[PATCH 1/2] pci: Add dev_flags bit to access VPD through function 0

[Mark D Rustad <mark.d.rustad@intel.com>]

Add a dev_flags bit, PCI_DEV_FLAGS_VPD_REF_F0, to access VPD through
function 0 to provide VPD access on other functions. This solves
concurrent access problems on many devices without changing the
attributes exposed in sysfs. Never set this bit on funciton 0 or
there will be an infinite recursion.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
---
 drivers/pci/access.c |   39 ++++++++++++++++++++++++++++++++++++++-
 include/linux/pci.h  |    2 ++
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index d9b64a175990..e435c087c354 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -439,6 +439,40 @@ static const struct pci_vpd_ops pci_vpd_pci22_ops = {
 	.release = pci_vpd_pci22_release,
 };
 
+static ssize_t pci_vpd_f0_read(struct pci_dev *dev, loff_t pos, size_t count,
+			       void *arg)
+{
+	struct pci_dev *tdev = pci_get_slot(dev->bus, PCI_SLOT(dev->devfn));
+	ssize_t ret;
+
+	if (!tdev)
+		return -ENODEV;
+
+	ret = pci_read_vpd(tdev, pos, count, arg);
+	pci_dev_put(tdev);
+	return ret;
+}
+
+static ssize_t pci_vpd_f0_write(struct pci_dev *dev, loff_t pos, size_t count,
+				const void *arg)
+{
+	struct pci_dev *tdev = pci_get_slot(dev->bus, PCI_SLOT(dev->devfn));
+	ssize_t ret;
+
+	if (!tdev)
+		return -ENODEV;
+
+	ret = pci_write_vpd(tdev, pos, count, arg);
+	pci_dev_put(tdev);
+	return ret;
+}
+
+static const struct pci_vpd_ops pci_vpd_f0_ops = {
+	.read = pci_vpd_f0_read,
+	.write = pci_vpd_f0_write,
+	.release = pci_vpd_pci22_release,
+};
+
 int pci_vpd_pci22_init(struct pci_dev *dev)
 {
 	struct pci_vpd_pci22 *vpd;
@@ -452,7 +486,10 @@ int pci_vpd_pci22_init(struct pci_dev *dev)
 		return -ENOMEM;
 
 	vpd->base.len = PCI_VPD_PCI22_SIZE;
-	vpd->base.ops = &pci_vpd_pci22_ops;
+	if (dev->dev_flags & PCI_DEV_FLAGS_VPD_REF_F0)
+		vpd->base.ops = &pci_vpd_f0_ops;
+	else
+		vpd->base.ops = &pci_vpd_pci22_ops;
 	mutex_init(&vpd->lock);
 	vpd->cap = cap;
 	vpd->busy = false;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 353db8dc4c6e..194df6d635e6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -180,6 +180,8 @@ enum pci_dev_flags {
 	PCI_DEV_FLAGS_NO_BUS_RESET = (__force pci_dev_flags_t) (1 << 6),
 	/* Do not use PM reset even if device advertises NoSoftRst- */
 	PCI_DEV_FLAGS_NO_PM_RESET = (__force pci_dev_flags_t) (1 << 7),
+	/* Get VPD from function 0 VPD */
+	PCI_DEV_FLAGS_VPD_REF_F0 = (__force pci_dev_flags_t) (1 << 8),
 };
 
 enum pci_irq_reroute_variant {