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authorChristian König <christian.koenig@amd.com>2017-10-24 22:40:26 +0300
committerBjorn Helgaas <bhelgaas@google.com>2017-10-26 00:07:31 +0300
commit8bb705e3e79d84e77edd4499e74483dd96a4626c (patch)
tree6e8ec3230481d768d7a5a53e12d6975fb1bd9e9f /drivers/pci/setup-res.c
parent276b738deb5bf856b9f6049fcd92a967f52643d7 (diff)
downloadlinux-8bb705e3e79d84e77edd4499e74483dd96a4626c.tar.xz
PCI: Add pci_resize_resource() for resizing BARs
Add a pci_resize_resource() interface to allow device drivers to resize BARs of their devices. This is useful for devices with large local storage, e.g., graphics devices. These devices often only expose 256MB BARs initially to be compatible with 32-bit systems. This function only tries to reprogram the windows of the bridge directly above the requesting device and only the BAR of the same type (usually mem, 64bit, prefetchable). This is done to avoid disturbing other drivers by changing the BARs of their devices. Drivers should use the following sequence to resize their BARs: 1. Disable memory decoding of the device using the PCI cfg dword. 2. Use pci_release_resource() to release all BARs which can move during the resize, including the one you want to resize. 3. Call pci_resize_resource() for each BAR you want to resize. 4. Call pci_assign_unassigned_bus_resources() to reassign new locations for all BARs which are not resized, but could move. 5. If everything worked as expected, enable memory decoding in the device again using the PCI cfg dword. Signed-off-by: Christian König <christian.koenig@amd.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'drivers/pci/setup-res.c')
-rw-r--r--drivers/pci/setup-res.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index e576e1a8d978..bf0089ef2177 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -396,6 +396,64 @@ int pci_reassign_resource(struct pci_dev *dev, int resno, resource_size_t addsiz
return 0;
}
+void pci_release_resource(struct pci_dev *dev, int resno)
+{
+ struct resource *res = dev->resource + resno;
+
+ dev_info(&dev->dev, "BAR %d: releasing %pR\n", resno, res);
+ release_resource(res);
+ res->end = resource_size(res) - 1;
+ res->start = 0;
+ res->flags |= IORESOURCE_UNSET;
+}
+EXPORT_SYMBOL(pci_release_resource);
+
+int pci_resize_resource(struct pci_dev *dev, int resno, int size)
+{
+ struct resource *res = dev->resource + resno;
+ int old, ret;
+ u32 sizes;
+ u16 cmd;
+
+ /* Make sure the resource isn't assigned before resizing it. */
+ if (!(res->flags & IORESOURCE_UNSET))
+ return -EBUSY;
+
+ pci_read_config_word(dev, PCI_COMMAND, &cmd);
+ if (cmd & PCI_COMMAND_MEMORY)
+ return -EBUSY;
+
+ sizes = pci_rebar_get_possible_sizes(dev, resno);
+ if (!sizes)
+ return -ENOTSUPP;
+
+ if (!(sizes & BIT(size)))
+ return -EINVAL;
+
+ old = pci_rebar_get_current_size(dev, resno);
+ if (old < 0)
+ return old;
+
+ ret = pci_rebar_set_size(dev, resno, size);
+ if (ret)
+ return ret;
+
+ res->end = res->start + pci_rebar_size_to_bytes(size) - 1;
+
+ /* Check if the new config works by trying to assign everything. */
+ ret = pci_reassign_bridge_resources(dev->bus->self, res->flags);
+ if (ret)
+ goto error_resize;
+
+ return 0;
+
+error_resize:
+ pci_rebar_set_size(dev, resno, old);
+ res->end = res->start + pci_rebar_size_to_bytes(old) - 1;
+ return ret;
+}
+EXPORT_SYMBOL(pci_resize_resource);
+
int pci_enable_resources(struct pci_dev *dev, int mask)
{
u16 cmd, old_cmd;