tty: add function to convert device name to number (fc61ed51) · Commits · 戴 / test

drivers/tty/tty_io.c

+50 −0

Original line number	Diff line number	Diff line
		@@ -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

		/**

+3 −0

Original line number	Diff line number	Diff line
		@@ -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;