Re: [PATCH 05/12] hw/pci-host/bonito: Do not use SysBus API to map local MMIO region

[Thomas Huth <thuth@redhat.com>]

On 18/10/2023 16.11, Philippe Mathieu-Daudé wrote:
> There is no point in exposing an internal MMIO region via
> SysBus and directly mapping it in the very same device.
> 
> Just map it without using the SysBus API.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   hw/pci-host/bonito.c | 29 ++++++++++++++---------------
>   1 file changed, 14 insertions(+), 15 deletions(-)
> 
> diff --git a/hw/pci-host/bonito.c b/hw/pci-host/bonito.c
> index ee6cb85e97..3b803bcad3 100644
> --- a/hw/pci-host/bonito.c
> +++ b/hw/pci-host/bonito.c
> @@ -654,7 +654,6 @@ static void bonito_host_realize(DeviceState *dev, Error **errp)
>   static void bonito_pci_realize(PCIDevice *dev, Error **errp)
>   {
>       PCIBonitoState *s = PCI_BONITO(dev);
> -    SysBusDevice *sysbus = SYS_BUS_DEVICE(s->pcihost);
>       PCIHostState *phb = PCI_HOST_BRIDGE(s->pcihost);
>       BonitoState *bs = s->pcihost;
>       MemoryRegion *pcimem_alias = g_new(MemoryRegion, 1);
> @@ -668,48 +667,48 @@ static void bonito_pci_realize(PCIDevice *dev, Error **errp)
>       /* set the north bridge register mapping */
>       memory_region_init_io(&s->iomem, OBJECT(s), &bonito_ops, s,
>                             "north-bridge-register", BONITO_INTERNAL_REG_SIZE);
> -    sysbus_init_mmio(sysbus, &s->iomem);
> -    sysbus_mmio_map(sysbus, 0, BONITO_INTERNAL_REG_BASE);
> +    memory_region_add_subregion(get_system_memory(), BONITO_INTERNAL_REG_BASE,
> +                                &s->iomem);
>   
>       /* set the north bridge pci configure  mapping */
>       memory_region_init_io(&phb->conf_mem, OBJECT(s), &bonito_pciconf_ops, s,
>                             "north-bridge-pci-config", BONITO_PCICONFIG_SIZE);
> -    sysbus_init_mmio(sysbus, &phb->conf_mem);
> -    sysbus_mmio_map(sysbus, 1, BONITO_PCICONFIG_BASE);
> +    memory_region_add_subregion(get_system_memory(), BONITO_PCICONFIG_BASE,
> +                                &phb->conf_mem);
>   
>       /* set the south bridge pci configure  mapping */
>       memory_region_init_io(&phb->data_mem, OBJECT(s), &bonito_spciconf_ops, s,
>                             "south-bridge-pci-config", BONITO_SPCICONFIG_SIZE);
> -    sysbus_init_mmio(sysbus, &phb->data_mem);
> -    sysbus_mmio_map(sysbus, 2, BONITO_SPCICONFIG_BASE);
> +    memory_region_add_subregion(get_system_memory(), BONITO_SPCICONFIG_BASE,
> +                                &phb->data_mem);
>   
>       create_unimplemented_device("bonito", BONITO_REG_BASE, BONITO_REG_SIZE);
>   
>       memory_region_init_io(&s->iomem_ldma, OBJECT(s), &bonito_ldma_ops, s,
>                             "ldma", 0x100);
> -    sysbus_init_mmio(sysbus, &s->iomem_ldma);
> -    sysbus_mmio_map(sysbus, 3, 0x1fe00200);
> +    memory_region_add_subregion(get_system_memory(), 0x1fe00200,
> +                                &s->iomem_ldma);
>   
>       /* PCI copier */
>       memory_region_init_io(&s->iomem_cop, OBJECT(s), &bonito_cop_ops, s,
>                             "cop", 0x100);
> -    sysbus_init_mmio(sysbus, &s->iomem_cop);
> -    sysbus_mmio_map(sysbus, 4, 0x1fe00300);
> +    memory_region_add_subregion(get_system_memory(), 0x1fe00300,
> +                                &s->iomem_cop);
>   
>       create_unimplemented_device("ROMCS", BONITO_FLASH_BASE, 60 * MiB);
>   
>       /* Map PCI IO Space  0x1fd0 0000 - 0x1fd1 0000 */
>       memory_region_init_alias(&s->bonito_pciio, OBJECT(s), "isa_mmio",
>                                get_system_io(), 0, BONITO_PCIIO_SIZE);
> -    sysbus_init_mmio(sysbus, &s->bonito_pciio);
> -    sysbus_mmio_map(sysbus, 5, BONITO_PCIIO_BASE);
> +    memory_region_add_subregion(get_system_memory(), BONITO_PCIIO_BASE,
> +                                &s->bonito_pciio);
>   
>       /* add pci local io mapping */
>   
>       memory_region_init_alias(&s->bonito_localio, OBJECT(s), "IOCS[0]",
>                                get_system_io(), 0, 256 * KiB);
> -    sysbus_init_mmio(sysbus, &s->bonito_localio);
> -    sysbus_mmio_map(sysbus, 6, BONITO_DEV_BASE);
> +    memory_region_add_subregion(get_system_memory(), BONITO_DEV_BASE,
> +                                &s->bonito_localio);
>       create_unimplemented_device("IOCS[1]", BONITO_DEV_BASE + 1 * 256 * KiB,
>                                   256 * KiB);
>       create_unimplemented_device("IOCS[2]", BONITO_DEV_BASE + 2 * 256 * KiB,

Would it make sense to cache the return value of get_system_memory() in a 
local variable instead of calling it again and again ...?

  Thomas