[PARISC] Truncate overlapping PAT PDC reported ranges

Deal with overlapping LBA MMIO resources,

rp3440 PDC BUG: PDC reports lmmio range for the last rope that overlaps
with the CPU HPA. Console output was:

...
Found devices:
1. Storm Peak Fast at 0xfffffffffe798000 [152] { 0, 0x0, 0x889, 0x00004 }
2. Storm Peak Fast at 0xfffffffffe799000 [153] { 0, 0x0, 0x889, 0x00004 }
...
FAILED: lba_fixup_bus() request for lmmio_space
[fffffffff0000000/fffffffffecffffe]

Output is now:

LBA: Truncating lmmio_space [fffffffff0000000/fffffffffecffffe] to
[fffffffff0000000,fffffffffe797fff]

My only concern with this patch is how C8000 (PAT PDC) will report
elmmio ranges when a gfx card is installed. I'll have to test this
another day.

Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: James Bottomley <jejb@parisc-linux.org>
Signed-off-by: Matthew Wilcox <willy@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

1 files changed, 90 insertions, 23 deletions

diff --git a/drivers/parisc/lba_pci.c b/drivers/parisc/lba_pci.c
index 4f6bdf0881b5..cbae8c8963fa 100644
--- a/drivers/parisc/lba_pci.c
+++ b/drivers/parisc/lba_pci.c
@@ -695,11 +695,71 @@ lba_claim_dev_resources(struct pci_dev *dev)
                 }
         }
 }
+
+
+/*
+ * truncate_pat_collision:  Deal with overlaps or outright collisions
+ *                      between PAT PDC reported ranges.
+ *
+ *   Broken PA8800 firmware will report lmmio range that
+ *   overlaps with CPU HPA. Just truncate the lmmio range.
+ *
+ *   BEWARE: conflicts with this lmmio range may be an
+ *   elmmio range which is pointing down another rope.
+ *
+ *  FIXME: only deals with one collision per range...theoretically we
+ *  could have several. Supporting more than one collision will get messy.
+ */
+static unsigned long
+truncate_pat_collision(struct resource *root, struct resource *new)
+{
+        unsigned long start = new->start;
+        unsigned long end = new->end;
+        struct resource *tmp = root->child;
+
+        if (end <= start || start < root->start || !tmp)
+                return 0;
+
+        /* find first overlap */
+        while (tmp && tmp->end < start)
+                tmp = tmp->sibling;
+
+        /* no entries overlap */
+        if (!tmp)  return 0;
+
+        /* found one that starts behind the new one
+        ** Don't need to do anything.
+        */
+        if (tmp->start >= end) return 0;
+
+        if (tmp->start <= start) {
+                /* "front" of new one overlaps */
+                new->start = tmp->end + 1;
+
+                if (tmp->end >= end) {
+                        /* AACCKK! totally overlaps! drop this range. */
+                        return 1;
+                }
+        } 
+
+        if (tmp->end < end ) {
+                /* "end" of new one overlaps */
+                new->end = tmp->start - 1;
+        }
+
+        printk(KERN_WARNING "LBA: Truncating lmmio_space [%lx/%lx] "
+                                        "to [%lx,%lx]\n",
+                        start, end,
+                        new->start, new->end );
+
+        return 0;       /* truncation successful */
+}
+
 #else
-#define lba_claim_dev_resources(dev)
+#define lba_claim_dev_resources(dev) do { } while (0)
+#define truncate_pat_collision(r,n)  (0)
 #endif
 
-
 /*
 ** The algorithm is generic code.
 ** But it needs to access local data structures to get the IRQ base.
@@ -747,6 +807,9 @@ lba_fixup_bus(struct pci_bus *bus)
                         lba_dump_res(&ioport_resource, 2);
                         BUG();
                 }
+                /* advertize Host bridge resources to PCI bus */
+                bus->resource[0] = &(ldev->hba.io_space);
+                i = 1;
 
                 if (ldev->hba.elmmio_space.start) {
                         err = request_resource(&iomem_resource,
@@ -760,23 +823,35 @@ lba_fixup_bus(struct pci_bus *bus)
 
                                 /* lba_dump_res(&iomem_resource, 2); */
                                 /* BUG(); */
-                        }
+                        } else
+                                bus->resource[i++] = &(ldev->hba.elmmio_space);
                 }
 
-                err = request_resource(&iomem_resource, &(ldev->hba.lmmio_space));
-                if (err < 0) {
-                        /*   FIXME  overlaps with elmmio will fail here.
-                         *   Need to prune (or disable) the distributed range.
-                         *
-                         *   BEWARE: conflicts with this lmmio range may be
-                         *   elmmio range which is pointing down another rope.
-                         */
-
-                        printk("FAILED: lba_fixup_bus() request for "
+
+                /*   Overlaps with elmmio can (and should) fail here.
+                 *   We will prune (or ignore) the distributed range.
+                 *
+                 *   FIXME: SBA code should register all elmmio ranges first.
+                 *      that would take care of elmmio ranges routed
+                 *      to a different rope (already discovered) from
+                 *      getting registered *after* LBA code has already
+                 *      registered it's distributed lmmio range.
+                 */
+                if (truncate_pat_collision(&iomem_resource,
+                                        &(ldev->hba.lmmio_space))) {
+
+                        printk(KERN_WARNING "LBA: lmmio_space [%lx/%lx] duplicate!\n",
+                                        ldev->hba.lmmio_space.start,
+                                        ldev->hba.lmmio_space.end);
+                } else {
+                        err = request_resource(&iomem_resource, &(ldev->hba.lmmio_space));
+                        if (err < 0) {
+                                printk(KERN_ERR "FAILED: lba_fixup_bus() request for "
                                         "lmmio_space [%lx/%lx]\n",
                                         ldev->hba.lmmio_space.start,
                                         ldev->hba.lmmio_space.end);
-                        /* lba_dump_res(&iomem_resource, 2); */
+                        } else
+                                bus->resource[i++] = &(ldev->hba.lmmio_space);
                 }
 
 #ifdef CONFIG_64BIT
@@ -791,18 +866,10 @@ lba_fixup_bus(struct pci_bus *bus)
                                 lba_dump_res(&iomem_resource, 2);
                                 BUG();
                         }
+                        bus->resource[i++] = &(ldev->hba.gmmio_space);
                 }
 #endif
 
-                /* advertize Host bridge resources to PCI bus */
-                bus->resource[0] = &(ldev->hba.io_space);
-                bus->resource[1] = &(ldev->hba.lmmio_space);
-                i=2;
-                if (ldev->hba.elmmio_space.start)
-                        bus->resource[i++] = &(ldev->hba.elmmio_space);
-                if (ldev->hba.gmmio_space.start)
-                        bus->resource[i++] = &(ldev->hba.gmmio_space);
-                        
         }
 
         list_for_each(ln, &bus->devices) {