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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/char_dev.c | |
download | kernel_samsung_tuna-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip kernel_samsung_tuna-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz kernel_samsung_tuna-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.bz2 |
Linux-2.6.12-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.c | 449 |
1 files changed, 449 insertions, 0 deletions
diff --git a/fs/char_dev.c b/fs/char_dev.c new file mode 100644 index 0000000..7357a91 --- /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); |