mtd: core: provide unique name for nvmem device

If there is more than one mtd device which supports OTP, there will
be a kernel warning about duplicated sysfs entries and the probing will
fail. This is because the nvmem device name is not unique. Make it
unique by prepending the name of the mtd. E.g. before the name was
"user-otp", now it will be "mtd0-user-otp".

For reference the kernel splash is:
[    4.665531] sysfs: cannot create duplicate filename '/bus/nvmem/devices/user-otp'
[    4.673056] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-next-20211101+ #1296
[    4.680565] Hardware name: Kontron SMARC-sAL28 (Single PHY) on SMARC Eval 2.0 carrier (DT)
[    4.688856] Call trace:
[    4.691303]  dump_backtrace+0x0/0x1bc
[    4.694984]  show_stack+0x24/0x30
[    4.698306]  dump_stack_lvl+0x68/0x84
[    4.701980]  dump_stack+0x18/0x34
[    4.705302]  sysfs_warn_dup+0x70/0x90
[    4.708973]  sysfs_do_create_link_sd+0x144/0x150
[    4.713603]  sysfs_create_link+0x2c/0x50
[    4.717535]  bus_add_device+0x74/0x120
[    4.721293]  device_add+0x330/0x890
[    4.724791]  device_register+0x2c/0x40
[    4.728550]  nvmem_register+0x240/0x9f0
[    4.732398]  mtd_otp_nvmem_register+0xb0/0x10c
[    4.736854]  mtd_device_parse_register+0x28c/0x2b4
[    4.741659]  spi_nor_probe+0x20c/0x2e0
[    4.745418]  spi_mem_probe+0x78/0xbc
[    4.749001]  spi_probe+0x90/0xf0
[    4.752237]  really_probe.part.0+0xa4/0x320
..
[    4.873936] mtd mtd1: Failed to register OTP NVMEM device
[    4.894468] spi-nor: probe of spi0.0 failed with error -17

Fixes: 4b361cfa8624 ("mtd: core: add OTP nvmem provider support")
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20211104134843.2642800-1-michael@walle.cc

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 9186268d361b42b812afe3bcf12edbe6a2b16552..fc0bed14bfb10123b4fb5fde91378834d3c8bb78 100644 (file)
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -825,8 +825,7 @@ static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
 
        /* OTP nvmem will be registered on the physical device */
        config.dev = mtd->dev.parent;
-       /* just reuse the compatible as name */
-       config.name = compatible;
+       config.name = kasprintf(GFP_KERNEL, "%s-%s", dev_name(&mtd->dev), compatible);
        config.id = NVMEM_DEVID_NONE;
        config.owner = THIS_MODULE;
        config.type = NVMEM_TYPE_OTP;
@@ -842,6 +841,7 @@ static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
                nvmem = NULL;
 
        of_node_put(np);
+       kfree(config.name);
 
        return nvmem;
 }