Add GPIOALT2 register for new an555 board.
Implement register access as RW with LOG_UNIMP for writes.
Add "has-gpioalt2" property to make each board configurable.

Reviewed-by: Owen Giles <owen.giles@hpe.com>
Reviewed-by: Robert Elliott <elliott@hpe.com>
Signed-off-by: Simon Xu <simonxhy0404@gmail.com>
---
 hw/arm/mps2-tz.c              |  7 +++++++
 hw/misc/mps2-fpgaio.c         | 13 +++++++++++++
 include/hw/misc/mps2-fpgaio.h |  2 ++
 3 files changed, 22 insertions(+)

diff --git a/hw/arm/mps2-tz.c b/hw/arm/mps2-tz.c
index 2cb461ca71..d9f64880f8 100644
--- a/hw/arm/mps2-tz.c
+++ b/hw/arm/mps2-tz.c
@@ -131,6 +131,7 @@ struct MPS2TZMachineClass {
     uint32_t fpgaio_num_leds; /* Number of LEDs in FPGAIO LED0 register */
     bool fpgaio_has_switches; /* Does FPGAIO have SWITCH register? */
     bool fpgaio_has_dbgctrl; /* Does FPGAIO have DBGCTRL register? */
+    bool fpgaio_has_gpioalt2; /* Does FPGAIO have GPIOALT2 register? */
     int numirq; /* Number of external interrupts */
     int uart_overflow_irq; /* number of the combined UART overflow IRQ */
     uint32_t init_svtor; /* init-svtor setting for SSE */
@@ -515,6 +516,7 @@ static MemoryRegion *make_fpgaio(MPS2TZMachineState *mms, void *opaque,
     qdev_prop_set_uint32(DEVICE(fpgaio), "num-leds", mmc->fpgaio_num_leds);
     qdev_prop_set_bit(DEVICE(fpgaio), "has-switches", mmc->fpgaio_has_switches);
     qdev_prop_set_bit(DEVICE(fpgaio), "has-dbgctrl", mmc->fpgaio_has_dbgctrl);
+    qdev_prop_set_bit(DEVICE(fpgaio), "has-gpioalt2", mmc->fpgaio_has_gpioalt2);
     sysbus_realize(SYS_BUS_DEVICE(fpgaio), &error_fatal);
     return sysbus_mmio_get_region(SYS_BUS_DEVICE(fpgaio), 0);
 }
@@ -1433,6 +1435,7 @@ static void mps2tz_an505_class_init(ObjectClass *oc, const void *data)
     mmc->fpgaio_num_leds = 2;
     mmc->fpgaio_has_switches = false;
     mmc->fpgaio_has_dbgctrl = false;
+    mmc->fpgaio_has_gpioalt2 = false;
     mmc->numirq = 92;
     mmc->uart_overflow_irq = 47;
     mmc->init_svtor = 0x10000000;
@@ -1467,6 +1470,7 @@ static void mps2tz_an521_class_init(ObjectClass *oc, const void *data)
     mmc->fpgaio_num_leds = 2;
     mmc->fpgaio_has_switches = false;
     mmc->fpgaio_has_dbgctrl = false;
+    mmc->fpgaio_has_gpioalt2 = false;
     mmc->numirq = 92;
     mmc->uart_overflow_irq = 47;
     mmc->init_svtor = 0x10000000;
@@ -1501,6 +1505,7 @@ static void mps3tz_an524_class_init(ObjectClass *oc, const void *data)
     mmc->fpgaio_num_leds = 10;
     mmc->fpgaio_has_switches = true;
     mmc->fpgaio_has_dbgctrl = false;
+    mmc->fpgaio_has_gpioalt2 = false;
     mmc->numirq = 95;
     mmc->uart_overflow_irq = 47;
     mmc->init_svtor = 0x10000000;
@@ -1540,6 +1545,7 @@ static void mps3tz_an547_class_init(ObjectClass *oc, const void *data)
     mmc->fpgaio_num_leds = 10;
     mmc->fpgaio_has_switches = true;
     mmc->fpgaio_has_dbgctrl = true;
+    mmc->fpgaio_has_gpioalt2 = false;
     mmc->numirq = 96;
     mmc->uart_overflow_irq = 48;
     mmc->init_svtor = 0x00000000;
@@ -1575,6 +1581,7 @@ static void mps3tz_an555_class_init(ObjectClass *oc, const void *data)
     mmc->fpgaio_num_leds = 10;
     mmc->fpgaio_has_switches = true;
     mmc->fpgaio_has_dbgctrl = true;
+    mmc->fpgaio_has_gpioalt2 = true;
     mmc->numirq = 96;
     mmc->uart_overflow_irq = 48;
     mmc->init_svtor = 0x00000000;
diff --git a/hw/misc/mps2-fpgaio.c b/hw/misc/mps2-fpgaio.c
index da78cb6070..6696384a25 100644
--- a/hw/misc/mps2-fpgaio.c
+++ b/hw/misc/mps2-fpgaio.c
@@ -31,6 +31,7 @@
 REG32(LED0, 0)
 REG32(DBGCTRL, 4)
 REG32(BUTTON, 8)
+REG32(GPIOALT2, 0xc)
 REG32(CLK1HZ, 0x10)
 REG32(CLK100HZ, 0x14)
 REG32(COUNTER, 0x18)
@@ -142,6 +143,9 @@ static uint64_t mps2_fpgaio_read(void *opaque, hwaddr offset, unsigned size)
          */
         r = 0;
         break;
+    case A_GPIOALT2:
+        r = s->gpioalt2;
+        break;
     case A_PRESCALE:
         r = s->prescale;
         break;
@@ -210,6 +214,14 @@ static void mps2_fpgaio_write(void *opaque, hwaddr offset, uint64_t value,
                       "MPS2 FPGAIO: DBGCTRL unimplemented\n");
         s->dbgctrl = value;
         break;
+    case A_GPIOALT2:
+        if (!s->has_gpioalt2) {
+            goto bad_offset;
+        }
+        qemu_log_mask(LOG_UNIMP,
+                      "MPS2 FPGAIO: GPIOALT2 unimplemented\n");
+        s->gpioalt2 = value;
+        break;
     case A_PRESCALE:
         resync_counter(s);
         s->prescale = value;
@@ -326,6 +338,7 @@ static const Property mps2_fpgaio_properties[] = {
     DEFINE_PROP_UINT32("num-leds", MPS2FPGAIO, num_leds, 2),
     DEFINE_PROP_BOOL("has-switches", MPS2FPGAIO, has_switches, false),
     DEFINE_PROP_BOOL("has-dbgctrl", MPS2FPGAIO, has_dbgctrl, false),
+    DEFINE_PROP_BOOL("has-gpioalt2", MPS2FPGAIO, has_gpioalt2, false),
 };
 
 static void mps2_fpgaio_class_init(ObjectClass *klass, const void *data)
diff --git a/include/hw/misc/mps2-fpgaio.h b/include/hw/misc/mps2-fpgaio.h
index edd9f23121..7512686616 100644
--- a/include/hw/misc/mps2-fpgaio.h
+++ b/include/hw/misc/mps2-fpgaio.h
@@ -40,11 +40,13 @@ struct MPS2FPGAIO {
     uint32_t num_leds;
     bool has_switches;
     bool has_dbgctrl;
+    bool has_gpioalt2;
 
     uint32_t led0;
     uint32_t prescale;
     uint32_t misc;
     uint32_t dbgctrl;
+    uint32_t gpioalt2;
 
     /* QEMU_CLOCK_VIRTUAL time at which counter and pscntr were last synced */
     int64_t pscntr_sync_ticks;
-- 
2.53.0

On Wed, 5 Aug 2026 at 16:30, Simon Xu <simonxhy0404@gmail.com> wrote:
>
> Add GPIOALT2 register for new an555 board.
> Implement register access as RW with LOG_UNIMP for writes.
> Add "has-gpioalt2" property to make each board configurable.
>
> Reviewed-by: Owen Giles <owen.giles@hpe.com>
> Reviewed-by: Robert Elliott <elliott@hpe.com>
> Signed-off-by: Simon Xu <simonxhy0404@gmail.com>

This patch should go in the series before the one where we add
the an555 board, so that all the features it's supposed to have
are implemented before we expose it to users.

>  static void mps2_fpgaio_class_init(ObjectClass *klass, const void *data)
> diff --git a/include/hw/misc/mps2-fpgaio.h b/include/hw/misc/mps2-fpgaio.h
> index edd9f23121..7512686616 100644
> --- a/include/hw/misc/mps2-fpgaio.h
> +++ b/include/hw/misc/mps2-fpgaio.h
> @@ -40,11 +40,13 @@ struct MPS2FPGAIO {
>      uint32_t num_leds;
>      bool has_switches;
>      bool has_dbgctrl;
> +    bool has_gpioalt2;
>
>      uint32_t led0;
>      uint32_t prescale;
>      uint32_t misc;
>      uint32_t dbgctrl;
> +    uint32_t gpioalt2;

We need to migrate this new device state. To do that we'll have to
add a new vmstate subsection to the mps2_fpgaio_vmstate. If
you look at iotkit-sysctl.c you can see an example of how this
is done: you add a new .subsections to the vmstate, which
contains &mps2_fpgaio_gpioalt2_vmstate, plus a NULL terminator.
That new mps2_fpgaio_gpioalt2_vmstate should look like this:

static const VMStateDescription mps2_fpgaio_gpioalt2_vmstate = {
    .name = "mps2-fpgaio/gpioalt2",
    .version_id = 1,
    .minimum_version_id = 1,
    .needed = needed_gpioalt2,
    .fields = (const VMStateField[]) {
        VMSTATE_UINT32(gpioalt2, MPS2FPGAIO),
        VMSTATE_END_OF_LIST()
    }
};

The needed_gpioalt2 function should return true if has_gpioalt2.
(It gets passed the MPS2FPGAIO* as a void*, so you need to
cast it to the right type with the QOM macro.)

thanks
-- PMM