PCI: Add Virtual Channel to save/restore support

While we don't really have any infrastructure for making use of VC
support, the system BIOS can configure the topology to non-default
VC values prior to boot.  This may be due to silicon bugs, desire to
reserve traffic classes, or perhaps just BIOS bugs.  When we reset
devices, the VC configuration may return to default values, which can
be incompatible with devices upstream.  For instance, Nvidia GRID
cards provide a PCIe switch and some number of GPUs, all supporting
VC.  The power-on default for VC is to support TC0-7 across VC0,
however some platforms will only enable TC0/VC0 mapping across the
topology.  When we do a secondary bus reset on the downstream switch
port, the GPU is reset to a TC0-7/VC0 mapping while the opposite end
of the link only enables TC0/VC0.  If the GPU attempts to use TC1-7,
it fails.

This patch attempts to provide complete support for VC save/restore,
even beyond the minimally required use case above.  This includes
save/restore and reload of the arbitration table, save/restore and
reload of the port arbitration tables, and re-enabling of the
channels for VC, VC9, and MFVC capabilities.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 21 insertions, 4 deletions

diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index 4a98e85438a7..5eefacd93e18 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -678,16 +678,33 @@
 
 /* Virtual Channel */
 #define PCI_VC_PORT_REG1        4
-#define  PCI_VC_REG1_EVCC       0x7     /* extended VC count */
+#define  PCI_VC_REG1_EVCC       0x00000007      /* extended VC count */
+#define  PCI_VC_REG1_LPEVCC     0x00000070      /* low prio extended VC count */
+#define  PCI_VC_REG1_ARB_SIZE   0x00000c00
 #define PCI_VC_PORT_REG2        8
-#define  PCI_VC_REG2_32_PHASE   0x2
-#define  PCI_VC_REG2_64_PHASE   0x4
-#define  PCI_VC_REG2_128_PHASE  0x8
+#define  PCI_VC_REG2_32_PHASE           0x00000002
+#define  PCI_VC_REG2_64_PHASE           0x00000004
+#define  PCI_VC_REG2_128_PHASE          0x00000008
+#define  PCI_VC_REG2_ARB_OFF            0xff000000
 #define PCI_VC_PORT_CTRL        12
+#define  PCI_VC_PORT_CTRL_LOAD_TABLE    0x00000001
 #define PCI_VC_PORT_STATUS      14
+#define  PCI_VC_PORT_STATUS_TABLE       0x00000001
 #define PCI_VC_RES_CAP          16
+#define  PCI_VC_RES_CAP_32_PHASE        0x00000002
+#define  PCI_VC_RES_CAP_64_PHASE        0x00000004
+#define  PCI_VC_RES_CAP_128_PHASE       0x00000008
+#define  PCI_VC_RES_CAP_128_PHASE_TB    0x00000010
+#define  PCI_VC_RES_CAP_256_PHASE       0x00000020
+#define  PCI_VC_RES_CAP_ARB_OFF         0xff000000
 #define PCI_VC_RES_CTRL         20
+#define  PCI_VC_RES_CTRL_LOAD_TABLE     0x00010000
+#define  PCI_VC_RES_CTRL_ARB_SELECT     0x000e0000
+#define  PCI_VC_RES_CTRL_ID             0x07000000
+#define  PCI_VC_RES_CTRL_ENABLE         0x80000000
 #define PCI_VC_RES_STATUS       26
+#define  PCI_VC_RES_STATUS_TABLE        0x00000001
+#define  PCI_VC_RES_STATUS_NEGO         0x00000002
 #define PCI_CAP_VC_BASE_SIZEOF          0x10
 #define PCI_CAP_VC_PER_VC_SIZEOF        0x0C