wbs)) {
            /* something went wrong with wait */
            return -ERESTARTSYS;
        }
    }

    count = min((int) count, CHUNKSIZE);
    if (copy_from_user(sd->sd_wb, buf, count)) {
        up(&sd->sd_wbs);
        return -EFAULT;
    }

    /* try to send the buffer */
    spin_lock_irqsave(&sd->sd_wlock, flags);
    status = write_status_check(sd, count);

    /* if we failed, and we want to block, then loop */
    while (status <= 0) {
        DECLARE_WAITQUEUE(wait, current);

        if (file->f_flags & O_NONBLOCK) {
            spin_unlock(&sd->sd_wlock);
            up(&sd->sd_wbs);
            return -EAGAIN;
        }

        set_current_state(TASK_INTERRUPTIBLE);
        add_wait_queue(&sd->sd_wq, &wait);
        spin_unlock_irqrestore(&sd->sd_wlock, flags);

        schedule_timeout(SCDRV_TIMEOUT);

        remove_wait_queue(&sd->sd_wq, &wait);
        if (signal_pending(current)) {
            /* wait was interrupted */
            up(&sd->sd_wbs);
            return -ERESTARTSYS;
        }

        spin_lock_irqsave(&sd->sd_wlock, flags);
        status = write_status_check(sd, count);
    }
    spin_unlock_irqrestore(&sd->sd_wlock, flags);

    /* release the write buffer and wake anyone who's waiting for it */
    up(&sd->sd_wbs);

    /* return the number of characters accepted (should be the complete
     * "chunk" as requested)
     */
    if ((status >= 0) && (status < count)) {
        pr_debug("Didn't accept the full chunk; %d of %d\n",
             status, (int) count);
    }
    return status;
}

static unsigned int
scdrv_poll(struct file *file, struct poll_table_struct *wait)
{
    unsigned int mask = 0;
    int status = 0;
    struct subch_data_s *sd = (struct subch_data_s *) file->private_data;
    unsigned long flags;

    poll_wait(file, &sd->sd_rq, wait);
    poll_wait(file, &sd->sd_wq, wait);

    spin_lock_irqsave(&sd->sd_rlock, flags);
    spin_lock(&sd->sd_wlock);
    status = ia64_sn_irtr_intr(sd->sd_nasid, sd->sd_subch);
    spin_unlock(&sd->sd_wlock);
    spin_unlock_irqrestore(&sd->sd_rlock, flags);

    if (status > 0) {
        if (status & SAL_IROUTER_INTR_RECV) {
            mask |= POLLIN | POLLRDNORM;
        }
        if (status & SAL_IROUTER_INTR_XMIT) {
            mask |= POLLOUT | POLLWRNORM;
        }
    }

    return mask;
}

static const struct file_operations scdrv_fops = {
    .owner =    THIS_MODULE,
    .read =     scdrv_read,
    .write =    scdrv_write,
    .poll =     scdrv_poll,
    .open =     scdrv_open,
    .release =  scdrv_release,
    .llseek =   noop_llseek,
};

static struct class *snsc_class;

/*
 * scdrv_init
 *
 * Called at boot time to initialize the system controller communication
 * facility.
 */
int __init
scdrv_init(void)
{
    geoid_t geoid;
    cnodeid_t cnode;
    char devname[32];
    char *devnamep;
    struct sysctl_data_s *scd;
    void *salbuf;
    dev_t first_dev, dev;
    nasid_t event_nasid;

    if (!ia64_platform_is("sn2"))
        return -ENODEV;

    event_nasid = ia64_sn_get_console_nasid();

    if (alloc_chrdev_region(&first_dev, 0, num_cnodes,
                SYSCTL_BASENAME) < 0) {
        printk("%s: failed to register SN system controller device\n",
               __func__);
        return -ENODEV;
    }
    snsc_class = class_create(THIS_MODULE, SYSCTL_BASENAME);

    for (cnode = 0; cnode < num_cnodes; cnode++) {
            geoid = cnodeid_get_geoid(cnode);
            devnamep = devname;
            format_module_id(devnamep, geo_module(geoid),
                     MODULE_FORMAT_BRIEF);
            devnamep = devname + strlen(devname);
            sprintf(devnamep, "^%d#%d", geo_slot(geoid),
                geo_slab(geoid));

            /* allocate sysctl device data */
            scd = kzalloc(sizeof (struct sysctl_data_s),
                      GFP_KERNEL);
            if (!scd) {
                printk("%s: failed to allocate device info"
                       "for %s/%s\n", __func__,
                       SYSCTL_BASENAME, devname);
                continue;
            }

            /* initialize sysctl device data fields */
            scd->scd_nasid = cnodeid_to_nasid(cnode);
            if (!(salbuf = kmalloc(SCDRV_BUFSZ, GFP_KERNEL))) {
                printk("%s: failed to allocate driver buffer"
                       "(%s%s)\n", __func__,
                       SYSCTL_BASENAME, devname);
                kfree(scd);
                continue;
            }

            if (ia64_sn_irtr_init(scd->scd_nasid, salbuf,
                          SCDRV_BUFSZ) < 0) {
                printk
                    ("%s: failed to initialize SAL for"
                     " system controller communication"
                     " (%s/%s): outdated PROM?\n",
                     __func__, SYSCTL_BASENAME, devname);
                kfree(scd);
                kfree(salbuf);
                continue;
            }

            dev = first_dev + cnode;
            cdev_init(&scd->scd_cdev, &scdrv_fops);
            if (cdev_add(&scd->scd_cdev, dev, 1)) {
                printk("%s: failed to register system"
                       " controller device (%s%s)\n",
                       __func__, SYSCTL_BASENAME, devname);
                kfree(scd);
                kfree(salbuf);
                continue;
            }

            device_create(snsc_class, NULL, dev, NULL,
                      "%s", devname);

            ia64_sn_irtr_intr_enable(scd->scd_nasid,
                         0 /*ignored */ ,
                         SAL_IROUTER_INTR_RECV);

                        /* on the console nasid, prepare to receive
                         * system controller environmental events
                         */
                        if(scd->scd_nasid == event_nasid) {
                                scdrv_event_init(scd);
                        }
    }
    return 0;
}

module_init(scdrv_init);