Commit e20f378d authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Greg Kroah-Hartman
Browse files

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: 0331c611 ("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: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: default avatarEric Curtin <ecurtin@redhat.com>
Reviewed-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20240209163454.98051-1-srinivas.kandagatla@linaro.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 23d62fb5

Documentation/ABI/testing/sysfs-nvmem-cells

+8 −8
Original line number Diff line number Diff line
@@ -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

drivers/nvmem/core.c

+3 −2
Original line number Diff line number Diff line
@@ -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;