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

Greg KH
2003-12-09T00:52:57Z

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;
}