PNP: support optional IRQ resources

This patch adds an IORESOURCE_IRQ_OPTIONAL flag for use when
assigning resources to a device.  If the flag is set and we are
unable to assign an IRQ to the device, we can leave the IRQ
disabled but allow the overall resource allocation to succeed.

Some devices request an IRQ, but can run without an IRQ
(possibly with degraded performance).  This flag lets us run
the device without the IRQ instead of just leaving the
device disabled.

This is a reimplementation of this previous change by Rene
Herman <rene.herman@gmail.com>:
    http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=3b73a223661ed137c5d3d2635f954382e94f5a43

I reimplemented this for two reasons:
    - to prepare for converting all resource options into a single linked
      list, as opposed to the per-resource-type lists we have now, and
    - to preserve the order and number of resource options.

In PNPBIOS and ACPI, we configure a device by giving firmware a
list of resource assignments.  It is important that this list
has exactly the same number of resources, in the same order,
as the "template" list we got from the firmware in the first
place.

The problem of a sound card MPU401 being left disabled for want of
an IRQ was reported by Uwe Bugla <uwe.bugla@gmx.de>.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Rene Herman <rene.herman@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>

4 files changed, 39 insertions, 44 deletions

diff --git a/drivers/pnp/interface.c b/drivers/pnp/interface.c
index b09f67de13d..7a9fb5544b8 100644
--- a/drivers/pnp/interface.c
+++ b/drivers/pnp/interface.c
@@ -90,6 +90,8 @@ static void pnp_print_irq(pnp_info_buffer_t * buffer, char *space,
 		pnp_printf(buffer, " High-Level");
 	if (irq->flags & IORESOURCE_IRQ_LOWLEVEL)
 		pnp_printf(buffer, " Low-Level");
+	if (irq->flags & IORESOURCE_IRQ_OPTIONAL)
+		pnp_printf(buffer, " (optional)");
 	pnp_printf(buffer, "\n");
 }
 
diff --git a/drivers/pnp/manager.c b/drivers/pnp/manager.c
index 7ea9e1e2800..a20accb5ef8 100644
--- a/drivers/pnp/manager.c
+++ b/drivers/pnp/manager.c
@@ -153,6 +153,15 @@ static int pnp_assign_irq(struct pnp_dev *dev, struct pnp_irq *rule, int idx)
 				goto __add;
 		}
 	}
+
+	if (rule->flags & IORESOURCE_IRQ_OPTIONAL) {
+		res->start = -1;
+		res->end = -1;
+		res->flags |= IORESOURCE_DISABLED;
+		dev_dbg(&dev->dev, "  irq %d disabled (optional)\n", idx);
+		goto __add;
+	}
+
 	dev_dbg(&dev->dev, "  couldn't assign irq %d\n", idx);
 	return -EBUSY;
 
diff --git a/drivers/pnp/quirks.c b/drivers/pnp/quirks.c
index 48e60171b3b..e8515ce0d29 100644
--- a/drivers/pnp/quirks.c
+++ b/drivers/pnp/quirks.c
@@ -121,34 +121,46 @@ static struct pnp_option *quirk_isapnp_mpu_options(struct pnp_dev *dev)
 	struct pnp_option *res;
 
 	/*
-	 * Build a functional IRQ-less variant of each MPU option.
+	 * Build a functional IRQ-optional variant of each MPU option.
 	 */
 
 	for (res = dev->dependent; res; res = res->next) {
 		struct pnp_option *curr;
 		struct pnp_port *port;
-		struct pnp_port *copy;
+		struct pnp_port *copy_port;
+		struct pnp_irq *irq;
+		struct pnp_irq *copy_irq;
 
 		port = res->port;
-		if (!port || !res->irq)
+		irq = res->irq;
+		if (!port || !irq)
 			continue;
 
-		copy = pnp_alloc(sizeof *copy);
-		if (!copy)
+		copy_port = pnp_alloc(sizeof *copy_port);
+		if (!copy_port)
+			break;
+
+		copy_irq = pnp_alloc(sizeof *copy_irq);
+		if (!copy_irq) {
+			kfree(copy_port);
 			break;
+		}
+
+		*copy_port = *port;
+		copy_port->next = NULL;
 
-		copy->min = port->min;
-		copy->max = port->max;
-		copy->align = port->align;
-		copy->size = port->size;
-		copy->flags = port->flags;
+		*copy_irq = *irq;
+		copy_irq->flags |= IORESOURCE_IRQ_OPTIONAL;
+		copy_irq->next = NULL;
 
 		curr = pnp_build_option(PNP_RES_PRIORITY_FUNCTIONAL);
 		if (!curr) {
-			kfree(copy);
+			kfree(copy_port);
+			kfree(copy_irq);
 			break;
 		}
-		curr->port = copy;
+		curr->port = copy_port;
+		curr->irq = copy_irq;
 
 		if (prev)
 			prev->next = curr;
@@ -157,7 +169,7 @@ static struct pnp_option *quirk_isapnp_mpu_options(struct pnp_dev *dev)
 		prev = curr;
 	}
 	if (head)
-		dev_info(&dev->dev, "adding IRQ-less MPU options\n");
+		dev_info(&dev->dev, "adding IRQ-optional MPU options\n");
 
 	return head;
 }
@@ -167,10 +179,6 @@ static void quirk_ad1815_mpu_resources(struct pnp_dev *dev)
 	struct pnp_option *res;
 	struct pnp_irq *irq;
 
-	/*
-	 * Distribute the independent IRQ over the dependent options
-	 */
-
 	res = dev->independent;
 	if (!res)
 		return;
@@ -179,33 +187,8 @@ static void quirk_ad1815_mpu_resources(struct pnp_dev *dev)
 	if (!irq || irq->next)
 		return;
 
-	res = dev->dependent;
-	if (!res)
-		return;
-
-	while (1) {
-		struct pnp_irq *copy;
-
-		copy = pnp_alloc(sizeof *copy);
-		if (!copy)
-			break;
-
-		bitmap_copy(copy->map.bits, irq->map.bits, PNP_IRQ_NR);
-		copy->flags = irq->flags;
-
-		copy->next = res->irq; /* Yes, this is NULL */
-		res->irq = copy;
-
-		if (!res->next)
-			break;
-		res = res->next;
-	}
-	kfree(irq);
-
-	res->next = quirk_isapnp_mpu_options(dev);
-
-	res = dev->independent;
-	res->irq = NULL;
+	irq->flags |= IORESOURCE_IRQ_OPTIONAL;
+	dev_info(&dev->dev, "made independent IRQ optional\n");
 }
 
 static void quirk_isapnp_mpu_resources(struct pnp_dev *dev)
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 39db059ffb8..2cd07cc2968 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -59,6 +59,7 @@ struct resource_list {
 #define IORESOURCE_IRQ_HIGHLEVEL	(1<<2)
 #define IORESOURCE_IRQ_LOWLEVEL		(1<<3)
 #define IORESOURCE_IRQ_SHAREABLE	(1<<4)
+#define IORESOURCE_IRQ_OPTIONAL 	(1<<5)
 
 /* PnP DMA specific bits (IORESOURCE_BITS) */
 #define IORESOURCE_DMA_TYPE_MASK	(3<<0)