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/*

 *              An implementation of a loadable kernel mode driver providing

 *              multiple kernel/user space bidirectional communications links.

 *

 *              Author:         Alan Cox <alan@redhat.com>

 *

 *              This program is free software; you can redistribute it and/or

 *              modify it under the terms of the GNU General Public License

 *              as published by the Free Software Foundation; either version

 *              2 of the License, or (at your option) any later version.

 *

 *              Adapted to become the Linux 2.0 Coda pseudo device

 *              Peter  Braam  <braam@maths.ox.ac.uk>

 *              Michael Callahan <mjc@emmy.smith.edu>

 *

 *              Changes for Linux 2.1

 *              Copyright (c) 1997 Carnegie-Mellon University

 */

#include <linux/module.h>

#include <linux/errno.h>

#include <linux/kernel.h>

#include <linux/major.h>

#include <linux/sched.h>

#include <linux/lp.h>

#include <linux/slab.h>

#include <linux/ioport.h>

#include <linux/fcntl.h>

#include <linux/delay.h>

#include <linux/skbuff.h>

#include <linux/proc_fs.h>

#include <linux/devfs_fs_kernel.h>

#include <linux/vmalloc.h>

#include <linux/fs.h>

#include <linux/file.h>

#include <linux/poll.h>

#include <linux/init.h>

#include <linux/list.h>

#include <linux/smp_lock.h>

#include <asm/io.h>

#include <asm/system.h>

#include <asm/poll.h>

#include <asm/uaccess.h>

#include <linux/coda.h>

#include <linux/coda_linux.h>

#include <linux/coda_fs_i.h>

#include <linux/coda_psdev.h>

#include <linux/coda_proc.h>

#define upc_free(r) kfree(r)

/*

 * Coda stuff

 */

extern struct file_system_type coda_fs_type;

/* statistics */

int           coda_hard;         /* allows signals during upcalls */

unsigned long coda_timeout = 30; /* .. secs, then signals will dequeue */

struct venus_comm coda_comms[MAX_CODADEVS];

kmem_cache_t *cii_cache, *cred_cache, *upc_cache;

/*

 * Device operations

 */

static unsigned int coda_psdev_poll(struct file *file, poll_table * wait)

{

        struct venus_comm *vcp = (struct venus_comm *) file->private_data;

        unsigned int mask = POLLOUT | POLLWRNORM;

        poll_wait(file, &vcp->vc_waitq, wait);

        if (!list_empty(&vcp->vc_pending))

                mask |= POLLIN | POLLRDNORM;

        return mask;

}

static int coda_psdev_ioctl(struct inode * inode, struct file * filp,

                            unsigned int cmd, unsigned long arg)

{

        unsigned int data;

        switch(cmd) {

        case CIOC_KERNEL_VERSION:

                data = CODA_KERNEL_VERSION;

                return put_user(data, (int *) arg);

        default:

                return -ENOTTY;

        }

        return 0;

}

/*

 *      Receive a message written by Venus to the psdev

 */

static ssize_t coda_psdev_write(struct file *file, const char *buf,

                                size_t nbytes, loff_t *off)

{

        struct venus_comm *vcp = (struct venus_comm *) file->private_data;

        struct upc_req *req = NULL;

        struct upc_req *tmp;

        struct list_head *lh;

        struct coda_in_hdr hdr;

        ssize_t retval = 0, count = 0;

        int error;

        /* Peek at the opcode, uniquefier */

        if (copy_from_user(&hdr, buf, 2 * sizeof(u_long)))

                return -EFAULT;

        CDEBUG(D_PSDEV, "(process,opc,uniq)=(%d,%ld,%ld), nbytes %ld\n",

               current->pid, hdr.opcode, hdr.unique, (long)nbytes);

        if (DOWNCALL(hdr.opcode)) {

                struct super_block *sb = NULL;

                union outputArgs *dcbuf;

                int size = sizeof(*dcbuf);

                sb = vcp->vc_sb;

                if ( !sb ) {

                        CDEBUG(D_PSDEV, "coda_psdev_write: downcall, no SB!\n");

                        count = nbytes;

                        goto out;

                }

                CDEBUG(D_PSDEV, "handling downcall\n");

                if  ( nbytes < sizeof(struct coda_out_hdr) ) {

                        printk("coda_downcall opc %ld uniq %ld, not enough!\n",

                               hdr.opcode, hdr.unique);

                        count = nbytes;

                        goto out;

                }

                if ( nbytes > size ) {

                        printk("Coda: downcall opc %ld, uniq %ld, too much!",

                               hdr.opcode, hdr.unique);

                        nbytes = size;

                }

                CODA_ALLOC(dcbuf, union outputArgs *, nbytes);

                if (copy_from_user(dcbuf, buf, nbytes)) {

                        CODA_FREE(dcbuf, nbytes);

                        retval = -EFAULT;

                        goto out;

                }

                /* what downcall errors does Venus handle ? */

                lock_kernel();

                error = coda_downcall(hdr.opcode, dcbuf, sb);

                unlock_kernel();

                CODA_FREE(dcbuf, nbytes);

                if (error) {

                        printk("psdev_write: coda_downcall error: %d\n", error);

                        retval = error;

                        goto out;

                }

                count = nbytes;

                goto out;

        }

        /* Look for the message on the processing queue. */

        lock_kernel();

        list_for_each(lh, &vcp->vc_processing) {

                tmp = list_entry(lh, struct upc_req , uc_chain);

                if (tmp->uc_unique == hdr.unique) {

                        req = tmp;

                        list_del(&req->uc_chain);

                        break;

                }

        }

        unlock_kernel();

        if (!req) {

                printk("psdev_write: msg (%ld, %ld) not found\n",

                        hdr.opcode, hdr.unique);

                retval = -ESRCH;

                goto out;

        }

        CDEBUG(D_PSDEV,"Eureka: uniq %ld on queue!\n", hdr.unique);

        /* move data into response buffer. */

        if (req->uc_outSize < nbytes) {

                printk("psdev_write: too much cnt: %d, cnt: %ld, opc: %ld, uniq: %ld.\n",

                       req->uc_outSize, (long)nbytes, hdr.opcode, hdr.unique);

                nbytes = req->uc_outSize; /* don't have more space! */

        }

        if (copy_from_user(req->uc_data, buf, nbytes)) {

                req->uc_flags |= REQ_ABORT;

                wake_up(&req->uc_sleep);

                retval = -EFAULT;

                goto out;

        }

        /* adjust outsize. is this useful ?? */

        req->uc_outSize = nbytes;

        req->uc_flags |= REQ_WRITE;

        count = nbytes;

        /* Convert filedescriptor into a file handle */

        if (req->uc_opcode == CODA_OPEN_BY_FD) {

                struct coda_open_by_fd_out *outp =

                        (struct coda_open_by_fd_out *)req->uc_data;

                outp->fh = fget(outp->fd);

        }

        CDEBUG(D_PSDEV,

               "Found! Count %ld for (opc,uniq)=(%ld,%ld), upc_req at %p\n",

                (long)count, hdr.opcode, hdr.unique, &req);

        wake_up(&req->uc_sleep);

out:

        return(count ? count : retval);

}

/*

 *      Read a message from the kernel to Venus

 */

static ssize_t coda_psdev_read(struct file * file, char * buf,

                               size_t nbytes, loff_t *off)

{

        DECLARE_WAITQUEUE(wait, current);

        struct venus_comm *vcp = (struct venus_comm *) file->private_data;

        struct upc_req *req;

        ssize_t retval = 0, count = 0;

        if (nbytes == 0)

                return 0;

        lock_kernel();

        add_wait_queue(&vcp->vc_waitq, &wait);

        set_current_state(TASK_INTERRUPTIBLE);

        while (list_empty(&vcp->vc_pending)) {

                if (file->f_flags & O_NONBLOCK) {

                        retval = -EAGAIN;

                        break;

                }

                if (signal_pending(current)) {

                        retval = -ERESTARTSYS;

                        break;

                }

                schedule();

        }

        set_current_state(TASK_RUNNING);

        remove_wait_queue(&vcp->vc_waitq, &wait);

        if (retval)

                goto out;

        req = list_entry(vcp->vc_pending.next, struct upc_req,uc_chain);

        list_del(&req->uc_chain);

        /* Move the input args into userspace */

        count = req->uc_inSize;

        if (nbytes < req->uc_inSize) {

                printk ("psdev_read: Venus read %ld bytes of %d in message\n",

                        (long)nbytes, req->uc_inSize);

                count = nbytes;

        }

        if (copy_to_user(buf, req->uc_data, count))

                retval = -EFAULT;

        /* If request was not a signal, enqueue and don't free */

        if (!(req->uc_flags & REQ_ASYNC)) {

                req->uc_flags |= REQ_READ;

                list_add(&(req->uc_chain), vcp->vc_processing.prev);

                goto out;

        }

        CDEBUG(D_PSDEV, "vcread: signal msg (%d, %d)\n",

                        req->uc_opcode, req->uc_unique);

        CODA_FREE(req->uc_data, sizeof(struct coda_in_hdr));

        upc_free(req);

out:

        unlock_kernel();

        return (count ? count : retval);

}

static int coda_psdev_open(struct inode * inode, struct file * file)

{

        struct venus_comm *vcp;

        int idx;

        lock_kernel();

        idx = MINOR(inode->i_rdev);

        if(idx >= MAX_CODADEVS) {

                unlock_kernel();

                return -ENODEV;

        }

        vcp = &coda_comms[idx];

        if(vcp->vc_inuse) {

                unlock_kernel();

                return -EBUSY;

        }

        if (!vcp->vc_inuse++) {

                INIT_LIST_HEAD(&vcp->vc_pending);

                INIT_LIST_HEAD(&vcp->vc_processing);

                init_waitqueue_head(&vcp->vc_waitq);

                vcp->vc_sb = 0;

                vcp->vc_seq = 0;

        }

        file->private_data = vcp;

        CDEBUG(D_PSDEV, "device %i - inuse: %d\n", idx, vcp->vc_inuse);

        unlock_kernel();

        return 0;

}

static int coda_psdev_release(struct inode * inode, struct file * file)

{

        struct venus_comm *vcp = (struct venus_comm *) file->private_data;

        struct upc_req *req;

        struct list_head *lh, *next;

        lock_kernel();

        if ( !vcp->vc_inuse ) {

                unlock_kernel();

                printk("psdev_release: Not open.\n");

                return -1;

        }

        CDEBUG(D_PSDEV, "psdev_release: inuse %d\n", vcp->vc_inuse);

        if (--vcp->vc_inuse) {

                unlock_kernel();

                return 0;

        }

        /* Wakeup clients so they can return. */

        CDEBUG(D_PSDEV, "wake up pending clients\n");

        lh = vcp->vc_pending.next;

        next = lh;

        while ( (lh = next) != &vcp->vc_pending) {

                next = lh->next;

                req = list_entry(lh, struct upc_req, uc_chain);

                /* Async requests need to be freed here */

                if (req->uc_flags & REQ_ASYNC) {

                        CODA_FREE(req->uc_data, sizeof(struct coda_in_hdr));

                        upc_free(req);

                        continue;

                }

                req->uc_flags |= REQ_ABORT;

                wake_up(&req->uc_sleep);

        }

        lh = &vcp->vc_processing;

        CDEBUG(D_PSDEV, "wake up processing clients\n");

        while ( (lh = lh->next) != &vcp->vc_processing) {

                req = list_entry(lh, struct upc_req, uc_chain);

                req->uc_flags |= REQ_ABORT;

                wake_up(&req->uc_sleep);

        }

        CDEBUG(D_PSDEV, "Done.\n");

        unlock_kernel();

        return 0;

}

static struct file_operations coda_psdev_fops = {

        owner:          THIS_MODULE,

        read:           coda_psdev_read,

        write:          coda_psdev_write,

        poll:           coda_psdev_poll,

        ioctl:          coda_psdev_ioctl,

        open:           coda_psdev_open,

        release:        coda_psdev_release,

};

static devfs_handle_t devfs_handle;

static int init_coda_psdev(void)

{

        if(devfs_register_chrdev(CODA_PSDEV_MAJOR,"coda_psdev",

                                 &coda_psdev_fops)) {

              printk(KERN_ERR "coda_psdev: unable to get major %d\n",

                     CODA_PSDEV_MAJOR);

              return -EIO;

        }

        devfs_handle = devfs_mk_dir (NULL, "coda", NULL);

        devfs_register_series (devfs_handle, "%u", MAX_CODADEVS, DEVFS_FL_NONE,

                               CODA_PSDEV_MAJOR, 0,

                               S_IFCHR | S_IRUSR | S_IWUSR,

                               &coda_psdev_fops, NULL);

        coda_sysctl_init();

        return 0;

}

MODULE_AUTHOR("Peter J. Braam <braam@cs.cmu.edu>");

MODULE_LICENSE("GPL");

static int __init init_coda(void)

{

        int status;

        printk(KERN_INFO "Coda Kernel/Venus communications, v5.3.18, coda@cs.cmu.edu\n");

        status = init_coda_psdev();

        if ( status ) {

                printk("Problem (%d) in init_coda_psdev\n", status);

                return status;

        }

        status = register_filesystem(&coda_fs_type);

        if (status) {

                printk("coda: failed to register filesystem!\n");

                devfs_unregister(devfs_handle);

                devfs_unregister_chrdev(CODA_PSDEV_MAJOR,"coda_psdev");

                coda_sysctl_clean();

        }

        return status;

}

static void __exit exit_coda(void)

{

        int err;

        err = unregister_filesystem(&coda_fs_type);

        if ( err != 0 ) {

                printk("coda: failed to unregister filesystem\n");

        }

        devfs_unregister(devfs_handle);

        devfs_unregister_chrdev(CODA_PSDEV_MAJOR, "coda_psdev");

        coda_sysctl_clean();

}

module_init(init_coda);

module_exit(exit_coda);