Hi everybody, my router firmware concatenates two identical flash chips into a single mtd using mtd_concat_create(), and sets up partitions in a way where one of them crosses the chip boundary. When porting OpenWRT support for the board from a mach-file based setup to a device-tree based one, I found that there is no generic way to create a mtd_concat device from within the dts. The following patches attempt to provide that possibility.
This is a third roll of that patch series, the first one can be seen at [1]. The second one [2] was a blunder of my own making. Apologies for not being able to address the correct recipients two times in a row. In the first discussion, concerns were raised that a driver for a "virtual" device like this might have no place in the device tree system. However, I would argue that specifying a composite device is very similar to specifying the partitions of a mtd, which can also done in the device tree. In fact, I believe this is the only way to be able to specify the partitions of such a concat device in the dts file (but I'm happy to be corrected if I'm mistaken). I have made the example in the dt-binding documentation a bit more expressive in this detail. In the second roll I have also addressed all issues that reviewers have brought up so far, hopefully to their satisfaction. These were mainly whitespace fixes and improved comments. Best regards, Bernhard [1] http://lists.infradead.org/pipermail/linux-mtd/2018-September/083832.html [2] https://lkml.org/lkml/2018/9/7/1015 Bernhard Frauendienst (3): mtd: core: add get_mtd_device_by_node dt-bindings: add bindings for mtd-concat devices mtd: mtdconcat: add dt driver for concat devices .../devicetree/bindings/mtd/mtd-concat.txt | 36 +++++ drivers/mtd/Kconfig | 2 + drivers/mtd/Makefile | 3 + drivers/mtd/composite/Kconfig | 12 ++ drivers/mtd/composite/Makefile | 6 + drivers/mtd/composite/virt_concat.c | 128 ++++++++++++++++++ drivers/mtd/mtdcore.c | 38 ++++++ include/linux/mtd/mtd.h | 2 + 8 files changed, 228 insertions(+) create mode 100644 Documentation/devicetree/bindings/mtd/mtd-concat.txt create mode 100644 drivers/mtd/composite/Kconfig create mode 100644 drivers/mtd/composite/Makefile create mode 100644 drivers/mtd/composite/virt_concat.c -- 2.18.0
