[PATCH 3/4] PCI: Use cached MSI cap while enabling MSI interrupts

[Gavin Shan <shangw@linux.vnet.ibm.com>]

The patch intends to use the cached MSI capability offset in
pci_dev instead of polling that from config space when enabling
MSI interrupts.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
---
 drivers/pci/msi.c |   32 +++++++++++++++-----------------
 drivers/pci/msi.h |    1 -
 2 files changed, 15 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 1ec1ba9..449db36 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -299,10 +299,10 @@ void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
 		int pos = entry->msi_attrib.pos;
 		u16 msgctl;
 
-		pci_read_config_word(dev, msi_control_reg(pos), &msgctl);
+		pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &msgctl);
 		msgctl &= ~PCI_MSI_FLAGS_QSIZE;
 		msgctl |= entry->msi_attrib.multiple << 4;
-		pci_write_config_word(dev, msi_control_reg(pos), msgctl);
+		pci_write_config_word(dev, pos + PCI_MSI_FLAGS, msgctl);
 
 		pci_write_config_dword(dev, msi_lower_address_reg(pos),
 					msg->address_lo);
@@ -546,14 +546,14 @@ out_unroll:
 static int msi_capability_init(struct pci_dev *dev, int nvec)
 {
 	struct msi_desc *entry;
-	int pos, ret;
+	int ret;
 	u16 control;
 	unsigned mask;
 
-	pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
-	msi_set_enable(dev, 0);	/* Disable MSI during set up */
+	/* Disable MSI during set up */
+	msi_set_enable(dev, 0);
 
-	pci_read_config_word(dev, msi_control_reg(pos), &control);
+	pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);
 	/* MSI Entry Initialization */
 	entry = alloc_msi_entry(dev);
 	if (!entry)
@@ -564,9 +564,9 @@ static int msi_capability_init(struct pci_dev *dev, int nvec)
 	entry->msi_attrib.entry_nr	= 0;
 	entry->msi_attrib.maskbit	= is_mask_bit_support(control);
 	entry->msi_attrib.default_irq	= dev->irq;	/* Save IOAPIC IRQ */
-	entry->msi_attrib.pos		= pos;
+	entry->msi_attrib.pos		= dev->msi_cap;
 
-	entry->mask_pos = msi_mask_reg(pos, entry->msi_attrib.is_64);
+	entry->mask_pos = msi_mask_reg(dev->msi_cap, entry->msi_attrib.is_64);
 	/* All MSIs are unmasked by default, Mask them all */
 	if (entry->msi_attrib.maskbit)
 		pci_read_config_dword(dev, entry->mask_pos, &entry->masked);
@@ -807,13 +807,12 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type)
  */
 int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec)
 {
-	int status, pos, maxvec;
+	int status, maxvec;
 	u16 msgctl;
 
-	pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
-	if (!pos)
+	if (!dev->msi_cap)
 		return -EINVAL;
-	pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &msgctl);
+	pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl);
 	maxvec = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1);
 	if (nvec > maxvec)
 		return maxvec;
@@ -838,14 +837,13 @@ EXPORT_SYMBOL(pci_enable_msi_block);
 
 int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec)
 {
-	int ret, pos, nvec;
+	int ret, nvec;
 	u16 msgctl;
 
-	pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
-	if (!pos)
+	if (!dev->msi_cap)
 		return -EINVAL;
 
-	pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &msgctl);
+	pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl);
 	ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1);
 
 	if (maxvec)
@@ -915,7 +913,7 @@ int pci_msix_table_size(struct pci_dev *dev)
 	if (!pos)
 		return 0;
 
-	pci_read_config_word(dev, msi_control_reg(pos), &control);
+	pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &control);
 	return multi_msix_capable(control);
 }
 
diff --git a/drivers/pci/msi.h b/drivers/pci/msi.h
index 65c42f8..6aa7b19 100644
--- a/drivers/pci/msi.h
+++ b/drivers/pci/msi.h
@@ -6,7 +6,6 @@
 #ifndef MSI_H
 #define MSI_H
 
-#define msi_control_reg(base)		(base + PCI_MSI_FLAGS)
 #define msi_lower_address_reg(base)	(base + PCI_MSI_ADDRESS_LO)
 #define msi_upper_address_reg(base)	(base + PCI_MSI_ADDRESS_HI)
 #define msi_data_reg(base, is64bit)	\
-- 
1.7.5.4