PCI: Add defines for TLP Header/Prefix log sizes

Add defines for AER and DPC capabilities TLP Header Logging register sizes
(PCIe r6.2, sec 7.8.4 / 7.9.14) and replace literals with them.

Link: https://lore.kernel.org/r/20250114170840.1633-4-ilpo.jarvinen@linux.intel.com
Suggested-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Author: ij-intel

drivers/pci/pcie/dpc.c

@@ -215,18 +215,18 @@ static void dpc_process_rp_pio_error(struct pci_dev *pdev)
 				first_error == i ? " (First)" : "");
 	}
 
-	if (pdev->dpc_rp_log_size < 4)
+	if (pdev->dpc_rp_log_size < PCIE_STD_NUM_TLP_HEADERLOG)
 		goto clear_status;
 	pcie_read_tlp_log(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG, &tlp_log);
 	pci_err(pdev, "TLP Header: %#010x %#010x %#010x %#010x\n",
 		tlp_log.dw[0], tlp_log.dw[1], tlp_log.dw[2], tlp_log.dw[3]);
 
-	if (pdev->dpc_rp_log_size < 5)
+	if (pdev->dpc_rp_log_size < PCIE_STD_NUM_TLP_HEADERLOG + 1)
 		goto clear_status;
 	pci_read_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_IMPSPEC_LOG, &log);
 	pci_err(pdev, "RP PIO ImpSpec Log %#010x\n", log);
 
-	for (i = 0; i < pdev->dpc_rp_log_size - 5; i++) {
+	for (i = 0; i < pdev->dpc_rp_log_size - PCIE_STD_NUM_TLP_HEADERLOG - 1; i++) {
 		pci_read_config_dword(pdev,
 			cap + PCI_EXP_DPC_RP_PIO_TLPPREFIX_LOG + i * 4, &prefix);
 		pci_err(pdev, "TLP Prefix Header: dw%d, %#010x\n", i, prefix);
@@ -404,7 +404,9 @@ void pci_dpc_init(struct pci_dev *pdev)
 	if (!pdev->dpc_rp_log_size) {
 		pdev->dpc_rp_log_size =
 				FIELD_GET(PCI_EXP_DPC_RP_PIO_LOG_SIZE, cap);
-		if (pdev->dpc_rp_log_size < 4 || pdev->dpc_rp_log_size > 9) {
+		if (pdev->dpc_rp_log_size < PCIE_STD_NUM_TLP_HEADERLOG ||
+		    pdev->dpc_rp_log_size > PCIE_STD_NUM_TLP_HEADERLOG + 1 +
+					    PCIE_STD_MAX_TLP_PREFIXLOG) {
 			pci_err(pdev, "RP PIO log size %u is invalid\n",
 				pdev->dpc_rp_log_size);
 			pdev->dpc_rp_log_size = 0;

drivers/pci/pcie/tlp.c

@@ -28,7 +28,7 @@ int pcie_read_tlp_log(struct pci_dev *dev, int where,
 
 	memset(tlp_log, 0, sizeof(*tlp_log));
 
-	for (i = 0; i < 4; i++) {
+	for (i = 0; i < PCIE_STD_NUM_TLP_HEADERLOG; i++) {
 		ret = pci_read_config_dword(dev, where + i * 4,
 					    &tlp_log->dw[i]);
 		if (ret)

drivers/pci/quirks.c

@@ -12,6 +12,7 @@
  * file, where their drivers can use them.
  */
 
+#include <linux/aer.h>
 #include <linux/align.h>
 #include <linux/bitfield.h>
 #include <linux/types.h>
@@ -6233,8 +6234,9 @@ static void dpc_log_size(struct pci_dev *dev)
 		return;
 
 	if (FIELD_GET(PCI_EXP_DPC_RP_PIO_LOG_SIZE, val) == 0) {
-		pci_info(dev, "Overriding RP PIO Log Size to 4\n");
-		dev->dpc_rp_log_size = 4;
+		pci_info(dev, "Overriding RP PIO Log Size to %d\n",
+			 PCIE_STD_NUM_TLP_HEADERLOG);
+		dev->dpc_rp_log_size = PCIE_STD_NUM_TLP_HEADERLOG;
 	}
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x461f, dpc_log_size);

include/linux/aer.h

@@ -16,10 +16,17 @@
 #define AER_CORRECTABLE			2
 #define DPC_FATAL			3
 
+/*
+ * AER and DPC capabilities TLP Logging register sizes (PCIe r6.2, sec 7.8.4
+ * & 7.9.14).
+ */
+#define PCIE_STD_NUM_TLP_HEADERLOG     4
+#define PCIE_STD_MAX_TLP_PREFIXLOG     4
+
 struct pci_dev;
 
 struct pcie_tlp_log {
-	u32 dw[4];
+	u32 dw[PCIE_STD_NUM_TLP_HEADERLOG];
 };
 
 struct aer_capability_regs {