pcie_read_tlp_log() handles only 4 Header Log DWORDs but TLP Prefix Log
(PCIe r6.1 secs 7.8.4.12 & 7.9.14.13) may also be present.

Generalize pcie_read_tlp_log() and struct pcie_tlp_log to handle also
TLP Prefix Log. The relevant registers are formatted identically in AER
and DPC Capability, but has these variations:

a) The offsets of TLP Prefix Log registers vary.
b) DPC RP PIO TLP Prefix Log register can be < 4 DWORDs.
c) AER TLP Prefix Log Present (PCIe r6.1 sec 7.8.4.7) can indicate
   Prefix Log is not present.

Therefore callers must pass the offset of the TLP Prefix Log register
and the entire length to pcie_read_tlp_log() to be able to read the
correct number of TLP Prefix DWORDs from the correct offset.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/pci/pci.h             |  5 +++-
 drivers/pci/pcie/aer.c        |  5 +++-
 drivers/pci/pcie/dpc.c        | 13 +++++----
 drivers/pci/pcie/tlp.c        | 50 +++++++++++++++++++++++++++++++----
 include/linux/aer.h           |  1 +
 include/uapi/linux/pci_regs.h | 10 ++++---
 6 files changed, 66 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 55fcf3bac4f7..7797b2544d00 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h

@@ -550,7 +550,9 @@ struct aer_err_info {
 int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info);
 void aer_print_error(struct pci_dev *dev, struct aer_err_info *info);
 
-int pcie_read_tlp_log(struct pci_dev *dev, int where, struct pcie_tlp_log *log);
+int pcie_read_tlp_log(struct pci_dev *dev, int where, int where2,
+		      unsigned int tlp_len, struct pcie_tlp_log *log);
+unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc);
 #endif	/* CONFIG_PCIEAER */
 
 #ifdef CONFIG_PCIEPORTBUS

@@ -569,6 +571,7 @@ void pci_dpc_init(struct pci_dev *pdev);
 void dpc_process_error(struct pci_dev *pdev);
 pci_ers_result_t dpc_reset_link(struct pci_dev *pdev);
 bool pci_dpc_recovered(struct pci_dev *pdev);
+unsigned int dpc_tlp_log_len(struct pci_dev *dev);
 #else
 static inline void pci_save_dpc_state(struct pci_dev *dev) { }
 static inline void pci_restore_dpc_state(struct pci_dev *dev) { }

diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 80c5ba8d8296..656dbf1ac45b 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c

@@ -1248,7 +1248,10 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
 
 		if (info->status & AER_LOG_TLP_MASKS) {
 			info->tlp_header_valid = 1;
-			pcie_read_tlp_log(dev, aer + PCI_ERR_HEADER_LOG, &info->tlp);
+			pcie_read_tlp_log(dev, aer + PCI_ERR_HEADER_LOG,
+					  aer + PCI_ERR_PREFIX_LOG,
+					  aer_tlp_log_len(dev, aercc),
+					  &info->tlp);
 		}
 	}
 

diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index 2b6ef7efa3c1..7933b3cedb59 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c

@@ -190,7 +190,7 @@ pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
 static void dpc_process_rp_pio_error(struct pci_dev *pdev)
 {
 	u16 cap = pdev->dpc_cap, dpc_status, first_error;
-	u32 status, mask, sev, syserr, exc, log, prefix;
+	u32 status, mask, sev, syserr, exc, log;
 	struct pcie_tlp_log tlp_log;
 	int i;
 

@@ -217,20 +217,19 @@ static void dpc_process_rp_pio_error(struct pci_dev *pdev)
 
 	if (pdev->dpc_rp_log_size < 4)
 		goto clear_status;
-	pcie_read_tlp_log(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG, &tlp_log);
+	pcie_read_tlp_log(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG,
+			  cap + PCI_EXP_DPC_RP_PIO_TLPPREFIX_LOG,
+			  dpc_tlp_log_len(pdev), &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]);
+	for (i = 0; i < pdev->dpc_rp_log_size - 5; i++)
+		pci_err(pdev, "TLP Prefix Header: dw%d, %#010x\n", i, tlp_log.prefix[i]);
 
 	if (pdev->dpc_rp_log_size < 5)
 		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++) {
-		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);
-	}
  clear_status:
 	pci_write_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_STATUS, status);
 }

diff --git a/drivers/pci/pcie/tlp.c b/drivers/pci/pcie/tlp.c
index 65ac7b5d8a87..0c4bf6a50d7e 100644
--- a/drivers/pci/pcie/tlp.c
+++ b/drivers/pci/pcie/tlp.c

@@ -11,26 +11,66 @@
 
 #include "../pci.h"
 
+/**
+ * aer_tlp_log_len - Calculates AER Capability TLP Header/Prefix Log length
+ * @dev: PCIe device
+ *
+ * Return: TLP Header/Prefix Log length
+ */
+unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc)