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);