[PATCH 3/9] intc/grlib_irqmp: implements the multiprocessor status register

[Clément Chigot]

This implements the multiprocessor status register in grlib-irqmp and bind
it to a start signal, which will be later wired in leon3-generic to
start a cpu.

Co-developed-by: Frederic Konrad <konrad.frederic@yahoo.fr>
Signed-off-by: Clément Chigot <chigot@adacore.com>
---
 hw/intc/grlib_irqmp.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/hw/intc/grlib_irqmp.c b/hw/intc/grlib_irqmp.c
index 2bacc0ff56..be0e840181 100644
--- a/hw/intc/grlib_irqmp.c
+++ b/hw/intc/grlib_irqmp.c
@@ -63,6 +63,7 @@ struct IRQMP {
 
     unsigned int ncpus;
     IRQMPState *state;
+    qemu_irq start_signal[IRQMP_MAX_CPU];
     qemu_irq irq;
 };
 
@@ -70,6 +71,7 @@ struct IRQMPState {
     uint32_t level;
     uint32_t pending;
     uint32_t clear;
+    uint32_t mpstatus;
     uint32_t broadcast;
 
     uint32_t mask[IRQMP_MAX_CPU];
@@ -180,10 +182,12 @@ static uint64_t grlib_irqmp_read(void *opaque, hwaddr 
addr,
         return state->force[0];
 
     case CLEAR_OFFSET:
-    case MP_STATUS_OFFSET:
         /* Always read as 0 */
         return 0;
 
+    case MP_STATUS_OFFSET:
+        return state->mpstatus;
+
     case BROADCAST_OFFSET:
         return state->broadcast;
 
@@ -222,8 +226,9 @@ static uint64_t grlib_irqmp_read(void *opaque, hwaddr addr,
 static void grlib_irqmp_write(void *opaque, hwaddr addr,
                               uint64_t value, unsigned size)
 {
-    IRQMP      *irqmp = opaque;
+    IRQMP *irqmp = opaque;
     IRQMPState *state;
+    int i;
 
     assert(irqmp != NULL);
     state = irqmp->state;
@@ -256,7 +261,13 @@ static void grlib_irqmp_write(void *opaque, hwaddr addr,
         return;
 
     case MP_STATUS_OFFSET:
-        /* Read Only (no SMP support) */
+        value &= 0xffff;
+        for (i = 0; i < irqmp->ncpus; i++) {
+            if ((value >> i) & 1) {
+                qemu_set_irq(irqmp->start_signal[i], 1);
+                state->mpstatus &= ~(1 << i);
+            }
+        }
         return;
 
     case BROADCAST_OFFSET:
@@ -323,6 +334,8 @@ static void grlib_irqmp_reset(DeviceState *d)
 
     memset(irqmp->state, 0, sizeof *irqmp->state);
     irqmp->state->parent = irqmp;
+    irqmp->state->mpstatus = ((irqmp->ncpus - 1) << 28)
+        | ((1 << irqmp->ncpus) - 2);
 }
 
 static void grlib_irqmp_realize(DeviceState *dev, Error **errp)
@@ -336,6 +349,9 @@ static void grlib_irqmp_realize(DeviceState *dev, Error 
**errp)
     }
 
     qdev_init_gpio_in(dev, grlib_irqmp_set_irq, MAX_PILS);
+    /* Transitionning from 0 to 1 starts the CPUs.  */
+    qdev_init_gpio_out_named(dev, irqmp->start_signal, "grlib-start-cpu",
+                             IRQMP_MAX_CPU);
     qdev_init_gpio_out_named(dev, &irqmp->irq, "grlib-irq", 1);
     memory_region_init_io(&irqmp->iomem, OBJECT(dev), &grlib_irqmp_ops, irqmp,
                           "irqmp", IRQMP_REG_SIZE);
-- 
2.25.1