aboutsummaryrefslogtreecommitdiff
path: root/fs/char_dev.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/char_dev.c
downloadlinux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'fs/char_dev.c')
-rw-r--r--fs/char_dev.c449
1 files changed, 449 insertions, 0 deletions
diff --git a/fs/char_dev.c b/fs/char_dev.c
new file mode 100644
index 00000000000..7357a9127df
--- /dev/null
+++ b/fs/char_dev.c
@@ -0,0 +1,449 @@
+/*
+ * linux/fs/char_dev.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+#include <linux/config.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include <linux/major.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/smp_lock.h>
+#include <linux/devfs_fs_kernel.h>
+
+#include <linux/kobject.h>
+#include <linux/kobj_map.h>
+#include <linux/cdev.h>
+
+#ifdef CONFIG_KMOD
+#include <linux/kmod.h>
+#endif
+
+static struct kobj_map *cdev_map;
+
+/* degrade to linked list for small systems */
+#define MAX_PROBE_HASH (CONFIG_BASE_SMALL ? 1 : 255)
+
+static DECLARE_MUTEX(chrdevs_lock);
+
+static struct char_device_struct {
+ struct char_device_struct *next;
+ unsigned int major;
+ unsigned int baseminor;
+ int minorct;
+ const char *name;
+ struct file_operations *fops;
+ struct cdev *cdev; /* will die */
+} *chrdevs[MAX_PROBE_HASH];
+
+/* index in the above */
+static inline int major_to_index(int major)
+{
+ return major % MAX_PROBE_HASH;
+}
+
+/* get char device names in somewhat random order */
+int get_chrdev_list(char *page)
+{
+ struct char_device_struct *cd;
+ int i, len;
+
+ len = sprintf(page, "Character devices:\n");
+
+ down(&chrdevs_lock);
+ for (i = 0; i < ARRAY_SIZE(chrdevs) ; i++) {
+ for (cd = chrdevs[i]; cd; cd = cd->next)
+ len += sprintf(page+len, "%3d %s\n",
+ cd->major, cd->name);
+ }
+ up(&chrdevs_lock);
+
+ return len;
+}
+
+/*
+ * Register a single major with a specified minor range.
+ *
+ * If major == 0 this functions will dynamically allocate a major and return
+ * its number.
+ *
+ * If major > 0 this function will attempt to reserve the passed range of
+ * minors and will return zero on success.
+ *
+ * Returns a -ve errno on failure.
+ */
+static struct char_device_struct *
+__register_chrdev_region(unsigned int major, unsigned int baseminor,
+ int minorct, const char *name)
+{
+ struct char_device_struct *cd, **cp;
+ int ret = 0;
+ int i;
+
+ cd = kmalloc(sizeof(struct char_device_struct), GFP_KERNEL);
+ if (cd == NULL)
+ return ERR_PTR(-ENOMEM);
+
+ memset(cd, 0, sizeof(struct char_device_struct));
+
+ down(&chrdevs_lock);
+
+ /* temporary */
+ if (major == 0) {
+ for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
+ if (chrdevs[i] == NULL)
+ break;
+ }
+
+ if (i == 0) {
+ ret = -EBUSY;
+ goto out;
+ }
+ major = i;
+ ret = major;
+ }
+
+ cd->major = major;
+ cd->baseminor = baseminor;
+ cd->minorct = minorct;
+ cd->name = name;
+
+ i = major_to_index(major);
+
+ for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
+ if ((*cp)->major > major ||
+ ((*cp)->major == major && (*cp)->baseminor >= baseminor))
+ break;
+ if (*cp && (*cp)->major == major &&
+ (*cp)->baseminor < baseminor + minorct) {
+ ret = -EBUSY;
+ goto out;
+ }
+ cd->next = *cp;
+ *cp = cd;
+ up(&chrdevs_lock);
+ return cd;
+out:
+ up(&chrdevs_lock);
+ kfree(cd);
+ return ERR_PTR(ret);
+}
+
+static struct char_device_struct *
+__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
+{
+ struct char_device_struct *cd = NULL, **cp;
+ int i = major_to_index(major);
+
+ up(&chrdevs_lock);
+ for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
+ if ((*cp)->major == major &&
+ (*cp)->baseminor == baseminor &&
+ (*cp)->minorct == minorct)
+ break;
+ if (*cp) {
+ cd = *cp;
+ *cp = cd->next;
+ }
+ up(&chrdevs_lock);
+ return cd;
+}
+
+int register_chrdev_region(dev_t from, unsigned count, const char *name)
+{
+ struct char_device_struct *cd;
+ dev_t to = from + count;
+ dev_t n, next;
+
+ for (n = from; n < to; n = next) {
+ next = MKDEV(MAJOR(n)+1, 0);
+ if (next > to)
+ next = to;
+ cd = __register_chrdev_region(MAJOR(n), MINOR(n),
+ next - n, name);
+ if (IS_ERR(cd))
+ goto fail;
+ }
+ return 0;
+fail:
+ to = n;
+ for (n = from; n < to; n = next) {
+ next = MKDEV(MAJOR(n)+1, 0);
+ kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
+ }
+ return PTR_ERR(cd);
+}
+
+int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
+ const char *name)
+{
+ struct char_device_struct *cd;
+ cd = __register_chrdev_region(0, baseminor, count, name);
+ if (IS_ERR(cd))
+ return PTR_ERR(cd);
+ *dev = MKDEV(cd->major, cd->baseminor);
+ return 0;
+}
+
+int register_chrdev(unsigned int major, const char *name,
+ struct file_operations *fops)
+{
+ struct char_device_struct *cd;
+ struct cdev *cdev;
+ char *s;
+ int err = -ENOMEM;
+
+ cd = __register_chrdev_region(major, 0, 256, name);
+ if (IS_ERR(cd))
+ return PTR_ERR(cd);
+
+ cdev = cdev_alloc();
+ if (!cdev)
+ goto out2;
+
+ cdev->owner = fops->owner;
+ cdev->ops = fops;
+ kobject_set_name(&cdev->kobj, "%s", name);
+ for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
+ *s = '!';
+
+ err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
+ if (err)
+ goto out;
+
+ cd->cdev = cdev;
+
+ return major ? 0 : cd->major;
+out:
+ kobject_put(&cdev->kobj);
+out2:
+ kfree(__unregister_chrdev_region(cd->major, 0, 256));
+ return err;
+}
+
+void unregister_chrdev_region(dev_t from, unsigned count)
+{
+ dev_t to = from + count;
+ dev_t n, next;
+
+ for (n = from; n < to; n = next) {
+ next = MKDEV(MAJOR(n)+1, 0);
+ if (next > to)
+ next = to;
+ kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
+ }
+}
+
+int unregister_chrdev(unsigned int major, const char *name)
+{
+ struct char_device_struct *cd;
+ cd = __unregister_chrdev_region(major, 0, 256);
+ if (cd && cd->cdev)
+ cdev_del(cd->cdev);
+ kfree(cd);
+ return 0;
+}
+
+static DEFINE_SPINLOCK(cdev_lock);
+
+static struct kobject *cdev_get(struct cdev *p)
+{
+ struct module *owner = p->owner;
+ struct kobject *kobj;
+
+ if (owner && !try_module_get(owner))
+ return NULL;
+ kobj = kobject_get(&p->kobj);
+ if (!kobj)
+ module_put(owner);
+ return kobj;
+}
+
+void cdev_put(struct cdev *p)
+{
+ if (p) {
+ kobject_put(&p->kobj);
+ module_put(p->owner);
+ }
+}
+
+/*
+ * Called every time a character special file is opened
+ */
+int chrdev_open(struct inode * inode, struct file * filp)
+{
+ struct cdev *p;
+ struct cdev *new = NULL;
+ int ret = 0;
+
+ spin_lock(&cdev_lock);
+ p = inode->i_cdev;
+ if (!p) {
+ struct kobject *kobj;
+ int idx;
+ spin_unlock(&cdev_lock);
+ kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
+ if (!kobj)
+ return -ENXIO;
+ new = container_of(kobj, struct cdev, kobj);
+ spin_lock(&cdev_lock);
+ p = inode->i_cdev;
+ if (!p) {
+ inode->i_cdev = p = new;
+ inode->i_cindex = idx;
+ list_add(&inode->i_devices, &p->list);
+ new = NULL;
+ } else if (!cdev_get(p))
+ ret = -ENXIO;
+ } else if (!cdev_get(p))
+ ret = -ENXIO;
+ spin_unlock(&cdev_lock);
+ cdev_put(new);
+ if (ret)
+ return ret;
+ filp->f_op = fops_get(p->ops);
+ if (!filp->f_op) {
+ cdev_put(p);
+ return -ENXIO;
+ }
+ if (filp->f_op->open) {
+ lock_kernel();
+ ret = filp->f_op->open(inode,filp);
+ unlock_kernel();
+ }
+ if (ret)
+ cdev_put(p);
+ return ret;
+}
+
+void cd_forget(struct inode *inode)
+{
+ spin_lock(&cdev_lock);
+ list_del_init(&inode->i_devices);
+ inode->i_cdev = NULL;
+ spin_unlock(&cdev_lock);
+}
+
+void cdev_purge(struct cdev *cdev)
+{
+ spin_lock(&cdev_lock);
+ while (!list_empty(&cdev->list)) {
+ struct inode *inode;
+ inode = container_of(cdev->list.next, struct inode, i_devices);
+ list_del_init(&inode->i_devices);
+ inode->i_cdev = NULL;
+ }
+ spin_unlock(&cdev_lock);
+}
+
+/*
+ * Dummy default file-operations: the only thing this does
+ * is contain the open that then fills in the correct operations
+ * depending on the special file...
+ */
+struct file_operations def_chr_fops = {
+ .open = chrdev_open,
+};
+
+static struct kobject *exact_match(dev_t dev, int *part, void *data)
+{
+ struct cdev *p = data;
+ return &p->kobj;
+}
+
+static int exact_lock(dev_t dev, void *data)
+{
+ struct cdev *p = data;
+ return cdev_get(p) ? 0 : -1;
+}
+
+int cdev_add(struct cdev *p, dev_t dev, unsigned count)
+{
+ p->dev = dev;
+ p->count = count;
+ return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
+}
+
+static void cdev_unmap(dev_t dev, unsigned count)
+{
+ kobj_unmap(cdev_map, dev, count);
+}
+
+void cdev_del(struct cdev *p)
+{
+ cdev_unmap(p->dev, p->count);
+ kobject_put(&p->kobj);
+}
+
+
+static void cdev_default_release(struct kobject *kobj)
+{
+ struct cdev *p = container_of(kobj, struct cdev, kobj);
+ cdev_purge(p);
+}
+
+static void cdev_dynamic_release(struct kobject *kobj)
+{
+ struct cdev *p = container_of(kobj, struct cdev, kobj);
+ cdev_purge(p);
+ kfree(p);
+}
+
+static struct kobj_type ktype_cdev_default = {
+ .release = cdev_default_release,
+};
+
+static struct kobj_type ktype_cdev_dynamic = {
+ .release = cdev_dynamic_release,
+};
+
+struct cdev *cdev_alloc(void)
+{
+ struct cdev *p = kmalloc(sizeof(struct cdev), GFP_KERNEL);
+ if (p) {
+ memset(p, 0, sizeof(struct cdev));
+ p->kobj.ktype = &ktype_cdev_dynamic;
+ INIT_LIST_HEAD(&p->list);
+ kobject_init(&p->kobj);
+ }
+ return p;
+}
+
+void cdev_init(struct cdev *cdev, struct file_operations *fops)
+{
+ memset(cdev, 0, sizeof *cdev);
+ INIT_LIST_HEAD(&cdev->list);
+ cdev->kobj.ktype = &ktype_cdev_default;
+ kobject_init(&cdev->kobj);
+ cdev->ops = fops;
+}
+
+static struct kobject *base_probe(dev_t dev, int *part, void *data)
+{
+ if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
+ /* Make old-style 2.4 aliases work */
+ request_module("char-major-%d", MAJOR(dev));
+ return NULL;
+}
+
+void __init chrdev_init(void)
+{
+ cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
+}
+
+
+/* Let modules do char dev stuff */
+EXPORT_SYMBOL(register_chrdev_region);
+EXPORT_SYMBOL(unregister_chrdev_region);
+EXPORT_SYMBOL(alloc_chrdev_region);
+EXPORT_SYMBOL(cdev_init);
+EXPORT_SYMBOL(cdev_alloc);
+EXPORT_SYMBOL(cdev_del);
+EXPORT_SYMBOL(cdev_add);
+EXPORT_SYMBOL(register_chrdev);
+EXPORT_SYMBOL(unregister_chrdev);