Re: [PATCH 5/6] hw/arm/raspi: Dynamically create machines based on the board revision

[Igor Mammedov <imammedo@redhat.com>]

On Mon,  3 Feb 2020 09:26:18 +0100
Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:

> We added tiny helpers extracting different values from the board
> revision, we can now create a full board based on its revision.
> The 'raspi-common' type is common to all raspi boards.
> 
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>  hw/arm/raspi.c | 93 +++++++++++++++++++++++++++++++++-----------------
>  1 file changed, 62 insertions(+), 31 deletions(-)
> 
> diff --git a/hw/arm/raspi.c b/hw/arm/raspi.c
> index 656d834e07..12dc4d1486 100644
> --- a/hw/arm/raspi.c
> +++ b/hw/arm/raspi.c
> @@ -44,12 +44,17 @@ static const struct {
>      [C_BCM2837] = {TYPE_BCM2837},
>  };
>  
> -typedef struct RasPiState {
> +typedef struct RaspiMachineState {
> +    /*< private >*/
> +    MachineState parent_obj;
> +    /*< public >*/
>      BCM283XState soc;
>      MemoryRegion ram;
> -} RasPiState;
> +} RaspiMachineState;
>  
>  typedef struct RaspiBoardInfo {
> +    const char *name;
> +    const char *desc;
>      /*
>       * Board revision codes:
>       * www.raspberrypi.org/documentation/hardware/raspberrypi/revision-codes/
> @@ -57,16 +62,32 @@ typedef struct RaspiBoardInfo {
>      uint32_t board_rev;
>  } RaspiBoardInfo;
>  
> -enum { BOARD_PI2, BOARD_PI3 };
> +typedef struct RaspiMachineClass {
> +    /*< private >*/
> +    MachineClass parent_obj;
> +    /*< public >*/
> +    const RaspiBoardInfo *config;
> +} RaspiMachineClass;
> +
> +#define TYPE_RASPI_MACHINE       MACHINE_TYPE_NAME("raspi-common")
> +#define RASPI_MACHINE(obj) \
> +    OBJECT_CHECK(RaspiMachineState, (obj), TYPE_RASPI_MACHINE)
> +
> +#define RASPI_MACHINE_CLASS(klass) \
> +     OBJECT_CLASS_CHECK(RaspiMachineClass, (klass), TYPE_RASPI_MACHINE)
> +#define RASPI_MACHINE_GET_CLASS(obj) \
> +     OBJECT_GET_CLASS(RaspiMachineClass, (obj), TYPE_RASPI_MACHINE)
>  
>  static const RaspiBoardInfo raspi_boards[] = {
> -    [BOARD_PI2] =
>      {
> +        .name = MACHINE_TYPE_NAME("raspi2"),
> +        .desc = "Raspberry Pi 2B",
>          .board_rev = 0xa21041,
>      },
>  #ifdef TARGET_AARCH64
> -    [BOARD_PI3] =
>      {
> +        .name = MACHINE_TYPE_NAME("raspi3"),
> +        .desc = "Raspberry Pi 3B",
>          .board_rev = 0xa02082,
>      },
>  #endif
> @@ -221,7 +242,7 @@ static void setup_boot(MachineState *machine, int version, size_t ram_size)
>  
>  static void raspi_init(MachineState *machine, const RaspiBoardInfo *config)
>  {
> -    RasPiState *s = g_new0(RasPiState, 1);
> +    RaspiMachineState *s = RASPI_MACHINE(machine);
>      int version = board_version(config);
>      uint32_t vcram_size;
>      DriveInfo *di;
> @@ -271,15 +292,22 @@ static void raspi_init(MachineState *machine, const RaspiBoardInfo *config)
>      setup_boot(machine, version, machine->ram_size - vcram_size);
>  }
>  
> -static void raspi2_init(MachineState *machine)
> +static void raspi_machine_init(MachineState *machine)
>  {
> -    raspi_init(machine, &raspi_boards[BOARD_PI2]);
> +    RaspiMachineClass *rmc = RASPI_MACHINE_GET_CLASS(machine);
> +
> +    raspi_init(machine, rmc->config);
>  }
>  
> -static void raspi2_machine_init(MachineClass *mc)
> +static void raspi_machine_class_init(ObjectClass *oc, void *data)
>  {
> -    mc->desc = "Raspberry Pi 2";
> -    mc->init = raspi2_init;
> +    MachineClass *mc = MACHINE_CLASS(oc);
> +    RaspiMachineClass *rmc = RASPI_MACHINE_CLASS(oc);
> +    const RaspiBoardInfo *config = data;
> +
> +    rmc->config = config;
> +    mc->desc = config->desc;
> +    mc->init = raspi_machine_init;
>      mc->block_default_type = IF_SD;
>      mc->no_parallel = 1;
>      mc->no_floppy = 1;
> @@ -287,29 +315,32 @@ static void raspi2_machine_init(MachineClass *mc)
>      mc->max_cpus = BCM283X_NCPUS;
>      mc->min_cpus = BCM283X_NCPUS;
>      mc->default_cpus = BCM283X_NCPUS;
> -    mc->default_ram_size = 1 * GiB;
> +    mc->default_ram_size = board_ram_size(config);
>      mc->ignore_memory_transaction_failures = true;
> +}
> +
> +static const TypeInfo raspi_machine_type = {
> +    .name = TYPE_RASPI_MACHINE,
> +    .parent = TYPE_MACHINE,
> +    .instance_size = sizeof(RaspiMachineState),
> +    .class_size = sizeof(RaspiMachineClass),
> +    .abstract = true,
>  };
> -DEFINE_MACHINE("raspi2", raspi2_machine_init)
>  
> -#ifdef TARGET_AARCH64
> -static void raspi3_init(MachineState *machine)
> +static void raspi_machine_types(void)
>  {
> -    raspi_init(machine, &raspi_boards[BOARD_PI3]);
> +    int i;
> +
> +    type_register_static(&raspi_machine_type);
> +    for (i = 0; i < ARRAY_SIZE(raspi_boards); ++i) {
> +        TypeInfo ti = {
> +            .name       = raspi_boards[i].name,
> +            .parent     = TYPE_RASPI_MACHINE,
> +            .class_init = raspi_machine_class_init,
> +            .class_data = (void *)&raspi_boards[i],
> +        };
> +        type_register(&ti);
> +    }

from what I've seen we do something like this in cases where
we need to generate a lot of classes based on data.

The thing is that it's harder to deal with compared to typical
template where one defines machine classes and per machine
type foo_class_init() functions. Yes it's a bit more boiler
plate but it's what is typically used/consistent with machine types.
So if one would have touch touch that future, one wouldn't have
to wrap their brain around yet another way to define machine.

>  }
>  
> -static void raspi3_machine_init(MachineClass *mc)
> -{
> -    mc->desc = "Raspberry Pi 3";
> -    mc->init = raspi3_init;
> -    mc->block_default_type = IF_SD;
> -    mc->no_parallel = 1;
> -    mc->no_floppy = 1;
> -    mc->no_cdrom = 1;
> -    mc->max_cpus = BCM283X_NCPUS;
> -    mc->min_cpus = BCM283X_NCPUS;
> -    mc->default_cpus = BCM283X_NCPUS;
> -    mc->default_ram_size = 1 * GiB;
> -}
> -DEFINE_MACHINE("raspi3", raspi3_machine_init)
> -#endif
> +type_init(raspi_machine_types)