Re: [Qemu-devel] [PATCH v3 4/4] hw/arm/sysbus-fdt: Add support for instantiating generic devices

[Auger Eric <eric.auger@redhat.com>]

Hi Geert,

On 07/25/2018 04:34 PM, Geert Uytterhoeven wrote:
> Add a fallback for instantiating generic devices without a type-specific
> or compatible-specific instantation method.  This will be used when no
> other match is found.
> 
> The generic instantation method creates a device node with "reg" and
> (optional) "interrupts" properties, and copies the "compatible"
> property and other optional properties from the host.
> For now the following optional properties are copied, if found:
>   - "#gpio-cells",
>   - "gpio-controller",
>   - "#interrupt-cells",
>   - "interrupt-controller",
>   - "interrupt-names".
> 
> More can be added when needed.
> 
> This avoids having to write device-specific instantation methods for
instantiation
> each and every "simple" device using only a set of generic properties.
> Devices that need more specialized handling can still provide their
> own instantation method.
> 
> This has been tested on a Renesas Salvator-XS board with R-Car H3 ES2.0
> with SATA:
> 
>     -device vfio-platform,host=ee300000.sata
> 
> and GPIO (needs VFIO No-IOMMU support):
> 
>     -device vfio-platform,host=e6055400.gpio
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> v3:
>   - New.
> ---
>  hw/arm/sysbus-fdt.c | 102 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 102 insertions(+)
> 
> diff --git a/hw/arm/sysbus-fdt.c b/hw/arm/sysbus-fdt.c
> index 0e24c803a1c2c734..8040af00ccf131d7 100644
> --- a/hw/arm/sysbus-fdt.c
> +++ b/hw/arm/sysbus-fdt.c
> @@ -415,6 +415,99 @@ static int add_amd_xgbe_fdt_node(SysBusDevice *sbdev, void *opaque)
>      return 0;
>  }
>  
> +static HostProperty generic_copied_properties[] = {
> +    {"compatible", false},
> +    {"#gpio-cells", true},
> +    {"gpio-controller", true},
> +    {"#interrupt-cells", true},
> +    {"interrupt-controller", true},
> +    {"interrupt-names", true},
I think we would need to enumerate the other source properties which
were not copied to the guest fdt and either warn the userspace those
were omitted or fail. We may end up generating an incomplete guest dt
node that may not work properly.
> +};
> +
> +/**
> + * add_generic_fdt_node
> + *
> + * Generates a generic DT node by copying properties from the host
> + */
> +static int add_generic_fdt_node(SysBusDevice *sbdev, void *opaque)
> +{
> +    PlatformBusFDTData *data = opaque;
> +    VFIOPlatformDevice *vdev = VFIO_PLATFORM_DEVICE(sbdev);
> +    const char *parent_node = data->pbus_node_name;
> +    void *guest_fdt = data->fdt, *host_fdt;
> +    VFIODevice *vbasedev = &vdev->vbasedev;
> +    char **node_path, *node_name, *dt_name;
> +    PlatformBusDevice *pbus = data->pbus;
> +    int i, irq_number;
> +    uint32_t *reg_attr, *irq_attr;
> +    uint64_t mmio_base;
> +
> +    host_fdt = load_device_tree_from_sysfs();
> +
> +    dt_name = sysfs_to_dt_name(vbasedev->name);
> +    if (!dt_name) {
> +        error_report("%s incorrect sysfs device name %s", __func__,
> +                     vbasedev->name);
> +        exit(1);
> +    }
> +    node_path = qemu_fdt_node_path(host_fdt, dt_name, vdev->compat,
> +                                   &error_fatal);
> +    if (!node_path || !node_path[0]) {
> +        error_report("%s unable to retrieve node path for %s/%s", __func__,
> +                     dt_name, vdev->compat);
> +        exit(1);
> +    }
> +
> +    if (node_path[1]) {
> +        error_report("%s more than one node matching %s/%s!", __func__, dt_name,
> +                     vdev->compat);
> +        exit(1);
> +    }
> +
> +    mmio_base = platform_bus_get_mmio_addr(pbus, sbdev, 0);
> +    node_name = g_strdup_printf("%s/%s@%" PRIx64, parent_node,
> +                               vbasedev->name, mmio_base);
> +    qemu_fdt_add_subnode(guest_fdt, node_name);
> +
> +    /* Copy generic properties */
> +    copy_properties_from_host(generic_copied_properties,
> +                              ARRAY_SIZE(generic_copied_properties), host_fdt,
> +                              guest_fdt, node_path[0], node_name);
> +
> +    /* Copy reg (remapped) */
> +    reg_attr = g_new(uint32_t, vbasedev->num_regions * 2);
> +    for (i = 0; i < vbasedev->num_regions; i++) {
> +        mmio_base = platform_bus_get_mmio_addr(pbus, sbdev, i);
> +        reg_attr[2 * i] = cpu_to_be32(mmio_base);
> +        reg_attr[2 * i + 1] = cpu_to_be32(
> +                                memory_region_size(vdev->regions[i]->mem));
> +    }
> +    qemu_fdt_setprop(guest_fdt, node_name, "reg", reg_attr,
> +                     vbasedev->num_regions * 2 * sizeof(uint32_t));
> +
> +    /* Copy interrupts (remapped) */
> +    if (vbasedev->num_irqs) {
> +        irq_attr = g_new(uint32_t, vbasedev->num_irqs * 3);
> +        for (i = 0; i < vbasedev->num_irqs; i++) {
> +            irq_number = platform_bus_get_irqn(pbus, sbdev , i)
> +                             + data->irq_start;
> +            irq_attr[3 * i] = cpu_to_be32(GIC_FDT_IRQ_TYPE_SPI);
> +            irq_attr[3 * i + 1] = cpu_to_be32(irq_number);
> +            irq_attr[3 * i + 2] = cpu_to_be32(GIC_FDT_IRQ_FLAGS_LEVEL_HI);
I think this part is not generic enough. How can you assume the IRQs are
level or edge? Can't you copy the source interrupt properties and just
overwrite the IRQ number?

Thanks

Eric
> +        }
> +        qemu_fdt_setprop(guest_fdt, node_name, "interrupts",
> +                         irq_attr, vbasedev->num_irqs * 3 * sizeof(uint32_t));
> +        g_free(irq_attr);
> +    }
> +
> +    g_free(reg_attr);
> +    g_free(node_name);
> +    g_strfreev(node_path);
> +    g_free(dt_name);
> +    g_free(host_fdt);
> +    return 0;
> +}
> +
>  /* DT compatible matching */
>  static bool vfio_platform_match(SysBusDevice *sbdev,
>                                  const BindingEntry *entry)
> @@ -423,6 +516,11 @@ static bool vfio_platform_match(SysBusDevice *sbdev,
>      const char *compat;
>      unsigned int n;
>  
> +    if (!entry->compat) {
> +        /* Generic DT fallback */
> +        return true;
> +    }
> +
>      for (n = vdev->num_compat, compat = vdev->compat; n > 0;
>           n--, compat += strlen(compat) + 1) {
>          if (!strcmp(entry->compat, compat)) {
> @@ -459,6 +557,10 @@ static const BindingEntry bindings[] = {
>      VFIO_PLATFORM_BINDING("amd,xgbe-seattle-v1a", add_amd_xgbe_fdt_node),
>  #endif
>      TYPE_BINDING(TYPE_RAMFB_DEVICE, no_fdt_node),
> +#ifdef CONFIG_LINUX
> +    /* Generic DT fallback must be last */
> +    VFIO_PLATFORM_BINDING(NULL, add_generic_fdt_node),
> +#endif
>      TYPE_BINDING("", NULL), /* last element */
>  };
>  
>