linux-kernel - [PATCH v4 1/9] PCI/PTM: Cache PTM Capability offset

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Date:   Fri,  9 Sep 2022 15:24:57 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Rajvi Jingar <rajvi.jingar@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     Koba Ko <koba.ko@...onical.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "David E . Box" <david.e.box@...ux.intel.com>,
        Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v4 1/9] PCI/PTM: Cache PTM Capability offset

From: Bjorn Helgaas <bhelgaas@...gle.com>

Cache the PTM Capability offset instead of searching for it every time we
enable/disable PTM or save/restore PTM state.  No functional change
intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/pci/pcie/ptm.c | 41 +++++++++++++++++------------------------
 include/linux/pci.h    |  1 +
 2 files changed, 18 insertions(+), 24 deletions(-)

diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
index 368a254e3124..85382c135885 100644
--- a/drivers/pci/pcie/ptm.c
+++ b/drivers/pci/pcie/ptm.c
@@ -31,13 +31,9 @@ static void pci_ptm_info(struct pci_dev *dev)
 
 void pci_disable_ptm(struct pci_dev *dev)
 {
-	int ptm;
+	u16 ptm = dev->ptm_cap;
 	u16 ctrl;
 
-	if (!pci_is_pcie(dev))
-		return;
-
-	ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
 	if (!ptm)
 		return;
 
@@ -48,14 +44,10 @@ void pci_disable_ptm(struct pci_dev *dev)
 
 void pci_save_ptm_state(struct pci_dev *dev)
 {
-	int ptm;
+	u16 ptm = dev->ptm_cap;
 	struct pci_cap_saved_state *save_state;
 	u16 *cap;
 
-	if (!pci_is_pcie(dev))
-		return;
-
-	ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
 	if (!ptm)
 		return;
 
@@ -69,16 +61,15 @@ void pci_save_ptm_state(struct pci_dev *dev)
 
 void pci_restore_ptm_state(struct pci_dev *dev)
 {
+	u16 ptm = dev->ptm_cap;
 	struct pci_cap_saved_state *save_state;
-	int ptm;
 	u16 *cap;
 
-	if (!pci_is_pcie(dev))
+	if (!ptm)
 		return;
 
 	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM);
-	ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
-	if (!save_state || !ptm)
+	if (!save_state)
 		return;
 
 	cap = (u16 *)&save_state->cap.data[0];
@@ -87,7 +78,7 @@ void pci_restore_ptm_state(struct pci_dev *dev)
 
 void pci_ptm_init(struct pci_dev *dev)
 {
-	int pos;
+	u16 ptm;
 	u32 cap, ctrl;
 	u8 local_clock;
 	struct pci_dev *ups;
@@ -117,13 +108,14 @@ void pci_ptm_init(struct pci_dev *dev)
 		return;
 	}
 
-	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
-	if (!pos)
+	ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
+	if (!ptm)
 		return;
 
+	dev->ptm_cap = ptm;
 	pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_PTM, sizeof(u16));
 
-	pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);
+	pci_read_config_dword(dev, ptm + PCI_PTM_CAP, &cap);
 	local_clock = (cap & PCI_PTM_GRANULARITY_MASK) >> 8;
 
 	/*
@@ -148,7 +140,7 @@ void pci_ptm_init(struct pci_dev *dev)
 	}
 
 	ctrl |= dev->ptm_granularity << 8;
-	pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl);
+	pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl);
 	dev->ptm_enabled = 1;
 
 	pci_ptm_info(dev);
@@ -156,18 +148,19 @@ void pci_ptm_init(struct pci_dev *dev)
 
 int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
 {
-	int pos;
+	u16 ptm;
 	u32 cap, ctrl;
 	struct pci_dev *ups;
 
 	if (!pci_is_pcie(dev))
 		return -EINVAL;
 
-	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
-	if (!pos)
+	ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
+	if (!ptm)
 		return -EINVAL;
 
-	pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);
+	dev->ptm_cap = ptm;
+	pci_read_config_dword(dev, ptm + PCI_PTM_CAP, &cap);
 	if (!(cap & PCI_PTM_CAP_REQ))
 		return -EINVAL;
 
@@ -192,7 +185,7 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
 
 	ctrl = PCI_PTM_CTRL_ENABLE;
 	ctrl |= dev->ptm_granularity << 8;
-	pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl);
+	pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl);
 	dev->ptm_enabled = 1;
 
 	pci_ptm_info(dev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 060af91bafcd..54be939023a3 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -475,6 +475,7 @@ struct pci_dev {
 	unsigned int	broken_cmd_compl:1;	/* No compl for some cmds */
 #endif
 #ifdef CONFIG_PCIE_PTM
+	u16		ptm_cap;		/* PTM Capability */
 	unsigned int	ptm_root:1;
 	unsigned int	ptm_enabled:1;
 	u8		ptm_granularity;
-- 
2.25.1