initial_commit

1 files changed, 575 insertions, 0 deletions

diff --git a/fs/char_dev.c b/fs/char_dev.c
new file mode 100644
index 00000000..dca9e5e0
--- /dev/null
+++ b/fs/char_dev.c
@@ -0,0 +1,575 @@
+/*
+ *  linux/fs/char_dev.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#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/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>
+#include <linux/tty.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 |
+		/* no writeback happens */
+		BDI_CAP_NO_ACCT_AND_WRITEBACK),
+};
+
+static struct kobj_map *cdev_map;
+
+static DEFINE_MUTEX(chrdevs_lock);
+
+static struct char_device_struct {
+	struct char_device_struct *next;
+	unsigned int major;
+	unsigned int baseminor;
+	int minorct;
+	char name[64];
+	struct cdev *cdev;		/* will die */
+} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
+
+/* index in the above */
+static inline int major_to_index(unsigned major)
+{
+	return major % CHRDEV_MAJOR_HASH_SIZE;
+}
+
+#ifdef CONFIG_PROC_FS
+
+void chrdev_show(struct seq_file *f, off_t offset)
+{
+	struct char_device_struct *cd;
+
+	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);
+	}
+}
+
+#endif /* CONFIG_PROC_FS */
+
+/*
+ * 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 = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
+	if (cd == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_lock(&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;
+	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)->baseminor + (*cp)->minorct > baseminor))))
+			break;
+
+	/* 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;
+	mutex_unlock(&chrdevs_lock);
+	return cd;
+out:
+	mutex_unlock(&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);
+
+	mutex_lock(&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;
+	}
+	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;
+	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);
+}
+
+/**
+ * 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)
+{
+	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;
+}
+
+/**
+ * __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;
+	int err = -ENOMEM;
+
+	cd = __register_chrdev_region(major, baseminor, count, 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);
+		
+	err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
+	if (err)
+		goto out;
+
+	cd->cdev = cdev;
+
+	return major ? 0 : cd->major;
+out:
+	kobject_put(&cdev->kobj);
+out2:
+	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;
+	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));
+	}
+}
+
+/**
+ * __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, baseminor, count);
+	if (cd && cd->cdev)
+		cdev_del(cd->cdev);
+	kfree(cd);
+}
+
+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) {
+		struct module *owner = p->owner;
+		kobject_put(&p->kobj);
+		module_put(owner);
+	}
+}
+
+/*
+ * Called every time a character special file is opened
+ */
+static 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);
+		/* 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;
+			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;
+
+	ret = -ENXIO;
+	filp->f_op = fops_get(p->ops);
+	if (!filp->f_op)
+		goto out_cdev_put;
+
+	if (filp->f_op->open) {
+		ret = filp->f_op->open(inode,filp);
+		if (ret)
+			goto out_cdev_put;
+	}
+
+	return 0;
+
+ out_cdev_put:
+	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);
+}
+
+static 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...
+ */
+const struct file_operations def_chr_fops = {
+	.open = chrdev_open,
+	.llseek = noop_llseek,
+};
+
+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;
+}
+
+/**
+ * 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;
+	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);
+}
+
+/**
+ * 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);
+	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,
+};
+
+/**
+ * cdev_alloc() - allocate a cdev structure
+ *
+ * Allocates and returns a cdev structure, or NULL on failure.
+ */
+struct cdev *cdev_alloc(void)
+{
+	struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
+	if (p) {
+		INIT_LIST_HEAD(&p->list);
+		kobject_init(&p->kobj, &ktype_cdev_dynamic);
+	}
+	return p;
+}
+
+/**
+ * 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);
+	kobject_init(&cdev->kobj, &ktype_cdev_default);
+	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);
+	bdi_init(&directly_mappable_cdev_bdi);
+}
+
+
+/* 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);
+EXPORT_SYMBOL(directly_mappable_cdev_bdi);