[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 507983c513c3..ad84bc2802a6 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 3b8f9c68ad3c..41bfc49301ad 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 0e27f2404a83..e346fe31f97a 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 1f15ce279a23..108f0d91e11e 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);