From: Julien Grall <julien.grall@linaro.org>
Date: Fri, 16 May 2014 14:40:32 +0000 (+0100)
Subject: xen/arm: IRQ: Handle multiple action per IRQ
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=ba30e2bdc15918982242315717541bd76dd527e7;p=people%2Froyger%2Fxen.git

xen/arm: IRQ: Handle multiple action per IRQ

On ARM, it may happen (eg ARM SMMU) to setup multiple handler for the same
interrupt.

To be able to use multiple action, the driver has to explicitly call
{setup,request}_irq with IRQF_SHARED as 2nd parameter.

The behavior stays the same on x86, e.g only one action is handled.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---

diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 1b62d83959..3a9a688852 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -171,7 +171,6 @@ int request_irq(unsigned int irq, unsigned int irqflags,
 void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, int is_fiq)
 {
     struct irq_desc *desc = irq_to_desc(irq);
-    struct irqaction *action = desc->action;
 
     /* TODO: perfc_incr(irqs); */
 
@@ -182,7 +181,7 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, int is_fiq)
     spin_lock(&desc->lock);
     desc->handler->ack(desc);
 
-    if ( action == NULL )
+    if ( !desc->action )
     {
         printk("Unknown %s %#3.3x\n",
                is_fiq ? "FIQ" : "IRQ", irq);
@@ -214,12 +213,21 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, int is_fiq)
 
     desc->status |= IRQ_INPROGRESS;
 
-    action = desc->action;
     while ( desc->status & IRQ_PENDING )
     {
+        struct irqaction *action;
+
         desc->status &= ~IRQ_PENDING;
+        action = desc->action;
+
         spin_unlock_irq(&desc->lock);
-        action->handler(irq, action->dev_id, regs);
+
+        do
+        {
+            action->handler(irq, action->dev_id, regs);
+            action = action->next;
+        } while ( action );
+
         spin_lock_irq(&desc->lock);
     }
 
@@ -236,34 +244,71 @@ void release_irq(unsigned int irq, const void *dev_id)
 {
     struct irq_desc *desc;
     unsigned long flags;
-   struct irqaction *action;
+    struct irqaction *action, **action_ptr;
 
     desc = irq_to_desc(irq);
 
     spin_lock_irqsave(&desc->lock,flags);
 
-    desc->handler->shutdown(desc);
+    action_ptr = &desc->action;
+    for ( ;; )
+    {
+        action = *action_ptr;
+        if ( !action )
+        {
+            printk(XENLOG_WARNING "Trying to free already-free IRQ %u\n", irq);
+            spin_unlock_irqrestore(&desc->lock, flags);
+            return;
+        }
+
+        if ( action->dev_id == dev_id )
+            break;
+
+        action_ptr = &action->next;
+    }
+
+    /* Found it - remove it from the action list */
+    *action_ptr = action->next;
 
-    action = desc->action;
-    desc->action  = NULL;
-    desc->status &= ~IRQ_GUEST;
+    /* If this was the last action, shut down the IRQ */
+    if ( !desc->action )
+    {
+        desc->handler->shutdown(desc);
+        desc->status &= ~IRQ_GUEST;
+    }
 
     spin_unlock_irqrestore(&desc->lock,flags);
 
     /* Wait to make sure it's not being used on another CPU */
     do { smp_mb(); } while ( desc->status & IRQ_INPROGRESS );
 
-    if ( action && action->free_on_release )
+    if ( action->free_on_release )
         xfree(action);
 }
 
-static int __setup_irq(struct irq_desc *desc, struct irqaction *new)
+static int __setup_irq(struct irq_desc *desc, unsigned int irqflags,
+                       struct irqaction *new)
 {
-    if ( desc->action != NULL )
-        return -EBUSY;
+    bool_t shared = !!(irqflags & IRQF_SHARED);
+
+    ASSERT(new != NULL);
+
+    /* Sanity checks:
+     *  - if the IRQ is marked as shared
+     *  - dev_id is not NULL when IRQF_SHARED is set
+     */
+    if ( desc->action != NULL && (!(desc->status & IRQF_SHARED) || !shared) )
+        return -EINVAL;
+    if ( shared && new->dev_id == NULL )
+        return -EINVAL;
+
+    if ( shared )
+        desc->status |= IRQF_SHARED;
 
-    desc->action  = new;
-    dsb(sy);
+    new->next = desc->action;
+    dsb(ish);
+    desc->action = new;
+    dsb(ish);
 
     return 0;
 }
@@ -291,7 +336,7 @@ int setup_irq(unsigned int irq, unsigned int irqflags, struct irqaction *new)
 
     disabled = (desc->action == NULL);
 
-    rc = __setup_irq(desc, new);
+    rc = __setup_irq(desc, irqflags, new);
     if ( rc )
         goto err;
 
@@ -355,7 +400,7 @@ int route_irq_to_guest(struct domain *d, unsigned int irq,
         goto out;
     }
 
-    retval = __setup_irq(desc, action);
+    retval = __setup_irq(desc, 0, action);
     if ( retval )
         goto out;
 
diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index ef291ff431..1c3abcff35 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -37,6 +37,8 @@
 
 #define CONFIG_VIDEO 1
 
+#define CONFIG_IRQ_HAS_MULTIPLE_ACTION 1
+
 #define OPT_CONSOLE_STR "dtuart"
 
 #ifdef MAX_PHYS_CPUS
diff --git a/xen/include/xen/irq.h b/xen/include/xen/irq.h
index f9a18d838e..40c0f3fdd2 100644
--- a/xen/include/xen/irq.h
+++ b/xen/include/xen/irq.h
@@ -14,6 +14,9 @@ struct irqaction {
     const char *name;
     void *dev_id;
     bool_t free_on_release;
+#ifdef CONFIG_IRQ_HAS_MULTIPLE_ACTION
+    struct irqaction *next;
+#endif
 };
 
 /*
@@ -27,6 +30,7 @@ struct irqaction {
 #define IRQ_MOVE_PENDING  (1u<<5) /* IRQ is migrating to another CPUs */
 #define IRQ_PER_CPU       (1u<<6) /* IRQ is per CPU */
 #define IRQ_GUEST_EOI_PENDING (1u<<7) /* IRQ was disabled, pending a guest EOI */
+#define IRQF_SHARED       (1<<8)  /* IRQ is shared */
 
 /* Special IRQ numbers. */
 #define AUTO_ASSIGN_IRQ         (-1)