[Xen-devel] [PATCH 1/2] xen: arm: log warning for interrupt configuration mismatch

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

The ICFGR register is not necessarily writeable, in particular it is
IMPLEMENTATION DEFINED for a PPI if the configuration register is
writeable. Log a warning if the hardware has ignored our write and
update the actual type in the irq descriptor so subsequent code can do
the right thing.

This most likely implies a buggy firmware description (e.g.
device-tree).

The issue is observed for example on the APM Mustang board where the
device tree (as shipped by Linux) describes all 3 timer interrupts as
rising edge but the PPI is hard-coded to level triggered (as makes
sense for an arch timer interrupt).

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Pranavkumar Sawargaonkar <psawargaonkar@xxxxxxx>
---
 xen/arch/arm/gic-v2.c |   16 +++++++++++++++-
 xen/arch/arm/gic-v3.c |   16 +++++++++++++++-
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/gic-v2.c b/xen/arch/arm/gic-v2.c
index 31fb81a..6836ab6 100644
--- a/xen/arch/arm/gic-v2.c
+++ b/xen/arch/arm/gic-v2.c
@@ -211,7 +211,7 @@ static void gicv2_set_irq_properties(struct irq_desc *desc,
                                    const cpumask_t *cpu_mask,
                                    unsigned int priority)
 {
-    uint32_t cfg, edgebit;
+    uint32_t cfg, actual, edgebit;
     unsigned int mask = gicv2_cpu_mask(cpu_mask);
     unsigned int irq = desc->irq;
     unsigned int type = desc->arch.type;
@@ -229,6 +229,20 @@ static void gicv2_set_irq_properties(struct irq_desc *desc,
         cfg |= edgebit;
     writel_gicd(cfg, GICD_ICFGR + (irq / 16) * 4);
 
+    actual = readl_gicd(GICD_ICFGR + (irq / 16) * 4);
+    if ( ( cfg & edgebit ) ^ ( actual & edgebit ) )
+    {
+        printk(XENLOG_WARNING "GICv2: WARNING: "
+               "CPU%d: Failed to configure IRQ%u as %s-triggered. "
+               "H/w forces to %s-triggered.\n",
+               smp_processor_id(), desc->irq,
+               cfg & edgebit ? "Edge" : "Level",
+               actual & edgebit ? "Edge" : "Level");
+        desc->arch.type = actual & edgebit ?
+            DT_IRQ_TYPE_EDGE_RISING :
+            DT_IRQ_TYPE_LEVEL_LOW;
+    }
+
     /* Set target CPU mask (RAZ/WI on uniprocessor) */
     writeb_gicd(mask, GICD_ITARGETSR + irq);
     /* Set priority */
diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index 47452ca..339b0cd 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -465,7 +465,7 @@ static void gicv3_set_irq_properties(struct irq_desc *desc,
                                      const cpumask_t *cpu_mask,
                                      unsigned int priority)
 {
-    uint32_t cfg, edgebit;
+    uint32_t cfg, actual, edgebit;
     uint64_t affinity;
     void __iomem *base;
     unsigned int cpu = gicv3_get_cpu_from_mask(cpu_mask);
@@ -492,6 +492,20 @@ static void gicv3_set_irq_properties(struct irq_desc *desc,
 
     writel_relaxed(cfg, base);
 
+    actual = readl_relaxed(base);
+    if ( ( cfg & edgebit ) ^ ( actual & edgebit ) )
+    {
+        printk(XENLOG_WARNING "GICv3: WARNING: "
+               "CPU%d: Failed to configure IRQ%u as %s-triggered. "
+               "H/w forces to %s-triggered.\n",
+               smp_processor_id(), desc->irq,
+               cfg & edgebit ? "Edge" : "Level",
+               actual & edgebit ? "Edge" : "Level");
+        desc->arch.type = actual & edgebit ?
+            DT_IRQ_TYPE_EDGE_RISING :
+            DT_IRQ_TYPE_LEVEL_LOW;
+    }
+
     affinity = gicv3_mpidr_to_affinity(cpu);
     /* Make sure we don't broadcast the interrupt */
     affinity &= ~GICD_IROUTER_SPI_MODE_ANY;
-- 
1.7.10.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel