Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754160Ab0HSPUI (ORCPT ); Thu, 19 Aug 2010 11:20:08 -0400 Received: from mail.issp.bas.bg ([195.96.236.10]:56572 "EHLO mail.issp.bas.bg" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754008Ab0HSPUF (ORCPT ); Thu, 19 Aug 2010 11:20:05 -0400 From: Marin Mitov Organization: Institute of Solid State Physics To: linux-kernel@vger.kernel.org Subject: [RFC][PATCH] add dma_reserve_coherent_memory()/dma_free_reserved_memory() API Date: Thu, 19 Aug 2010 18:18:35 +0300 User-Agent: KMail/1.13.3 (Linux/2.6.36-rc1; KDE/4.4.3; x86_64; ; ) Cc: Linux Media Mailing List , FUJITA Tomonori MIME-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <201008191818.36068.mitov@issp.bas.bg> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3409 Lines: 107 Hi all, struct device contains a member: struct dma_coherent_mem *dma_mem; to hold information for a piece of memory declared dma-coherent. Alternatively the same member could also be used to hold preallocated dma-coherent memory for latter per-device use. This tric is already used in drivers/staging/dt3155v4l.c dt3155_alloc_coherent()/dt3155_free_coherent() Here proposed for general use by popular demand from video4linux folks. Helps for videobuf-dma-contig framework. Signed-off-by: Marin Mitov ====================================================================== --- a/drivers/base/dma-coherent.c 2010-08-19 15:50:42.000000000 +0300 +++ b/drivers/base/dma-coherent.c 2010-08-19 17:27:56.000000000 +0300 @@ -93,6 +93,83 @@ void *dma_mark_declared_memory_occupied( EXPORT_SYMBOL(dma_mark_declared_memory_occupied); /** + * dma_reserve_coherent_memory() - reserve coherent memory for per-device use + * + * @dev: device from which we allocate memory + * @size: size of requested memory area in bytes + * @flags: same as in dma_declare_coherent_memory() + * + * This function reserves coherent memory allocating it early (during probe()) + * to support latter allocations from per-device coherent memory pools. + * For a given device one could use either dma_declare_coherent_memory() or + * dma_reserve_coherent_memory(), but not both, becase the result of these + * functions is stored in a single struct device member - dma_mem + * + * Returns DMA_MEMORY_MAP on success, or 0 if failed. + * (same as dma_declare_coherent_memory() + */ +int dma_reserve_coherent_memory(struct device *dev, size_t size, int flags) +{ + struct dma_coherent_mem *mem; + dma_addr_t dev_base; + int pages = size >> PAGE_SHIFT; + int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long); + + if ((flags & DMA_MEMORY_MAP) == 0) + goto out; + if (!size) + goto out; + if (dev->dma_mem) + goto out; + + mem = kzalloc(sizeof(*mem), GFP_KERNEL); + if (!mem) + goto out; + mem->virt_base = dma_alloc_coherent(dev, size, &dev_base, + DT3155_COH_FLAGS); + if (!mem->virt_base) + goto err_alloc_coherent; + mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL); + if (!mem->bitmap) + goto err_bitmap; + + mem->device_base = dev_base; + mem->size = pages; + mem->flags = flags; + dev->dma_mem = mem; + return DMA_MEMORY_MAP; + +err_bitmap: + dma_free_coherent(dev, size, mem->virt_base, dev_base); +err_alloc_coherent: + kfree(mem); +out: + return 0; +} +EXPORT_SYMBOL(dma_reserve_coherent_memory); + +/** + * dma_free_reserved_memory() - free the reserved dma-coherent memoty + * + * @dev: device for which we free the dma-coherent memory + * + * same as dma_release_declared_memory() + */ +void dma_free_reserved_memory(struct device *dev) +{ + struct dma_coherent_mem *mem = dev->dma_mem; + + if (!mem) + return; + dev->dma_mem = NULL; + dma_free_coherent(dev, mem->size << PAGE_SHIFT, + mem->virt_base, mem->device_base); + kfree(mem->bitmap); + kfree(mem); +} +EXPORT_SYMBOL(dma_free_reserved_memory); + +/** * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area * * @dev: device from which we allocate memory -- 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/