[SPARC64]: Add PCI MSI support on Niagara.

This is kind of hokey, we could use the hardware provided facilities
much better.

MSIs are assosciated with MSI Queues.  MSI Queues generate interrupts
when any MSI assosciated with it is signalled.  This suggests a
two-tiered IRQ dispatch scheme:

	MSI Queue interrupt --> queue interrupt handler
		MSI dispatch --> driver interrupt handler

But we just get one-level under Linux currently.  What I'd like to do
is possibly stick the IRQ actions into a per-MSI-Queue data structure,
and dispatch them form there, but the generic IRQ layer doesn't
provide a way to do that right now.

So, the current kludge is to "ACK" the interrupt by processing the
MSI Queue data structures and ACK'ing them, then we run the actual
handler like normal.

We are wasting a lot of useful information, for example the MSI data
and address are provided with ever MSI, as well as a system tick if
available.  If we could pass this into the IRQ handler it could help
with certain things, in particular for PCI-Express error messages.

The MSI entries on sparc64 also tell you exactly which bus/device/fn
sent the MSI, which would be great for error handling when no
registered IRQ handler can service the interrupt.

We override the disable/enable IRQ chip methods in sun4v_msi, so we
have to call {mask,unmask}_msi_irq() directly from there.  This is
another ugly wart.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 95 insertions, 9 deletions

diff --git a/arch/sparc64/kernel/irq.c b/arch/sparc64/kernel/irq.c
index 2873835e2626..b5ff3ee5ace1 100644
--- a/arch/sparc64/kernel/irq.c
+++ b/arch/sparc64/kernel/irq.c
@@ -22,6 +22,7 @@
 #include <linux/seq_file.h>
 #include <linux/bootmem.h>
 #include <linux/irq.h>
+#include <linux/msi.h>
 
 #include <asm/ptrace.h>
 #include <asm/processor.h>
@@ -87,7 +88,6 @@ struct ino_bucket ivector_table[NUM_IVECS] __attribute__ ((aligned (SMP_CACHE_BY
 #define irq_work(__cpu) &(trap_block[(__cpu)].irq_worklist)
 
 static unsigned int virt_to_real_irq_table[NR_IRQS];
-static unsigned char virt_irq_cur = 1;
 
 static unsigned char virt_irq_alloc(unsigned int real_irq)
 {
@@ -95,26 +95,32 @@ static unsigned char virt_irq_alloc(unsigned int real_irq)
 
         BUILD_BUG_ON(NR_IRQS >= 256);
 
-        ent = virt_irq_cur;
+        for (ent = 1; ent < NR_IRQS; ent++) {
+                if (!virt_to_real_irq_table[ent])
+                        break;
+        }
         if (ent >= NR_IRQS) {
                 printk(KERN_ERR "IRQ: Out of virtual IRQs.\n");
                 return 0;
         }
 
-        virt_irq_cur = ent + 1;
         virt_to_real_irq_table[ent] = real_irq;
 
         return ent;
 }
 
-#if 0 /* Currently unused. */
-static unsigned char real_to_virt_irq(unsigned int real_irq)
+static void virt_irq_free(unsigned int virt_irq)
 {
-        struct ino_bucket *bucket = __bucket(real_irq);
+        unsigned int real_irq;
 
-        return bucket->virt_irq;
+        if (virt_irq >= NR_IRQS)
+                return;
+
+        real_irq = virt_to_real_irq_table[virt_irq];
+        virt_to_real_irq_table[virt_irq] = 0;
+
+        __bucket(real_irq)->virt_irq = 0;
 }
-#endif
 
 static unsigned int virt_to_real_irq(unsigned char virt_irq)
 {
@@ -341,6 +347,20 @@ static void sun4v_irq_disable(unsigned int virt_irq)
         }
 }
 
+#ifdef CONFIG_PCI_MSI
+static void sun4v_msi_enable(unsigned int virt_irq)
+{
+        sun4v_irq_enable(virt_irq);
+        unmask_msi_irq(virt_irq);
+}
+
+static void sun4v_msi_disable(unsigned int virt_irq)
+{
+        mask_msi_irq(virt_irq);
+        sun4v_irq_disable(virt_irq);
+}
+#endif
+
 static void sun4v_irq_end(unsigned int virt_irq)
 {
         struct ino_bucket *bucket = virt_irq_to_bucket(virt_irq);
@@ -398,6 +418,18 @@ static struct irq_chip sun4v_irq_ack = {
         .end            = sun4v_irq_end,
 };
 
+#ifdef CONFIG_PCI_MSI
+static struct irq_chip sun4v_msi = {
+        .typename       = "sun4v+msi",
+        .mask           = mask_msi_irq,
+        .unmask         = unmask_msi_irq,
+        .enable         = sun4v_msi_enable,
+        .disable        = sun4v_msi_disable,
+        .ack            = run_pre_handler,
+        .end            = sun4v_irq_end,
+};
+#endif
+
 void irq_install_pre_handler(int virt_irq,
                              void (*func)(unsigned int, void *, void *),
                              void *arg1, void *arg2)
@@ -411,7 +443,11 @@ void irq_install_pre_handler(int virt_irq,
 
         chip = get_irq_chip(virt_irq);
         if (chip == &sun4u_irq_ack ||
-            chip == &sun4v_irq_ack)
+            chip == &sun4v_irq_ack
+#ifdef CONFIG_PCI_MSI
+            || chip == &sun4v_msi
+#endif
+            )
                 return;
 
         chip = (chip == &sun4u_irq ?
@@ -489,6 +525,56 @@ out:
         return bucket->virt_irq;
 }
 
+#ifdef CONFIG_PCI_MSI
+unsigned int sun4v_build_msi(u32 devhandle, unsigned int *virt_irq_p,
+                             unsigned int msi_start, unsigned int msi_end)
+{
+        struct ino_bucket *bucket;
+        struct irq_handler_data *data;
+        unsigned long sysino;
+        unsigned int devino;
+
+        BUG_ON(tlb_type != hypervisor);
+
+        /* Find a free devino in the given range.  */
+        for (devino = msi_start; devino < msi_end; devino++) {
+                sysino = sun4v_devino_to_sysino(devhandle, devino);
+                bucket = &ivector_table[sysino];
+                if (!bucket->virt_irq)
+                        break;
+        }
+        if (devino >= msi_end)
+                return 0;
+
+        sysino = sun4v_devino_to_sysino(devhandle, devino);
+        bucket = &ivector_table[sysino];
+        bucket->virt_irq = virt_irq_alloc(__irq(bucket));
+        *virt_irq_p = bucket->virt_irq;
+        set_irq_chip(bucket->virt_irq, &sun4v_msi);
+
+        data = get_irq_chip_data(bucket->virt_irq);
+        if (unlikely(data))
+                return devino;
+
+        data = kzalloc(sizeof(struct irq_handler_data), GFP_ATOMIC);
+        if (unlikely(!data)) {
+                prom_printf("IRQ: kzalloc(irq_handler_data) failed.\n");
+                prom_halt();
+        }
+        set_irq_chip_data(bucket->virt_irq, data);
+
+        data->imap = ~0UL;
+        data->iclr = ~0UL;
+
+        return devino;
+}
+
+void sun4v_destroy_msi(unsigned int virt_irq)
+{
+        virt_irq_free(virt_irq);
+}
+#endif
+
 void ack_bad_irq(unsigned int virt_irq)
 {
         struct ino_bucket *bucket = virt_irq_to_bucket(virt_irq);