diff options
| -rw-r--r-- | drivers/tty/tty_io.c | 50 | ||||
| -rw-r--r-- | include/linux/tty.h | 3 |
2 files changed, 53 insertions, 0 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 49abf04c90b2..974b13d24401 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -325,6 +325,56 @@ static struct tty_driver *get_tty_driver(dev_t device, int *index) return NULL; } +/** + * tty_dev_name_to_number - return dev_t for device name + * @name: user space name of device under /dev + * @number: pointer to dev_t that this function will populate + * + * This function converts device names like ttyS0 or ttyUSB1 into dev_t + * like (4, 64) or (188, 1). If no corresponding driver is registered then + * the function returns -ENODEV. + * + * Locking: this acquires tty_mutex to protect the tty_drivers list from + * being modified while we are traversing it, and makes sure to + * release it before exiting. + */ +int tty_dev_name_to_number(const char *name, dev_t *number) +{ + struct tty_driver *p; + int ret; + int index, prefix_length = 0; + const char *str; + + for (str = name; *str && !isdigit(*str); str++) + ; + + if (!*str) + return -EINVAL; + + ret = kstrtoint(str, 10, &index); + if (ret) + return ret; + + prefix_length = str - name; + mutex_lock(&tty_mutex); + + list_for_each_entry(p, &tty_drivers, tty_drivers) + if (prefix_length == strlen(p->name) && strncmp(name, + p->name, prefix_length) == 0) { + if (index < p->num) { + *number = MKDEV(p->major, p->minor_start + index); + goto out; + } + } + + /* if here then driver wasn't found */ + ret = -ENODEV; +out: + mutex_unlock(&tty_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(tty_dev_name_to_number); + #ifdef CONFIG_CONSOLE_POLL /** diff --git a/include/linux/tty.h b/include/linux/tty.h index b75b2d51ba2b..8156a9ee6fe6 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -402,6 +402,7 @@ extern int __init tty_init(void); extern const char *tty_name(const struct tty_struct *tty); extern struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode, struct file *filp); +extern int tty_dev_name_to_number(const char *name, dev_t *number); #else static inline void tty_kref_put(struct tty_struct *tty) { } @@ -425,6 +426,8 @@ static inline const char *tty_name(const struct tty_struct *tty) static inline struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode, struct file *filp) { return NULL; } +static inline int tty_dev_name_to_number(const char *name, dev_t *number) +{ return -ENOTSUPP; } #endif extern struct ktermios tty_std_termios; |