powerpc: Remove all usages of NO_IRQ

NO_IRQ has been == 0 on powerpc for just over ten years (since commit
0ebfff1491 ("[POWERPC] Add new interrupt mapping core and change
platforms to use it")). It's also 0 on most other arches.

Although it's fairly harmless, every now and then it causes confusion
when a driver is built on powerpc and another arch which doesn't define
NO_IRQ. There's at least 6 definitions of NO_IRQ in drivers/, at least
some of which are to work around that problem.

So we'd like to remove it. This is fairly trivial in the arch code, we
just convert:

    if (irq == NO_IRQ)	to	if (!irq)
    if (irq != NO_IRQ)	to	if (irq)
    irq = NO_IRQ;	to	irq = 0;
    return NO_IRQ;	to	return 0;

And a few other odd cases as well.

At least for now we keep the #define NO_IRQ, because there is driver
code that uses NO_IRQ and the fixes to remove those will go via other
trees.

Note we also change some occurrences in PPC sound drivers, drivers/ps3,
and drivers/macintosh.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/macintosh/macio_asic.c

@@ -236,7 +236,7 @@ static void macio_create_fixup_irq(struct macio_dev *dev, int index,
 	unsigned int irq;
 
 	irq = irq_create_mapping(NULL, line);
-	if (irq != NO_IRQ) {
+	if (!irq) {
 		dev->interrupt[index].start = irq;
 		dev->interrupt[index].flags = IORESOURCE_IRQ;
 		dev->interrupt[index].name = dev_name(&dev->ofdev.dev);
@@ -299,7 +299,7 @@ static void macio_setup_interrupts(struct macio_dev *dev)
 			break;
 		res = &dev->interrupt[j];
 		irq = irq_of_parse_and_map(np, i++);
-		if (irq == NO_IRQ)
+		if (!irq)
 			break;
 		res->start = irq;
 		res->flags = IORESOURCE_IRQ;

drivers/macintosh/rack-meter.c

@@ -427,7 +427,7 @@ static int rackmeter_probe(struct macio_dev* mdev,
 	rm->irq = macio_irq(mdev, 1);
 #else
 	rm->irq = irq_of_parse_and_map(i2s, 1);
-	if (rm->irq == NO_IRQ ||
+	if (!rm->irq ||
 	    of_address_to_resource(i2s, 0, &ri2s) ||
 	    of_address_to_resource(i2s, 1, &rdma)) {
 		printk(KERN_ERR

drivers/macintosh/smu.c

@@ -279,7 +279,7 @@ int smu_queue_cmd(struct smu_cmd *cmd)
 	spin_unlock_irqrestore(&smu->lock, flags);
 
 	/* Workaround for early calls when irq isn't available */
-	if (!smu_irq_inited || smu->db_irq == NO_IRQ)
+	if (!smu_irq_inited || !smu->db_irq)
 		smu_spinwait_cmd(cmd);
 
 	return 0;
@@ -498,8 +498,8 @@ int __init smu_init (void)
 	INIT_LIST_HEAD(&smu->cmd_list);
 	INIT_LIST_HEAD(&smu->cmd_i2c_list);
 	smu->of_node = np;
-	smu->db_irq = NO_IRQ;
-	smu->msg_irq = NO_IRQ;
+	smu->db_irq = 0;
+	smu->msg_irq = 0;
 
 	/* smu_cmdbuf_abs is in the low 2G of RAM, can be converted to a
 	 * 32 bits value safely
@@ -587,13 +587,13 @@ static int smu_late_init(void)
 
 	if (smu->db_node) {
 		smu->db_irq = irq_of_parse_and_map(smu->db_node, 0);
-		if (smu->db_irq == NO_IRQ)
+		if (!smu->db_irq)
 			printk(KERN_ERR "smu: failed to map irq for node %s\n",
 			       smu->db_node->full_name);
 	}
 	if (smu->msg_node) {
 		smu->msg_irq = irq_of_parse_and_map(smu->msg_node, 0);
-		if (smu->msg_irq == NO_IRQ)
+		if (!smu->msg_irq)
 			printk(KERN_ERR "smu: failed to map irq for node %s\n",
 			       smu->msg_node->full_name);
 	}
@@ -602,23 +602,23 @@ static int smu_late_init(void)
 	 * Try to request the interrupts
 	 */
 
-	if (smu->db_irq != NO_IRQ) {
+	if (smu->db_irq) {
 		if (request_irq(smu->db_irq, smu_db_intr,
 				IRQF_SHARED, "SMU doorbell", smu) < 0) {
 			printk(KERN_WARNING "SMU: can't "
 			       "request interrupt %d\n",
 			       smu->db_irq);
-			smu->db_irq = NO_IRQ;
+			smu->db_irq = 0;
 		}
 	}
 
-	if (smu->msg_irq != NO_IRQ) {
+	if (smu->msg_irq) {
 		if (request_irq(smu->msg_irq, smu_msg_intr,
 				IRQF_SHARED, "SMU message", smu) < 0) {
 			printk(KERN_WARNING "SMU: can't "
 			       "request interrupt %d\n",
 			       smu->msg_irq);
-			smu->msg_irq = NO_IRQ;
+			smu->msg_irq = 0;
 		}
 	}
 

drivers/macintosh/via-cuda.c

@@ -209,7 +209,7 @@ static int __init via_cuda_start(void)
     cuda_irq = IRQ_MAC_ADB;
 #else
     cuda_irq = irq_of_parse_and_map(vias, 0);
-    if (cuda_irq == NO_IRQ) {
+    if (!cuda_irq) {
 	printk(KERN_ERR "via-cuda: can't map interrupts for %s\n",
 	       vias->full_name);
 	return -ENODEV;

drivers/macintosh/via-pmu.c

@@ -145,7 +145,7 @@ static int pmu_fully_inited;
 static int pmu_has_adb;
 static struct device_node *gpio_node;
 static unsigned char __iomem *gpio_reg;
-static int gpio_irq = NO_IRQ;
+static int gpio_irq = 0;
 static int gpio_irq_enabled = -1;
 static volatile int pmu_suspended;
 static spinlock_t pmu_lock;
@@ -402,7 +402,7 @@ static int __init via_pmu_start(void)
 	batt_req.complete = 1;
 
 	irq = irq_of_parse_and_map(vias, 0);
-	if (irq == NO_IRQ) {
+	if (!irq) {
 		printk(KERN_ERR "via-pmu: can't map interrupt\n");
 		return -ENODEV;
 	}
@@ -424,7 +424,7 @@ static int __init via_pmu_start(void)
 		if (gpio_node)
 			gpio_irq = irq_of_parse_and_map(gpio_node, 0);
 
-		if (gpio_irq != NO_IRQ) {
+		if (gpio_irq) {
 			if (request_irq(gpio_irq, gpio1_interrupt,
 					IRQF_NO_SUSPEND, "GPIO1 ADB",
 					(void *)0))