tile PCI RC: support PCIe TRIO 0 MAC 0 on Gx72 system

On Tilera Gx72 systems, the logic for figuring out whether
a given port is root complex is slightly different.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

2 files changed, 33 insertions, 3 deletions

diff --git a/arch/tile/include/hv/drv_trio_intf.h b/arch/tile/include/hv/drv_trio_intf.h
index ec643a02b4c5..237e04dee66c 100644
--- a/arch/tile/include/hv/drv_trio_intf.h
+++ b/arch/tile/include/hv/drv_trio_intf.h
@@ -168,6 +168,9 @@ pcie_stream_intr_config_sel_t;
 struct pcie_trio_ports_property
 {
   struct pcie_port_property ports[TILEGX_TRIO_PCIES];
+
+  /** Set if this TRIO belongs to a Gx72 device. */
+  uint8_t is_gx72;
 };
 
 /* Flags indicating traffic class. */
diff --git a/arch/tile/kernel/pci_gx.c b/arch/tile/kernel/pci_gx.c
index de5008b72fa3..f2bf200b641b 100644
--- a/arch/tile/kernel/pci_gx.c
+++ b/arch/tile/kernel/pci_gx.c
@@ -436,9 +436,26 @@ int __init tile_pci_init(void)
 
         /*
          * Now determine which PCIe ports are configured to operate in RC
-         * mode.  To use a port, it must be allowed to be in RC mode by the
+         * mode. There is a differece in the port configuration capability
+         * between the Gx36 and Gx72 devices.
+         *
+         * The Gx36 has configuration capability for each of the 3 PCIe
+         * interfaces (disable, auto endpoint, auto RC, etc.).
+         * On the Gx72, you can only select one of the 3 PCIe interfaces per
+         * TRIO to train automatically. Further, the allowable training modes
+         * are reduced to four options (auto endpoint, auto RC, stream x1,
+         * stream x4).
+         *
+         * For Gx36 ports, it must be allowed to be in RC mode by the
          * Board Information Block, and the hardware strapping pins must be
          * set to RC mode.
+         *
+         * For Gx72 ports, the port will operate in RC mode if either of the
+         * following is true:
+         * 1. It is allowed to be in RC mode by the Board Information Block,
+         *    and the BIB doesn't allow the EP mode.
+         * 2. It is allowed to be in either the RC or the EP mode by the BIB,
+         *    and the hardware strapping pin is set to RC mode.
          */
         for (i = 0; i < TILEGX_NUM_TRIO; i++) {
                 gxio_trio_context_t *context = &trio_contexts[i];
@@ -447,8 +464,18 @@ int __init tile_pci_init(void)
                         continue;
 
                 for (j = 0; j < TILEGX_TRIO_PCIES; j++) {
-                        if (pcie_ports[i].ports[j].allow_rc &&
-                            strapped_for_rc(context, j)) {
+                        int is_rc = 0;
+
+                        if (pcie_ports[i].is_gx72 &&
+                            pcie_ports[i].ports[j].allow_rc) {
+                                if (!pcie_ports[i].ports[j].allow_ep ||
+                                    strapped_for_rc(context, j))
+                                        is_rc = 1;
+                        } else if (pcie_ports[i].ports[j].allow_rc &&
+                                   strapped_for_rc(context, j)) {
+                                is_rc = 1;
+                        }
+                        if (is_rc) {
                                 pcie_rc[i][j] = 1;
                                 num_rc_controllers++;
                         }