[PATCH v2 2/4] PCI: Cache ACS capabilities

[Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>]

ACS capabilities are the RO values set by the hardware. Cache them to avoid
reading it all the time when required and also to override any capability
in quirks.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/pci/pci.c   | 26 +++++++++++++++-----------
 include/linux/pci.h |  1 +
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 9f594fc6dade..4eb5b487c982 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -892,7 +892,6 @@ static const char *disable_acs_redir_param;
 static const char *config_acs_param;
 
 struct pci_acs {
-	u16 cap;
 	u16 ctrl;
 	u16 fw_ctrl;
 };
@@ -995,27 +994,27 @@ static void __pci_config_acs(struct pci_dev *dev, struct pci_acs *caps,
 static void pci_std_enable_acs(struct pci_dev *dev, struct pci_acs *caps)
 {
 	/* Source Validation */
-	caps->ctrl |= (caps->cap & PCI_ACS_SV);
+	caps->ctrl |= (dev->acs_capabilities & PCI_ACS_SV);
 
 	/* P2P Request Redirect */
-	caps->ctrl |= (caps->cap & PCI_ACS_RR);
+	caps->ctrl |= (dev->acs_capabilities & PCI_ACS_RR);
 
 	/* P2P Completion Redirect */
-	caps->ctrl |= (caps->cap & PCI_ACS_CR);
+	caps->ctrl |= (dev->acs_capabilities & PCI_ACS_CR);
 
 	/* Upstream Forwarding */
-	caps->ctrl |= (caps->cap & PCI_ACS_UF);
+	caps->ctrl |= (dev->acs_capabilities & PCI_ACS_UF);
 
 	/* Enable Translation Blocking for external devices and noats */
 	if (pci_ats_disabled() || dev->external_facing || dev->untrusted)
-		caps->ctrl |= (caps->cap & PCI_ACS_TB);
+		caps->ctrl |= (dev->acs_capabilities & PCI_ACS_TB);
 }
 
 /**
  * pci_enable_acs - enable ACS if hardware support it
  * @dev: the PCI device
  */
-static void pci_enable_acs(struct pci_dev *dev)
+void pci_enable_acs(struct pci_dev *dev)
 {
 	struct pci_acs caps;
 	bool enable_acs = false;
@@ -1031,7 +1030,6 @@ static void pci_enable_acs(struct pci_dev *dev)
 	if (!pos)
 		return;
 
-	pci_read_config_word(dev, pos + PCI_ACS_CAP, &caps.cap);
 	pci_read_config_word(dev, pos + PCI_ACS_CTRL, &caps.ctrl);
 	caps.fw_ctrl = caps.ctrl;
 
@@ -3543,7 +3541,7 @@ void pci_configure_ari(struct pci_dev *dev)
 static bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags)
 {
 	int pos;
-	u16 cap, ctrl;
+	u16 ctrl;
 
 	pos = pdev->acs_cap;
 	if (!pos)
@@ -3554,8 +3552,7 @@ static bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags)
 	 * or only required if controllable.  Features missing from the
 	 * capability field can therefore be assumed as hard-wired enabled.
 	 */
-	pci_read_config_word(pdev, pos + PCI_ACS_CAP, &cap);
-	acs_flags &= (cap | PCI_ACS_EC);
+	acs_flags &= (pdev->acs_capabilities | PCI_ACS_EC);
 
 	pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl);
 	return (ctrl & acs_flags) == acs_flags;
@@ -3676,7 +3673,14 @@ bool pci_acs_path_enabled(struct pci_dev *start,
  */
 void pci_acs_init(struct pci_dev *dev)
 {
+	int pos;
+
 	dev->acs_cap = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ACS);
+	pos = dev->acs_cap;
+	if (!pos)
+		return;
+
+	pci_read_config_word(dev, pos + PCI_ACS_CAP, &dev->acs_capabilities);
 }
 
 void pci_rebar_init(struct pci_dev *pdev)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index bf97d49c23cf..c6ee1dfdb0fb 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -543,6 +543,7 @@ struct pci_dev {
 	struct npem	*npem;		/* Native PCIe Enclosure Management */
 #endif
 	u16		acs_cap;	/* ACS Capability offset */
+	u16		acs_capabilities; /* ACS Capabilities */
 	u8		supported_speeds; /* Supported Link Speeds Vector */
 	phys_addr_t	rom;		/* Physical address if not from BAR */
 	size_t		romlen;		/* Length if not from BAR */

-- 
2.48.1