[Qemu-devel] [PATCH v2 1/4] openpic: fix sense and priority bits

[Scott Wood <scottwood@freescale.com>]

Previously, the sense and priority bits were masked off when writing
to IVPR, and all interrupts were treated as edge-triggered (despite
the existence of code for handling level-triggered interrupts).

Polarity is implemented only as storage.  We don't simulate the
bad effects that you'd get on real hardware if you set this incorrectly,
but at least the guest sees the right thing when it reads back the register.

Sense now controls level/edge on FSL external interrupts (and all
interrupts on non-FSL MPIC).  FSL internal interrupts do not have a sense
bit (reads as zero), but are level.  FSL timers and IPIs do not have
sense or polarity bits (read as zero), and are edge-triggered.  To
accommodate FSL internal interrupts, QEMU's internal notion of whether an
interrupt is level-triggered is separated from the IVPR bit.

Signed-off-by: Scott Wood <scottwood@freescale.com>
---
v2: use an enum rather than multiple booleans for IRQ type.

 hw/openpic.c |   77 +++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 71 insertions(+), 6 deletions(-)

diff --git a/hw/openpic.c b/hw/openpic.c
index 35a7fe3..66179c2 100644
--- a/hw/openpic.c
+++ b/hw/openpic.c
@@ -162,6 +162,12 @@ static uint32_t openpic_cpu_read_internal(void *opaque, hwaddr addr,
 static void openpic_cpu_write_internal(void *opaque, hwaddr addr,
                                        uint32_t val, int idx);
 
+typedef enum IRQType {
+    IRQ_TYPE_NORMAL = 0,
+    IRQ_TYPE_FSLINT,        /* FSL internal interrupt -- level only */
+    IRQ_TYPE_FSLSPECIAL,    /* FSL timer/IPI interrupt, edge, no polarity */
+} IRQType;
+
 typedef struct IRQQueue {
     /* Round up to the nearest 64 IRQs so that the queue length
      * won't change when moving between 32 and 64 bit hosts.
@@ -178,6 +184,8 @@ typedef struct IRQSource {
     int last_cpu;
     int output;     /* IRQ level, e.g. OPENPIC_OUTPUT_INT */
     int pending;    /* TRUE if IRQ is pending */
+    IRQType type;
+    bool level:1;   /* level-triggered */
     bool nomask:1;  /* critical interrupts ignore mask on some FSL MPICs */
 } IRQSource;
 
@@ -422,7 +430,7 @@ static void openpic_set_irq(void *opaque, int n_IRQ, int level)
     src = &opp->src[n_IRQ];
     DPRINTF("openpic: set irq %d = %d ivpr=0x%08x\n",
             n_IRQ, level, src->ivpr);
-    if (src->ivpr & IVPR_SENSE_MASK) {
+    if (src->level) {
         /* level-sensitive irq */
         src->pending = level;
         if (!level) {
@@ -455,6 +463,19 @@ static void openpic_reset(DeviceState *d)
     for (i = 0; i < opp->max_irq; i++) {
         opp->src[i].ivpr = opp->ivpr_reset;
         opp->src[i].idr  = opp->idr_reset;
+
+        switch (opp->src[i].type) {
+        case IRQ_TYPE_NORMAL:
+            opp->src[i].level = !!(opp->ivpr_reset & IVPR_SENSE_MASK);
+            break;
+
+        case IRQ_TYPE_FSLINT:
+            opp->src[i].ivpr |= IVPR_POLARITY_MASK;
+            break;
+
+        case IRQ_TYPE_FSLSPECIAL:
+            break;
+        }
     }
     /* Initialise IRQ destinations */
     for (i = 0; i < MAX_CPU; i++) {
@@ -530,10 +551,36 @@ static inline void write_IRQreg_idr(OpenPICState *opp, int n_IRQ, uint32_t val)
 
 static inline void write_IRQreg_ivpr(OpenPICState *opp, int n_IRQ, uint32_t val)
 {
-    /* NOTE: not fully accurate for special IRQs, but simple and sufficient */
+    uint32_t mask;
+
+    /* NOTE when implementing newer FSL MPIC models: starting with v4.0,
+     * the polarity bit is read-only on internal interrupts.
+     */
+    mask = IVPR_MASK_MASK | IVPR_PRIORITY_MASK | IVPR_SENSE_MASK |
+           IVPR_POLARITY_MASK | opp->vector_mask;
+
     /* ACTIVITY bit is read-only */
-    opp->src[n_IRQ].ivpr = (opp->src[n_IRQ].ivpr & IVPR_ACTIVITY_MASK) |
-        (val & (IVPR_MASK_MASK | IVPR_PRIORITY_MASK | opp->vector_mask));
+    opp->src[n_IRQ].ivpr =
+        (opp->src[n_IRQ].ivpr & IVPR_ACTIVITY_MASK) | (val & mask);
+
+    /* For FSL internal interrupts, The sense bit is reserved and zero,
+     * and the interrupt is always level-triggered.  Timers and IPIs
+     * have no sense or polarity bits, and are edge-triggered.
+     */
+    switch (opp->src[n_IRQ].type) {
+    case IRQ_TYPE_NORMAL:
+        opp->src[n_IRQ].level = !!(opp->src[n_IRQ].ivpr & IVPR_SENSE_MASK);
+        break;
+
+    case IRQ_TYPE_FSLINT:
+        opp->src[n_IRQ].ivpr &= ~IVPR_SENSE_MASK;
+        break;
+
+    case IRQ_TYPE_FSLSPECIAL:
+        opp->src[n_IRQ].ivpr &= ~(IVPR_POLARITY_MASK | IVPR_SENSE_MASK);
+        break;
+    }
+
     openpic_update_irq(opp, n_IRQ);
     DPRINTF("Set IVPR %d to 0x%08x -> 0x%08x\n", n_IRQ, val,
             opp->src[n_IRQ].ivpr);
@@ -976,7 +1023,7 @@ static uint32_t openpic_cpu_read_internal(void *opaque, hwaddr addr,
                 retval = IVPR_VECTOR(opp, src->ivpr);
             }
             IRQ_resetbit(&dst->raised, n_IRQ);
-            if (!(src->ivpr & IVPR_SENSE_MASK)) {
+            if (!src->level) {
                 /* edge-sensitive IRQ */
                 src->ivpr &= ~IVPR_ACTIVITY_MASK;
                 src->pending = 0;
@@ -984,7 +1031,7 @@ static uint32_t openpic_cpu_read_internal(void *opaque, hwaddr addr,
 
             if ((n_IRQ >= opp->irq_ipi0) &&  (n_IRQ < (opp->irq_ipi0 + MAX_IPI))) {
                 src->idr &= ~(1 << idx);
-                if (src->idr && !(src->ivpr & IVPR_SENSE_MASK)) {
+                if (src->idr && !src->level) {
                     /* trigger on CPUs that didn't know about it yet */
                     openpic_set_irq(opp, n_IRQ, 1);
                     openpic_set_irq(opp, n_IRQ, 0);
@@ -1282,7 +1329,25 @@ static int openpic_init(SysBusDevice *dev)
         opp->brr1 = FSL_BRR1_IPID | FSL_BRR1_IPMJ | FSL_BRR1_IPMN;
         msi_supported = true;
         list = list_be;
+
+        for (i = 0; i < FSL_MPIC_20_MAX_EXT; i++) {
+            opp->src[i].level = false;
+        }
+
+        /* Internal interrupts, including message and MSI */
+        for (i = 16; i < MAX_SRC; i++) {
+            opp->src[i].type = IRQ_TYPE_FSLINT;
+            opp->src[i].level = true;
+        }
+
+        /* timers and IPIs */
+        for (i = MAX_SRC; i < MAX_IRQ; i++) {
+            opp->src[i].type = IRQ_TYPE_FSLSPECIAL;
+            opp->src[i].level = false;
+        }
+
         break;
+
     case OPENPIC_MODEL_RAVEN:
         opp->nb_irqs = RAVEN_MAX_EXT;
         opp->vid = VID_REVISION_1_3;
-- 
1.7.9.5