n_hdlc.c

powerpc内核mpc8241linux系统下char驱动程序

/* generic HDLC line discipline for Linux
 *
 * Written by Paul Fulghum [e-mail]
 * for Microgate Corporation
 *
 * Microgate and SyncLink are registered trademarks of Microgate Corporation
 *
 * Adapted from ppp.c, written by Michael Callahan <[e-mail]>,
 *	Al Longyear <[e-mail]>, Paul Mackerras <[e-mail]>
 *
 * Original release 01/11/99
 *
 * This code is released under the GNU General Public License (GPL)
 *
 * This module implements the tty line discipline N_HDLC for use with
 * tty device drivers that support bit-synchronous HDLC communications.
 *
 * All HDLC data is frame oriented which means:
 *
 * 1. tty write calls represent one complete transmit frame of data
 *    The device driver should accept the complete frame or none of 
 *    the frame (busy) in the write method. Each write call should have
 *    a byte count in the range of 2-4096 bytes (2 is min HDLC frame
 *    with 1 addr byte and 1 ctrl byte).
 *
 * 2. receive callbacks from the device driver represents
 *    one received frame. The device driver should bypass
 *    the tty flip buffer and call the line discipline receive
 *    callback directly to avoid fragmenting or concatenating
 *    multiple frames into a single receive callback.
 *
 *    The HDLC line discipline queues the receive frames in seperate
 *    buffers so complete receive frames can be returned by the
 *    tty read calls.
 *
 * 3. tty read calls returns an entire frame of data or nothing.
 *    
 * 4. all send and receive data is considered raw. No processing
 *    or translation is performed by the line discipline, regardless
 *    of the tty flags
 *
 * 5. When line discipline is queried for the amount of receive
 *    data available (FIOC), 0 is returned if no data available,
 *    otherwise the count of the next available frame is returned.
 *    (instead of the sum of all received frame counts).
 *
 * These conventions allow the standard tty programming interface
 * to be used for synchronous HDLC applications when used with
 * this line discipline (or another line discipline that is frame
 * oriented such as N_PPP).
 *
 * The SyncLink driver (synclink.c) implements both asynchronous
 * (using standard line discipline N_TTY) and synchronous HDLC
 * (using N_HDLC) communications, with the latter using the above
 * conventions.
 *
 * This implementation is very basic and does not maintain
 * any statistics. The main point is to enforce the raw data
 * and frame orientation of HDLC communications.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#define HDLC_MAGIC 0x239e
#define HDLC_VERSION "1.0"

#include <linux/version.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>

#undef VERSION
#define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))

#if LINUX_VERSION_CODE < VERSION(2,1,14)
#include <linux/ioport.h>
#endif

#if LINUX_VERSION_CODE >= VERSION(2,1,23)
#include <linux/poll.h>
#endif

#include <linux/in.h>
#include <linux/malloc.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/sched.h>	/* to get the struct task_struct */
#include <linux/string.h>	/* used in new tty drivers */
#include <linux/signal.h>	/* used in new tty drivers */
#include <asm/system.h>
#include <asm/bitops.h>
#include <asm/termios.h>
#include <linux/if.h>

#include <linux/ioctl.h>

#ifdef CONFIG_KERNELD
#include <linux/kerneld.h>
#endif

#if LINUX_VERSION_CODE >= VERSION(2,1,4)
#include <asm/segment.h>
#define GET_USER(error,value,addr) error = get_user(value,addr)
#define COPY_FROM_USER(error,dest,src,size) error = copy_from_user(dest,src,size) ? -EFAULT : 0
#define PUT_USER(error,value,addr) error = put_user(value,addr)
#define COPY_TO_USER(error,dest,src,size) error = copy_to_user(dest,src,size) ? -EFAULT : 0

#if LINUX_VERSION_CODE >= VERSION(2,1,5)
#include <asm/uaccess.h>
#endif

#else  /* 2.0.x and 2.1.x before 2.1.4 */

#define GET_USER(error,value,addr)					  \
do {									  \
	error = verify_area (VERIFY_READ, (void *) addr, sizeof (value)); \
	if (error == 0)							  \
		value = get_user(addr);					  \
} while (0)

#define COPY_FROM_USER(error,dest,src,size)				  \
do {									  \
	error = verify_area (VERIFY_READ, (void *) src, size);		  \
	if (error == 0)							  \
		memcpy_fromfs (dest, src, size);			  \
} while (0)

#define PUT_USER(error,value,addr)					   \
do {									   \
	error = verify_area (VERIFY_WRITE, (void *) addr, sizeof (value)); \
	if (error == 0)							   \
		put_user (value, addr);					   \
} while (0)

#define COPY_TO_USER(error,dest,src,size)				  \
do {									  \
	error = verify_area (VERIFY_WRITE, (void *) dest, size);		  \
	if (error == 0)							  \
		memcpy_tofs (dest, src, size);				  \
} while (0)

#endif

#if LINUX_VERSION_CODE < VERSION(2,1,0)
#define __init
typedef int spinlock_t;
#define spin_lock_irqsave(a,b) {save_flags((b));cli();}
#define spin_unlock_irqrestore(a,b) {restore_flags((b));}
#define spin_lock(a)
#define spin_unlock(a)
#define schedule_timeout(a){current->timeout = jiffies + (a); schedule();}
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,37)
#define test_and_set_bit(nr, addr)	set_bit(nr, addr)
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,57)
#define signal_pending(p)	((p)->signal & ~(p)->blocked)
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,25)
#define net_device_stats	enet_statistics
#endif

#if LINUX_VERSION_CODE < VERSION(2,1,60)
typedef int		rw_ret_t;
typedef unsigned int	rw_count_t;
#else
typedef ssize_t		rw_ret_t;
typedef size_t		rw_count_t;
#endif

/*
 * Buffers for individual HDLC frames
 */
#define MAX_HDLC_FRAME_SIZE 4096
#define DEFAULT_RX_BUF_COUNT 10
#define MAX_RX_BUF_COUNT 30
#define DEFAULT_TX_BUF_COUNT 1

typedef struct _n_hdlc_buf
{
	struct _n_hdlc_buf *link;
	int count;
	char buf[MAX_HDLC_FRAME_SIZE];
} N_HDLC_BUF;

typedef struct _n_hdlc_buf_list
{
	N_HDLC_BUF *head;
	N_HDLC_BUF *tail;
	int count;
	spinlock_t spinlock;
	
} N_HDLC_BUF_LIST;

/*
 * Per device instance data structure
 */
struct n_hdlc {
	int		magic;		/* magic value for structure	*/
	__u32		flags;		/* miscellaneous control flags	*/
	
	struct tty_struct *tty;		/* ptr to TTY structure	*/
	struct tty_struct *backup_tty;	/* TTY to use if tty gets closed */
	
	/* Queues for select() functionality */
	struct wait_queue *read_wait;
	struct wait_queue *write_wait;

	int		tbusy;		/* reentrancy flag for tx wakeup code */
	int		woke_up;
	N_HDLC_BUF	*tbuf;		/* currently transmitting tx buffer */
	N_HDLC_BUF_LIST tx_buf_list;	/* list of pending transmit frame buffers */	
	N_HDLC_BUF_LIST	rx_buf_list;	/* list of received frame buffers */
	N_HDLC_BUF_LIST tx_free_buf_list;	/* list unused transmit frame buffers */	
	N_HDLC_BUF_LIST	rx_free_buf_list;	/* list unused received frame buffers */
};

/*
 * HDLC buffer list manipulation functions
 */
void n_hdlc_buf_list_init(N_HDLC_BUF_LIST *list);
void n_hdlc_buf_put(N_HDLC_BUF_LIST *list,N_HDLC_BUF *buf);
N_HDLC_BUF* n_hdlc_buf_get(N_HDLC_BUF_LIST *list);

/* Local functions */

static struct n_hdlc *n_hdlc_alloc (void);

#if LINUX_VERSION_CODE >= VERSION(2,1,19) 
MODULE_PARM(debuglevel, "i");
#endif

/* debug level can be set by insmod for debugging purposes */
#define DEBUG_LEVEL_INFO	1
int debuglevel=0;

/* TTY callbacks */

static rw_ret_t n_hdlc_tty_read(struct tty_struct *,
	struct file *, __u8 *, rw_count_t);
static rw_ret_t n_hdlc_tty_write(struct tty_struct *,
	struct file *, const __u8 *, rw_count_t);
static int n_hdlc_tty_ioctl(struct tty_struct *,
	struct file *, unsigned int, unsigned long);
#if LINUX_VERSION_CODE < VERSION(2,1,23)
static int n_hdlc_tty_select (struct tty_struct *tty, struct inode *inode,
		      struct file *filp, int sel_type, select_table * wait);
#else
static unsigned int n_hdlc_tty_poll (struct tty_struct *tty, struct file *filp,
				  poll_table * wait);
#endif
static int n_hdlc_tty_open (struct tty_struct *);
static void n_hdlc_tty_close (struct tty_struct *);
static int n_hdlc_tty_room (struct tty_struct *tty);
static void n_hdlc_tty_receive (struct tty_struct *tty,
	const __u8 * cp, char *fp, int count);
static void n_hdlc_tty_wakeup (struct tty_struct *tty);

#define bset(p,b)	((p)[(b) >> 5] |= (1 << ((b) & 0x1f)))

#define tty2n_hdlc(tty)	((struct n_hdlc *) ((tty)->disc_data))
#define n_hdlc2tty(n_hdlc)	((n_hdlc)->tty)

/* Define this string only once for all macro invocations */
static char szVersion[] = HDLC_VERSION;

/* n_hdlc_release()
 *
 *	release an n_hdlc per device line discipline info structure
 *
 */
static void n_hdlc_release (struct n_hdlc *n_hdlc)
{
	struct tty_struct *tty = n_hdlc2tty (n_hdlc);
	N_HDLC_BUF *buf;
	
	if (debuglevel >= DEBUG_LEVEL_INFO)	
		printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__);
		
	/* Ensure that the n_hdlcd process is not hanging on select()/poll() */
	wake_up_interruptible (&n_hdlc->read_wait);
	wake_up_interruptible (&n_hdlc->write_wait);

	if (tty != NULL && tty->disc_data == n_hdlc)
		tty->disc_data = NULL;	/* Break the tty->n_hdlc link */

	/* Release transmit and receive buffers */
	for(;;) {
		buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
		if (buf) {
			kfree(buf);
		} else
			break;
	}
	for(;;) {
		buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
		if (buf) {
			kfree(buf);
		} else
			break;
	}
	for(;;) {
		buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
		if (buf) {
			kfree(buf);
		} else
			break;
	}
	for(;;) {
		buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
		if (buf) {
			kfree(buf);
		} else
			break;
	}
	
	kfree(n_hdlc);
	
}	/* end of n_hdlc_release() */

/* n_hdlc_tty_close()
 *
 *	Called when the line discipline is changed to something
 *	else, the tty is closed, or the tty detects a hangup.
 */
static void n_hdlc_tty_close(struct tty_struct *tty)
{
	struct n_hdlc *n_hdlc = tty2n_hdlc (tty);

	if (debuglevel >= DEBUG_LEVEL_INFO)	
		printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__);
		
	if (n_hdlc != NULL) {
		if (n_hdlc->magic != HDLC_MAGIC) {
			printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n");
			return;
		}
		tty->disc_data = NULL;
		if (tty == n_hdlc->backup_tty)
			n_hdlc->backup_tty = 0;
		if (tty != n_hdlc->tty)
			return;
		if (n_hdlc->backup_tty) {
			n_hdlc->tty = n_hdlc->backup_tty;
		} else {
			n_hdlc_release (n_hdlc);
			MOD_DEC_USE_COUNT;
		}
	}
	
	if (debuglevel >= DEBUG_LEVEL_INFO)	
		printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__);
		
}	/* end of n_hdlc_tty_close() */

/* n_hdlc_tty_open
 * 
 * 	called when line discipline changed to n_hdlc
 * 	
 * Arguments:	tty	pointer to tty info structure
 * Return Value:	0 if success, otherwise error code
 */
static int n_hdlc_tty_open (struct tty_struct *tty)
{
	struct n_hdlc *n_hdlc = tty2n_hdlc (tty);