drivers/char/riscom8: clean up irq handling

Make irq handling more efficient, by passing board pointer via
request_irq() to our irq handler's dev_id argument.

This eliminates a table lookup upon each interrupt, and eliminates an
associated global variable (the table).

Signed-off-by: Jeff Garzik <[e-mail]>

drivers/char/riscom8.c

···
 
 #define RS_EVENT_WRITE_WAKEUP	0
 
-static struct riscom_board * IRQ_to_board[16];
 static struct tty_driver *riscom_driver;
 
 static struct riscom_board rc_board[RC_NBOARD] =  {
···
 }
 
 /* The main interrupt processing routine */
-static irqreturn_t rc_interrupt(int irq, void * dev_id)
+static irqreturn_t rc_interrupt(int dummy, void * dev_id)
 {
 	unsigned char status;
 	unsigned char ack;
-	struct riscom_board *bp;
+	struct riscom_board *bp = dev_id;
 	unsigned long loop = 0;
 	int handled = 0;
-
-	bp = IRQ_to_board[irq];
 
 	if (!(bp->flags & RC_BOARD_ACTIVE))
 		return IRQ_NONE;
···
  */
 
 /* Called with disabled interrupts */
-static inline int rc_setup_board(struct riscom_board * bp)
+static int rc_setup_board(struct riscom_board * bp)
 {
 	int error;
 
···
 		return 0;
 	
 	error = request_irq(bp->irq, rc_interrupt, IRQF_DISABLED,
-			    "RISCom/8", NULL);
+			    "RISCom/8", bp);
 	if (error) 
 		return error;
 	
···
 	bp->DTR = ~0;
 	rc_out(bp, RC_DTR, bp->DTR);	        /* Drop DTR on all ports */
 	
-	IRQ_to_board[bp->irq] = bp;
 	bp->flags |= RC_BOARD_ACTIVE;
 	
 	return 0;
 }
 
 /* Called with disabled interrupts */
-static inline void rc_shutdown_board(struct riscom_board *bp)
+static void rc_shutdown_board(struct riscom_board *bp)
 {
 	if (!(bp->flags & RC_BOARD_ACTIVE))
 		return;
···
 	bp->flags &= ~RC_BOARD_ACTIVE;
 	
 	free_irq(bp->irq, NULL);
-	IRQ_to_board[bp->irq] = NULL;
 	
 	bp->DTR = ~0;
 	rc_out(bp, RC_DTR, bp->DTR);	       /* Drop DTR on all ports */
···
 	if (!riscom_driver)	
 		return -ENOMEM;
 	
-	memset(IRQ_to_board, 0, sizeof(IRQ_to_board));
 	riscom_driver->owner = THIS_MODULE;
 	riscom_driver->name = "ttyL";
 	riscom_driver->major = RISCOM8_NORMAL_MAJOR;