PCI: endpoint: Introduce pci_epc_bar_type BAR_DISABLED

Add a pci_epc_bar_type BAR_DISABLED to more clearly differentiate from
BAR_RESERVED.

This BAR type will only be used to describe a BAR that the EPC driver
should disable, and will thus never be available to an EPF driver.
(Unlike BAR_RESERVED, which will never be disabled by default by an EPC
driver.)

Co-developed-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Tested-by: Koichiro Den <den@valinux.co.jp>
Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Link: https://patch.msgid.link/20260312130229.2282001-17-cassel@kernel.org

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index e546b3dbb240391d80710a4322b48b3dc4f87031..6c3c58185fc5dbd09905c790caaaf37c7d5b6b17 100644 (file)
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -103,8 +103,9 @@ enum pci_barno pci_epc_get_next_free_bar(const struct pci_epc_features
                bar++;
 
        for (i = bar; i < PCI_STD_NUM_BARS; i++) {
-               /* If the BAR is not reserved, return it. */
-               if (epc_features->bar[i].type != BAR_RESERVED)
+               /* If the BAR is not reserved or disabled, return it. */
+               if (epc_features->bar[i].type != BAR_RESERVED &&
+                   epc_features->bar[i].type != BAR_DISABLED)
                        return i;
        }
 

diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index ebcdf70aa9b9b95a98aa8e0f0409e49cfba6fe48..334c2b7578d00833b8f862b3fbc27fa30c74f510 100644 (file)
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -191,13 +191,21 @@ struct pci_epc {
  * @BAR_RESIZABLE: The BAR implements the PCI-SIG Resizable BAR Capability.
  *                NOTE: An EPC driver can currently only set a single supported
  *                size.
- * @BAR_RESERVED: The BAR should not be touched by an EPF driver.
+ * @BAR_RESERVED: Used for HW-backed BARs (e.g. MSI-X table, DMA regs). The BAR
+ *               should not be disabled by an EPC driver. The BAR should not be
+ *               reprogrammed by an EPF driver. An EPF driver is allowed to
+ *               disable the BAR if absolutely necessary. (However, right now
+ *               there is no EPC operation to disable a BAR that has not been
+ *               programmed using pci_epc_set_bar().)
+ * @BAR_DISABLED: The BAR should be disabled by an EPC driver. The BAR will be
+ *               unavailable to an EPF driver.
  */
 enum pci_epc_bar_type {
        BAR_PROGRAMMABLE = 0,
        BAR_FIXED,
        BAR_RESIZABLE,
        BAR_RESERVED,
+       BAR_DISABLED,
 };
 
 /**