1 files changed, 449 insertions, 0 deletions

diff --git a/fs/char_dev.c b/fs/char_dev.c
new file mode 100644
index 000000000000..7357a9127df1
--- /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);