From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH] drivers/char/mem.c: Add /dev/ioports, supporting 16-bit and 32-bit ports Date: Tue, 29 Dec 2015 14:28:01 +0100 Message-ID: <5873998.uv0CPtuiff@wuerfel> References: <20140509191914.GA7286@jtriplet-mobl1> <201512222256.20580.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Santosh Shukla Cc: "H. Peter Anvin" , josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org, Greg Kroah-Hartman , akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, Linux Kernel Mailing List , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, yuanhan.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org List-Id: linux-api@vger.kernel.org On Wednesday 23 December 2015 17:04:40 Santosh Shukla wrote: > On 23 December 2015 at 03:26, Arnd Bergmann wrote: > > On Tuesday 22 December 2015, Santosh Shukla wrote: > >> } > >> > >> So I care for /dev/ioport types interface who could do more than byte > >> data copy to/from user-space. I tested this patch with little > >> modification and could able to run pmd driver for arm/arm64 case. > >> > >> Like to know how to address pci_io region mapping problem for > >> arm/arm64, in-case /dev/ioports approach is not acceptable or else I > >> can spent time on restructuring the patch? > >> > > > > For the use case you describe, can't you use the vfio framework to > > access the PCI BARs? > > > > I looked at file: drivers/vfio/pci/vfio_pci.c, func vfio_pci_map() and > it look to me that it only maps ioresource_mem pci region, pasting > code snap: > > if (!(pci_resource_flags(pdev, index) & IORESOURCE_MEM)) > return -EINVAL; > .... > > and I want to map ioresource_io pci region for arm platform in my > use-case. Not sure vfio maps pci_iobar region? Mapping I/O BARs is not portable, notably it doesn't work on x86. You should be able access them using the read/write interface on the vfio device. Arnd