PCI: endpoint: Clean up hardware description for BARs

The hardware description for BARs is scattered in many different variables
in pci_epc_features. Some of these things are mutually exclusive, so it
can create confusion over which variable that has precedence over another.

Improve the situation by creating a struct pci_epc_bar_desc, and a new
enum pci_epc_bar_type, and convert the endpoint controller drivers to use
this more well defined format.

Additionally, some endpoint controller drivers mark the BAR succeeding a
"64-bit only BAR" as reserved, while some do not. By definition, a 64-bit
BAR uses the succeeding BAR for the upper 32-bits, so an EPF driver cannot
use a BAR succeeding a 64-bit BAR. Ensure that all endpoint controller
drivers are uniform, and actually describe a reserved BAR as reserved.

Signed-off-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Kishon Vijay Abraham I <kishon@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20240216134524.1142149-2-cassel@kernel.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

1 files changed, 28 insertions, 6 deletions

diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index 40ea18f5aa02..4ccb4f4f3883 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -146,15 +146,39 @@ struct pci_epc {
 };
 
 /**
+ * @BAR_PROGRAMMABLE: The BAR mask can be configured by the EPC.
+ * @BAR_FIXED: The BAR mask is fixed by the hardware.
+ * @BAR_RESERVED: The BAR should not be touched by an EPF driver.
+ */
+enum pci_epc_bar_type {
+	BAR_PROGRAMMABLE = 0,
+	BAR_FIXED,
+	BAR_RESERVED,
+};
+
+/**
+ * struct pci_epc_bar_desc - hardware description for a BAR
+ * @type: the type of the BAR
+ * @fixed_size: the fixed size, only applicable if type is BAR_FIXED_MASK.
+ * @only_64bit: if true, an EPF driver is not allowed to choose if this BAR
+ *		should be configured as 32-bit or 64-bit, the EPF driver must
+ *		configure this BAR as 64-bit. Additionally, the BAR succeeding
+ *		this BAR must be set to type BAR_RESERVED.
+ */
+struct pci_epc_bar_desc {
+	enum pci_epc_bar_type type;
+	u64 fixed_size;
+	bool only_64bit;
+};
+
+/**
  * struct pci_epc_features - features supported by a EPC device per function
  * @linkup_notifier: indicate if the EPC device can notify EPF driver on link up
  * @core_init_notifier: indicate cores that can notify about their availability
  *			for initialization
  * @msi_capable: indicate if the endpoint function has MSI capability
  * @msix_capable: indicate if the endpoint function has MSI-X capability
- * @reserved_bar: bitmap to indicate reserved BAR unavailable to function driver
- * @bar_fixed_64bit: bitmap to indicate fixed 64bit BARs
- * @bar_fixed_size: Array specifying the size supported by each BAR
+ * @bar: array specifying the hardware description for each BAR
  * @align: alignment size required for BAR buffer allocation
  */
 struct pci_epc_features {
@@ -162,9 +186,7 @@ struct pci_epc_features {
 	unsigned int	core_init_notifier : 1;
 	unsigned int	msi_capable : 1;
 	unsigned int	msix_capable : 1;
-	u8	reserved_bar;
-	u8	bar_fixed_64bit;
-	u64	bar_fixed_size[PCI_STD_NUM_BARS];
+	struct	pci_epc_bar_desc bar[PCI_STD_NUM_BARS];
 	size_t	align;
 };