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nvmem: include bit index in cell sysfs file name 

Creating sysfs files for all Cells caused a boot failure for linux-6.8-rc1 on
Apple M1, which (in downstream dts files) has multiple nvmem cells that use the
same byte address. This causes the device probe to fail with

[    0.605336] sysfs: cannot create duplicate filename '/devices/platform/soc@200000000/2922bc000.efuse/apple_efuses_nvmem0/cells/efuse@a10'
[    0.605347] CPU: 7 PID: 1 Comm: swapper/0 Tainted: G S                 6.8.0-rc1-arnd-5+ #133
[    0.605355] Hardware name: Apple Mac Studio (M1 Ultra, 2022) (DT)
[    0.605362] Call trace:
[    0.605365]  show_stack+0x18/0x2c
[    0.605374]  dump_stack_lvl+0x60/0x80
[    0.605383]  dump_stack+0x18/0x24
[    0.605388]  sysfs_warn_dup+0x64/0x80
[    0.605395]  sysfs_add_bin_file_mode_ns+0xb0/0xd4
[    0.605402]  internal_create_group+0x268/0x404
[    0.605409]  sysfs_create_groups+0x38/0x94
[    0.605415]  devm_device_add_groups+0x50/0x94
[    0.605572]  nvmem_populate_sysfs_cells+0x180/0x1b0
[    0.605682]  nvmem_register+0x38c/0x470
[    0.605789]  devm_nvmem_register+0x1c/0x6c
[    0.605895]  apple_efuses_probe+0xe4/0x120
[    0.606000]  platform_probe+0xa8/0xd0

As far as I can tell, this is a problem for any device with multiple cells on
different bits of the same address. Avoid the issue by changing the file name
to include the first bit number.

Fixes: 0331c61194 ("nvmem: core: Expose cells through sysfs")
Link: https://github.com/AsahiLinux/linux/blob/bd0a1a7d4/arch/arm64/boot/dts/apple/t600x-dieX.dtsi#L156
Cc:  <regressions@lists.linux.dev>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Rafał Miłecki <rafal@milecki.pl>
Cc: Chen-Yu Tsai <wenst@chromium.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:  <asahi@lists.linux.dev>
Cc: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20240209163454.98051-1-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Arnd Bergmann 2024-02-09 16:34:54 +00:00 committed by Greg Kroah-Hartman
parent 23d62fb5d3
commit e20f378d99
2 changed files with 11 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
Documentation/ABI/testing/sysfs-nvmem-cells
View File

@ -4,18 +4,18 @@ KernelVersion: 6.5
Contact: Miquel Raynal <miquel.raynal@bootlin.com>
Description:
The "cells" folder contains one file per cell exposed by the
NVMEM device. The name of the file is: <name>@<where>, with
<name> being the cell name and <where> its location in the NVMEM
device, in hexadecimal (without the '0x' prefix, to mimic device
tree node names). The length of the file is the size of the cell
(when known). The content of the file is the binary content of
the cell (may sometimes be ASCII, likely without trailing
character).
NVMEM device. The name of the file is: "<name>@<byte>,<bit>",
with <name> being the cell name and <where> its location in
the NVMEM device, in hexadecimal bytes and bits (without the
'0x' prefix, to mimic device tree node names). The length of
the file is the size of the cell (when known). The content of
the file is the binary content of the cell (may sometimes be
ASCII, likely without trailing character).
Note: This file is only present if CONFIG_NVMEM_SYSFS
is enabled.
Example::
hexdump -C /sys/bus/nvmem/devices/1-00563/cells/product-name@d
hexdump -C /sys/bus/nvmem/devices/1-00563/cells/product-name@d,0
00000000 54 4e 34 38 4d 2d 50 2d 44 4e |TN48M-P-DN|
0000000a

5
drivers/nvmem/core.c
View File

@ -460,8 +460,9 @@ static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
list_for_each_entry(entry, &nvmem->cells, node) {
sysfs_bin_attr_init(&attrs[i]);
attrs[i].attr.name = devm_kasprintf(&nvmem->dev, GFP_KERNEL,
"%s@%x", entry->name,
entry->offset);
"%s@%x,%x", entry->name,
entry->offset,
entry->bit_offset);
attrs[i].attr.mode = 0444;
attrs[i].size = entry->bytes;
attrs[i].read = &nvmem_cell_attr_read;