[PATCH] sysfs support for vcs devices (was Re: State of devfs in 2.6?)

From: Greg KH (greg_at_kroah.com)
Date: 12/09/03

  • Next message: pinotj_at_club-internet.fr: "Re: Re: [Oops] i386 mm/slab.c (cache_flusharray)" 
    Date:	Mon, 8 Dec 2003 16:51:36 -0800
To: Andreas Jellinghaus <aj@dungeon.inka.de>

    On Mon, Dec 08, 2003 at 03:34:28PM -0800, Greg KH wrote:
    > On Tue, Dec 09, 2003 at 12:04:08AM +0100, Andreas Jellinghaus wrote:
    > > - 18 vcc/ devices
    >
    > Hm, good catch. I wonder why these aren't getting picked up in
    > /sys/class/tty as they are tty devices. I thought they used to be
    > there...

    Ah, they really aren't tty devices, they are char devices. That's why
    they never have showed up.

    Anyway, here's a patch against 2.6.0-test11 that adds sysfs support for
    all of the vcs devices. Now udev has support for them :)

    thanks for pointing these out,

    greg k-h

    # add /sys/class/vc support for the vcs devices.

    diff -Nru a/drivers/char/vc_screen.c b/drivers/char/vc_screen.c
    --- a/drivers/char/vc_screen.c Mon Dec 8 16:49:54 2003
    +++ b/drivers/char/vc_screen.c Mon Dec 8 16:49:54 2003
    @@ -36,6 +36,7 @@
     #include <linux/kbd_kern.h>
     #include <linux/console.h>
     #include <linux/smp_lock.h>
    +#include <linux/device.h>
     #include <asm/uaccess.h>
     #include <asm/byteorder.h>
     #include <asm/unaligned.h>
    @@ -469,6 +470,85 @@
             .open = vcs_open,
     };
     
    +/* vc class implementation */
    +
    +struct vc_dev {
    + struct list_head node;
    + dev_t dev;
    + struct class_device class_dev;
    +};
    +#define to_vc_dev(d) container_of(d, struct vc_dev, class_dev)
    +
    +static LIST_HEAD(vc_dev_list);
    +static spinlock_t vc_dev_list_lock = SPIN_LOCK_UNLOCKED;
    +
    +static void release_vc_dev(struct class_device *class_dev)
    +{
    + struct vc_dev *vc_dev = to_vc_dev(class_dev);
    + kfree(vc_dev);
    +}
    +
    +static struct class vc_class = {
    + .name = "vc",
    + .release = &release_vc_dev,
    +};
    +
    +static ssize_t show_dev(struct class_device *class_dev, char *buf)
    +{
    + struct vc_dev *vc_dev = to_vc_dev(class_dev);
    + return print_dev_t(buf, vc_dev->dev);
    +}
    +static CLASS_DEVICE_ATTR(dev, S_IRUGO, show_dev, NULL);
    +
    +static int vc_add_class_device(dev_t dev, char *name, int minor)
    +{
    + struct vc_dev *vc_dev = NULL;
    + int retval;
    +
    + vc_dev = kmalloc(sizeof(*vc_dev), GFP_KERNEL);
    + if (!vc_dev)
    + return -ENOMEM;
    + memset(vc_dev, 0x00, sizeof(*vc_dev));
    +
    + vc_dev->dev = dev;
    + vc_dev->class_dev.class = &vc_class;
    + snprintf(vc_dev->class_dev.class_id, BUS_ID_SIZE, name, minor);
    + retval = class_device_register(&vc_dev->class_dev);
    + if (retval)
    + goto error;
    + class_device_create_file(&vc_dev->class_dev, &class_device_attr_dev);
    + spin_lock(&vc_dev_list_lock);
    + list_add(&vc_dev->node, &vc_dev_list);
    + spin_unlock(&vc_dev_list_lock);
    + return 0;
    +error:
    + kfree(vc_dev);
    + return retval;
    +}
    +
    +static void vc_remove_class_device(int minor)
    +{
    + struct vc_dev *vc_dev = NULL;
    + struct list_head *tmp;
    + int found = 0;
    +
    + spin_lock(&vc_dev_list_lock);
    + list_for_each(tmp, &vc_dev_list) {
    + vc_dev = list_entry(tmp, struct vc_dev, node);
    + if (MINOR(vc_dev->dev) == minor) {
    + found = 1;
    + break;
    + }
    + }
    + if (found) {
    + list_del(&vc_dev->node);
    + spin_unlock(&vc_dev_list_lock);
    + class_device_unregister(&vc_dev->class_dev);
    + } else {
    + spin_unlock(&vc_dev_list_lock);
    + }
    +}
    +
     void vcs_make_devfs(struct tty_struct *tty)
     {
             devfs_mk_cdev(MKDEV(VCS_MAJOR, tty->index + 1),
    @@ -477,19 +557,26 @@
             devfs_mk_cdev(MKDEV(VCS_MAJOR, tty->index + 129),
                             S_IFCHR|S_IRUSR|S_IWUSR,
                             "vcc/a%u", tty->index + 1);
    + vc_add_class_device(MKDEV(VCS_MAJOR, tty->index + 1), "vcs%u", tty->index + 1);
    + vc_add_class_device(MKDEV(VCS_MAJOR, tty->index + 129), "vcsa%u", tty->index + 1);
     }
     void vcs_remove_devfs(struct tty_struct *tty)
     {
             devfs_remove("vcc/%u", tty->index + 1);
             devfs_remove("vcc/a%u", tty->index + 1);
    + vc_remove_class_device(tty->index + 1);
    + vc_remove_class_device(tty->index + 129);
     }
     
     int __init vcs_init(void)
     {
             if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
                     panic("unable to get major %d for vcs device", VCS_MAJOR);
    + class_register(&vc_class);
     
             devfs_mk_cdev(MKDEV(VCS_MAJOR, 0), S_IFCHR|S_IRUSR|S_IWUSR, "vcc/0");
             devfs_mk_cdev(MKDEV(VCS_MAJOR, 128), S_IFCHR|S_IRUSR|S_IWUSR, "vcc/a0");
    + vc_add_class_device(MKDEV(VCS_MAJOR, 0), "vcs", 0);
    + vc_add_class_device(MKDEV(VCS_MAJOR, 128), "vcsa", 128);
             return 0;
     }
    -
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