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Message-ID: <CAL_Jsq+9dZiAndnbC3fZDjZWU90K4BBR=ckuDxfy5_mBcRL=nA@mail.gmail.com>
Date: Mon, 21 Apr 2014 10:29:11 -0500
From: Rob Herring <robherring2@...il.com>
To: Santosh Shilimkar <santosh.shilimkar@...com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
Grygorii Strashko <grygorii.strashko@...com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Russell King <linux@....linux.org.uk>,
Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
Grant Likely <grant.likely@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v2 2/7] of: introduce of_dma_get_range() helper
On Sat, Apr 19, 2014 at 9:32 AM, Santosh Shilimkar
<santosh.shilimkar@...com> wrote:
> From: Grygorii Strashko <grygorii.strashko@...com>
>
> 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@...uxfoundation.org>
> Cc: Russell King <linux@....linux.org.uk>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Olof Johansson <olof@...om.net>
> Cc: Grant Likely <grant.likely@...aro.org>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...com>
> ---
> drivers/of/platform.c | 85 +++++++++++++++++++++++++++++++++++++++++++
> include/linux/of_platform.h | 8 ++++
This belongs in drivers/of/address.c and of_address.h.
> 2 files changed, 93 insertions(+)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 404d1da..2265a55 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -485,4 +485,89 @@ int of_platform_populate(struct device_node *root,
> return rc;
> }
> EXPORT_SYMBOL_GPL(of_platform_populate);
> +
> +/**
> + * 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-range" property
dma-ranges
> + * 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,
drop extern.
> + phys_addr_t *paddr, phys_addr_t *size)
> +{
> + struct device_node *node = np;
> + const u32 *ranges = NULL;
__be32
> + 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;
You need an of_node_put here if you are getting the next parent.
> + }
> +
> + 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);
You should set this after the following call succeeds.
> + *paddr = of_translate_dma_address(np, ranges);
This is going to search for dma-ranges again, but you have already
done that. Is there a case that just reading the CPU addr will not
work? I suppose we could have more than one level of translation. It
also seems a bit abusive that the DMA address is the ranges property.
I don't really have a better suggestion though.
> + if (*paddr == OF_BAD_ADDR) {
As I mentioned, this is potentially a size mismatch.
Rob
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