* Copyright (C) 1991, 1992 Linus Torvalds
*/
-#include <linux/config.h>
#include <linux/init.h>
#include <linux/fs.h>
+#include <linux/kdev_t.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/seq_file.h>
#include <linux/kobject.h>
#include <linux/kobj_map.h>
#include <linux/cdev.h>
+#include <linux/mutex.h>
+#include <linux/backing-dev.h>
-#ifdef CONFIG_KMOD
-#include <linux/kmod.h>
+#include "internal.h"
+
+/*
+ * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
+ * devices
+ * - permits shared-mmap for read, write and/or exec
+ * - does not permit private mmap in NOMMU mode (can't do COW)
+ * - no readahead or I/O queue unplugging required
+ */
+struct backing_dev_info directly_mappable_cdev_bdi = {
+ .name = "char",
+ .capabilities = (
+#ifdef CONFIG_MMU
+ /* permit private copies of the data to be taken */
+ BDI_CAP_MAP_COPY |
#endif
+ /* permit direct mmap, for read, write or exec */
+ BDI_CAP_MAP_DIRECT |
+ BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
+};
static struct kobj_map *cdev_map;
-#define MAX_PROBE_HASH 255 /* random */
-
-static DECLARE_MUTEX(chrdevs_lock);
+static DEFINE_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;
+ char name[64];
struct cdev *cdev; /* will die */
-} *chrdevs[MAX_PROBE_HASH];
+} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
/* index in the above */
static inline int major_to_index(int major)
{
- return major % MAX_PROBE_HASH;
+ return major % CHRDEV_MAJOR_HASH_SIZE;
}
-/* get char device names in somewhat random order */
-int get_chrdev_list(char *page)
+#ifdef CONFIG_PROC_FS
+
+void chrdev_show(struct seq_file *f, off_t offset)
{
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);
+ if (offset < CHRDEV_MAJOR_HASH_SIZE) {
+ mutex_lock(&chrdevs_lock);
+ for (cd = chrdevs[offset]; cd; cd = cd->next)
+ seq_printf(f, "%3d %s\n", cd->major, cd->name);
+ mutex_unlock(&chrdevs_lock);
}
- up(&chrdevs_lock);
-
- return len;
}
+#endif /* CONFIG_PROC_FS */
+
/*
* Register a single major with a specified minor range.
*
int ret = 0;
int i;
- cd = kmalloc(sizeof(struct char_device_struct), GFP_KERNEL);
+ cd = kzalloc(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);
+ mutex_lock(&chrdevs_lock);
/* temporary */
if (major == 0) {
cd->major = major;
cd->baseminor = baseminor;
cd->minorct = minorct;
- cd->name = name;
+ strlcpy(cd->name, name, sizeof(cd->name));
i = major_to_index(major);
for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
if ((*cp)->major > major ||
- ((*cp)->major == major && (*cp)->baseminor >= baseminor))
+ ((*cp)->major == major &&
+ (((*cp)->baseminor >= baseminor) ||
+ ((*cp)->baseminor + (*cp)->minorct > baseminor))))
break;
- if (*cp && (*cp)->major == major &&
- (*cp)->baseminor < baseminor + minorct) {
- ret = -EBUSY;
- goto out;
+
+ /* Check for overlapping minor ranges. */
+ if (*cp && (*cp)->major == major) {
+ int old_min = (*cp)->baseminor;
+ int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
+ int new_min = baseminor;
+ int new_max = baseminor + minorct - 1;
+
+ /* New driver overlaps from the left. */
+ if (new_max >= old_min && new_max <= old_max) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ /* New driver overlaps from the right. */
+ if (new_min <= old_max && new_min >= old_min) {
+ ret = -EBUSY;
+ goto out;
+ }
}
+
cd->next = *cp;
*cp = cd;
- up(&chrdevs_lock);
+ mutex_unlock(&chrdevs_lock);
return cd;
out:
- up(&chrdevs_lock);
+ mutex_unlock(&chrdevs_lock);
kfree(cd);
return ERR_PTR(ret);
}
struct char_device_struct *cd = NULL, **cp;
int i = major_to_index(major);
- up(&chrdevs_lock);
+ mutex_lock(&chrdevs_lock);
for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
if ((*cp)->major == major &&
(*cp)->baseminor == baseminor &&
cd = *cp;
*cp = cd->next;
}
- up(&chrdevs_lock);
+ mutex_unlock(&chrdevs_lock);
return cd;
}
+/**
+ * register_chrdev_region() - register a range of device numbers
+ * @from: the first in the desired range of device numbers; must include
+ * the major number.
+ * @count: the number of consecutive device numbers required
+ * @name: the name of the device or driver.
+ *
+ * Return value is zero on success, a negative error code on failure.
+ */
int register_chrdev_region(dev_t from, unsigned count, const char *name)
{
struct char_device_struct *cd;
return PTR_ERR(cd);
}
+/**
+ * alloc_chrdev_region() - register a range of char device numbers
+ * @dev: output parameter for first assigned number
+ * @baseminor: first of the requested range of minor numbers
+ * @count: the number of minor numbers required
+ * @name: the name of the associated device or driver
+ *
+ * Allocates a range of char device numbers. The major number will be
+ * chosen dynamically, and returned (along with the first minor number)
+ * in @dev. Returns zero or a negative error code.
+ */
int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
const char *name)
{
return 0;
}
-int register_chrdev(unsigned int major, const char *name,
- struct file_operations *fops)
+/**
+ * __register_chrdev() - create and register a cdev occupying a range of minors
+ * @major: major device number or 0 for dynamic allocation
+ * @baseminor: first of the requested range of minor numbers
+ * @count: the number of minor numbers required
+ * @name: name of this range of devices
+ * @fops: file operations associated with this devices
+ *
+ * If @major == 0 this functions will dynamically allocate a major and return
+ * its number.
+ *
+ * If @major > 0 this function will attempt to reserve a device with the given
+ * major number and will return zero on success.
+ *
+ * Returns a -ve errno on failure.
+ *
+ * The name of this device has nothing to do with the name of the device in
+ * /dev. It only helps to keep track of the different owners of devices. If
+ * your module name has only one type of devices it's ok to use e.g. the name
+ * of the module here.
+ */
+int __register_chrdev(unsigned int major, unsigned int baseminor,
+ unsigned int count, const char *name,
+ const 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);
+ cd = __register_chrdev_region(major, baseminor, count, name);
if (IS_ERR(cd))
return PTR_ERR(cd);
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);
+ err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
if (err)
goto out;
out:
kobject_put(&cdev->kobj);
out2:
- kfree(__unregister_chrdev_region(cd->major, 0, 256));
+ kfree(__unregister_chrdev_region(cd->major, baseminor, count));
return err;
}
+/**
+ * unregister_chrdev_region() - return a range of device numbers
+ * @from: the first in the range of numbers to unregister
+ * @count: the number of device numbers to unregister
+ *
+ * This function will unregister a range of @count device numbers,
+ * starting with @from. The caller should normally be the one who
+ * allocated those numbers in the first place...
+ */
void unregister_chrdev_region(dev_t from, unsigned count)
{
dev_t to = from + count;
}
}
-int unregister_chrdev(unsigned int major, const char *name)
+/**
+ * __unregister_chrdev - unregister and destroy a cdev
+ * @major: major device number
+ * @baseminor: first of the range of minor numbers
+ * @count: the number of minor numbers this cdev is occupying
+ * @name: name of this range of devices
+ *
+ * Unregister and destroy the cdev occupying the region described by
+ * @major, @baseminor and @count. This function undoes what
+ * __register_chrdev() did.
+ */
+void __unregister_chrdev(unsigned int major, unsigned int baseminor,
+ unsigned int count, const char *name)
{
struct char_device_struct *cd;
- cd = __unregister_chrdev_region(major, 0, 256);
+
+ cd = __unregister_chrdev_region(major, baseminor, count);
if (cd && cd->cdev)
cdev_del(cd->cdev);
kfree(cd);
- return 0;
}
static DEFINE_SPINLOCK(cdev_lock);
void cdev_put(struct cdev *p)
{
if (p) {
+ struct module *owner = p->owner;
kobject_put(&p->kobj);
- module_put(p->owner);
+ module_put(owner);
}
}
/*
* Called every time a character special file is opened
*/
-int chrdev_open(struct inode * inode, struct file * filp)
+static int chrdev_open(struct inode *inode, struct file *filp)
{
struct cdev *p;
struct cdev *new = NULL;
return -ENXIO;
new = container_of(kobj, struct cdev, kobj);
spin_lock(&cdev_lock);
+ /* Check i_cdev again in case somebody beat us to it while
+ we dropped the 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))
cdev_put(new);
if (ret)
return ret;
+
+ ret = -ENXIO;
filp->f_op = fops_get(p->ops);
- if (!filp->f_op) {
- cdev_put(p);
- return -ENXIO;
- }
+ if (!filp->f_op)
+ goto out_cdev_put;
+
if (filp->f_op->open) {
- lock_kernel();
ret = filp->f_op->open(inode,filp);
- unlock_kernel();
+ if (ret)
+ goto out_cdev_put;
}
- if (ret)
- cdev_put(p);
+
+ return 0;
+
+ out_cdev_put:
+ cdev_put(p);
return ret;
}
+int cdev_index(struct inode *inode)
+{
+ int idx;
+ struct kobject *kobj;
+
+ kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
+ if (!kobj)
+ return -1;
+ kobject_put(kobj);
+ return idx;
+}
+
void cd_forget(struct inode *inode)
{
spin_lock(&cdev_lock);
* is contain the open that then fills in the correct operations
* depending on the special file...
*/
-struct file_operations def_chr_fops = {
+const struct file_operations def_chr_fops = {
.open = chrdev_open,
};
return cdev_get(p) ? 0 : -1;
}
+/**
+ * cdev_add() - add a char device to the system
+ * @p: the cdev structure for the device
+ * @dev: the first device number for which this device is responsible
+ * @count: the number of consecutive minor numbers corresponding to this
+ * device
+ *
+ * cdev_add() adds the device represented by @p to the system, making it
+ * live immediately. A negative error code is returned on failure.
+ */
int cdev_add(struct cdev *p, dev_t dev, unsigned count)
{
p->dev = dev;
kobj_unmap(cdev_map, dev, count);
}
+/**
+ * cdev_del() - remove a cdev from the system
+ * @p: the cdev structure to be removed
+ *
+ * cdev_del() removes @p from the system, possibly freeing the structure
+ * itself.
+ */
void cdev_del(struct cdev *p)
{
cdev_unmap(p->dev, p->count);
.release = cdev_dynamic_release,
};
+/**
+ * cdev_alloc() - allocate a cdev structure
+ *
+ * Allocates and returns a cdev structure, or NULL on failure.
+ */
struct cdev *cdev_alloc(void)
{
- struct cdev *p = kmalloc(sizeof(struct cdev), GFP_KERNEL);
+ struct cdev *p = kzalloc(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);
+ kobject_init(&p->kobj, &ktype_cdev_dynamic);
}
return p;
}
-void cdev_init(struct cdev *cdev, struct file_operations *fops)
+/**
+ * cdev_init() - initialize a cdev structure
+ * @cdev: the structure to initialize
+ * @fops: the file_operations for this device
+ *
+ * Initializes @cdev, remembering @fops, making it ready to add to the
+ * system with cdev_add().
+ */
+void cdev_init(struct cdev *cdev, const struct file_operations *fops)
{
memset(cdev, 0, sizeof *cdev);
INIT_LIST_HEAD(&cdev->list);
- cdev->kobj.ktype = &ktype_cdev_default;
- kobject_init(&cdev->kobj);
+ kobject_init(&cdev->kobj, &ktype_cdev_default);
cdev->ops = fops;
}
void __init chrdev_init(void)
{
cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
+ bdi_init(&directly_mappable_cdev_bdi);
}
EXPORT_SYMBOL(cdev_alloc);
EXPORT_SYMBOL(cdev_del);
EXPORT_SYMBOL(cdev_add);
-EXPORT_SYMBOL(register_chrdev);
-EXPORT_SYMBOL(unregister_chrdev);
+EXPORT_SYMBOL(cdev_index);
+EXPORT_SYMBOL(__register_chrdev);
+EXPORT_SYMBOL(__unregister_chrdev);
+EXPORT_SYMBOL(directly_mappable_cdev_bdi);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff