[PATCH 4/9] PCI: endpoint: Introduce pci_epc_bar_type BAR_DISABLED

[Niklas Cassel <cassel@kernel.org>]

Add a pci_epc_bar_type BAR_64BIT_UPPER to more clearly differentiate
BAR_DISABLED from BAR_RESERVED.

This BAR type will only be used for a BAR that the EPC driver should
disable. (Unlike a BAR_RESERVED, which is still enabled.)

Co-developed-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/endpoint/pci-epc-core.c |  5 +++--
 include/linux/pci-epc.h             | 12 ++++++++++--
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 8de321e1c342..5045e22367cf 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -103,9 +103,10 @@ 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 the BAR is not reserved or disabled, return it. */
 		if (epc_features->bar[i].type != BAR_RESERVED &&
-		    epc_features->bar[i].type != BAR_64BIT_UPPER)
+		    epc_features->bar[i].type != BAR_64BIT_UPPER &&
+		    epc_features->bar[i].type != BAR_DISABLED)
 			return i;
 	}
 
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index f7f48f43d370..8687b9c3462b 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -191,7 +191,14 @@ 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 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.
  * @BAR_64BIT_UPPER: Should only be set on a BAR if the preceding BAR is marked
  *		     as only_64bit.
  */
@@ -200,6 +207,7 @@ enum pci_epc_bar_type {
 	BAR_FIXED,
 	BAR_RESIZABLE,
 	BAR_RESERVED,
+	BAR_DISABLED,
 	BAR_64BIT_UPPER,
 };
 
@@ -238,7 +246,7 @@ struct pci_epc_bar_rsvd_region {
  *
  *		only_64bit should not be set on a BAR of type BAR_RESERVED.
  *		(If BARx is a 64-bit BAR that an EPF driver is not allowed to
- *		touch, then both BARx and BARx+1 must be set to type
+ *		reprogram, then both BARx and BARx+1 must be set to type
  *		BAR_RESERVED.)
  * @nr_rsvd_regions: number of fixed subregions described for BAR_RESERVED
  * @rsvd_regions: fixed subregions behind BAR_RESERVED
-- 
2.53.0