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 1b62d839594b55ba273d12b37fb6804aaf86a510..3a9a6888524178b6bc561ce5af4384fff2fe247c 100644 (file)
--- 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 ef291ff4313531d174c3e968cf7a54d9f04d2ba4..1c3abcff35381de639d2a8d01ccf4c4291a8dd5a 100644 (file)
--- 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 f9a18d838e5020323c8b5098a8b9ef5d37882e5e..40c0f3fdd2d6a9c93d75448c63dafda203aa18aa 100644 (file)
--- 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)