On 04/19/2014 09:32 AM, Santosh Shilimkar wrote:
> From: Grygorii Strashko <grygorii.strashko@xxxxxx>
[..]
> + * Look in bottom up direction for the first "dma-range" 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.
> + */
> +extern int of_dma_get_range(struct device_node *np, dma_addr_t *dma_addr,
> + phys_addr_t *paddr, phys_addr_t *size)
> +{
> + struct device_node *node = np;
> + const u32 *ranges = NULL;
> + int len, naddr, nsize, pna;
> + int ret = 0;
> +
> + 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
> + */
> + *dma_addr = of_read_number(ranges, naddr);
> + *paddr = of_translate_dma_address(np, ranges);
I am probably missing something but I'm wondering the need for a
translate step here instead of doing something like:
*paddr = of_read_number(ranges + naddr, pna);
Perhaps there is a need to do a translate step of the DMA Address in
dma-ranges all the way to the parent, which can be different from the
CPU Address (second address in dma-ranges).
in which case the format of dma-ranges after parsing looks like
<DMA-Addr Translate(DMA-Addr) Size>
to the caller, and not, <DMA-Addr CPU-Addr Size>
But for keystone if something like the following is used,
dma-ranges = <0x80000000 0x8 0x00000000 0x80000000>;
Then, the above fragment I proposed would return 0x8 0x00000000 which is
sufficient?
thanks,
-Joel
> + 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;
> + }
> +
> + *size = of_read_number(ranges + naddr + pna, nsize);
> +
> + pr_debug("dma_addr(%pad) cpu_addr(%pa) size(%pa)\n",
> + dma_addr, paddr, size);
> +
> +out:
> + of_node_put(node);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(of_dma_get_range);
> #endif /* CONFIG_OF_ADDRESS */
> diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
> index 05cb4a9..ba7d3dc 100644
> --- a/include/linux/of_platform.h
> +++ b/include/linux/of_platform.h
> @@ -72,6 +72,8 @@ extern int of_platform_populate(struct device_node *root,
> const struct of_device_id *matches,
> const struct of_dev_auxdata *lookup,
> struct device *parent);
> +extern int of_dma_get_range(struct device_node *np, dma_addr_t *dma_addr,
> + phys_addr_t *paddr, phys_addr_t *size);
> #else
> static inline int of_platform_populate(struct device_node *root,
> const struct of_device_id *matches,
> @@ -80,6 +82,12 @@ static inline int of_platform_populate(struct device_node *root,
> {
> return -ENODEV;
> }
> +
> +static inline int of_dma_get_range(struct device_node *np, dma_addr_t *dma_addr,
> + phys_addr_t *paddr, phys_addr_t *size)
> +{
> + return -ENODEV;
> +}
> #endif
>
> #endif /* _LINUX_OF_PLATFORM_H */
>
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