Hi Rafał, Thank you for working on this. I hacked together the same functionality based on kernel 5.10 some months ago, while I was testing an MTD parser based TLV NVMEM cells parser, and have some general comments. On Mon, 20 Dec 2021, at 06:47, Rafał Miłecki wrote: > From: Rafał Miłecki <rafal@xxxxxxxxxx> > > This allows reading NVMEM cells using /sys/bus/nvmem/devices/*/cells/* > which may be helpful for userspace & debugging purposes. > > Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx> > --- > Documentation/driver-api/nvmem.rst | 11 ++++++ > drivers/nvmem/core.c | 60 ++++++++++++++++++++++++++++++ > 2 files changed, 71 insertions(+) > > diff --git a/Documentation/driver-api/nvmem.rst > b/Documentation/driver-api/nvmem.rst > index 287e86819640..20f7d68143be 100644 > --- a/Documentation/driver-api/nvmem.rst > +++ b/Documentation/driver-api/nvmem.rst > @@ -185,6 +185,17 @@ ex:: > * > 0001000 > > +Single cells can be read using files located at:: > + > + /sys/bus/nvmem/devices/*/cells/* > + > +ex:: > + > + hexdump -C /sys/bus/nvmem/devices/mtd0/cells/mac I found that NVMEM cell names did not need to be unique, but sysfs entry names do. I am not sure if there are characters that NVMEM cell names allow, but sysfs entry names forbid. I used an ID allocator, in a similar style to what is done for MTD sysfs devices in mtdcore.c. Could the cell (data) binary attribute be in a subfolder for each cell? Example: /sys/bus/nvmem/devices/mtd0/cells/cell0/cell or /sys/bus/nvmem/devices/mtd0/cells/cell0/cell_data This way, we can easily expose additional properties of the cell. I exposed the name, offset, bytes, bit_offset, and an of_node link (where available) this way. I only needed these for testing, but the cell length (bytes) provided a cheap means for initial validation. I did not look into cell post-processing, but it should be considered: https://lore.kernel.org/all/20211006144729.15268-1-srinivas.kandagatla@xxxxxxxxxx/ and RFC https://lore.kernel.org/all/CAL_JsqL55mZJ6jUyQACer2pKMNDV08-FgwBREsJVgitnuF18Cg@xxxxxxxxxxxxxx/ Will the cell data exposed here be prior to post-processing? Thank you Cheers, -- John Thomson
