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. <fp> may be NULL to indicate 88 * all data received is TTY_NORMAL. 89 * 90 * void (*write_wakeup)(struct tty_struct *); 91 * 92 * This function is called by the low-level tty driver to signal 93 * that line discpline should try to send more characters to the 94 * low-level driver for transmission. If the line discpline does 95 * not have any more data to send, it can just return. If the line 96 * discipline does have some data to send, please arise a tasklet 97 * or workqueue to do the real data transfer. Do not send data in 98 * this hook, it may leads to a deadlock. 99 * 100 * int (*hangup)(struct tty_struct *) 101 * 102 * Called on a hangup. Tells the discipline that it should 103 * cease I/O to the tty driver. Can sleep. The driver should 104 * seek to perform this action quickly but should wait until 105 * any pending driver I/O is completed. 106 * 107 * void (*fasync)(struct tty_struct *, int on) 108 * 109 * Notify line discipline when signal-driven I/O is enabled or 110 * disabled. 111 * 112 * void (*dcd_change)(struct tty_struct *tty, unsigned int status) 113 * 114 * Tells the discipline that the DCD pin has changed its status. 115 * Used exclusively by the N_PPS (Pulse-Per-Second) line discipline. 116 * 117 * int (*receive_buf2)(struct tty_struct *, const unsigned char *cp, 118 * char *fp, int count); 119 * 120 * This function is called by the low-level tty driver to send 121 * characters received by the hardware to the line discpline for 122 * processing. <cp> is a pointer to the buffer of input 123 * character received by the device. <fp> is a pointer to a 124 * pointer of flag bytes which indicate whether a character was 125 * received with a parity error, etc. <fp> may be NULL to indicate 126 * all data received is TTY_NORMAL. 127 * If assigned, prefer this function for automatic flow control. 128 */ 129 130 #include <linux/fs.h> 131 #include <linux/wait.h> 132 133 134 /* 135 * the semaphore definition 136 */ 137 struct ld_semaphore { 138 long count; 139 raw_spinlock_t wait_lock; 140 unsigned int wait_readers; 141 struct list_head read_wait; 142 struct list_head write_wait; 143 #ifdef CONFIG_DEBUG_LOCK_ALLOC 144 struct lockdep_map dep_map; 145 #endif 146 }; 147 148 extern void __init_ldsem(struct ld_semaphore *sem, const char *name, 149 struct lock_class_key *key); 150 151 #define init_ldsem(sem) \ 152 do { \ 153 static struct lock_class_key __key; \ 154 \ 155 __init_ldsem((sem), #sem, &__key); \ 156 } while (0) 157 158 159 extern int ldsem_down_read(struct ld_semaphore *sem, long timeout); 160 extern int ldsem_down_read_trylock(struct ld_semaphore *sem); 161 extern int ldsem_down_write(struct ld_semaphore *sem, long timeout); 162 extern int ldsem_down_write_trylock(struct ld_semaphore *sem); 163 extern void ldsem_up_read(struct ld_semaphore *sem); 164 extern void ldsem_up_write(struct ld_semaphore *sem); 165 166 #ifdef CONFIG_DEBUG_LOCK_ALLOC 167 extern int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass, 168 long timeout); 169 extern int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass, 170 long timeout); 171 #else 172 # define ldsem_down_read_nested(sem, subclass, timeout) \ 173 ldsem_down_read(sem, timeout) 174 # define ldsem_down_write_nested(sem, subclass, timeout) \ 175 ldsem_down_write(sem, timeout) 176 #endif 177 178 179 struct tty_ldisc_ops { 180 int magic; 181 char *name; 182 int num; 183 int flags; 184 185 /* 186 * The following routines are called from above. 187 */ 188 int (*open)(struct tty_struct *); 189 void (*close)(struct tty_struct *); 190 void (*flush_buffer)(struct tty_struct *tty); 191 ssize_t (*chars_in_buffer)(struct tty_struct *tty); 192 ssize_t (*read)(struct tty_struct *tty, struct file *file, 193 unsigned char __user *buf, size_t nr); 194 ssize_t (*write)(struct tty_struct *tty, struct file *file, 195 const unsigned char *buf, size_t nr); 196 int (*ioctl)(struct tty_struct *tty, struct file *file, 197 unsigned int cmd, unsigned long arg); 198 long (*compat_ioctl)(struct tty_struct *tty, struct file *file, 199 unsigned int cmd, unsigned long arg); 200 void (*set_termios)(struct tty_struct *tty, struct ktermios *old); 201 unsigned int (*poll)(struct tty_struct *, struct file *, 202 struct poll_table_struct *); 203 int (*hangup)(struct tty_struct *tty); 204 205 /* 206 * The following routines are called from below. 207 */ 208 void (*receive_buf)(struct tty_struct *, const unsigned char *cp, 209 char *fp, int count); 210 void (*write_wakeup)(struct tty_struct *); 211 void (*dcd_change)(struct tty_struct *, unsigned int); 212 void (*fasync)(struct tty_struct *tty, int on); 213 int (*receive_buf2)(struct tty_struct *, const unsigned char *cp, 214 char *fp, int count); 215 216 struct module *owner; 217 218 int refcount; 219 }; 220 221 struct tty_ldisc { 222 struct tty_ldisc_ops *ops; 223 struct tty_struct *tty; 224 }; 225 226 #define TTY_LDISC_MAGIC 0x5403 227 228 #define LDISC_FLAG_DEFINED 0x00000001 229 230 #define MODULE_ALIAS_LDISC(ldisc) \ 231 MODULE_ALIAS("tty-ldisc-" __stringify(ldisc)) 232 233 #endif /* _LINUX_TTY_LDISC_H */ 234