Merge branch 'pci/resource'

- Rename find_resource() to find_resource_space() to make it more
  descriptive for exporting outside resource.c (Ilpo Järvinen)

- Document find_resource_space() and the resource_constraint struct it uses
  (Ilpo Järvinen)

- Add typedef resource_alignf to make it simpler to declare allocation
  constraint alignf callbacks (Ilpo Järvinen)

- Open-code the no-constraint simple alignment case to make the
  simple_align_resource() default callback unnecessary (Ilpo Järvinen)

- Export find_resource_space() because PCI bridge window allocation needs
  to learn whether there's space for a window (Ilpo Järvinen)

- Fix a double-counting problem in PCI calculate_memsize() that led to
  allocating larger windows each time a bus was removed and rescanned (Ilpo
  Järvinen)

- When we don't have space to allocate larger bridge windows, allocate
  windows only large enough for the downstream devices to prevent cases
  where a device worked originally, but not after being removed and
  re-added (Ilpo Järvinen)

* pci/resource:
  PCI: Relax bridge window tail sizing rules
  PCI: Make minimum bridge window alignment reference more obvious
  PCI: Fix resource double counting on remove & rescan
  resource: Export find_resource_space()
  resource: Handle simple alignment inside __find_resource_space()
  resource: Use typedef for alignf callback
  resource: Document find_resource_space() and resource_constraint
  resource: Rename find_resource() to find_resource_space()

5 files changed, 157 insertions, 61 deletions

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 826b5016a101..dfc99b3cb958 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -176,10 +176,7 @@ static void pci_clip_resource_to_region(struct pci_bus *bus,
 static int pci_bus_alloc_from_region(struct pci_bus *bus, struct resource *res,
 		resource_size_t size, resource_size_t align,
 		resource_size_t min, unsigned long type_mask,
-		resource_size_t (*alignf)(void *,
-					  const struct resource *,
-					  resource_size_t,
-					  resource_size_t),
+		resource_alignf alignf,
 		void *alignf_data,
 		struct pci_bus_region *region)
 {
@@ -250,10 +247,7 @@ static int pci_bus_alloc_from_region(struct pci_bus *bus, struct resource *res,
 int pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
 		resource_size_t size, resource_size_t align,
 		resource_size_t min, unsigned long type_mask,
-		resource_size_t (*alignf)(void *,
-					  const struct resource *,
-					  resource_size_t,
-					  resource_size_t),
+		resource_alignf alignf,
 		void *alignf_data)
 {
 #ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 909e6a7c3cc3..23082bc0ca37 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -14,6 +14,7 @@
  *	     tighter packing. Prefetchable range support.
  */
 
+#include <linux/bitops.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -21,6 +22,8 @@
 #include <linux/errno.h>
 #include <linux/ioport.h>
 #include <linux/cache.h>
+#include <linux/limits.h>
+#include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
 #include "pci.h"
@@ -829,11 +832,9 @@ static resource_size_t calculate_memsize(resource_size_t size,
 		size = min_size;
 	if (old_size == 1)
 		old_size = 0;
-	if (size < old_size)
-		size = old_size;
 
-	size = ALIGN(max(size, add_size) + children_add_size, align);
-	return size;
+	size = max(size, add_size) + children_add_size;
+	return ALIGN(max(size, old_size), align);
 }
 
 resource_size_t __weak pcibios_window_alignment(struct pci_bus *bus,
@@ -959,7 +960,7 @@ static inline resource_size_t calculate_mem_align(resource_size_t *aligns,
 	for (order = 0; order <= max_order; order++) {
 		resource_size_t align1 = 1;
 
-		align1 <<= (order + 20);
+		align1 <<= order + __ffs(SZ_1M);
 
 		if (!align)
 			min_align = align1;
@@ -972,6 +973,67 @@ static inline resource_size_t calculate_mem_align(resource_size_t *aligns,
 }
 
 /**
+ * pbus_upstream_space_available - Check no upstream resource limits allocation
+ * @bus:	The bus
+ * @mask:	Mask the resource flag, then compare it with type
+ * @type:	The type of resource from bridge
+ * @size:	The size required from the bridge window
+ * @align:	Required alignment for the resource
+ *
+ * Checks that @size can fit inside the upstream bridge resources that are
+ * already assigned.
+ *
+ * Return: %true if enough space is available on all assigned upstream
+ * resources.
+ */
+static bool pbus_upstream_space_available(struct pci_bus *bus, unsigned long mask,
+					  unsigned long type, resource_size_t size,
+					  resource_size_t align)
+{
+	struct resource_constraint constraint = {
+		.max = RESOURCE_SIZE_MAX,
+		.align = align,
+	};
+	struct pci_bus *downstream = bus;
+	struct resource *r;
+
+	while ((bus = bus->parent)) {
+		if (pci_is_root_bus(bus))
+			break;
+
+		pci_bus_for_each_resource(bus, r) {
+			if (!r || !r->parent || (r->flags & mask) != type)
+				continue;
+
+			if (resource_size(r) >= size) {
+				struct resource gap = {};
+
+				if (find_resource_space(r, &gap, size, &constraint) == 0) {
+					gap.flags = type;
+					pci_dbg(bus->self,
+						"Assigned bridge window %pR to %pR free space at %pR\n",
+						r, &bus->busn_res, &gap);
+					return true;
+				}
+			}
+
+			if (bus->self) {
+				pci_info(bus->self,
+					 "Assigned bridge window %pR to %pR cannot fit 0x%llx required for %s bridging to %pR\n",
+					 r, &bus->busn_res,
+					 (unsigned long long)size,
+					 pci_name(downstream->self),
+					 &downstream->busn_res);
+			}
+
+			return false;
+		}
+	}
+
+	return true;
+}
+
+/**
  * pbus_size_mem() - Size the memory window of a given bus
  *
  * @bus:		The bus
@@ -997,7 +1059,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
 			 struct list_head *realloc_head)
 {
 	struct pci_dev *dev;
-	resource_size_t min_align, align, size, size0, size1;
+	resource_size_t min_align, win_align, align, size, size0, size1;
 	resource_size_t aligns[24]; /* Alignments from 1MB to 8TB */
 	int order, max_order;
 	struct resource *b_res = find_bus_resource_of_type(bus,
@@ -1049,7 +1111,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
 			 * resources.
 			 */
 			align = pci_resource_alignment(dev, r);
-			order = __ffs(align) - 20;
+			order = __ffs(align) - __ffs(SZ_1M);
 			if (order < 0)
 				order = 0;
 			if (order >= ARRAY_SIZE(aligns)) {
@@ -1076,10 +1138,23 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
 		}
 	}
 
+	win_align = window_alignment(bus, b_res->flags);
 	min_align = calculate_mem_align(aligns, max_order);
-	min_align = max(min_align, window_alignment(bus, b_res->flags));
+	min_align = max(min_align, win_align);
 	size0 = calculate_memsize(size, min_size, 0, 0, resource_size(b_res), min_align);
 	add_align = max(min_align, add_align);
+
+	if (bus->self && size0 &&
+	    !pbus_upstream_space_available(bus, mask | IORESOURCE_PREFETCH, type,
+					   size0, add_align)) {
+		min_align = 1ULL << (max_order + __ffs(SZ_1M));
+		min_align = max(min_align, win_align);
+		size0 = calculate_memsize(size, min_size, 0, 0, resource_size(b_res), win_align);
+		add_align = win_align;
+		pci_info(bus->self, "bridge window %pR to %pR requires relaxed alignment rules\n",
+			 b_res, &bus->busn_res);
+	}
+
 	size1 = (!realloc_head || (realloc_head && !add_size && !children_add_size)) ? size0 :
 		calculate_memsize(size, min_size, add_size, children_add_size,
 				resource_size(b_res), add_align);
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index db7fe25f3370..6e9fb667a1c5 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -188,6 +188,42 @@ enum {
 #define DEFINE_RES_DMA(_dma)						\
 	DEFINE_RES_DMA_NAMED((_dma), NULL)
 
+/**
+ * typedef resource_alignf - Resource alignment callback
+ * @data:	Private data used by the callback
+ * @res:	Resource candidate range (an empty resource space)
+ * @size:	The minimum size of the empty space
+ * @align:	Alignment from the constraints
+ *
+ * Callback allows calculating resource placement and alignment beyond min,
+ * max, and align fields in the struct resource_constraint.
+ *
+ * Return: Start address for the resource.
+ */
+typedef resource_size_t (*resource_alignf)(void *data,
+					   const struct resource *res,
+					   resource_size_t size,
+					   resource_size_t align);
+
+/**
+ * struct resource_constraint - constraints to be met while searching empty
+ *				resource space
+ * @min:		The minimum address for the memory range
+ * @max:		The maximum address for the memory range
+ * @align:		Alignment for the start address of the empty space
+ * @alignf:		Additional alignment constraints callback
+ * @alignf_data:	Data provided for @alignf callback
+ *
+ * Contains the range and alignment constraints that have to be met during
+ * find_resource_space(). @alignf can be NULL indicating no alignment beyond
+ * @align is necessary.
+ */
+struct resource_constraint {
+	resource_size_t min, max, align;
+	resource_alignf alignf;
+	void *alignf_data;
+};
+
 /* PC/ISA/whatever - the normal PC address spaces: IO and memory */
 extern struct resource ioport_resource;
 extern struct resource iomem_resource;
@@ -207,10 +243,7 @@ extern void arch_remove_reservations(struct resource *avail);
 extern int allocate_resource(struct resource *root, struct resource *new,
 			     resource_size_t size, resource_size_t min,
 			     resource_size_t max, resource_size_t align,
-			     resource_size_t (*alignf)(void *,
-						       const struct resource *,
-						       resource_size_t,
-						       resource_size_t),
+			     resource_alignf alignf,
 			     void *alignf_data);
 struct resource *lookup_resource(struct resource *root, resource_size_t start);
 int adjust_resource(struct resource *res, resource_size_t start,
@@ -264,6 +297,9 @@ static inline bool resource_union(const struct resource *r1, const struct resour
 	return true;
 }
 
+int find_resource_space(struct resource *root, struct resource *new,
+			resource_size_t size, struct resource_constraint *constraint);
+
 /* Convenience shorthand with allocation */
 #define request_region(start,n,name)		__request_region(&ioport_resource, (start), (n), (name), 0)
 #define request_muxed_region(start,n,name)	__request_region(&ioport_resource, (start), (n), (name), IORESOURCE_MUXED)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 98893a89bb5b..e83ac93a4dcb 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1552,10 +1552,7 @@ int __must_check pci_bus_alloc_resource(struct pci_bus *bus,
 			struct resource *res, resource_size_t size,
 			resource_size_t align, resource_size_t min,
 			unsigned long type_mask,
-			resource_size_t (*alignf)(void *,
-						  const struct resource *,
-						  resource_size_t,
-						  resource_size_t),
+			resource_alignf alignf,
 			void *alignf_data);
 
 
diff --git a/kernel/resource.c b/kernel/resource.c
index fcbca39dbc45..14777afb0a99 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -48,14 +48,6 @@ struct resource iomem_resource = {
 };
 EXPORT_SYMBOL(iomem_resource);
 
-/* constraints to be met while allocating resources */
-struct resource_constraint {
-	resource_size_t min, max, align;
-	resource_size_t (*alignf)(void *, const struct resource *,
-			resource_size_t, resource_size_t);
-	void *alignf_data;
-};
-
 static DEFINE_RWLOCK(resource_lock);
 
 static struct resource *next_resource(struct resource *p, bool skip_children)
@@ -610,14 +602,6 @@ void __weak arch_remove_reservations(struct resource *avail)
 {
 }
 
-static resource_size_t simple_align_resource(void *data,
-					     const struct resource *avail,
-					     resource_size_t size,
-					     resource_size_t align)
-{
-	return avail->start;
-}
-
 static void resource_clip(struct resource *res, resource_size_t min,
 			  resource_size_t max)
 {
@@ -628,16 +612,16 @@ static void resource_clip(struct resource *res, resource_size_t min,
 }
 
 /*
- * Find empty slot in the resource tree with the given range and
+ * Find empty space in the resource tree with the given range and
  * alignment constraints
  */
-static int __find_resource(struct resource *root, struct resource *old,
-			 struct resource *new,
-			 resource_size_t  size,
-			 struct resource_constraint *constraint)
+static int __find_resource_space(struct resource *root, struct resource *old,
+				 struct resource *new, resource_size_t size,
+				 struct resource_constraint *constraint)
 {
 	struct resource *this = root->child;
 	struct resource tmp = *new, avail, alloc;
+	resource_alignf alignf = constraint->alignf;
 
 	tmp.start = root->start;
 	/*
@@ -666,8 +650,12 @@ static int __find_resource(struct resource *root, struct resource *old,
 		avail.flags = new->flags & ~IORESOURCE_UNSET;
 		if (avail.start >= tmp.start) {
 			alloc.flags = avail.flags;
-			alloc.start = constraint->alignf(constraint->alignf_data, &avail,
-					size, constraint->align);
+			if (alignf) {
+				alloc.start = alignf(constraint->alignf_data,
+						     &avail, size, constraint->align);
+			} else {
+				alloc.start = avail.start;
+			}
 			alloc.end = alloc.start + size - 1;
 			if (alloc.start <= alloc.end &&
 			    resource_contains(&avail, &alloc)) {
@@ -687,15 +675,27 @@ next:		if (!this || this->end == root->end)
 	return -EBUSY;
 }
 
-/*
- * Find empty slot in the resource tree given range and alignment.
+/**
+ * find_resource_space - Find empty space in the resource tree
+ * @root:	Root resource descriptor
+ * @new:	Resource descriptor awaiting an empty resource space
+ * @size:	The minimum size of the empty space
+ * @constraint:	The range and alignment constraints to be met
+ *
+ * Finds an empty space under @root in the resource tree satisfying range and
+ * alignment @constraints.
+ *
+ * Return:
+ * * %0		- if successful, @new members start, end, and flags are altered.
+ * * %-EBUSY	- if no empty space was found.
  */
-static int find_resource(struct resource *root, struct resource *new,
+int find_resource_space(struct resource *root, struct resource *new,
 			resource_size_t size,
-			struct resource_constraint  *constraint)
+			struct resource_constraint *constraint)
 {
-	return  __find_resource(root, NULL, new, size, constraint);
+	return  __find_resource_space(root, NULL, new, size, constraint);
 }
+EXPORT_SYMBOL_GPL(find_resource_space);
 
 /**
  * reallocate_resource - allocate a slot in the resource tree given range & alignment.
@@ -717,7 +717,7 @@ static int reallocate_resource(struct resource *root, struct resource *old,
 
 	write_lock(&resource_lock);
 
-	if ((err = __find_resource(root, old, &new, newsize, constraint)))
+	if ((err = __find_resource_space(root, old, &new, newsize, constraint)))
 		goto out;
 
 	if (resource_contains(&new, old)) {
@@ -761,18 +761,12 @@ out:
 int allocate_resource(struct resource *root, struct resource *new,
 		      resource_size_t size, resource_size_t min,
 		      resource_size_t max, resource_size_t align,
-		      resource_size_t (*alignf)(void *,
-						const struct resource *,
-						resource_size_t,
-						resource_size_t),
+		      resource_alignf alignf,
 		      void *alignf_data)
 {
 	int err;
 	struct resource_constraint constraint;
 
-	if (!alignf)
-		alignf = simple_align_resource;
-
 	constraint.min = min;
 	constraint.max = max;
 	constraint.align = align;
@@ -786,7 +780,7 @@ int allocate_resource(struct resource *root, struct resource *new,
 	}
 
 	write_lock(&resource_lock);
-	err = find_resource(root, new, size, &constraint);
+	err = find_resource_space(root, new, size, &constraint);
 	if (err >= 0 && __request_resource(root, new))
 		err = -EBUSY;
 	write_unlock(&resource_lock);