Re: [PATCH v3 04/20] nubus: use bitmap to manage available slots

[Philippe Mathieu-Daudé]

On 9/16/21 12:05 PM, Mark Cave-Ayland wrote:
> Convert nubus_device_realize() to use a bitmap to manage available slots to 
> allow
> for future Nubus devices to be plugged into arbitrary slots from the command 
> line.
> 
> Update mac_nubus_bridge_init() to only allow slots 0x9 to 0xe on a Macintosh
> machines as documented in "Desigining Cards and Drivers for the Macintosh 
> Family".
> 
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> ---
>  hw/nubus/mac-nubus-bridge.c |  3 +++
>  hw/nubus/nubus-bus.c        |  2 +-
>  hw/nubus/nubus-device.c     | 29 +++++++++++++++++++++++++----
>  include/hw/nubus/nubus.h    |  4 ++--
>  4 files changed, 31 insertions(+), 7 deletions(-)

> -    if (nubus->current_slot < NUBUS_FIRST_SLOT ||
> -            nubus->current_slot > NUBUS_LAST_SLOT) {
> -        error_setg(errp, "Cannot register nubus card, not enough slots");
> +    if (nd->slot < NUBUS_FIRST_SLOT || nd->slot > NUBUS_LAST_SLOT) {
> +        error_setg(errp, "Cannot register nubus card, slot must be "
> +                         "between %d and %d", NUBUS_FIRST_SLOT,
> +                         NUBUS_LAST_SLOT);
>          return;
>      }
>  
> -    nd->slot = nubus->current_slot++;
> +    nubus->slot_available_mask &= ~BIT(nd->slot);

Having slot_available_mask an unsigned long (instead of
uint32_t) we could use the clearer:

       clear_bit(nd->slot, &nubus->slot_available_mask);

Anyhow,

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

>  
>      /* Super */
>      slot_offset = (nd->slot - 6) * NUBUS_SUPER_SLOT_SIZE;
> diff --git a/include/hw/nubus/nubus.h b/include/hw/nubus/nubus.h
> index 357f621d15..8ff4736259 100644
> --- a/include/hw/nubus/nubus.h
> +++ b/include/hw/nubus/nubus.h

>  #define TYPE_NUBUS_DEVICE "nubus-device"
> @@ -36,7 +36,7 @@ struct NubusBus {
>      MemoryRegion super_slot_io;
>      MemoryRegion slot_io;
>  
> -    int current_slot;
> +    uint32_t slot_available_mask;
>  };
>  
>  struct NubusDevice {
>