[PATCH] allow i8042 interrupt sharing

Ed Tomlinson has a machine on which some other device grabs IRQ12 first, and
the 8042 doesn't work.  Enabling shared iRQs in the 8042 driver fixes it up.
Alan has confirmed that this is OK.

drivers/input/serio/i8042.c

@@ -62,6 +62,12 @@ static unsigned char i8042_last_e0;
 static unsigned char i8042_mux_open;
 struct timer_list i8042_timer;
 
+/*
+ * Shared IRQ's require a device pointer, but this driver doesn't support
+ * multiple devices
+ */
+#define i8042_request_irq_cookie (&i8042_timer)
+
 static unsigned long i8042_unxlate_seen[256 / BITS_PER_LONG];
 static unsigned char i8042_unxlate_table[128] = {
 	  0,118, 22, 30, 38, 37, 46, 54, 61, 62, 70, 69, 78, 85,102, 13,
@@ -235,7 +241,8 @@ static int i8042_open(struct serio *port)
 		if (i8042_mux_open++)
 			return 0;
 
-	if (request_irq(values->irq, i8042_interrupt, 0, "i8042", NULL)) {
+	if (request_irq(values->irq, i8042_interrupt,
+			SA_SHIRQ, "i8042", i8042_request_irq_cookie)) {
 		printk(KERN_ERR "i8042.c: Can't get irq %d for %s, unregistering the port.\n", values->irq, values->name);
 		values->exists = 0;
 		serio_unregister_port(port);
@@ -275,7 +282,7 @@ static void i8042_close(struct serio *port)
 		return;
 	}
 
-	free_irq(values->irq, NULL);
+	free_irq(values->irq, i8042_request_irq_cookie);
 
 	i8042_flush();
 }
@@ -572,9 +579,10 @@ static int __init i8042_check_mux(struct i8042_values *values)
  * Check if AUX irq is available.
  */
 
-	if (request_irq(values->irq, i8042_interrupt, 0, "i8042", NULL))
+	if (request_irq(values->irq, i8042_interrupt, SA_SHIRQ,
+				"i8042", i8042_request_irq_cookie))
                 return -1;
-	free_irq(values->irq, NULL);
+	free_irq(values->irq, i8042_request_irq_cookie);
 
 /*
  * Get rid of bytes in the queue.
@@ -643,9 +651,10 @@ static int __init i8042_check_aux(struct i8042_values *values)
  * in trying to detect AUX presence.
  */
 
-	if (request_irq(values->irq, i8042_interrupt, 0, "i8042", NULL))
+	if (request_irq(values->irq, i8042_interrupt, SA_SHIRQ,
+				"i8042", i8042_request_irq_cookie))
                 return -1;
-	free_irq(values->irq, NULL);
+	free_irq(values->irq, i8042_request_irq_cookie);
 
 /*
  * Get rid of bytes in the queue.