include/linux/lp.h

Source file repositories/reference/linux-study-clean/include/linux/lp.h

File Facts

System
Linux kernel
Corpus path
include/linux/lp.h
Extension
.h
Size
2827 bytes
Lines
102
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct lp_stats {
	unsigned long chars;
	unsigned long sleeps;
	unsigned int maxrun;
	unsigned int maxwait;
	unsigned int meanwait;
	unsigned int mdev;
};
#endif

struct lp_struct {
	struct pardevice *dev;
	unsigned long flags;
	unsigned int chars;
	unsigned int time;
	unsigned int wait;
	char *lp_buffer;
#ifdef LP_STATS
	unsigned int lastcall;
	unsigned int runchars;
	struct lp_stats stats;
#endif
	wait_queue_head_t waitq;
	unsigned int last_error;
	struct mutex port_mutex;
	wait_queue_head_t dataq;
	long timeout;
	unsigned int best_mode;
	unsigned int current_mode;
	unsigned long bits;
};

/*
 * The following constants describe the various signals of the printer port
 * hardware.  Note that the hardware inverts some signals and that some
 * signals are active low.  An example is LP_STROBE, which must be programmed
 * with 1 for being active and 0 for being inactive, because the strobe signal
 * gets inverted, but it is also active low.
 */


/* 
 * defines for 8255 control port
 * base + 2 
 * accessed with LP_C(minor)
 */
#define LP_PINTEN	0x10  /* high to read data in or-ed with data out */
#define LP_PSELECP	0x08  /* inverted output, active low */
#define LP_PINITP	0x04  /* unchanged output, active low */
#define LP_PAUTOLF	0x02  /* inverted output, active low */
#define LP_PSTROBE	0x01  /* short high output on raising edge */

/* 
 * the value written to ports to test existence. PC-style ports will 
 * return the value written. AT-style ports will return 0. so why not
 * make them the same ? 
 */
#define LP_DUMMY	0x00

/*
 * This is the port delay time, in microseconds.
 * It is used only in the lp_init() and lp_reset() routine.
 */
#define LP_DELAY 	50

#endif

Annotation

Implementation Notes