[PATCH RFC v4 16/21] PCI: Calculate fixed areas of bridge windows based on fixed BARs

[Sergey Miroshnichenko <s.miroshnichenko@yadro.com>]

For every (IO, MEM, MEM64) bridge window, count the fixed resources of
its children endpoints and children bridge windows:

| <- BAR -> |    | <- child bus fixed_range_hard -> |   | <- fixed BAR -> |
                 | <-            bus's fixed_range_hard                -> |
| <-                       bus's bridge window                         -> |

These ranges will be later used to arrange bridge windows in a way which
covers every immovable BAR as well as the movable ones during hotplug.

Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
---
 drivers/pci/pci.h       | 14 +++++++
 drivers/pci/probe.c     | 82 +++++++++++++++++++++++++++++++++++++++++
 drivers/pci/setup-bus.c | 17 +++++++++
 include/linux/pci.h     |  6 +++
 4 files changed, 119 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 56b905068ac5..14e3ebe68010 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -364,6 +364,20 @@ static inline bool pci_dev_is_disconnected(const struct pci_dev *dev)
 	return dev->error_state == pci_channel_io_perm_failure;
 }
 
+static inline int pci_get_bridge_resource_idx(struct resource *r)
+{
+	int idx = 1;
+
+	if (r->flags & IORESOURCE_IO)
+		idx = 0;
+	else if (!(r->flags & IORESOURCE_PREFETCH))
+		idx = 1;
+	else if (r->flags & IORESOURCE_MEM_64)
+		idx = 2;
+
+	return idx;
+}
+
 /* pci_dev priv_flags */
 #define PCI_DEV_ADDED 0
 #define PCI_DEV_IGNORE 1
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 62f4058a001f..70b15654f253 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -551,6 +551,7 @@ void pci_read_bridge_bases(struct pci_bus *child)
 static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
 {
 	struct pci_bus *b;
+	int idx;
 
 	b = kzalloc(sizeof(*b), GFP_KERNEL);
 	if (!b)
@@ -567,6 +568,11 @@ static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
 	if (parent)
 		b->domain_nr = parent->domain_nr;
 #endif
+	for (idx = 0; idx < PCI_BRIDGE_RESOURCE_NUM; ++idx) {
+		b->fixed_range_hard[idx].start = (resource_size_t)-1;
+		b->fixed_range_hard[idx].end = 0;
+	}
+
 	return b;
 }
 
@@ -3337,6 +3343,81 @@ static void pci_setup_bridges(struct pci_bus *bus)
 		pci_setup_bridge(bus);
 }
 
+static void pci_bus_update_fixed_range_hard(struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+	int idx;
+	resource_size_t start, end;
+
+	for (idx = 0; idx < PCI_BRIDGE_RESOURCE_NUM; ++idx) {
+		bus->fixed_range_hard[idx].start = (resource_size_t)-1;
+		bus->fixed_range_hard[idx].end = 0;
+	}
+
+	list_for_each_entry(dev, &bus->devices, bus_list)
+		if (dev->subordinate)
+			pci_bus_update_fixed_range_hard(dev->subordinate);
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		int i;
+
+		for (i = 0; i < PCI_BRIDGE_RESOURCES; ++i) {
+			struct resource *r = &dev->resource[i];
+
+			if (!r->flags || (r->flags & IORESOURCE_UNSET) || !r->parent)
+				continue;
+
+			if (r->flags & IORESOURCE_PCI_FIXED) {
+				idx = pci_get_bridge_resource_idx(r);
+				start = bus->fixed_range_hard[idx].start;
+				end = bus->fixed_range_hard[idx].end;
+
+				if (start > r->start)
+					start = r->start;
+				if (end < r->end)
+					end = r->end;
+
+				if (bus->fixed_range_hard[idx].start != start ||
+				    bus->fixed_range_hard[idx].end != end) {
+					dev_dbg(&bus->dev, "%s: Found fixed 0x%llx-0x%llx in %s, expand the fixed bridge window %d to 0x%llx-0x%llx\n",
+						__func__,
+						(unsigned long long)r->start,
+						(unsigned long long)r->end,
+						dev_name(&dev->dev), idx,
+						(unsigned long long)start,
+						(unsigned long long)end);
+					bus->fixed_range_hard[idx].start = start;
+					bus->fixed_range_hard[idx].end = end;
+				}
+			}
+		}
+
+		if (dev->subordinate) {
+			struct pci_bus *child = dev->subordinate;
+
+			for (idx = 0; idx < PCI_BRIDGE_RESOURCE_NUM; ++idx) {
+				start = bus->fixed_range_hard[idx].start;
+				end = bus->fixed_range_hard[idx].end;
+
+				if (start > child->fixed_range_hard[idx].start)
+					start = child->fixed_range_hard[idx].start;
+				if (end < child->fixed_range_hard[idx].end)
+					end = child->fixed_range_hard[idx].end;
+
+				if (start < bus->fixed_range_hard[idx].start ||
+				    end > bus->fixed_range_hard[idx].end) {
+					dev_dbg(&bus->dev, "%s: Expand the fixed bridge window %d from %s to 0x%llx-0x%llx\n",
+						__func__, idx, dev_name(&child->dev),
+						(unsigned long long)start,
+						(unsigned long long)end);
+					bus->fixed_range_hard[idx].start = start;
+					bus->fixed_range_hard[idx].end = end;
+				}
+			}
+		}
+	}
+}
+
 static struct pci_dev *pci_find_next_new_device(struct pci_bus *bus)
 {
 	struct pci_dev *dev;
@@ -3437,6 +3518,7 @@ unsigned int pci_rescan_bus(struct pci_bus *bus)
 		pci_bus_rescan_prepare(root);
 
 		max = pci_scan_child_bus(root);
+		pci_bus_update_fixed_range_hard(root);
 
 		pci_reassign_root_bus_resources(root);
 
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index c1559a4a8564..a1fd7f3c5ea8 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -879,9 +879,17 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size,
 	resource_size_t children_add_size = 0;
 	resource_size_t min_align, align;
 
+	resource_size_t fixed_start = bus->fixed_range_hard[0].start;
+	resource_size_t fixed_end = bus->fixed_range_hard[0].end;
+	resource_size_t fixed_size = (fixed_start < fixed_end) ?
+		(fixed_end - fixed_start + 1) : 0;
+
 	if (!b_res)
 		return;
 
+	if (min_size < fixed_size)
+		min_size = fixed_size;
+
 	min_align = window_alignment(bus, IORESOURCE_IO);
 	list_for_each_entry(dev, &bus->devices, bus_list) {
 		int i;
@@ -990,6 +998,15 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
 	resource_size_t children_add_size = 0;
 	resource_size_t children_add_align = 0;
 	resource_size_t add_align = 0;
+	bool is_mem64 = (mask & IORESOURCE_MEM_64);
+
+	resource_size_t fixed_start = bus->fixed_range_hard[is_mem64 ? 2 : 1].start;
+	resource_size_t fixed_end = bus->fixed_range_hard[is_mem64 ? 2 : 1].end;
+	resource_size_t fixed_size = (fixed_start < fixed_end) ?
+		(fixed_end - fixed_start + 1) : 0;
+
+	if (min_size < fixed_size)
+		min_size = fixed_size;
 
 	if (!b_res)
 		return -ENOSPC;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 26aa59cb6220..7a4d62d84bc1 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -572,6 +572,12 @@ struct pci_bus {
 	struct list_head resources;	/* Address space routed to this bus */
 	struct resource busn_res;	/* Bus numbers routed to this bus */
 
+	/*
+	 * If there are fixed resources in the bridge window, the hard range
+	 * contains the lowest and the highest addresses of them.
+	 */
+	struct resource fixed_range_hard[PCI_BRIDGE_RESOURCE_NUM];
+
 	struct pci_ops	*ops;		/* Configuration access functions */
 	struct msi_controller *msi;	/* MSI controller */
 	void		*sysdata;	/* Hook for sys-specific extension */
-- 
2.20.1