serial: mrst_max3110: Make the IRQ option runtime

And while we are at it allow it to fail to find one. Without this the IRQ
option will cause the 3110 driver to fail on 0.7 SFI firmware.

Acked-by: Feng Tang <[e-mail]>
Signed-off-by: Alan Cox <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/serial/Kconfig

···
 	  the Intel Moorestown platform. On other systems use the max3100
 	  driver.
 
-config MRST_MAX3110_IRQ
-	boolean "Enable GPIO IRQ for Max3110 over Moorestown"
-	default n
-	depends on SERIAL_MRST_MAX3110 && GPIO_LANGWELL
-	help
-	  This has to be enabled after Moorestown GPIO driver is loaded
-
 config SERIAL_MFD_HSU
 	tristate "Medfield High Speed UART support"
 	depends on PCI

drivers/serial/mrst_max3110.c

···
 	return ret;
 }
 
-#ifdef CONFIG_MRST_MAX3110_IRQ
 static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
 {
 	struct uart_max3110 *max = dev_id;
···
 
 	return IRQ_HANDLED;
 }
-#else
+
 /* if don't use RX IRQ, then need a thread to polling read */
 static int max3110_read_thread(void *_max)
 {
···
 
 	return 0;
 }
-#endif
 
 static int serial_m3110_startup(struct uart_port *port)
 {
···
 	/* as we use thread to handle tx/rx, need set low latency */
 	port->state->port.tty->low_latency = 1;
 
-#ifdef CONFIG_MRST_MAX3110_IRQ
-	ret = request_irq(max->irq, serial_m3110_irq,
-				IRQ_TYPE_EDGE_FALLING, "max3110", max);
-	if (ret)
-		return ret;
-
-	/* Enable RX IRQ only */
-	config |= WC_RXA_IRQ_ENABLE;
-#else
-	/* If IRQ is disabled, start a read thread for input data */
-	max->read_thread =
-		kthread_run(max3110_read_thread, max, "max3110_read");
-	if (IS_ERR(max->read_thread)) {
-		ret = PTR_ERR(max->read_thread);
+	if (max->irq) {
 		max->read_thread = NULL;
-		pr_err(PR_FMT "Can't create read thread!");
-		return ret;
+		ret = request_irq(max->irq, serial_m3110_irq,
+				IRQ_TYPE_EDGE_FALLING, "max3110", max);
+		if (ret) {
+			max->irq = 0;
+			pr_err(PR_FMT "unable to allocate IRQ, polling\n");
+		}  else {
+			/* Enable RX IRQ only */
+			config |= WC_RXA_IRQ_ENABLE;
+		}
 	}
-#endif
+
+	if (max->irq == 0) {
+		/* If IRQ is disabled, start a read thread for input data */
+		max->read_thread =
+			kthread_run(max3110_read_thread, max, "max3110_read");
+		if (IS_ERR(max->read_thread)) {
+			ret = PTR_ERR(max->read_thread);
+			max->read_thread = NULL;
+			pr_err(PR_FMT "Can't create read thread!\n");
+			return ret;
+		}
+	}
 
 	ret = max3110_out(max, config);
 	if (ret) {
-#ifdef CONFIG_MRST_MAX3110_IRQ
-		free_irq(max->irq, max);
-#else
-		kthread_stop(max->read_thread);
+		if (max->irq)
+			free_irq(max->irq, max);
+		if (max->read_thread)
+			kthread_stop(max->read_thread);
 		max->read_thread = NULL;
-#endif
 		return ret;
 	}
 
···
 		max->read_thread = NULL;
 	}
 
-#ifdef CONFIG_MRST_MAX3110_IRQ
-	free_irq(max->irq, max);
-#endif
+	if (max->irq)
+		free_irq(max->irq, max);
 
 	/* Disable interrupts from this port */
 	config = WC_TAG | WC_SW_SHDI;