Re: [PATCH 4/7] of: configure the platform device dma_mask and dma_pfn_offset

[Rob Herring]

On Thu, Mar 6, 2014 at 3:19 AM, Santosh Shilimkar
<santosh.shilimkar@xxxxxx> wrote:
> From: Grygorii Strashko <grygorii.strashko@xxxxxx>
>
> Retrieve DMA configuration from DT and setup platform device's DMA
> parameters.
>
> The DMA configuration in DT has to be specified using "dma-ranges"
> property if supported. The DMA configuration applied
> by dt_dma_configure() as following:
>  - call of_get_dma_range() and get supported DMA range info
>    (dma_addr, cpu_addr, dma_size);
>  - if "not found" then fill dma_mask as DMA_BIT_MASK(32)
>    (this is default behaviour);
>  - if "failed" then clean up dma_mask (DMA not supported)
>  - if ok then update devices DMA configuration:
>       set dma_mask to (dma_addr + dma_size - 1)
>       set dma_pfn_offset to PFN_DOWN(cpu_addr - dma_addr)
>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Olof Johansson <olof@xxxxxxxxx>
> Cc: Grant Likely <grant.likely@xxxxxxxxxx>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
> ---
>  drivers/of/platform.c |   75 +++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 72 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index bd080db..53bb12f 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -187,6 +187,77 @@ struct platform_device *of_device_alloc(struct device_node *np,
>  EXPORT_SYMBOL(of_device_alloc);
>
>  /**
> + * dt_dma_configure - apply default DMA configuration from dt

s/dt_/of_/

> + * @dev:       Device to apply DMA configuration
> + *
> + * Try to get devices's DMA configuration from DT and apply it.
> + * The DMA configuration is represented in DT by "dma-ranges" property.
> + * It configures:
> + *     dma_pfn_offset, dma_mask and coherent_dma_mask.
> + *
> + * In case if DMA configuration can't be acquired from DT the default one is
> + * applied:
> + *     dma_pfn_offset = 0,
> + *     dma_mask = DMA_BIT_MASK(32)

This is really set to &coherent_dma_mask.

> + *     coherent_dma_mask = DMA_BIT_MASK(32).
> +
> + * In case if platform code need to use own DMA configuration - it can use
> + * Platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE event to fix up
> + * DMA configuration.
> + */
> +static void dt_dma_configure(struct device *dev)

s/dt_/of_/

> +{
> +       dma_addr_t dma_addr;
> +       phys_addr_t paddr, size;
> +       dma_addr_t dma_mask;
> +       int ret;
> +
> +       /*
> +        * if dma-ranges property doesn't exist - use 32 bits DMA mask
> +        * by default and don't set skip archdata.dma_pfn_offset
> +        */
> +       ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size);
> +       if (ret == -ENODEV) {
> +               dev->coherent_dma_mask = DMA_BIT_MASK(32);
> +               if (!dev->dma_mask)
> +                       dev->dma_mask = &dev->coherent_dma_mask;
> +               return;
> +       }
> +
> +       /* if failed - disable DMA for device */
> +       if (ret < 0) {
> +               dev_err(dev, "failed to configure DMA\n");
> +               return;
> +       }
> +
> +       /* DMA ranges found. Calculate and set dma_pfn_offset */
> +       dev->dma_pfn_offset = PFN_DOWN(paddr - dma_addr);
> +
> +       /* Configure DMA mask */
> +       dev->dma_mask = &dev->coherent_dma_mask;
> +       if (!dev->dma_mask)

This condition is impossible.

> +               return;
> +
> +       dma_mask = dma_addr + size - 1;
> +
> +       ret = dma_set_mask(dev, dma_mask);
> +       if (ret < 0) {
> +               dev_err(dev, "failed to set DMA mask %pad\n", &dma_mask);
> +               dev->dma_mask = NULL;
> +               return;
> +       }
> +
> +       dev_dbg(dev, "dma_pfn_offset(%#08lx) dma_mask(%pad)\n",
> +               dev->dma_pfn_offset, dev->dma_mask);
> +
> +       ret = dma_set_coherent_mask(dev, dma_mask);

I think these 2 calls belong in the drivers, not here.

> +       if (ret < 0) {
> +               dev_err(dev, "failed to set coherent DMA mask %pad\n",
> +                       &dma_mask);
> +       }
> +}
> +
> +/**
>   * of_platform_device_create_pdata - Alloc, initialize and register an of_device
>   * @np: pointer to node to create device for
>   * @bus_id: name to assign device
> @@ -214,9 +285,7 @@ static struct platform_device *of_platform_device_create_pdata(
>  #if defined(CONFIG_MICROBLAZE)
>         dev->archdata.dma_mask = 0xffffffffUL;
>  #endif
> -       dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
> -       if (!dev->dev.dma_mask)
> -               dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
> +       dt_dma_configure(&dev->dev);
>         dev->dev.bus = &platform_bus_type;
>         dev->dev.platform_data = platform_data;
>
> --
> 1.7.9.5
>
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