[PATCH 4/4] PCI: save/restore max Latency Value for device LTR

[Xudong Hao <xudong.hao@xxxxxxxxx>]

LTR: Save Max snoop/no-snoop Latency Value in pci_save_pcie_state, and restore
them in pci_restore_pcie_state.

Signed-off-by: Xudong Hao <xudong.hao@xxxxxxxxx>
---
 drivers/pci/pci.c   |   71 ++++++++++++++++++++++++++++++++++++++++++++++++---
 drivers/pci/probe.c |    5 +++-
 2 files changed, 71 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 35127c1..7172f15 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -912,6 +912,54 @@ static void pci_restore_pcie_state(struct pci_dev *dev)
 		pci_write_config_word(dev, pos + PCI_EXP_SLTCTL2, cap[i++]);
 }
 
+#define PCI_LTR_SAVE_REGS	2
+
+static int pci_save_ltr_value(struct pci_dev *dev)
+{
+	int i = 0, pos;
+	struct pci_cap_saved_state *save_state;
+	u16 *cap;
+	u16 ctrl;
+
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
+	if (!pos)
+		return -ENOTSUPP;
+
+	/* Check if LTR is eanbled before save value */
+	pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &ctrl);
+	if (!(ctrl & PCI_EXP_LTR_EN))
+		return -ENOTSUPP;
+
+	save_state = pci_find_saved_cap(dev, PCI_EXT_CAP_ID_LTR);
+	if (!save_state) {
+		dev_err(&dev->dev, "buffer not found in %s\n", __func__);
+		return -ENOMEM;
+	}
+	cap = (u16 *)&save_state->cap.data[0];
+
+	pci_read_config_word(dev, pos + PCI_LTR_MAX_SNOOP_LAT, &cap[i++]);
+	pci_read_config_word(dev, pos + PCI_LTR_MAX_NOSNOOP_LAT, &cap[i++]);
+	return 0;
+}
+
+static void pci_restore_ltr_value(struct pci_dev *dev)
+{
+	int i = 0, pos;
+	struct pci_cap_saved_state *save_state;
+	u16 *cap;
+
+	if (!pci_ltr_supported(dev))
+		return;
+
+	save_state = pci_find_saved_cap(dev, PCI_EXT_CAP_ID_LTR);
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
+	if (!save_state || !pos)
+		return;
+	cap = (u16 *)&save_state->cap.data[0];
+
+	pci_write_config_word(dev, pos + PCI_LTR_MAX_SNOOP_LAT, cap[i++]);
+	pci_write_config_word(dev, pos + PCI_LTR_MAX_NOSNOOP_LAT, cap[i++]);
+}
 
 static int pci_save_pcix_state(struct pci_dev *dev)
 {
@@ -966,6 +1014,11 @@ pci_save_state(struct pci_dev *dev)
 		return i;
 	if ((i = pci_save_pcix_state(dev)) != 0)
 		return i;
+
+	if (pci_ltr_supported(dev))
+		if ((i = pci_save_ltr_value(dev)) != 0)
+			return i;
+
 	return 0;
 }
 
@@ -1034,6 +1087,7 @@ void pci_restore_state(struct pci_dev *dev)
 	pci_restore_pcix_state(dev);
 	pci_restore_msi_state(dev);
 	pci_restore_iov_state(dev);
+	pci_restore_ltr_value(dev);
 
 	dev->state_saved = false;
 }
@@ -1955,12 +2009,15 @@ static void pci_add_saved_cap(struct pci_dev *pci_dev,
  * @size: requested size of the buffer
  */
 static int pci_add_cap_save_buffer(
-	struct pci_dev *dev, char cap, unsigned int size)
+	struct pci_dev *dev, char cap, unsigned int size, bool is_extcap)
 {
 	int pos;
 	struct pci_cap_saved_state *save_state;
 
-	pos = pci_find_capability(dev, cap);
+	if (is_extcap)
+		pos = pci_find_ext_capability(dev, cap);
+	else
+		pos = pci_find_capability(dev, cap);
 	if (pos <= 0)
 		return 0;
 
@@ -1984,15 +2041,21 @@ void pci_allocate_cap_save_buffers(struct pci_dev *dev)
 	int error;
 
 	error = pci_add_cap_save_buffer(dev, PCI_CAP_ID_EXP,
-					PCI_EXP_SAVE_REGS * sizeof(u16));
+					PCI_EXP_SAVE_REGS * sizeof(u16), 0);
 	if (error)
 		dev_err(&dev->dev,
 			"unable to preallocate PCI Express save buffer\n");
 
-	error = pci_add_cap_save_buffer(dev, PCI_CAP_ID_PCIX, sizeof(u16));
+	error = pci_add_cap_save_buffer(dev, PCI_CAP_ID_PCIX, sizeof(u16), 0);
 	if (error)
 		dev_err(&dev->dev,
 			"unable to preallocate PCI-X save buffer\n");
+
+	error = pci_add_cap_save_buffer(dev, PCI_EXT_CAP_ID_LTR,
+					PCI_LTR_SAVE_REGS * sizeof(u16), 1);
+	if (error)
+		dev_err(&dev->dev,
+			"unable to preallocate LTR save buffer\n");
 }
 
 void pci_free_cap_save_buffers(struct pci_dev *dev)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 658ac97..a6eb509 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1232,7 +1232,10 @@ static void pci_init_capabilities(struct pci_dev *dev)
 	/* MSI/MSI-X list */
 	pci_msi_init_pci_dev(dev);
 
-	/* Buffers for saving PCIe and PCI-X capabilities */
+	/* 
+	 * Buffers for saving PCIe and PCI-X capabilities
+	 * and for saving LTR extented capabilities.
+	 */
 	pci_allocate_cap_save_buffers(dev);
 
 	/* Power Management */
-- 
1.5.5

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