On Mon, Nov 3, 2008 at 12:12, Juergen Beisert <jbe@xxxxxxxxxxxxxx> wrote: > On Montag, 3. November 2008, Kay Sievers wrote: >> On Mon, Nov 3, 2008 at 11:12, Juergen Beisert <jbe@xxxxxxxxxxxxxx> wrote: >> > has anybody an idea how to write some rules to match devices from the mtd >> > framework? ... >> Seems, there is not much you can do with the current information it >> exposes. What is the hardware behind these mtd devices? Are these >> devices show up somewhere in /sys/devices/, maybe as platform devices? >> Then we could try to make the kernel use these as parents for the >> block devices, so the block devices would not be "virtual". > > MTDs are simple memory devices. Flash (NOR or NAND type) and SRAM for example. > They are connected through a simple address/data bus, some also via SPI > interface. About each of these devices the kernel knows at least the > manufacturer and the device name (for flash memory this info can be > autodetected). For the other types mostly a platform structure provides this > information. On my ARM (i.MX27 CPU) tree types of memory is available: > > SRAM: > /sys/bus/platform/devices/mtd-ram.0 > > NAND-flash: > /sys/bus/platform/devices/mxc_nand.0 > > NOR-flash: > /sys/bus/platform/devices/physmap-flash.0 > > Currently the NOR flash is using three partitions so I get: > > $ ls -l /dev/mtd* > crw-rw---- 1 root root 90, 0 Jan 1 00:00 /dev/mtd0 > crw-rw---- 1 root root 90, 1 Jan 1 00:00 /dev/mtd0ro > crw-rw---- 1 root root 90, 2 Jan 1 00:00 /dev/mtd1 > crw-rw---- 1 root root 90, 3 Jan 1 00:00 /dev/mtd1ro > crw-rw---- 1 root root 90, 4 Jan 1 00:00 /dev/mtd2 > crw-rw---- 1 root root 90, 5 Jan 1 00:00 /dev/mtd2ro > crw-rw---- 1 root root 90, 6 Jan 1 00:00 /dev/mtd3 > crw-rw---- 1 root root 90, 7 Jan 1 00:00 /dev/mtd3ro > crw-rw---- 1 root root 90, 8 Jan 1 00:00 /dev/mtd4 > crw-rw---- 1 root root 90, 9 Jan 1 00:00 /dev/mtd4ro > crw-rw---- 1 root root 90, 10 Jan 1 00:00 /dev/mtd5 > crw-rw---- 1 root root 90, 11 Jan 1 00:00 /dev/mtd5ro > brw-rw---- 1 root root 31, 0 Jan 1 00:00 /dev/mtdblock0 > brw-rw---- 1 root root 31, 1 Jan 1 00:00 /dev/mtdblock1 > brw-rw---- 1 root root 31, 2 Jan 1 00:00 /dev/mtdblock2 > brw-rw---- 1 root root 31, 3 Jan 1 00:00 /dev/mtdblock3 > brw-rw---- 1 root root 31, 4 Jan 1 00:00 /dev/mtdblock4 > brw-rw---- 1 root root 31, 5 Jan 1 00:00 /dev/mtdblock5 > > mtd*0 ... mtd*3 are the three partitions on the NOR flash (its also the memory > to boot from), mtd*4 is the NAND memory, mtd*5 is the SRAM. All I want is to > detect the NAND and the SRAM to create special links or node names for these > devices to be independent from the partition count of the NOR memory and the > changing device node numbers when this count changes. It is something that should be changed in mtd. NAND for example registers the device in drivers/mtd/nand/mxc_nand.c. Before that, it has handled the platform device *pdev. We would need to pass the pdev down to the mtd core and set "struct gendisk->driverfs_dev" to &pdev->dev, and the NAND mtd devices would show up with a device path like: /sys/devices/platform/mxc_nand.0/blockmtdblock4 With these devices as parents, you can match on any property or device name with usual udev rules. Kay -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
