1 #ifndef _LINUX_TTY_LDISC_H 2 #define _LINUX_TTY_LDISC_H 3 4 /* 5 * This structure defines the interface between the tty line discipline 6 * implementation and the tty routines. The following routines can be 7 * defined; unless noted otherwise, they are optional, and can be 8 * filled in with a null pointer. 9 * 10 * int (*open)(struct tty_struct *); 11 * 12 * This function is called when the line discipline is associated 13 * with the tty. The line discipline can use this as an 14 * opportunity to initialize any state needed by the ldisc routines. 15 * 16 * void (*close)(struct tty_struct *); 17 * 18 * This function is called when the line discipline is being 19 * shutdown, either because the tty is being closed or because 20 * the tty is being changed to use a new line discipline 21 * 22 * void (*flush_buffer)(struct tty_struct *tty); 23 * 24 * This function instructs the line discipline to clear its 25 * buffers of any input characters it may have queued to be 26 * delivered to the user mode process. 27 * 28 * ssize_t (*chars_in_buffer)(struct tty_struct *tty); 29 * 30 * This function returns the number of input characters the line 31 * discipline may have queued up to be delivered to the user mode 32 * process. 33 * 34 * ssize_t (*read)(struct tty_struct * tty, struct file * file, 35 * unsigned char * buf, size_t nr); 36 * 37 * This function is called when the user requests to read from 38 * the tty. The line discipline will return whatever characters 39 * it has buffered up for the user. If this function is not 40 * defined, the user will receive an EIO error. 41 * 42 * ssize_t (*write)(struct tty_struct * tty, struct file * file, 43 * const unsigned char * buf, size_t nr); 44 * 45 * This function is called when the user requests to write to the 46 * tty. The line discipline will deliver the characters to the 47 * low-level tty device for transmission, optionally performing 48 * some processing on the characters first. If this function is 49 * not defined, the user will receive an EIO error. 50 * 51 * int (*ioctl)(struct tty_struct * tty, struct file * file, 52 * unsigned int cmd, unsigned long arg); 53 * 54 * This function is called when the user requests an ioctl which 55 * is not handled by the tty layer or the low-level tty driver. 56 * It is intended for ioctls which affect line discpline 57 * operation. Note that the search order for ioctls is (1) tty 58 * layer, (2) tty low-level driver, (3) line discpline. So a 59 * low-level driver can "grab" an ioctl request before the line 60 * discpline has a chance to see it. 61 * 62 * long (*compat_ioctl)(struct tty_struct * tty, struct file * file, 63 * unsigned int cmd, unsigned long arg); 64 * 65 * Process ioctl calls from 32-bit process on 64-bit system 66 * 67 * void (*set_termios)(struct tty_struct *tty, struct ktermios * old); 68 * 69 * This function notifies the line discpline that a change has 70 * been made to the termios structure. 71 * 72 * int (*poll)(struct tty_struct * tty, struct file * file, 73 * poll_table *wait); 74 * 75 * This function is called when a user attempts to select/poll on a 76 * tty device. It is solely the responsibility of the line 77 * discipline to handle poll requests. 78 * 79 * void (*receive_buf)(struct tty_struct *, const unsigned char *cp, 80 * char *fp, int count); 81 * 82 * This function is called by the low-level tty driver to send 83 * characters received by the hardware to the line discpline for 84 * processing. <cp> is a pointer to the buffer of input 85 * character received by the device. <fp> is a pointer to a 86 * pointer of flag bytes which indicate whether a character was 87 * received with a parity error, etc. 88 * 89 * void (*write_wakeup)(struct tty_struct *); 90 * 91 * This function is called by the low-level tty driver to signal 92 * that line discpline should try to send more characters to the 93 * low-level driver for transmission. If the line discpline does 94 * not have any more data to send, it can just return. 95 * 96 * int (*hangup)(struct tty_struct *) 97 * 98 * Called on a hangup. Tells the discipline that it should 99 * cease I/O to the tty driver. Can sleep. The driver should 100 * seek to perform this action quickly but should wait until 101 * any pending driver I/O is completed. 102 * 103 * void (*fasync)(struct tty_struct *, int on) 104 * 105 * Notify line discipline when signal-driven I/O is enabled or 106 * disabled. 107 * 108 * void (*dcd_change)(struct tty_struct *tty, unsigned int status) 109 * 110 * Tells the discipline that the DCD pin has changed its status. 111 * Used exclusively by the N_PPS (Pulse-Per-Second) line discipline. 112 */ 113 114 #include <linux/fs.h> 115 #include <linux/wait.h> 116 #include <linux/wait.h> 117 118 119 /* 120 * the semaphore definition 121 */ 122 struct ld_semaphore { 123 long count; 124 raw_spinlock_t wait_lock; 125 unsigned int wait_readers; 126 struct list_head read_wait; 127 struct list_head write_wait; 128 #ifdef CONFIG_DEBUG_LOCK_ALLOC 129 struct lockdep_map dep_map; 130 #endif 131 }; 132 133 extern void __init_ldsem(struct ld_semaphore *sem, const char *name, 134 struct lock_class_key *key); 135 136 #define init_ldsem(sem) \ 137 do { \ 138 static struct lock_class_key __key; \ 139 \ 140 __init_ldsem((sem), #sem, &__key); \ 141 } while (0) 142 143 144 extern int ldsem_down_read(struct ld_semaphore *sem, long timeout); 145 extern int ldsem_down_read_trylock(struct ld_semaphore *sem); 146 extern int ldsem_down_write(struct ld_semaphore *sem, long timeout); 147 extern int ldsem_down_write_trylock(struct ld_semaphore *sem); 148 extern void ldsem_up_read(struct ld_semaphore *sem); 149 extern void ldsem_up_write(struct ld_semaphore *sem); 150 151 #ifdef CONFIG_DEBUG_LOCK_ALLOC 152 extern int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass, 153 long timeout); 154 extern int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass, 155 long timeout); 156 #else 157 # define ldsem_down_read_nested(sem, subclass, timeout) \ 158 ldsem_down_read(sem, timeout) 159 # define ldsem_down_write_nested(sem, subclass, timeout) \ 160 ldsem_down_write(sem, timeout) 161 #endif 162 163 164 struct tty_ldisc_ops { 165 int magic; 166 char *name; 167 int num; 168 int flags; 169 170 /* 171 * The following routines are called from above. 172 */ 173 int (*open)(struct tty_struct *); 174 void (*close)(struct tty_struct *); 175 void (*flush_buffer)(struct tty_struct *tty); 176 ssize_t (*chars_in_buffer)(struct tty_struct *tty); 177 ssize_t (*read)(struct tty_struct *tty, struct file *file, 178 unsigned char __user *buf, size_t nr); 179 ssize_t (*write)(struct tty_struct *tty, struct file *file, 180 const unsigned char *buf, size_t nr); 181 int (*ioctl)(struct tty_struct *tty, struct file *file, 182 unsigned int cmd, unsigned long arg); 183 long (*compat_ioctl)(struct tty_struct *tty, struct file *file, 184 unsigned int cmd, unsigned long arg); 185 void (*set_termios)(struct tty_struct *tty, struct ktermios *old); 186 unsigned int (*poll)(struct tty_struct *, struct file *, 187 struct poll_table_struct *); 188 int (*hangup)(struct tty_struct *tty); 189 190 /* 191 * The following routines are called from below. 192 */ 193 void (*receive_buf)(struct tty_struct *, const unsigned char *cp, 194 char *fp, int count); 195 void (*write_wakeup)(struct tty_struct *); 196 void (*dcd_change)(struct tty_struct *, unsigned int); 197 void (*fasync)(struct tty_struct *tty, int on); 198 199 struct module *owner; 200 201 int refcount; 202 }; 203 204 struct tty_ldisc { 205 struct tty_ldisc_ops *ops; 206 atomic_t users; 207 wait_queue_head_t wq_idle; 208 }; 209 210 #define TTY_LDISC_MAGIC 0x5403 211 212 #define LDISC_FLAG_DEFINED 0x00000001 213 214 #define MODULE_ALIAS_LDISC(ldisc) \ 215 MODULE_ALIAS("tty-ldisc-" __stringify(ldisc)) 216 217 #endif /* _LINUX_TTY_LDISC_H */ 218