From 6107e5cb907cffc5576cc1297847f9fc69a8d5d9 Mon Sep 17 00:00:00 2001

From: Heiner Kallweit <hkallweit1@gmail.com>

Date: Fri, 20 Aug 2021 15:32:42 -0500

Subject: [PATCH] PCI/VPD: Add pci_vpd_check_csum()

Git-commit: 6107e5cb907cffc5576cc1297847f9fc69a8d5d9

References: git-fixes

Patch-mainline: v5.15-rc1

VPD checksum information and checksum calculation are specified by PCIe

r5.0, sec 6.28.2.2.  Therefore checksum handling can and should be moved

into the PCI VPD core.

Add pci_vpd_check_csum() to validate the VPD checksum.

[bhelgaas: split to separate patch]

Link: https://lore.kernel.org/r/1643bd7a-088e-1028-c9b0-9d112cf48d63@gmail.com

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Signed-off-by: Oliver Neukum <oneukum@suse.com>

---

 drivers/pci/vpd.c   | 23 +++++++++++++++++++++++

 include/linux/pci.h |  9 +++++++++

 2 files changed, 32 insertions(+)

diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c

index b1d012900f1e..01e57594781e 100644

--- a/drivers/pci/vpd.c

+++ b/drivers/pci/vpd.c

@@ -413,6 +413,29 @@ int pci_vpd_find_ro_info_keyword(const void *buf, unsigned int len,

 }

 EXPORT_SYMBOL_GPL(pci_vpd_find_ro_info_keyword);

+int pci_vpd_check_csum(const void *buf, unsigned int len)

+{

+	const u8 *vpd = buf;

+	unsigned int size;

+	u8 csum = 0;

+	int rv_start;

+

+	rv_start = pci_vpd_find_ro_info_keyword(buf, len, PCI_VPD_RO_KEYWORD_CHKSUM, &size);

+	if (rv_start == -ENOENT) /* no checksum in VPD */

+		return 1;

+	else if (rv_start < 0)

+		return rv_start;

+

+	if (!size)

+		return -EINVAL;

+

+	while (rv_start >= 0)

+		csum += vpd[rv_start--];

+

+	return csum ? -EILSEQ : 0;

+}

+EXPORT_SYMBOL_GPL(pci_vpd_check_csum);

+

 #ifdef CONFIG_PCI_QUIRKS

 /*

  * Quirk non-zero PCI functions to route VPD access through function 0 for

diff --git a/include/linux/pci.h b/include/linux/pci.h

index 9e3b60963a52..827b7eefd550 100644

--- a/include/linux/pci.h

+++ b/include/linux/pci.h

@@ -2376,6 +2376,15 @@ int pci_vpd_find_info_keyword(const u8 *buf, unsigned int off,

 int pci_vpd_find_ro_info_keyword(const void *buf, unsigned int len,

 				 const char *kw, unsigned int *size);

+/**

+ * pci_vpd_check_csum - Check VPD checksum

+ * @buf: Pointer to buffered VPD data

+ * @len: VPD size

+ *

+ * Returns 1 if VPD has no checksum, otherwise 0 or an errno

+ */

+int pci_vpd_check_csum(const void *buf, unsigned int len);

+

 /* PCI <-> OF binding helpers */

 #ifdef CONFIG_OF

 struct device_node;

-- 

2.26.2