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snsc.c

/*
 * 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 <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 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",
                   __FUNCTION__);
            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", __FUNCTION__);
            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 */
      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", __FUNCTION__, rv);
            return -EBUSY;
      }

      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",
                         __FUNCTION__, (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,
};

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",
                   __FUNCTION__);
            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", __FUNCTION__,
                               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", __FUNCTION__,
                               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",
                             __FUNCTION__, 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",
                               __FUNCTION__, SYSCTL_BASENAME, devname);
                        kfree(scd);
                        kfree(salbuf);
                        continue;
                  }

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

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