Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753476Ab2H3XH5 (ORCPT ); Thu, 30 Aug 2012 19:07:57 -0400 Received: from g4t0014.houston.hp.com ([15.201.24.17]:44445 "EHLO g4t0014.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753401Ab2H3XHx convert rfc822-to-8bit (ORCPT ); Thu, 30 Aug 2012 19:07:53 -0400 From: "Worth, Kevin" To: "Hans J. Koch" CC: "linux-kernel@vger.kernel.org" , "u.kleine-koenig@pengutronix.de" , "Greg Kroah-Hartman" Subject: RE: Using uio_pdrv to create an platform device for an FPGA, mmap() fails Thread-Topic: Using uio_pdrv to create an platform device for an FPGA, mmap() fails Thread-Index: Ac2GO7tG6QS6FR2kSHyjyyZF3zS91wAI7NcAAB9odFAAASiZgAACZr2QAAS3hwAAAS6M4A== Date: Thu, 30 Aug 2012 23:03:04 +0000 Message-ID: References: <20120830032735.GA2599@local> <20120830190019.GB4819@local> <20120830222408.GC4819@local> In-Reply-To: <20120830222408.GC4819@local> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [16.210.48.13] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6076 Lines: 179 >[Added Greg Kroah-Hartman to Cc:] > >On Thu, Aug 30, 2012 at 08:10:11PM +0000, Worth, Kevin wrote: >> >> Thanks for the reply, Hans. Your question about opening /dev/uio0 O_RDWR >> >> prompted me to check out how I was creating /dev/uio0 ... my system >> >> isn't using udev, and I was accidentally creating it with major/minor >> >> number 254/0 instead of the correct 253/0 (found by looking at >> >> /proc/devices). Fixed that and the mmap() call started working. >> > >> >Good. >> > >> >> >> >> Verified that if /dev/uio0 has permissions 0644, root can open it O_RDWR >> >> and mmap PROT_READ | PROT_WRITE using the below code and write to an >> >> address within my memory map. Of course this contradicts the statement >> >> "/dev/uioX is a read-only file" in the UIO howto. >> > >> >You're right. That wants to be fixed... >> > >> >> >> >> Including my updated, tested code for completeness. >> >> Note I also cleaned up the device registration a little by >> >> using a different platform_device_register_ call and removing fields >> >> in the struct uio_info that get filled in by uio_pdrv automatically. >> > >> >If you want to have that included in the mainline, please choose a more >> >descriptive name than "myfpga" and send a proper patch. >> >> I wasn't sure about submitting as a patch since it's for a custom FPGA >> that I don't expect the community will be using, > >That doesn't matter. If it helps YOU that the code is maintained in mainline, >post it. > >> but the code seems like >> possibly useful sample/example code. > >That is another good argument. Perhaps this could be genericized to be a generic "Memory Map Userspace IO Device" that takes a base address and a length in config (since those are really the only things that are particular to my device/usage). Could be enhanced to allow for additional maps, etc. or just serve as a working example. Docs could then also simply refer to this as an example of a device that uses the uio_pdrv driver. > >> Perhaps patching the HOWTO like >> http://www.kernel.org/doc/htmldocs/uio-howto.html#uio_pci_generic_example >> is the right approach? > >Oh, if you could hack up a patch for the documentation, that would be great. >But please make it a second patch, don't mix it with your driver code. Certainly these would belong in separate patches. > >Thanks, >Hans > >> >> > >> >Thanks, >> >Hans >> > >> >> >> >> -Kevin >> >> >> >> # lsuio -m -v >> >> uio0: name=uio_myfpga, version=0.1, events=0 >> >> map[0]: addr=0xD0000000, size=262144, mmap test: OK >> >> Device attributes: >> >> uevent=DRIVER=uio_pdrv >> >> modalias=platform:uio_pdrv >> >> >> >> ------Kernelspace------ >> >> #include >> >> #include >> >> #include >> >> >> >> #define MYFPGA_BASE 0xd0000000 // 3G >> >> #define MYFPGA_SIZE 0x00040000 // 256k >> >> >> >> static struct resource myfpga_resources[] = { >> >> { >> >> .start = MYFPGA_BASE, >> >> .end = MYFPGA_BASE + MYFPGA_SIZE - 1, >> >> .name = "myfpga", >> >> .flags = IORESOURCE_MEM >> >> } >> >> }; >> >> >> >> static struct uio_info myfpga_uio_info = { >> >> .name = "uio_myfpga", >> >> .version = "0.1", >> >> }; >> >> >> >> static struct platform_device *myfpga_uio_pdev; >> >> >> >> static int __init myfpga_init(void) >> >> { >> >> myfpga_uio_pdev = platform_device_register_resndata (NULL, >> >> "uio_pdrv", >> >> -1, >> >> myfpga_resources, >> >> 1, >> >> &myfpga_uio_info, >> >> sizeof(struct uio_info) >> >> ); >> >> if (IS_ERR(myfpga_uio_pdev)) { >> >> return PTR_ERR(myfpga_uio_pdev); >> >> } >> >> >> >> return 0; >> >> } >> >> >> >> static void __exit myfpga_exit(void) >> >> { >> >> platform_device_unregister(myfpga_uio_pdev); >> >> } >> >> >> >> module_init(myfpga_init); >> >> module_exit(myfpga_exit); >> >> >> >> ------Userspace------- >> >> #include >> >> #include >> >> #include >> >> >> >> #include >> >> #include >> >> #include >> >> #include >> >> #include >> >> #include >> >> #include >> >> >> >> #define MYFPGA_BASE 0xd0000000 // 3G >> >> #define MYFPGA_SIZE 0x00040000 // 256k >> >> #define MYFPGA_MAP_NUM 0 // First and only defined map >> >> >> >> #define BIT32(n) (1 << (n)) >> >> >> >> /* Use mmap()'ped address "iomem", not physical MYFPGA address */ >> >> #define MYFPGA_REG(iomem) (volatile uint32_t*)(iomem + 0x8) // Third 32-bit reg >> >> >> >> int main (int argc, char *argv[]) >> >> { >> >> int fd; >> >> void *iomem; >> >> fd = open("/dev/uio0", O_RDWR|O_SYNC); >> >> if (fd < 0) { >> >> printf("failed to open /dev/uio0, quitting\n"); >> >> return -1; >> >> } >> >> /* Note offset has a special meaning with uio devices */ >> >> iomem = mmap(NULL, MYFPGA_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, >> >> MYFPGA_MAP_NUM * getpagesize()); >> >> if (iomem == MAP_FAILED) { >> >> printf("mmap failed, quitting\n"); >> >> close(fd); >> >> return -2; >> >> } >> >> >> >> /* Set bit 5 of MYFPGA_REG register */ >> >> *MYFPGA_REG(iomem) |= BIT32(5); >> >> >> >> munmap(iomem, MYFPGA_SIZE); >> >> close(fd); >> >> return 0; >> >> } >> >> >> >> >> -- 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/