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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2008-11-11 17:45:52 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-01-08 16:25:07 +1100
commitc1f343028d35ba4e88cd4a3c44e0d8b8a84264ee (patch)
treea6b41683b1297f6bc4a5867cbab47ce3c76ba9e0 /arch
parent24f030175d30f019be41766cdf88c2ff03de19ff (diff)
powerpc/pci: Reserve legacy regions on PCI
There's a problem on some embedded platforms when we re-assign everything on PCI, such as 44x. The generic code tries to avoid assigning devices to addresses overlapping the low legacy addresses such as VGA hard decoded areas using constants that are unfortunately no good for us, as they don't take into account the address translation we do to access PCI busses. Thus we end up allocating things like IO BARs to 0, which is technically legal, but will shadow hard decoded ports for use by things like VGA cards. This works around it by attempting to reserve legacy regions before we try to assign addresses. NOTE: This may have nasty side effects in cases I haven't tested yet: - We try to use FW mappings (ie. powermac) and the FW has allocated a conflicting address over those legacy regions. This will typically happen. I would expect the new code to just fail with an informative message without harm but I haven't had a chance to test that scenario yet. - A device with fixed BARs overlapping those legacy addresses such as an IDE controller in legacy mode is in the system. I don't know for sure yet what will happen there, I have to test :-) Ideally, we should change PCIBIOS_MIN_IO/MIN_MEM accross the board to take a bus pointer so they can provide appropriate per-bus translated values to the generic code but that's a more invasive patch. I will do that in the future, but in the meantime, this fixes the problem locally Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kernel/pci-common.c71
1 files changed, 70 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 2538030954d..da5a3855a0c 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -16,7 +16,7 @@
* 2 of the License, or (at your option) any later version.
*/
-#undef DEBUG
+#define DEBUG
#include <linux/kernel.h>
#include <linux/pci.h>
@@ -1356,6 +1356,63 @@ static void __init pcibios_allocate_resources(int pass)
}
}
+static void __init pcibios_reserve_legacy_regions(struct pci_bus *bus)
+{
+ struct pci_controller *hose = pci_bus_to_host(bus);
+ resource_size_t offset;
+ struct resource *res, *pres;
+ int i;
+
+ pr_debug("Reserving legacy ranges for domain %04x\n", pci_domain_nr(bus));
+
+ /* Check for IO */
+ if (!(hose->io_resource.flags & IORESOURCE_IO))
+ goto no_io;
+ offset = (unsigned long)hose->io_base_virt - _IO_BASE;
+ res = kzalloc(sizeof(struct resource), GFP_KERNEL);
+ BUG_ON(res == NULL);
+ res->name = "Legacy IO";
+ res->flags = IORESOURCE_IO;
+ res->start = offset;
+ res->end = (offset + 0xfff) & 0xfffffffful;
+ pr_debug("Candidate legacy IO: %pR\n", res);
+ if (request_resource(&hose->io_resource, res)) {
+ printk(KERN_DEBUG
+ "PCI %04x:%02x Cannot reserve Legacy IO %pR\n",
+ pci_domain_nr(bus), bus->number, res);
+ kfree(res);
+ }
+
+ no_io:
+ /* Check for memory */
+ offset = hose->pci_mem_offset;
+ pr_debug("hose mem offset: %016llx\n", (unsigned long long)offset);
+ for (i = 0; i < 3; i++) {
+ pres = &hose->mem_resources[i];
+ if (!(pres->flags & IORESOURCE_MEM))
+ continue;
+ pr_debug("hose mem res: %pR\n", pres);
+ if ((pres->start - offset) <= 0xa0000 &&
+ (pres->end - offset) >= 0xbffff)
+ break;
+ }
+ if (i >= 3)
+ return;
+ res = kzalloc(sizeof(struct resource), GFP_KERNEL);
+ BUG_ON(res == NULL);
+ res->name = "Legacy VGA memory";
+ res->flags = IORESOURCE_MEM;
+ res->start = 0xa0000 + offset;
+ res->end = 0xbffff + offset;
+ pr_debug("Candidate VGA memory: %pR\n", res);
+ if (request_resource(pres, res)) {
+ printk(KERN_DEBUG
+ "PCI %04x:%02x Cannot reserve VGA memory %pR\n",
+ pci_domain_nr(bus), bus->number, res);
+ kfree(res);
+ }
+}
+
void __init pcibios_resource_survey(void)
{
struct pci_bus *b;
@@ -1371,6 +1428,18 @@ void __init pcibios_resource_survey(void)
pcibios_allocate_resources(1);
}
+ /* Before we start assigning unassigned resource, we try to reserve
+ * the low IO area and the VGA memory area if they intersect the
+ * bus available resources to avoid allocating things on top of them
+ */
+ if (!(ppc_pci_flags & PPC_PCI_PROBE_ONLY)) {
+ list_for_each_entry(b, &pci_root_buses, node)
+ pcibios_reserve_legacy_regions(b);
+ }
+
+ /* Now, if the platform didn't decide to blindly trust the firmware,
+ * we proceed to assigning things that were left unassigned
+ */
if (!(ppc_pci_flags & PPC_PCI_PROBE_ONLY)) {
pr_debug("PCI: Assigning unassigned resouces...\n");
pci_assign_unassigned_resources();