x86, ioapic: Fix the EOI register detection mechanism

Maciej W. Rozycki reported:

> 82093AA I/O APIC has its version set to 0x11 and it
> does not support the EOI register.  Similarly I/O APICs
> integrated into the 82379AB south bridge and the 82374EB/SB
> EISA component.

IO-APIC versions below 0x20 don't support EOI register.

Some of the Intel ICH Specs (ICH2 to ICH5) documents the io-apic
version as 0x2. This is an error with documentation and these
ICH chips use io-apic's of version 0x20 and indeed has a working
EOI register for the io-apic.

Fix the EOI register detection mechanism to check for version
0x20 and beyond.

And also, a platform can potentially  have io-apic's with
different versions. Make the EOI register check per io-apic.

Reported-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: ebiederm@xmission.com
Cc: garyhade@us.ibm.com
LKML-Reference: <20091201233335.065361533@sbs-t61.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 61 insertions, 54 deletions

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index b377b973899e..78960a3b0ed0 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -539,23 +539,41 @@ static void __init replace_pin_at_irq_node(struct irq_cfg *cfg, int node,
         add_pin_to_irq_node(cfg, node, newapic, newpin);
 }
 
+static void __io_apic_modify_irq(struct irq_pin_list *entry,
+                                 int mask_and, int mask_or,
+                                 void (*final)(struct irq_pin_list *entry))
+{
+        unsigned int reg, pin;
+
+        pin = entry->pin;
+        reg = io_apic_read(entry->apic, 0x10 + pin * 2);
+        reg &= mask_and;
+        reg |= mask_or;
+        io_apic_modify(entry->apic, 0x10 + pin * 2, reg);
+        if (final)
+                final(entry);
+}
+
 static void io_apic_modify_irq(struct irq_cfg *cfg,
                                int mask_and, int mask_or,
                                void (*final)(struct irq_pin_list *entry))
 {
-        int pin;
         struct irq_pin_list *entry;
 
-        for_each_irq_pin(entry, cfg->irq_2_pin) {
-                unsigned int reg;
-                pin = entry->pin;
-                reg = io_apic_read(entry->apic, 0x10 + pin * 2);
-                reg &= mask_and;
-                reg |= mask_or;
-                io_apic_modify(entry->apic, 0x10 + pin * 2, reg);
-                if (final)
-                        final(entry);
-        }
+        for_each_irq_pin(entry, cfg->irq_2_pin)
+                __io_apic_modify_irq(entry, mask_and, mask_or, final);
+}
+
+static void __mask_and_edge_IO_APIC_irq(struct irq_pin_list *entry)
+{
+        __io_apic_modify_irq(entry, ~IO_APIC_REDIR_LEVEL_TRIGGER,
+                             IO_APIC_REDIR_MASKED, NULL);
+}
+
+static void __unmask_and_level_IO_APIC_irq(struct irq_pin_list *entry)
+{
+        __io_apic_modify_irq(entry, ~IO_APIC_REDIR_MASKED,
+                             IO_APIC_REDIR_LEVEL_TRIGGER, NULL);
 }
 
 static void __unmask_IO_APIC_irq(struct irq_cfg *cfg)
@@ -579,18 +597,6 @@ static void __mask_IO_APIC_irq(struct irq_cfg *cfg)
         io_apic_modify_irq(cfg, ~0, IO_APIC_REDIR_MASKED, &io_apic_sync);
 }
 
-static void __mask_and_edge_IO_APIC_irq(struct irq_cfg *cfg)
-{
-        io_apic_modify_irq(cfg, ~IO_APIC_REDIR_LEVEL_TRIGGER,
-                        IO_APIC_REDIR_MASKED, NULL);
-}
-
-static void __unmask_and_level_IO_APIC_irq(struct irq_cfg *cfg)
-{
-        io_apic_modify_irq(cfg, ~IO_APIC_REDIR_MASKED,
-                        IO_APIC_REDIR_LEVEL_TRIGGER, NULL);
-}
-
 static void mask_IO_APIC_irq_desc(struct irq_desc *desc)
 {
         struct irq_cfg *cfg = desc->chip_data;
@@ -2492,17 +2498,42 @@ static void ack_apic_edge(unsigned int irq)
 
 atomic_t irq_mis_count;
 
-static int use_eoi_reg __read_mostly;
-
+/*
+ * IO-APIC versions below 0x20 don't support EOI register.
+ * For the record, here is the information about various versions:
+ *     0Xh     82489DX
+ *     1Xh     I/OAPIC or I/O(x)APIC which are not PCI 2.2 Compliant
+ *     2Xh     I/O(x)APIC which is PCI 2.2 Compliant
+ *     30h-FFh Reserved
+ *
+ * Some of the Intel ICH Specs (ICH2 to ICH5) documents the io-apic
+ * version as 0x2. This is an error with documentation and these ICH chips
+ * use io-apic's of version 0x20.
+ *
+ * For IO-APIC's with EOI register, we use that to do an explicit EOI.
+ * Otherwise, we simulate the EOI message manually by changing the trigger
+ * mode to edge and then back to level, with RTE being masked during this.
+*/
 static void __eoi_ioapic_irq(unsigned int irq, struct irq_cfg *cfg)
 {
         struct irq_pin_list *entry;
 
         for_each_irq_pin(entry, cfg->irq_2_pin) {
-                if (irq_remapped(irq))
-                        io_apic_eoi(entry->apic, entry->pin);
-                else
-                        io_apic_eoi(entry->apic, cfg->vector);
+                if (mp_ioapics[entry->apic].apicver >= 0x20) {
+                        /*
+                         * Intr-remapping uses pin number as the virtual vector
+                         * in the RTE. Actual vector is programmed in
+                         * intr-remapping table entry. Hence for the io-apic
+                         * EOI we use the pin number.
+                         */
+                        if (irq_remapped(irq))
+                                io_apic_eoi(entry->apic, entry->pin);
+                        else
+                                io_apic_eoi(entry->apic, cfg->vector);
+                } else {
+                        __mask_and_edge_IO_APIC_irq(entry);
+                        __unmask_and_level_IO_APIC_irq(entry);
+                }
         }
 }
 
@@ -2520,23 +2551,6 @@ static void eoi_ioapic_irq(struct irq_desc *desc)
         spin_unlock_irqrestore(&ioapic_lock, flags);
 }
 
-static int ioapic_supports_eoi(void)
-{
-        struct pci_dev *root;
-
-        root = pci_get_bus_and_slot(0, PCI_DEVFN(0, 0));
-        if (root && root->vendor == PCI_VENDOR_ID_INTEL &&
-            mp_ioapics[0].apicver >= 0x2) {
-                use_eoi_reg = 1;
-                printk(KERN_INFO "IO-APIC supports EOI register\n");
-        } else
-                printk(KERN_INFO "IO-APIC doesn't support EOI\n");
-
-        return 0;
-}
-
-fs_initcall(ioapic_supports_eoi);
-
 static void ack_apic_level(unsigned int irq)
 {
         struct irq_desc *desc = irq_to_desc(irq);
@@ -2587,14 +2601,7 @@ static void ack_apic_level(unsigned int irq)
         if (!(v & (1 << (i & 0x1f)))) {
                 atomic_inc(&irq_mis_count);
 
-                if (use_eoi_reg)
-                        eoi_ioapic_irq(desc);
-                else {
-                        spin_lock(&ioapic_lock);
-                        __mask_and_edge_IO_APIC_irq(cfg);
-                        __unmask_and_level_IO_APIC_irq(cfg);
-                        spin_unlock(&ioapic_lock);
-                }
+                eoi_ioapic_irq(desc);
         }
 
         /* Now we can move and renable the irq */