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

Hi Clément,

On 5/1/24 11:24, Clément Chigot wrote:
> 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(-)


> @@ -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)

Can you #define this magic '28' number?

> +        | ((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.  */

What about 1 -> 0?

> +    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);

On Fri, Jan 5, 2024 at 12:32 PM Philippe Mathieu-Daudé
<philmd@linaro.org> wrote:
>
> Hi Clément,
>
> On 5/1/24 11:24, Clément Chigot wrote:
> > 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(-)
>
>
> > @@ -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)
>
> Can you #define this magic '28' number?
>
> > +        | ((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.  */
>
> What about 1 -> 0?

It does nothing. I have updated the comment to mention it.
For the doc (also mention it in the commit message now).
  | [15:1] Power-down status of CPU [n]: reads ‘1’ = power-down, ‘0’ = running.
  | Write to start processor n: ‘1’=to start ‘0'=has no effect.


> > +    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);
>

On 5/1/24 14:23, Clément Chigot wrote:
> On Fri, Jan 5, 2024 at 12:32 PM Philippe Mathieu-Daudé
> <philmd@linaro.org> wrote:
>>
>> Hi Clément,
>>
>> On 5/1/24 11:24, Clément Chigot wrote:
>>> 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(-)
>>
>>
>>> @@ -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)
>>
>> Can you #define this magic '28' number?
>>
>>> +        | ((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.  */
>>
>> What about 1 -> 0?
> 
> It does nothing. I have updated the comment to mention it.
> For the doc (also mention it in the commit message now).
>    | [15:1] Power-down status of CPU [n]: reads ‘1’ = power-down, ‘0’ = running.
>    | Write to start processor n: ‘1’=to start ‘0'=has no effect.

Then grlib_irqmp_write() could be simplified as:

      case MP_STATUS_OFFSET:
-        /* Read Only (no SMP support) */
+        state->mpstatus = deposit32(state->mpstatus,
+                                    value, 0, IRQMP_MAX_CPU);
+        for (unsigned i = 0; i < irqmp->ncpus; i++) {
+            qemu_set_irq(irqmp->start_signal[i],
+                         extract32(value, i, 1));
+        }
          return;

On Fri, Jan 5, 2024 at 2:37 PM Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> On 5/1/24 14:23, Clément Chigot wrote:
> > On Fri, Jan 5, 2024 at 12:32 PM Philippe Mathieu-Daudé
> > <philmd@linaro.org> wrote:
> >>
> >> Hi Clément,
> >>
> >> On 5/1/24 11:24, Clément Chigot wrote:
> >>> 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(-)
> >>
> >>
> >>> @@ -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)
> >>
> >> Can you #define this magic '28' number?
> >>
> >>> +        | ((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.  */
> >>
> >> What about 1 -> 0?
> >
> > It does nothing. I have updated the comment to mention it.
> > For the doc (also mention it in the commit message now).
> >    | [15:1] Power-down status of CPU [n]: reads ‘1’ = power-down, ‘0’ = running.
> >    | Write to start processor n: ‘1’=to start ‘0'=has no effect.
>
> Then grlib_irqmp_write() could be simplified as:
>
>       case MP_STATUS_OFFSET:
> -        /* Read Only (no SMP support) */
> +        state->mpstatus = deposit32(state->mpstatus,
> +                                    value, 0, IRQMP_MAX_CPU);
> +        for (unsigned i = 0; i < irqmp->ncpus; i++) {
> +            qemu_set_irq(irqmp->start_signal[i],
> +                         extract32(value, i, 1));
> +        }
>           return;

No, because the logic between write and read is reversed.
Writing "1" starts the CPU but reading 1 means that the CPU is not
started. Therefore, when writing 1, we must trigger the start signal
and then write 0 in mpstatus.