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Subject[tip:x86/apic] x86, ioapic: Fix the EOI register detection mechanism
Commit-ID:  c29d9db338db606c3335a03f337e1d4b7f6bb727
Gitweb: http://git.kernel.org/tip/c29d9db338db606c3335a03f337e1d4b7f6bb727
Author: Suresh Siddha <suresh.b.siddha@intel.com>
AuthorDate: Tue, 1 Dec 2009 15:31:16 -0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 2 Dec 2009 10:11:01 +0100

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>
---
arch/x86/kernel/apic/io_apic.c | 115 +++++++++++++++++++++-------------------
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 b377b97..78960a3 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 */

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