Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752145Ab2H3UN4 (ORCPT ); Thu, 30 Aug 2012 16:13:56 -0400 Received: from g4t0017.houston.hp.com ([15.201.24.20]:36179 "EHLO g4t0017.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751121Ab2H3UNy convert rfc822-to-8bit (ORCPT ); Thu, 30 Aug 2012 16:13:54 -0400 From: "Worth, Kevin" To: "Hans J. Koch" CC: "linux-kernel@vger.kernel.org" , "u.kleine-koenig@pengutronix.de" 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: Ac2GO7tG6QS6FR2kSHyjyyZF3zS91wAI7NcAAB9odFAAASiZgAACZr2Q Date: Thu, 30 Aug 2012 20:10:11 +0000 Message-ID: References: <20120830032735.GA2599@local> <20120830190019.GB4819@local> In-Reply-To: <20120830190019.GB4819@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: 4781 Lines: 148 >> 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, but the code seems like possibly useful sample/example code. Perhaps patching the HOWTO like http://www.kernel.org/doc/htmldocs/uio-howto.html#uio_pci_generic_example is the right approach? > >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/