[PATCH] htirq: refactor so we only have one function that writes to the chip

This refactoring actually optimizes the code a little by caching the value
that we think the device is programmed with instead of reading it back from
the hardware.  Which simplifies the code a little and should speed things up a
bit.

This patch introduces the concept of a ht_irq_msg and modifies the
architecture read/write routines to update this code.

There is a minor consistency fix here as well as x86_64 forgot to initialize
the htirq as masked.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>
Acked-by: Bryan O'Sullivan <bos@pathscale.com>
Cc: <olson@pathscale.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 58 insertions, 82 deletions

diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index 507983c..ad84bc2 100644
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -2624,18 +2624,16 @@ void arch_teardown_msi_irq(unsigned int irq)
 
 static void target_ht_irq(unsigned int irq, unsigned int dest)
 {
-	u32 low, high;
-	low  = read_ht_irq_low(irq);
-	high = read_ht_irq_high(irq);
+	struct ht_irq_msg msg;
+	fetch_ht_irq_msg(irq, &msg);
 
-	low  &= ~(HT_IRQ_LOW_DEST_ID_MASK);
-	high &= ~(HT_IRQ_HIGH_DEST_ID_MASK);
+	msg.address_lo &= ~(HT_IRQ_LOW_DEST_ID_MASK);
+	msg.address_hi &= ~(HT_IRQ_HIGH_DEST_ID_MASK);
 
-	low  |= HT_IRQ_LOW_DEST_ID(dest);
-	high |= HT_IRQ_HIGH_DEST_ID(dest);
+	msg.address_lo |= HT_IRQ_LOW_DEST_ID(dest);
+	msg.address_hi |= HT_IRQ_HIGH_DEST_ID(dest);
 
-	write_ht_irq_low(irq, low);
-	write_ht_irq_high(irq, high);
+	write_ht_irq_msg(irq, &msg);
 }
 
 static void set_ht_irq_affinity(unsigned int irq, cpumask_t mask)
@@ -2673,7 +2671,7 @@ int arch_setup_ht_irq(unsigned int irq, struct pci_dev *dev)
 
 	vector = assign_irq_vector(irq);
 	if (vector >= 0) {
-		u32 low, high;
+		struct ht_irq_msg msg;
 		unsigned dest;
 		cpumask_t tmp;
 
@@ -2681,9 +2679,10 @@ int arch_setup_ht_irq(unsigned int irq, struct pci_dev *dev)
 		cpu_set(vector >> 8, tmp);
 		dest = cpu_mask_to_apicid(tmp);
 
-		high = 	HT_IRQ_HIGH_DEST_ID(dest);
+		msg.address_hi = HT_IRQ_HIGH_DEST_ID(dest);
 
-		low =	HT_IRQ_LOW_BASE |
+		msg.address_lo =
+			HT_IRQ_LOW_BASE |
 			HT_IRQ_LOW_DEST_ID(dest) |
 			HT_IRQ_LOW_VECTOR(vector) |
 			((INT_DEST_MODE == 0) ?
@@ -2695,8 +2694,7 @@ int arch_setup_ht_irq(unsigned int irq, struct pci_dev *dev)
 				HT_IRQ_LOW_MT_ARBITRATED) |
 			HT_IRQ_LOW_IRQ_MASKED;
 
-		write_ht_irq_low(irq, low);
-		write_ht_irq_high(irq, high);
+		write_ht_irq_msg(irq, &msg);
 
 		set_irq_chip_and_handler_name(irq, &ht_irq_chip,
 					      handle_edge_irq, "edge");
diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c
index 3b8f9c6..41bfc49 100644
--- a/arch/x86_64/kernel/io_apic.c
+++ b/arch/x86_64/kernel/io_apic.c
@@ -1955,18 +1955,16 @@ void arch_teardown_msi_irq(unsigned int irq)
 
 static void target_ht_irq(unsigned int irq, unsigned int dest, u8 vector)
 {
-	u32 low, high;
-	low  = read_ht_irq_low(irq);
-	high = read_ht_irq_high(irq);
+	struct ht_irq_msg msg;
+	fetch_ht_irq_msg(irq, &msg);
 
-	low  &= ~(HT_IRQ_LOW_VECTOR_MASK | HT_IRQ_LOW_DEST_ID_MASK);
-	high &= ~(HT_IRQ_HIGH_DEST_ID_MASK);
+	msg.address_lo &= ~(HT_IRQ_LOW_VECTOR_MASK | HT_IRQ_LOW_DEST_ID_MASK);
+	msg.address_hi &= ~(HT_IRQ_HIGH_DEST_ID_MASK);
 
-	low  |= HT_IRQ_LOW_VECTOR(vector) | HT_IRQ_LOW_DEST_ID(dest);
-	high |= HT_IRQ_HIGH_DEST_ID(dest);
+	msg.address_lo |= HT_IRQ_LOW_VECTOR(vector) | HT_IRQ_LOW_DEST_ID(dest);
+	msg.address_hi |= HT_IRQ_HIGH_DEST_ID(dest);
 
-	write_ht_irq_low(irq, low);
-	write_ht_irq_high(irq, high);
+	write_ht_irq_msg(irq, &msg);
 }
 
 static void set_ht_irq_affinity(unsigned int irq, cpumask_t mask)
@@ -1987,7 +1985,7 @@ static void set_ht_irq_affinity(unsigned int irq, cpumask_t mask)
 
 	dest = cpu_mask_to_apicid(tmp);
 
-	target_ht_irq(irq, dest, vector & 0xff);
+	target_ht_irq(irq, dest, vector);
 	set_native_irq_info(irq, mask);
 }
 #endif
@@ -2010,14 +2008,15 @@ int arch_setup_ht_irq(unsigned int irq, struct pci_dev *dev)
 
 	vector = assign_irq_vector(irq, TARGET_CPUS, &tmp);
 	if (vector >= 0) {
-		u32 low, high;
+		struct ht_irq_msg msg;
 		unsigned dest;
 
 		dest = cpu_mask_to_apicid(tmp);
 
-		high = 	HT_IRQ_HIGH_DEST_ID(dest);
+		msg.address_hi = HT_IRQ_HIGH_DEST_ID(dest);
 
-		low =	HT_IRQ_LOW_BASE |
+		msg.address_lo =
+			HT_IRQ_LOW_BASE |
 			HT_IRQ_LOW_DEST_ID(dest) |
 			HT_IRQ_LOW_VECTOR(vector) |
 			((INT_DEST_MODE == 0) ?
@@ -2026,10 +2025,10 @@ int arch_setup_ht_irq(unsigned int irq, struct pci_dev *dev)
 			HT_IRQ_LOW_RQEOI_EDGE |
 			((INT_DELIVERY_MODE != dest_LowestPrio) ?
 				HT_IRQ_LOW_MT_FIXED :
-				HT_IRQ_LOW_MT_ARBITRATED);
+				HT_IRQ_LOW_MT_ARBITRATED) |
+			HT_IRQ_LOW_IRQ_MASKED;
 
-		write_ht_irq_low(irq, low);
-		write_ht_irq_high(irq, high);
+		write_ht_irq_msg(irq, &msg);
 
 		set_irq_chip_and_handler_name(irq, &ht_irq_chip,
 					      handle_edge_irq, "edge");
diff --git a/drivers/pci/htirq.c b/drivers/pci/htirq.c
index 0e27f24..e346fe3 100644
--- a/drivers/pci/htirq.c
+++ b/drivers/pci/htirq.c
@@ -27,82 +27,55 @@ struct ht_irq_cfg {
 	struct pci_dev *dev;
 	unsigned pos;
 	unsigned idx;
+	struct ht_irq_msg msg;
 };
 
-void write_ht_irq_low(unsigned int irq, u32 data)
-{
-	struct ht_irq_cfg *cfg = get_irq_data(irq);
-	unsigned long flags;
-	spin_lock_irqsave(&ht_irq_lock, flags);
-	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
-	pci_write_config_dword(cfg->dev, cfg->pos + 4, data);
-	spin_unlock_irqrestore(&ht_irq_lock, flags);
-}
-
-void write_ht_irq_high(unsigned int irq, u32 data)
-{
-	struct ht_irq_cfg *cfg = get_irq_data(irq);
-	unsigned long flags;
-	spin_lock_irqsave(&ht_irq_lock, flags);
-	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx + 1);
-	pci_write_config_dword(cfg->dev, cfg->pos + 4, data);
-	spin_unlock_irqrestore(&ht_irq_lock, flags);
-}
 
-u32 read_ht_irq_low(unsigned int irq)
+void write_ht_irq_msg(unsigned int irq, struct ht_irq_msg *msg)
 {
 	struct ht_irq_cfg *cfg = get_irq_data(irq);
 	unsigned long flags;
-	u32 data;
 	spin_lock_irqsave(&ht_irq_lock, flags);
-	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
-	pci_read_config_dword(cfg->dev, cfg->pos + 4, &data);
+	if (cfg->msg.address_lo != msg->address_lo) {
+		pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
+		pci_write_config_dword(cfg->dev, cfg->pos + 4, msg->address_lo);
+	}
+	if (cfg->msg.address_hi != msg->address_hi) {
+		pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx + 1);
+		pci_write_config_dword(cfg->dev, cfg->pos + 4, msg->address_hi);
+	}
 	spin_unlock_irqrestore(&ht_irq_lock, flags);
-	return data;
+	cfg->msg = *msg;
 }
 
-u32 read_ht_irq_high(unsigned int irq)
+void fetch_ht_irq_msg(unsigned int irq, struct ht_irq_msg *msg)
 {
 	struct ht_irq_cfg *cfg = get_irq_data(irq);
-	unsigned long flags;
-	u32 data;
-	spin_lock_irqsave(&ht_irq_lock, flags);
-	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx + 1);
-	pci_read_config_dword(cfg->dev, cfg->pos + 4, &data);
-	spin_unlock_irqrestore(&ht_irq_lock, flags);
-	return data;
+	*msg = cfg->msg;
 }
 
 void mask_ht_irq(unsigned int irq)
 {
 	struct ht_irq_cfg *cfg;
-	unsigned long flags;
-	u32 data;
+	struct ht_irq_msg msg;
 
 	cfg = get_irq_data(irq);
 
-	spin_lock_irqsave(&ht_irq_lock, flags);
-	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
-	pci_read_config_dword(cfg->dev, cfg->pos + 4, &data);
-	data |= 1;
-	pci_write_config_dword(cfg->dev, cfg->pos + 4, data);
-	spin_unlock_irqrestore(&ht_irq_lock, flags);
+	msg = cfg->msg;
+	msg.address_lo |= 1;
+	write_ht_irq_msg(irq, &msg);
 }
 
 void unmask_ht_irq(unsigned int irq)
 {
 	struct ht_irq_cfg *cfg;
-	unsigned long flags;
-	u32 data;
+	struct ht_irq_msg msg;
 
 	cfg = get_irq_data(irq);
 
-	spin_lock_irqsave(&ht_irq_lock, flags);
-	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
-	pci_read_config_dword(cfg->dev, cfg->pos + 4, &data);
-	data &= ~1;
-	pci_write_config_dword(cfg->dev, cfg->pos + 4, data);
-	spin_unlock_irqrestore(&ht_irq_lock, flags);
+	msg = cfg->msg;
+	msg.address_lo &= ~1;
+	write_ht_irq_msg(irq, &msg);
 }
 
 /**
@@ -152,6 +125,9 @@ int ht_create_irq(struct pci_dev *dev, int idx)
 	cfg->dev = dev;
 	cfg->pos = pos;
 	cfg->idx = 0x10 + (idx * 2);
+	/* Initialize msg to a value that will never match the first write. */
+	cfg->msg.address_lo = 0xffffffff;
+	cfg->msg.address_hi = 0xffffffff;
 
 	irq = create_irq();
 	if (irq < 0) {
diff --git a/include/linux/htirq.h b/include/linux/htirq.h
index 1f15ce2..108f0d9 100644
--- a/include/linux/htirq.h
+++ b/include/linux/htirq.h
@@ -1,11 +1,14 @@
 #ifndef LINUX_HTIRQ_H
 #define LINUX_HTIRQ_H
 
+struct ht_irq_msg {
+	u32	address_lo;	/* low 32 bits of the ht irq message */
+	u32	address_hi;	/* high 32 bits of the it irq message */
+};
+
 /* Helper functions.. */
-void write_ht_irq_low(unsigned int irq, u32 data);
-void write_ht_irq_high(unsigned int irq, u32 data);
-u32  read_ht_irq_low(unsigned int irq);
-u32  read_ht_irq_high(unsigned int irq);
+void fetch_ht_irq_msg(unsigned int irq, struct ht_irq_msg *msg);
+void write_ht_irq_msg(unsigned int irq, struct ht_irq_msg *msg);
 void mask_ht_irq(unsigned int irq);
 void unmask_ht_irq(unsigned int irq);