hw/intc/arm_gic: Add Interrupt Group Registers

The Interrupt Group Registers allow the guest to configure interrupts
into one of two groups, where Group0 are higher priority and may
be routed to IRQ or FIQ, and Group1 are lower priority and always
routed to IRQ. (In a GIC with the security extensions Group0 is
Secure interrupts and Group 1 is NonSecure.)
The GICv2 always supports interrupt grouping; the GICv1 does only
if it implements the security extensions.

This patch implements the ability to read and write the registers;
the actual functionality the bits control will be added in a
subsequent patch.

Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1430502643-25909-5-git-send-email-peter.maydell@linaro.org
Message-id: 1429113742-8371-7-git-send-email-greg.bellows@linaro.org
[PMM: bring GIC_*_GROUP macros into line with the others, ie a
 simple SET/CLEAR/TEST rather than GROUP0/GROUP1;
 utility gic_has_groups() function;
 minor style fixes;
 bump vmstate version]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 47 insertions, 3 deletions

diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
index 29015c2e6d..1aa45209ce 100644
--- a/hw/intc/arm_gic.c
+++ b/hw/intc/arm_gic.c
@@ -45,6 +45,14 @@ static inline int gic_get_current_cpu(GICState *s)
     return 0;
 }
 
+/* Return true if this GIC config has interrupt groups, which is
+ * true if we're a GICv2, or a GICv1 with the security extensions.
+ */
+static inline bool gic_has_groups(GICState *s)
+{
+    return s->revision == 2 || s->security_extn;
+}
+
 /* TODO: Many places that call this routine could be optimized.  */
 /* Update interrupt status after enabled or pending bits have been changed.  */
 void gic_update(GICState *s)
@@ -305,8 +313,24 @@ static uint32_t gic_dist_readb(void *opaque, hwaddr offset, MemTxAttrs attrs)
         if (offset < 0x08)
             return 0;
         if (offset >= 0x80) {
-            /* Interrupt Security , RAZ/WI */
-            return 0;
+            /* Interrupt Group Registers: these RAZ/WI if this is an NS
+             * access to a GIC with the security extensions, or if the GIC
+             * doesn't have groups at all.
+             */
+            res = 0;
+            if (!(s->security_extn && !attrs.secure) && gic_has_groups(s)) {
+                /* Every byte offset holds 8 group status bits */
+                irq = (offset - 0x080) * 8 + GIC_BASE_IRQ;
+                if (irq >= s->num_irq) {
+                    goto bad_reg;
+                }
+                for (i = 0; i < 8; i++) {
+                    if (GIC_TEST_GROUP(irq + i, cm)) {
+                        res |= (1 << i);
+                    }
+                }
+            }
+            return res;
         }
         goto bad_reg;
     } else if (offset < 0x200) {
@@ -456,7 +480,27 @@ static void gic_dist_writeb(void *opaque, hwaddr offset,
         } else if (offset < 4) {
             /* ignored.  */
         } else if (offset >= 0x80) {
-            /* Interrupt Security Registers, RAZ/WI */
+            /* Interrupt Group Registers: RAZ/WI for NS access to secure
+             * GIC, or for GICs without groups.
+             */
+            if (!(s->security_extn && !attrs.secure) && gic_has_groups(s)) {
+                /* Every byte offset holds 8 group status bits */
+                irq = (offset - 0x80) * 8 + GIC_BASE_IRQ;
+                if (irq >= s->num_irq) {
+                    goto bad_reg;
+                }
+                for (i = 0; i < 8; i++) {
+                    /* Group bits are banked for private interrupts */
+                    int cm = (irq < GIC_INTERNAL) ? (1 << cpu) : ALL_CPU_MASK;
+                    if (value & (1 << i)) {
+                        /* Group1 (Non-secure) */
+                        GIC_SET_GROUP(irq + i, cm);
+                    } else {
+                        /* Group0 (Secure) */
+                        GIC_CLEAR_GROUP(irq + i, cm);
+                    }
+                }
+            }
         } else {
             goto bad_reg;
         }