Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751446AbaDVEKR (ORCPT ); Tue, 22 Apr 2014 00:10:17 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:39524 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750705AbaDVEKM (ORCPT ); Tue, 22 Apr 2014 00:10:12 -0400 Message-ID: <5355EB77.7000306@ti.com> Date: Mon, 21 Apr 2014 23:09:27 -0500 From: Joel Fernandes Reply-To: User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.1 MIME-Version: 1.0 To: Santosh Shilimkar , CC: , Grygorii Strashko , Russell King , Arnd Bergmann , Greg Kroah-Hartman , Linus Walleij , Grant Likely , Rob Herring , Catalin Marinas , Olof Johansson , Subject: Re: [PATCH v2 2/7] of: introduce of_dma_get_range() helper References: <1397917972-6293-1-git-send-email-santosh.shilimkar@ti.com> <1397917972-6293-3-git-send-email-santosh.shilimkar@ti.com> In-Reply-To: <1397917972-6293-3-git-send-email-santosh.shilimkar@ti.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/19/2014 09:32 AM, Santosh Shilimkar wrote: > From: Grygorii Strashko [..] > + * 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 to the caller, and not, 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 */ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/