ppdev.c

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/*
 * linux/drivers/char/ppdev.c
 *
 * This is the code behind /dev/parport* -- it allows a user-space
 * application to use the parport subsystem.
 *
 * Copyright (C) 1998-2000, 2002 Tim Waugh <[email protected]>
 *
 * 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.
 *
 * A /dev/parportx device node represents an arbitrary device
 * on port 'x'.  The following operations are possible:
 *
 * open     do nothing, set up default IEEE 1284 protocol to be COMPAT
 * close    release port and unregister device (if necessary)
 * ioctl
 *   EXCL   register device exclusively (may fail)
 *   CLAIM  (register device first time) parport_claim_or_block
 *   RELEASE    parport_release
 *   SETMODE    set the IEEE 1284 protocol to use for read/write
 *   SETPHASE   set the IEEE 1284 phase of a particular mode.  Not to be
 *              confused with ioctl(fd, SETPHASER, &stun). ;-)
 *   DATADIR    data_forward / data_reverse
 *   WDATA  write_data
 *   RDATA  read_data
 *   WCONTROL   write_control
 *   RCONTROL   read_control
 *   FCONTROL   frob_control
 *   RSTATUS    read_status
 *   NEGOT  parport_negotiate
 *   YIELD  parport_yield_blocking
 *   WCTLONIRQ  on interrupt, set control lines
 *   CLRIRQ clear (and return) interrupt count
 *   SETTIME    sets device timeout (struct timeval)
 *   GETTIME    gets device timeout (struct timeval)
 *   GETMODES   gets hardware supported modes (unsigned int)
 *   GETMODE    gets the current IEEE1284 mode
 *   GETPHASE   gets the current IEEE1284 phase
 *   GETFLAGS   gets current (user-visible) flags
 *   SETFLAGS   sets current (user-visible) flags
 * read/write   read or write in current IEEE 1284 protocol
 * select   wait for interrupt (in readfds)
 *
 * Changes:
 * Added SETTIME/GETTIME ioctl, Fred Barnes, 1999.
 *
 * Arnaldo Carvalho de Melo <[email protected]> 2000/08/25
 * - On error, copy_from_user and copy_to_user do not return -EFAULT,
 *   They return the positive number of bytes *not* copied due to address
 *   space errors.
 *
 * Added GETMODES/GETMODE/GETPHASE ioctls, Fred Barnes <[email protected]>, 03/01/2001.
 * Added GETFLAGS/SETFLAGS ioctls, Fred Barnes, 04/2001
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/ioctl.h>
#include <linux/parport.h>
#include <linux/ctype.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/major.h>
#include <linux/ppdev.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>

#define PP_VERSION "ppdev: user-space parallel port driver"
#define CHRDEV "ppdev"

struct pp_struct {
    struct pardevice * pdev;
    wait_queue_head_t irq_wait;
    atomic_t irqc;
    unsigned int flags;
    int irqresponse;
    unsigned char irqctl;
    struct ieee1284_info state;
    struct ieee1284_info saved_state;
    long default_inactivity;
};

/* pp_struct.flags bitfields */
#define PP_CLAIMED    (1<<0)
#define PP_EXCL       (1<<1)

/* Other constants */
#define PP_INTERRUPT_TIMEOUT (10 * HZ) /* 10s */
#define PP_BUFFER_SIZE 1024
#define PARDEVICE_MAX 8

/* ROUND_UP macro from fs/select.c */
#define ROUND_UP(x,y) (((x)+(y)-1)/(y))

static DEFINE_MUTEX(pp_do_mutex);
static inline void pp_enable_irq (struct pp_struct *pp)
{
    struct parport *port = pp->pdev->port;
    port->ops->enable_irq (port);
}

static ssize_t pp_read (struct file * file, char __user * buf, size_t count,
            loff_t * ppos)
{
    unsigned int minor = iminor(file->f_path.dentry->d_inode);
    struct pp_struct *pp = file->private_data;
    char * kbuffer;
    ssize_t bytes_read = 0;
    struct parport *pport;
    int mode;

    if (!(pp->flags & PP_CLAIMED)) {
        /* Don't have the port claimed */
        pr_debug(CHRDEV "%x: claim the port first\n", minor);
        return -EINVAL;
    }

    /* Trivial case. */
    if (count == 0)
        return 0;

    kbuffer = kmalloc(min_t(size_t, count, PP_BUFFER_SIZE), GFP_KERNEL);
    if (!kbuffer) {
        return -ENOMEM;
    }
    pport = pp->pdev->port;
    mode = pport->ieee1284.mode & ~(IEEE1284_DEVICEID | IEEE1284_ADDR);

    parport_set_timeout (pp->pdev,
                 (file->f_flags & O_NONBLOCK) ?
                 PARPORT_INACTIVITY_O_NONBLOCK :
                 pp->default_inactivity);

    while (bytes_read == 0) {
        ssize_t need = min_t(unsigned long, count, PP_BUFFER_SIZE);

        if (mode == IEEE1284_MODE_EPP) {
            /* various specials for EPP mode */
            int flags = 0;
            size_t (*fn)(struct parport *, void *, size_t, int);

            if (pp->flags & PP_W91284PIC) {
                flags |= PARPORT_W91284PIC;
            }
            if (pp->flags & PP_FASTREAD) {
                flags |= PARPORT_EPP_FAST;
            }
            if (pport->ieee1284.mode & IEEE1284_ADDR) {
                fn = pport->ops->epp_read_addr;
            } else {
                fn = pport->ops->epp_read_data;
            }
            bytes_read = (*fn)(pport, kbuffer, need, flags);
        } else {
            bytes_read = parport_read (pport, kbuffer, need);
        }

        if (bytes_read != 0)
            break;

        if (file->f_flags & O_NONBLOCK) {
            bytes_read = -EAGAIN;
            break;
        }

        if (signal_pending (current)) {
            bytes_read = -ERESTARTSYS;
            break;
        }

        cond_resched();
    }

    parport_set_timeout (pp->pdev, pp->default_inactivity);

    if (bytes_read > 0 && copy_to_user (buf, kbuffer, bytes_read))
        bytes_read = -EFAULT;

    kfree (kbuffer);
    pp_enable_irq (pp);
    return bytes_read;
}

static ssize_t pp_write (struct file * file, const char __user * buf,
             size_t count, loff_t * ppos)
{
    unsigned int minor = iminor(file->f_path.dentry->d_inode);
    struct pp_struct *pp = file->private_data;
    char * kbuffer;
    ssize_t bytes_written = 0;
    ssize_t wrote;
    int mode;
    struct parport *pport;

    if (!(pp->flags & PP_CLAIMED)) {
        /* Don't have the port claimed */
        pr_debug(CHRDEV "%x: claim the port first\n", minor);
        return -EINVAL;
    }

    kbuffer = kmalloc(min_t(size_t, count, PP_BUFFER_SIZE), GFP_KERNEL);
    if (!kbuffer) {
        return -ENOMEM;
    }
    pport = pp->pdev->port;
    mode = pport->ieee1284.mode & ~(IEEE1284_DEVICEID | IEEE1284_ADDR);

    parport_set_timeout (pp->pdev,
                 (file->f_flags & O_NONBLOCK) ?
                 PARPORT_INACTIVITY_O_NONBLOCK :
                 pp->default_inactivity);

    while (bytes_written < count) {
        ssize_t n = min_t(unsigned long, count - bytes_written, PP_BUFFER_SIZE);

        if (copy_from_user (kbuffer, buf + bytes_written, n)) {
            bytes_written = -EFAULT;
            break;
        }

        if ((pp->flags & PP_FASTWRITE) && (mode == IEEE1284_MODE_EPP)) {
            /* do a fast EPP write */
            if (pport->ieee1284.mode & IEEE1284_ADDR) {
                wrote = pport->ops->epp_write_addr (pport,
                    kbuffer, n, PARPORT_EPP_FAST);
            } else {
                wrote = pport->ops->epp_write_data (pport,
                    kbuffer, n, PARPORT_EPP_FAST);
            }
        } else {
            wrote = parport_write (pp->pdev->port, kbuffer, n);
        }

        if (wrote <= 0) {
            if (!bytes_written) {
                bytes_written = wrote;
            }
            break;
        }

        bytes_written += wrote;

        if (file->f_flags & O_NONBLOCK) {
            if (!bytes_written)
                bytes_written = -EAGAIN;
            break;
        }

        if (signal_pending (current)) {
            if (!bytes_written) {
                bytes_written = -EINTR;
            }
            break;
        }

        cond_resched();
    }

    parport_set_timeout (pp->pdev, pp->default_inactivity);

    kfree (kbuffer);
    pp_enable_irq (pp);
    return bytes_written;
}

static void pp_irq (void *private)
{
    struct pp_struct *pp = private;

    if (pp->irqresponse) {
        parport_write_control (pp->pdev->port, pp->irqctl);
        pp->irqresponse = 0;
    }

    atomic_inc (&pp->irqc);
    wake_up_interruptible (&pp->irq_wait);
}

static int register_device (int minor, struct pp_struct *pp)
{
    struct parport *port;
    struct pardevice * pdev = NULL;
    char *name;
    int fl;

    name = kasprintf(GFP_KERNEL, CHRDEV "%x", minor);
    if (name == NULL)
        return -ENOMEM;

    port = parport_find_number (minor);
    if (!port) {
        printk (KERN_WARNING "%s: no associated port!\n", name);
        kfree (name);
        return -ENXIO;
    }

    fl = (pp->flags & PP_EXCL) ? PARPORT_FLAG_EXCL : 0;
    pdev = parport_register_device (port, name, NULL,
                    NULL, pp_irq, fl, pp);
    parport_put_port (port);

    if (!pdev) {
        printk (KERN_WARNING "%s: failed to register device!\n", name);
        kfree (name);
        return -ENXIO;
    }

    pp->pdev = pdev;
    pr_debug("%s: registered pardevice\n", name);
    return 0;
}

static enum ieee1284_phase init_phase (int mode)
{
    switch (mode & ~(IEEE1284_DEVICEID
             | IEEE1284_ADDR)) {
    case IEEE1284_MODE_NIBBLE:
    case IEEE1284_MODE_BYTE:
        return IEEE1284_PH_REV_IDLE;
    }
    return IEEE1284_PH_FWD_IDLE;
}

static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    unsigned int minor = iminor(file->f_path.dentry->d_inode);
    struct pp_struct *pp = file->private_data;
    struct parport * port;
    void __user *argp = (void __user *)arg;

    /* First handle the cases that don't take arguments. */
    switch (cmd) {
    case PPCLAIM:
        {
        struct ieee1284_info *info;
        int ret;

        if (pp->flags & PP_CLAIMED) {
            pr_debug(CHRDEV "%x: you've already got it!\n", minor);
            return -EINVAL;
        }

        /* Deferred device registration. */
        if (!pp->pdev) {
            int err = register_device (minor, pp);
            if (err) {
                return err;
            }
        }

        ret = parport_claim_or_block (pp->pdev);
        if (ret < 0)
            return ret;

        pp->flags |= PP_CLAIMED;

        /* For interrupt-reporting to work, we need to be
         * informed of each interrupt. */
        pp_enable_irq (pp);

        /* We may need to fix up the state machine. */
        info = &pp->pdev->port->ieee1284;
        pp->saved_state.mode = info->mode;
        pp->saved_state.phase = info->phase;
        info->mode = pp->state.mode;
        info->phase = pp->state.phase;
        pp->default_inactivity = parport_set_timeout (pp->pdev, 0);
        parport_set_timeout (pp->pdev, pp->default_inactivity);

        return 0;
        }
    case PPEXCL:
        if (pp->pdev) {
            pr_debug(CHRDEV "%x: too late for PPEXCL; "
                "already registered\n", minor);
            if (pp->flags & PP_EXCL)
                /* But it's not really an error. */
                return 0;
            /* There's no chance of making the driver happy. */
            return -EINVAL;
        }

        /* Just remember to register the device exclusively
         * when we finally do the registration. */
        pp->flags |= PP_EXCL;
        return 0;
    case PPSETMODE:
        {
        int mode;
        if (copy_from_user (&mode, argp, sizeof (mode)))
            return -EFAULT;
        /* FIXME: validate mode */
        pp->state.mode = mode;
        pp->state.phase = init_phase (mode);

        if (pp->flags & PP_CLAIMED) {
            pp->pdev->port->ieee1284.mode = mode;
            pp->pdev->port->ieee1284.phase = pp->state.phase;
        }

        return 0;
        }
    case PPGETMODE:
        {
        int mode;

        if (pp->flags & PP_CLAIMED) {
            mode = pp->pdev->port->ieee1284.mode;
        } else {
            mode = pp->state.mode;
        }
        if (copy_to_user (argp, &mode, sizeof (mode))) {
            return -EFAULT;
        }
        return 0;
        }
    case PPSETPHASE:
        {
        int phase;
        if (copy_from_user (&phase, argp, sizeof (phase))) {
            return -EFAULT;
        }
        /* FIXME: validate phase */
        pp->state.phase = phase;

        if (pp->flags & PP_CLAIMED) {
            pp->pdev->port->ieee1284.phase = phase;
        }

        return 0;
        }
    case PPGETPHASE:
        {
        int phase;

        if (pp->flags & PP_CLAIMED) {
            phase = pp->pdev->port->ieee1284.phase;
        } else {
            phase = pp->state.phase;
        }
        if (copy_to_user (argp, &phase, sizeof (phase))) {
            return -EFAULT;
        }
        return 0;
        }
    case PPGETMODES:
        {
        unsigned int modes;

        port = parport_find_number (minor);
        if (!port)
            return -ENODEV;

        modes = port->modes;
        parport_put_port(port);
        if (copy_to_user (argp, &modes, sizeof (modes))) {
            return -EFAULT;
        }
        return 0;
        }
    case PPSETFLAGS:
        {
        int uflags;

        if (copy_from_user (&uflags, argp, sizeof (uflags))) {
            return -EFAULT;
        }
        pp->flags &= ~PP_FLAGMASK;
        pp->flags |= (uflags & PP_FLAGMASK);
        return 0;
        }
    case PPGETFLAGS:
        {
        int uflags;

        uflags = pp->flags & PP_FLAGMASK;
        if (copy_to_user (argp, &uflags, sizeof (uflags))) {
            return -EFAULT;
        }
        return 0;
        }
    }   /* end switch() */

    /* Everything else requires the port to be claimed, so check
     * that now. */
    if ((pp->flags & PP_CLAIMED) == 0) {
        pr_debug(CHRDEV "%x: claim the port first\n", minor);
        return -EINVAL;
    }

    port = pp->pdev->port;
    switch (cmd) {
        struct ieee1284_info *info;
        unsigned char reg;
        unsigned char mask;
        int mode;
        int ret;
        struct timeval par_timeout;
        long to_jiffies;

    case PPRSTATUS:
        reg = parport_read_status (port);
        if (copy_to_user (argp, &reg, sizeof (reg)))
            return -EFAULT;
        return 0;
    case PPRDATA:
        reg = parport_read_data (port);
        if (copy_to_user (argp, &reg, sizeof (reg)))
            return -EFAULT;
        return 0;
    case PPRCONTROL:
        reg = parport_read_control (port);
        if (copy_to_user (argp, &reg, sizeof (reg)))
            return -EFAULT;
        return 0;
    case PPYIELD:
        parport_yield_blocking (pp->pdev);
        return 0;

    case PPRELEASE:
        /* Save the state machine's state. */
        info = &pp->pdev->port->ieee1284;
        pp->state.mode = info->mode;
        pp->state.phase = info->phase;
        info->mode = pp->saved_state.mode;
        info->phase = pp->saved_state.phase;
        parport_release (pp->pdev);
        pp->flags &= ~PP_CLAIMED;
        return 0;

    case PPWCONTROL:
        if (copy_from_user (&reg, argp, sizeof (reg)))
            return -EFAULT;
        parport_write_control (port, reg);
        return 0;

    case PPWDATA:
        if (copy_from_user (&reg, argp, sizeof (reg)))
            return -EFAULT;
        parport_write_data (port, reg);
        return 0;

    case PPFCONTROL:
        if (copy_from_user (&mask, argp,
                    sizeof (mask)))
            return -EFAULT;
        if (copy_from_user (&reg, 1 + (unsigned char __user *) arg,
                    sizeof (reg)))
            return -EFAULT;
        parport_frob_control (port, mask, reg);
        return 0;

    case PPDATADIR:
        if (copy_from_user (&mode, argp, sizeof (mode)))
            return -EFAULT;
        if (mode)
            port->ops->data_reverse (port);
        else
            port->ops->data_forward (port);
        return 0;

    case PPNEGOT:
        if (copy_from_user (&mode, argp, sizeof (mode)))
            return -EFAULT;
        switch ((ret = parport_negotiate (port, mode))) {
        case 0: break;
        case -1: /* handshake failed, peripheral not IEEE 1284 */
            ret = -EIO;
            break;
        case 1:  /* handshake succeeded, peripheral rejected mode */
            ret = -ENXIO;
            break;
        }
        pp_enable_irq (pp);
        return ret;

    case PPWCTLONIRQ:
        if (copy_from_user (&reg, argp, sizeof (reg)))
            return -EFAULT;

        /* Remember what to set the control lines to, for next
         * time we get an interrupt. */
        pp->irqctl = reg;
        pp->irqresponse = 1;
        return 0;

    case PPCLRIRQ:
        ret = atomic_read (&pp->irqc);
        if (copy_to_user (argp, &ret, sizeof (ret)))
            return -EFAULT;
        atomic_sub (ret, &pp->irqc);
        return 0;

    case PPSETTIME:
        if (copy_from_user (&par_timeout, argp, sizeof(struct timeval))) {
            return -EFAULT;
        }
        /* Convert to jiffies, place in pp->pdev->timeout */
        if ((par_timeout.tv_sec < 0) || (par_timeout.tv_usec < 0)) {
            return -EINVAL;
        }
        to_jiffies = ROUND_UP(par_timeout.tv_usec, 1000000/HZ);
        to_jiffies += par_timeout.tv_sec * (long)HZ;
        if (to_jiffies <= 0) {
            return -EINVAL;
        }
        pp->pdev->timeout = to_jiffies;
        return 0;

    case PPGETTIME:
        to_jiffies = pp->pdev->timeout;
        memset(&par_timeout, 0, sizeof(par_timeout));
        par_timeout.tv_sec = to_jiffies / HZ;
        par_timeout.tv_usec = (to_jiffies % (long)HZ) * (1000000/HZ);
        if (copy_to_user (argp, &par_timeout, sizeof(struct timeval)))
            return -EFAULT;
        return 0;

    default:
        pr_debug(CHRDEV "%x: What? (cmd=0x%x)\n", minor, cmd);
        return -EINVAL;
    }

    /* Keep the compiler happy */
    return 0;
}

static long pp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    long ret;
    mutex_lock(&pp_do_mutex);
    ret = pp_do_ioctl(file, cmd, arg);
    mutex_unlock(&pp_do_mutex);
    return ret;
}

static int pp_open (struct inode * inode, struct file * file)
{
    unsigned int minor = iminor(inode);
    struct pp_struct *pp;

    if (minor >= PARPORT_MAX)
        return -ENXIO;

    pp = kmalloc (sizeof (struct pp_struct), GFP_KERNEL);
    if (!pp)
        return -ENOMEM;

    pp->state.mode = IEEE1284_MODE_COMPAT;
    pp->state.phase = init_phase (pp->state.mode);
    pp->flags = 0;
    pp->irqresponse = 0;
    atomic_set (&pp->irqc, 0);
    init_waitqueue_head (&pp->irq_wait);

    /* Defer the actual device registration until the first claim.
     * That way, we know whether or not the driver wants to have
     * exclusive access to the port (PPEXCL).
     */
    pp->pdev = NULL;
    file->private_data = pp;

    return 0;
}

static int pp_release (struct inode * inode, struct file * file)
{
    unsigned int minor = iminor(inode);
    struct pp_struct *pp = file->private_data;
    int compat_negot;

    compat_negot = 0;
    if (!(pp->flags & PP_CLAIMED) && pp->pdev &&
        (pp->state.mode != IEEE1284_MODE_COMPAT)) {
            struct ieee1284_info *info;

        /* parport released, but not in compatibility mode */
        parport_claim_or_block (pp->pdev);
        pp->flags |= PP_CLAIMED;
        info = &pp->pdev->port->ieee1284;
        pp->saved_state.mode = info->mode;
        pp->saved_state.phase = info->phase;
        info->mode = pp->state.mode;
        info->phase = pp->state.phase;
        compat_negot = 1;
    } else if ((pp->flags & PP_CLAIMED) && pp->pdev &&
        (pp->pdev->port->ieee1284.mode != IEEE1284_MODE_COMPAT)) {
        compat_negot = 2;
    }
    if (compat_negot) {
        parport_negotiate (pp->pdev->port, IEEE1284_MODE_COMPAT);
        pr_debug(CHRDEV "%x: negotiated back to compatibility "
            "mode because user-space forgot\n", minor);
    }

    if (pp->flags & PP_CLAIMED) {
        struct ieee1284_info *info;

        info = &pp->pdev->port->ieee1284;
        pp->state.mode = info->mode;
        pp->state.phase = info->phase;
        info->mode = pp->saved_state.mode;
        info->phase = pp->saved_state.phase;
        parport_release (pp->pdev);
        if (compat_negot != 1) {
            pr_debug(CHRDEV "%x: released pardevice "
                "because user-space forgot\n", minor);
        }
    }

    if (pp->pdev) {
        const char *name = pp->pdev->name;
        parport_unregister_device (pp->pdev);
        kfree (name);
        pp->pdev = NULL;
        pr_debug(CHRDEV "%x: unregistered pardevice\n", minor);
    }

    kfree (pp);

    return 0;
}

/* No kernel lock held - fine */
static unsigned int pp_poll (struct file * file, poll_table * wait)
{
    struct pp_struct *pp = file->private_data;
    unsigned int mask = 0;

    poll_wait (file, &pp->irq_wait, wait);
    if (atomic_read (&pp->irqc))
        mask |= POLLIN | POLLRDNORM;

    return mask;
}

static struct class *ppdev_class;

static const struct file_operations pp_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .read       = pp_read,
    .write      = pp_write,
    .poll       = pp_poll,
    .unlocked_ioctl = pp_ioctl,
    .open       = pp_open,
    .release    = pp_release,
};

static void pp_attach(struct parport *port)
{
    device_create(ppdev_class, port->dev, MKDEV(PP_MAJOR, port->number),
              NULL, "parport%d", port->number);
}

static void pp_detach(struct parport *port)
{
    device_destroy(ppdev_class, MKDEV(PP_MAJOR, port->number));
}

static struct parport_driver pp_driver = {
    .name       = CHRDEV,
    .attach     = pp_attach,
    .detach     = pp_detach,
};

static int __init ppdev_init (void)
{
    int err = 0;

    if (register_chrdev (PP_MAJOR, CHRDEV, &pp_fops)) {
        printk (KERN_WARNING CHRDEV ": unable to get major %d\n",
            PP_MAJOR);
        return -EIO;
    }
    ppdev_class = class_create(THIS_MODULE, CHRDEV);
    if (IS_ERR(ppdev_class)) {
        err = PTR_ERR(ppdev_class);
        goto out_chrdev;
    }
    err = parport_register_driver(&pp_driver);
    if (err < 0) {
        printk (KERN_WARNING CHRDEV ": unable to register with parport\n");
        goto out_class;
    }

    printk (KERN_INFO PP_VERSION "\n");
    goto out;

out_class:
    class_destroy(ppdev_class);
out_chrdev:
    unregister_chrdev(PP_MAJOR, CHRDEV);
out:
    return err;
}

static void __exit ppdev_cleanup (void)
{
    /* Clean up all parport stuff */
    parport_unregister_driver(&pp_driver);
    class_destroy(ppdev_class);
    unregister_chrdev (PP_MAJOR, CHRDEV);
}

module_init(ppdev_init);
module_exit(ppdev_cleanup);

MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(PP_MAJOR);