From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Thu, 18 Feb 2016 11:06:16 +0000 Subject: [RFC v3 07/15] iommu: iommu_get/put_single_reserved In-Reply-To: <1455264797-2334-8-git-send-email-eric.auger@linaro.org> References: <1455264797-2334-1-git-send-email-eric.auger@linaro.org> <1455264797-2334-8-git-send-email-eric.auger@linaro.org> Message-ID: <20160218110616.05108071@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, 12 Feb 2016 08:13:09 +0000 Eric Auger wrote: > This patch introduces iommu_get/put_single_reserved. > > iommu_get_single_reserved allows to allocate a new reserved iova page > and map it onto the physical page that contains a given physical address. > It returns the iova that is mapped onto the provided physical address. > Hence the physical address passed in argument does not need to be aligned. > > In case a mapping already exists between both pages, the IOVA mapped > to the PA is directly returned. > > Each time an iova is successfully returned a binding ref count is > incremented. > > iommu_put_single_reserved decrements the ref count and when this latter > is null, the mapping is destroyed and the iova is released. I wonder if there is a requirement for the caller to find out about the size of the mapping, or to impose a given size... MSIs clearly do not have that requirement (this is always a 32bit value), but since allocations usually pair address and size, I though I'd ask... Thanks, M. -- Jazz is not dead. It just smells funny.