Re: [PATCH v3 2/7] of: introduce of_dma_get_range() helper

[Rob Herring]

On Thu, Apr 24, 2014 at 10:30 AM, Santosh Shilimkar
<santosh.shilimkar@xxxxxx> wrote:
> From: Grygorii Strashko <grygorii.strashko@xxxxxx>
>
> The of_dma_get_range() allows to find "dma-range" property for
> the specified device and parse it.
>  dma-ranges format:
>    DMA addr (dma_addr)          : naddr cells
>    CPU addr (phys_addr_t)       : pna cells
>    size                         : nsize cells
>
> 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>

Reviewed-by: Rob Herring <robh@xxxxxxxxxx>

> ---
>  drivers/of/address.c       |   87 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of_address.h |    8 ++++
>  2 files changed, 95 insertions(+)
>
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index cb4242a..c54baee 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -721,3 +721,90 @@ void __iomem *of_iomap(struct device_node *np, int index)
>         return ioremap(res.start, resource_size(&res));
>  }
>  EXPORT_SYMBOL(of_iomap);
> +
> +/**
> + * of_dma_get_range - Get DMA range info
> + * @np:                device node to get DMA range info
> + * @dma_addr:  pointer to store initial DMA address of DMA range
> + * @paddr:     pointer to store initial CPU address of DMA range
> + * @size:      pointer to store size of DMA range
> + *
> + * Look in bottom up direction for the first "dma-ranges" property
> + * and parse it.
> + *  dma-ranges format:
> + *     DMA addr (dma_addr)     : naddr cells
> + *     CPU addr (phys_addr_t)  : pna cells
> + *     size                    : nsize cells
> + *
> + * It returns -ENODEV if "dma-ranges" property was not found
> + * for this device in DT.
> + */
> +int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *size)
> +{
> +       struct device_node *node = of_node_get(np);
> +       const __be32 *ranges = NULL;
> +       int len, naddr, nsize, pna;
> +       int ret = 0;
> +       u64 dmaaddr;
> +
> +       if (!node)
> +               return -EINVAL;
> +
> +       while (1) {
> +               naddr = of_n_addr_cells(node);
> +               nsize = of_n_size_cells(node);
> +               node = of_get_next_parent(node);
> +               if (!node)
> +                       break;
> +
> +               ranges = of_get_property(node, "dma-ranges", &len);
> +
> +               /* Ignore empty ranges, they imply no translation required */
> +               if (ranges && len > 0)
> +                       break;
> +
> +               /*
> +                * At least empty ranges has to be defined for parent node if
> +                * DMA is supported
> +                */
> +               if (!ranges)
> +                       break;
> +       }
> +
> +       if (!ranges) {
> +               pr_debug("%s: no dma-ranges found for node(%s)\n",
> +                        __func__, np->full_name);
> +               ret = -ENODEV;
> +               goto out;
> +       }
> +
> +       len /= sizeof(u32);
> +
> +       pna = of_n_addr_cells(node);
> +
> +       /* dma-ranges format:
> +        * DMA addr     : naddr cells
> +        * CPU addr     : pna cells
> +        * size         : nsize cells
> +        */
> +       dmaaddr = of_read_number(ranges, naddr);
> +       *paddr = of_translate_dma_address(np, ranges);
> +       if (*paddr == OF_BAD_ADDR) {
> +               pr_err("%s: translation of DMA address(%pad) to CPU address failed node(%s)\n",
> +                      __func__, dma_addr, np->full_name);
> +               ret = -EINVAL;
> +               goto out;
> +       }
> +       *dma_addr = dmaaddr;
> +
> +       *size = of_read_number(ranges + naddr + pna, nsize);
> +
> +       pr_debug("dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
> +                *dma_addr, *paddr, *size);
> +
> +out:
> +       of_node_put(node);
> +
> +       return ret;
> +}
> +EXPORT_SYMBOL_GPL(of_dma_get_range);
> diff --git a/include/linux/of_address.h b/include/linux/of_address.h
> index 5f6ed6b..4d7b325 100644
> --- a/include/linux/of_address.h
> +++ b/include/linux/of_address.h
> @@ -63,6 +63,8 @@ extern int of_pci_range_parser_init(struct of_pci_range_parser *parser,
>  extern struct of_pci_range *of_pci_range_parser_one(
>                                         struct of_pci_range_parser *parser,
>                                         struct of_pci_range *range);
> +extern int of_dma_get_range(struct device_node *np, u64 *dma_addr,
> +                               u64 *paddr, u64 *size);
>  #else /* CONFIG_OF_ADDRESS */
>  static inline struct device_node *of_find_matching_node_by_address(
>                                         struct device_node *from,
> @@ -90,6 +92,12 @@ static inline struct of_pci_range *of_pci_range_parser_one(
>  {
>         return NULL;
>  }
> +
> +static inline int of_dma_get_range(struct device_node *np, u64 *dma_addr,
> +                               u64 *paddr, u64 *size)
> +{
> +       return -ENODEV;
> +}
>  #endif /* CONFIG_OF_ADDRESS */
>
>  #ifdef CONFIG_OF
> --
> 1.7.9.5
>
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