Skiboot used to set the default Tunnel BAR register value when capi mode
was enabled. This approach was ok for the cxl driver, but prevented other
drivers from choosing different values.

Skiboot versions > 5.11 will not set the default value any longer. This
patch modifies the cxl driver to set/reset the Tunnel BAR register when
entering/exiting the cxl mode, with pnv_pci_set_tunnel_bar().

Signed-off-by: Philippe Bergheaud <>

v2: Restrict tunnel bar setting to power9.
    Do not fail cxl_configure_adapter() on tunnel bar setting error.
    Log an info message instead, and continue configuring capi mode.
 drivers/misc/cxl/pci.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 83f1d08058fc..355c789406f7 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1742,6 +1742,10 @@ static int cxl_configure_adapter(struct cxl *adapter, 
struct pci_dev *dev)
        /* Required for devices using CAPP DMA mode, harmless for others */
+       if (cxl_is_power9())
+               if (pnv_pci_set_tunnel_bar(dev, 0x00020000E0000000ull, 1))
+                       dev_info(&dev->dev, "Tunneled operations 
        if ((rc = pnv_phb_to_cxl_mode(dev, adapter->native->sl_ops->capi_mode)))
                goto err;
@@ -1768,6 +1772,8 @@ static void cxl_deconfigure_adapter(struct cxl *adapter)
        struct pci_dev *pdev = to_pci_dev(adapter->dev.parent);
+       if (cxl_is_power9())
+               pnv_pci_set_tunnel_bar(pdev, 0x00020000E0000000ull, 0);

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