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 (*read)(struct tty_struct * tty, struct file * file, 29 * unsigned char * buf, size_t nr); 30 * 31 * This function is called when the user requests to read from 32 * the tty. The line discipline will return whatever characters 33 * it has buffered up for the user. If this function is not 34 * defined, the user will receive an EIO error. 35 * 36 * ssize_t (*write)(struct tty_struct * tty, struct file * file, 37 * const unsigned char * buf, size_t nr); 38 * 39 * This function is called when the user requests to write to the 40 * tty. The line discipline will deliver the characters to the 41 * low-level tty device for transmission, optionally performing 42 * some processing on the characters first. If this function is 43 * not defined, the user will receive an EIO error. 44 * 45 * int (*ioctl)(struct tty_struct * tty, struct file * file, 46 * unsigned int cmd, unsigned long arg); 47 * 48 * This function is called when the user requests an ioctl which 49 * is not handled by the tty layer or the low-level tty driver. 50 * It is intended for ioctls which affect line discpline 51 * operation. Note that the search order for ioctls is (1) tty 52 * layer, (2) tty low-level driver, (3) line discpline. So a 53 * low-level driver can "grab" an ioctl request before the line 54 * discpline has a chance to see it. 55 * 56 * long (*compat_ioctl)(struct tty_struct * tty, struct file * file, 57 * unsigned int cmd, unsigned long arg); 58 * 59 * Process ioctl calls from 32-bit process on 64-bit system 60 * 61 * void (*set_termios)(struct tty_struct *tty, struct ktermios * old); 62 * 63 * This function notifies the line discpline that a change has 64 * been made to the termios structure. 65 * 66 * int (*poll)(struct tty_struct * tty, struct file * file, 67 * poll_table *wait); 68 * 69 * This function is called when a user attempts to select/poll on a 70 * tty device. It is solely the responsibility of the line 71 * discipline to handle poll requests. 72 * 73 * void (*receive_buf)(struct tty_struct *, const unsigned char *cp, 74 * char *fp, int count); 75 * 76 * This function is called by the low-level tty driver to send 77 * characters received by the hardware to the line discpline for 78 * processing. <cp> is a pointer to the buffer of input 79 * character received by the device. <fp> is a pointer to a 80 * pointer of flag bytes which indicate whether a character was 81 * received with a parity error, etc. <fp> may be NULL to indicate 82 * all data received is TTY_NORMAL. 83 * 84 * void (*write_wakeup)(struct tty_struct *); 85 * 86 * This function is called by the low-level tty driver to signal 87 * that line discpline should try to send more characters to the 88 * low-level driver for transmission. If the line discpline does 89 * not have any more data to send, it can just return. If the line 90 * discipline does have some data to send, please arise a tasklet 91 * or workqueue to do the real data transfer. Do not send data in 92 * this hook, it may leads to a deadlock. 93 * 94 * int (*hangup)(struct tty_struct *) 95 * 96 * Called on a hangup. Tells the discipline that it should 97 * cease I/O to the tty driver. Can sleep. The driver should 98 * seek to perform this action quickly but should wait until 99 * any pending driver I/O is completed. 100 * 101 * void (*dcd_change)(struct tty_struct *tty, unsigned int status) 102 * 103 * Tells the discipline that the DCD pin has changed its status. 104 * Used exclusively by the N_PPS (Pulse-Per-Second) line discipline. 105 * 106 * int (*receive_buf2)(struct tty_struct *, const unsigned char *cp, 107 * char *fp, int count); 108 * 109 * This function is called by the low-level tty driver to send 110 * characters received by the hardware to the line discpline for 111 * processing. <cp> is a pointer to the buffer of input 112 * character received by the device. <fp> is a pointer to a 113 * pointer of flag bytes which indicate whether a character was 114 * received with a parity error, etc. <fp> may be NULL to indicate 115 * all data received is TTY_NORMAL. 116 * If assigned, prefer this function for automatic flow control. 117 */ 118 119 #include <linux/fs.h> 120 #include <linux/wait.h> 121 122 123 /* 124 * the semaphore definition 125 */ 126 struct ld_semaphore { 127 long count; 128 raw_spinlock_t wait_lock; 129 unsigned int wait_readers; 130 struct list_head read_wait; 131 struct list_head write_wait; 132 #ifdef CONFIG_DEBUG_LOCK_ALLOC 133 struct lockdep_map dep_map; 134 #endif 135 }; 136 137 extern void __init_ldsem(struct ld_semaphore *sem, const char *name, 138 struct lock_class_key *key); 139 140 #define init_ldsem(sem) \ 141 do { \ 142 static struct lock_class_key __key; \ 143 \ 144 __init_ldsem((sem), #sem, &__key); \ 145 } while (0) 146 147 148 extern int ldsem_down_read(struct ld_semaphore *sem, long timeout); 149 extern int ldsem_down_read_trylock(struct ld_semaphore *sem); 150 extern int ldsem_down_write(struct ld_semaphore *sem, long timeout); 151 extern int ldsem_down_write_trylock(struct ld_semaphore *sem); 152 extern void ldsem_up_read(struct ld_semaphore *sem); 153 extern void ldsem_up_write(struct ld_semaphore *sem); 154 155 #ifdef CONFIG_DEBUG_LOCK_ALLOC 156 extern int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass, 157 long timeout); 158 extern int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass, 159 long timeout); 160 #else 161 # define ldsem_down_read_nested(sem, subclass, timeout) \ 162 ldsem_down_read(sem, timeout) 163 # define ldsem_down_write_nested(sem, subclass, timeout) \ 164 ldsem_down_write(sem, timeout) 165 #endif 166 167 168 struct tty_ldisc_ops { 169 int magic; 170 char *name; 171 int num; 172 int flags; 173 174 /* 175 * The following routines are called from above. 176 */ 177 int (*open)(struct tty_struct *); 178 void (*close)(struct tty_struct *); 179 void (*flush_buffer)(struct tty_struct *tty); 180 ssize_t (*read)(struct tty_struct *tty, struct file *file, 181 unsigned char __user *buf, size_t nr); 182 ssize_t (*write)(struct tty_struct *tty, struct file *file, 183 const unsigned char *buf, size_t nr); 184 int (*ioctl)(struct tty_struct *tty, struct file *file, 185 unsigned int cmd, unsigned long arg); 186 long (*compat_ioctl)(struct tty_struct *tty, struct file *file, 187 unsigned int cmd, unsigned long arg); 188 void (*set_termios)(struct tty_struct *tty, struct ktermios *old); 189 unsigned int (*poll)(struct tty_struct *, struct file *, 190 struct poll_table_struct *); 191 int (*hangup)(struct tty_struct *tty); 192 193 /* 194 * The following routines are called from below. 195 */ 196 void (*receive_buf)(struct tty_struct *, const unsigned char *cp, 197 char *fp, int count); 198 void (*write_wakeup)(struct tty_struct *); 199 void (*dcd_change)(struct tty_struct *, unsigned int); 200 int (*receive_buf2)(struct tty_struct *, const unsigned char *cp, 201 char *fp, int count); 202 203 struct module *owner; 204 205 int refcount; 206 }; 207 208 struct tty_ldisc { 209 struct tty_ldisc_ops *ops; 210 struct tty_struct *tty; 211 }; 212 213 #define TTY_LDISC_MAGIC 0x5403 214 215 #define LDISC_FLAG_DEFINED 0x00000001 216 217 #define MODULE_ALIAS_LDISC(ldisc) \ 218 MODULE_ALIAS("tty-ldisc-" __stringify(ldisc)) 219 220 #endif /* _LINUX_TTY_LDISC_H */ 221