Re: [PATCH v2 6/6] Driver: VMBus: Add device tree support

[Rob Herring]

On Tue, Jan 31, 2023 at 12:10 PM Saurabh Sengar
<ssengar@xxxxxxxxxxxxxxxxxxx> wrote:
>
> Update the driver to support device tree boot as well along with ACPI.
> At present the device tree parsing only provides the mmio region info
> and is not the exact copy of ACPI parsing. This is sufficient to cater
> all the current device tree usecases for VMBus.
>
> Signed-off-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/hv/vmbus_drv.c | 75 ++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 73 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 49030e756b9f..1741f1348f9f 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -2152,7 +2152,7 @@ void vmbus_device_unregister(struct hv_device *device_obj)
>         device_unregister(&device_obj->device);
>  }
>
> -
> +#ifdef CONFIG_ACPI
>  /*
>   * VMBUS is an acpi enumerated device. Get the information we
>   * need from DSDT.
> @@ -2262,6 +2262,7 @@ static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
>
>         return AE_OK;
>  }
> +#endif
>
>  static void vmbus_mmio_remove(void)
>  {
> @@ -2282,7 +2283,7 @@ static void vmbus_mmio_remove(void)
>         }
>  }
>
> -static void vmbus_reserve_fb(void)
> +static void __maybe_unused vmbus_reserve_fb(void)
>  {
>         resource_size_t start = 0, size;
>         struct pci_dev *pdev;
> @@ -2442,6 +2443,7 @@ void vmbus_free_mmio(resource_size_t start, resource_size_t size)
>  }
>  EXPORT_SYMBOL_GPL(vmbus_free_mmio);
>
> +#ifdef CONFIG_ACPI

It's better to put C 'if (!IS_ENABLED(CONFIG_ACPI)' code in the

>  static int vmbus_acpi_add(struct platform_device *pdev)
>  {
>         acpi_status result;
> @@ -2496,10 +2498,68 @@ static int vmbus_acpi_add(struct platform_device *pdev)
>                 vmbus_mmio_remove();
>         return ret_val;
>  }
> +#else
> +
> +static int vmbus_device_add(struct platform_device *pdev)
> +{
> +       struct resource **cur_res = &hyperv_mmio;
> +       struct device_node *np;
> +       u32 *ranges, len;
> +       u64 start;
> +       int nr_ranges, child_cells = 2, cur_cell = 0, ret = 0;
> +
> +       hv_dev = pdev;
> +       np = pdev->dev.of_node;
> +
> +       nr_ranges = device_property_count_u32(&pdev->dev, "ranges");

Parsing ranges yourself is a bad sign. It's a standard property and we
have functions which handle it. If those don't work, then something is
wrong with your DT or they need to be fixed/expanded.

> +       if (nr_ranges < 0)
> +               return nr_ranges;
> +       ranges = kcalloc(nr_ranges, sizeof(u32), GFP_KERNEL);
> +       if (!ranges)
> +               return -ENOMEM;
> +
> +       if (device_property_read_u32_array(&pdev->dev, "ranges", ranges, nr_ranges)) {
> +               ret =  -EINVAL;
> +               goto free_ranges;
> +       }
> +
> +       while (cur_cell < nr_ranges) {
> +               struct resource *res;
> +
> +               /* The first u64 in the ranges description isn't used currently. */
> +               cur_cell = cur_cell + child_cells;
> +               start = ranges[cur_cell++];
> +               start = (start << 32) | ranges[cur_cell++];
> +               len = ranges[cur_cell++];

To expand my last point, the format of ranges is <child_addr
parent_addr length>. That's not what your 'ranges' has. You've also
just ignored '#address-cells' and '#size-cells'.

> +
> +               res = kzalloc(sizeof(*res), GFP_ATOMIC);
> +               if (!res) {
> +                       ret = -ENOMEM;
> +                       goto free_ranges;
> +               }
> +
> +               res->name = "hyperv mmio";
> +               res->flags = IORESOURCE_MEM | IORESOURCE_MEM_64;
> +               res->start = start;
> +               res->end = start + len;
> +
> +               *cur_res = res;
> +               cur_res = &res->sibling;
> +       }
> +
> +free_ranges:
> +       kfree(ranges);
> +       return ret;
> +}
> +#endif
>
>  static int vmbus_platform_driver_probe(struct platform_device *pdev)
>  {
> +#ifdef CONFIG_ACPI
>         return vmbus_acpi_add(pdev);
> +#else
> +       return vmbus_device_add(pdev);
> +#endif
>  }
>
>  static int vmbus_platform_driver_remove(struct platform_device *pdev)
> @@ -2645,6 +2705,16 @@ static int vmbus_bus_resume(struct device *dev)
>  #define vmbus_bus_resume NULL
>  #endif /* CONFIG_PM_SLEEP */
>
> +static const struct of_device_id vmbus_of_match[] = {
> +       {
> +               .compatible = "msft,vmbus",
> +       },
> +       {
> +               /* sentinel */
> +       },
> +};
> +MODULE_DEVICE_TABLE(of, vmbus_of_match);
> +
>  static const struct acpi_device_id vmbus_acpi_device_ids[] = {
>         {"VMBUS", 0},
>         {"VMBus", 0},
> @@ -2679,6 +2749,7 @@ static struct platform_driver vmbus_platform_driver = {
>         .driver = {
>                 .name = "vmbus",
>                 .acpi_match_table = ACPI_PTR(vmbus_acpi_device_ids),
> +               .of_match_table = of_match_ptr(vmbus_of_match),
>                 .pm = &vmbus_bus_pm,
>                 .probe_type = PROBE_FORCE_SYNCHRONOUS,
>         }
> --
> 2.25.1
>