From nobody Sun Feb 8 04:17:55 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9353EC0015E for ; Mon, 17 Jul 2023 07:52:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230245AbjGQHwX (ORCPT ); Mon, 17 Jul 2023 03:52:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231186AbjGQHwD (ORCPT ); Mon, 17 Jul 2023 03:52:03 -0400 Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::223]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77576118 for ; Mon, 17 Jul 2023 00:51:53 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 7811C60007; Mon, 17 Jul 2023 07:51:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1689580311; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nH6/LjRkYId88yq613RlWdOphmfE4iRu7Ck+Oxwm0yc=; b=WDkqvzg8QAfJqTq4uPlJhLx4c7ON8Cote9uwAPhSzr8+CJy20QpkqHe28R/g8CfLl3pJuJ +QGUPfERJPkT6c9ZYfzQj8zwSFVhCzvCJxUGXrlLy5RzDHHSISRHCuxhSIgulWpbjB81KL 70XZc+DOzkMOjBw1uHYInwhVjcF/Y208/M96Yr1ZlfI2ltPEgV/x9VXYIGt46UuEYbNxhX XX45Bpn1e0TSLhRWK1pigr9VKlatROaI4ATRrdl7TgOp1ncXtdPWBXGcYR71sIBYoyS1+D 6Mv/8wk8U9BtgntdJqlGZRdlnhEAu0DUbpJnQd7+ZMreKIhEIsm+ediXMETSfQ== From: Miquel Raynal To: Srinivas Kandagatla , Greg Kroah-Hartman , Cc: Thomas Petazzoni , Robert Marko , Luka Perkov , Michael Walle , Randy Dunlap , Miquel Raynal Subject: [PATCH v6 1/3] ABI: sysfs-nvmem-cells: Expose cells through sysfs Date: Mon, 17 Jul 2023 09:51:45 +0200 Message-Id: <20230717075147.43326-2-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230717075147.43326-1-miquel.raynal@bootlin.com> References: <20230717075147.43326-1-miquel.raynal@bootlin.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-GND-Sasl: miquel.raynal@bootlin.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The binary content of nvmem devices is available to the user so in the easiest cases, finding the content of a cell is rather easy as it is just a matter of looking at a known and fixed offset. However, nvmem layouts have been recently introduced to cope with more advanced situations, where the offset and size of the cells is not known in advance or is dynamic. When using layouts, more advanced parsers are used by the kernel in order to give direct access to the content of each cell regardless of their position/size in the underlying device, but these information were not accessible to the user. By exposing the nvmem cells to the user through a dedicated cell/ folder containing one file per cell, we provide a straightforward access to useful user information without the need for re-writing a userland parser. Content of nvmem cells is usually: product names, manufacturing date, MAC addresses, etc, Signed-off-by: Miquel Raynal Reviewed-by: Greg Kroah-Hartman --- Documentation/ABI/testing/sysfs-nvmem-cells | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-nvmem-cells diff --git a/Documentation/ABI/testing/sysfs-nvmem-cells b/Documentation/AB= I/testing/sysfs-nvmem-cells new file mode 100644 index 000000000000..b2d15a8d36e5 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-nvmem-cells @@ -0,0 +1,19 @@ +What: /sys/bus/nvmem/devices/.../cells/ +Date: May 2023 +KernelVersion: 6.5 +Contact: Miquel Raynal +Description: + The "cells" folder contains one file per cell exposed by + the nvmem device. The name of the file is the cell name. + 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 + 00000000 54 4e 34 38 4d 2d 50 2d 44 4e |TN48M-P-DN| + 0000000a --=20 2.34.1 From nobody Sun Feb 8 04:17:55 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC87DEB64DC for ; Mon, 17 Jul 2023 07:52:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230526AbjGQHwS (ORCPT ); Mon, 17 Jul 2023 03:52:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231187AbjGQHwD (ORCPT ); Mon, 17 Jul 2023 03:52:03 -0400 Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B9D9E11F for ; Mon, 17 Jul 2023 00:51:53 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 9237360006; Mon, 17 Jul 2023 07:51:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1689580312; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=un3Uwaotmlox+IhpuLnflkjcgnz89/YG1Do8CcofnC8=; b=lVX2afz+B4qHgh/0ieV127PWztHw9UJvh71z5wscYgDB5/SvgkKR28zKhnY88MpfJ31hF9 5HDWe6wAG8fQvwv2dGi9OLO7TIWBQnbp8HUQs2OcxsUSVHpMGPHU0q8RBU9T3dRLdSFVcm UB81cej5nuRO2KkhXGtjs0uxXsKvytd9mn5Mb/8TfnTymzPH3XEG6sDBEayofBwF2tSB34 NVNaGLUoqVyaCIGM6TbL0707/IkBJ/rr3jTPSzHZkbQNZwsTmbGwK6N9TYbR4sMv4EmZhW ggw34CztVbuFV8j2dz6a4oTcl1d0b4eoT/5bXGncQePmzTzfbgLp0e0ZODGPYQ== From: Miquel Raynal To: Srinivas Kandagatla , Greg Kroah-Hartman , Cc: Thomas Petazzoni , Robert Marko , Luka Perkov , Michael Walle , Randy Dunlap , Miquel Raynal Subject: [PATCH v6 2/3] nvmem: core: Create all cells before adding the nvmem device Date: Mon, 17 Jul 2023 09:51:46 +0200 Message-Id: <20230717075147.43326-3-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230717075147.43326-1-miquel.raynal@bootlin.com> References: <20230717075147.43326-1-miquel.raynal@bootlin.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-GND-Sasl: miquel.raynal@bootlin.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Let's pack all the cells creation in one place, so they are all created before we add the nvmem device. Signed-off-by: Miquel Raynal --- drivers/nvmem/core.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 3f8c7718412b..48659106a1e2 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -998,12 +998,6 @@ struct nvmem_device *nvmem_register(const struct nvmem= _config *config) if (rval) goto err_remove_cells; =20 - dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); - - rval =3D device_add(&nvmem->dev); - if (rval) - goto err_remove_cells; - rval =3D nvmem_add_cells_from_fixed_layout(nvmem); if (rval) goto err_remove_cells; @@ -1012,6 +1006,12 @@ struct nvmem_device *nvmem_register(const struct nvm= em_config *config) if (rval) goto err_remove_cells; =20 + dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); + + rval =3D device_add(&nvmem->dev); + if (rval) + goto err_remove_cells; + blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem); =20 return nvmem; --=20 2.34.1 From nobody Sun Feb 8 04:17:55 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DDE1C0015E for ; Mon, 17 Jul 2023 07:52:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231206AbjGQHw1 (ORCPT ); Mon, 17 Jul 2023 03:52:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53570 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230199AbjGQHwE (ORCPT ); Mon, 17 Jul 2023 03:52:04 -0400 Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D51E1137 for ; Mon, 17 Jul 2023 00:51:54 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 9B6B06000D; Mon, 17 Jul 2023 07:51:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1689580313; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RrYa81jVjDuF0o+K2o6QuVvcpzCkZHcHCjfMG1eLeRQ=; b=nQsJwRtoYotAmiu65aNlIFeLw8qkDU99mqiMm6NqYr2VGAquKTZvhPAXsn+5KaVambzyLb MI3y8tUGuwj8lo+pc5lzY5oFoth0ttRacPQFxsIVIPkzoCleiDoLNayYdAWRY/J3r4zKIe +GCqkxSpcO9HUm0nSlvICoX5zznxVJoZhE4OPPKmT8lL8R6MGjUD8k7nSC7WMPvvL5Z0+k T3QNQxvVNUiOAYdsZpieRq36ZreOUy73a/27Cu57k7XRqqT9ZDkVKvc/y6QOeh90cMWeIu JIP0EImpult9T/ONt3J8LfN4cNUhTExD9PwSrjbPa3nYY1Y1mN9JRnLMKDUYmw== From: Miquel Raynal To: Srinivas Kandagatla , Greg Kroah-Hartman , Cc: Thomas Petazzoni , Robert Marko , Luka Perkov , Michael Walle , Randy Dunlap , Miquel Raynal Subject: [PATCH v6 3/3] nvmem: core: Expose cells through sysfs Date: Mon, 17 Jul 2023 09:51:47 +0200 Message-Id: <20230717075147.43326-4-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230717075147.43326-1-miquel.raynal@bootlin.com> References: <20230717075147.43326-1-miquel.raynal@bootlin.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-GND-Sasl: miquel.raynal@bootlin.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The binary content of nvmem devices is available to the user so in the easiest cases, finding the content of a cell is rather easy as it is just a matter of looking at a known and fixed offset. However, nvmem layouts have been recently introduced to cope with more advanced situations, where the offset and size of the cells is not known in advance or is dynamic. When using layouts, more advanced parsers are used by the kernel in order to give direct access to the content of each cell, regardless of its position/size in the underlying device. Unfortunately, these information are not accessible by users, unless by fully re-implementing the parser logic in userland. Let's expose the cells and their content through sysfs to avoid these situations. Of course the relevant NVMEM sysfs Kconfig option must be enabled for this support to be available. Not all nvmem devices expose cells. Indeed, the .bin_attrs attribute group member will be filled at runtime only when relevant and will remain empty otherwise. In this case, as the cells attribute group will be empty, it will not lead to any additional folder/file creation. Exposed cells are read-only. There is, in practice, everything in the core to support a write path, but as I don't see any need for that, I prefer to keep the interface simple (and probably safer). The interface is documented as being in the "testing" state which means we can later add a write attribute if though relevant. There is one limitation though: if a layout is built as a module but is not properly installed in the system and loaded manually with insmod while the nvmem device driver was built-in, the cells won't appear in sysfs. But if done like that, the cells won't be usable by the built-in kernel drivers anyway. Signed-off-by: Miquel Raynal Reviewed-by: Greg Kroah-Hartman --- drivers/nvmem/core.c | 101 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 101 insertions(+) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 48659106a1e2..6c04a9cf6919 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -325,6 +325,43 @@ static umode_t nvmem_bin_attr_is_visible(struct kobjec= t *kobj, return nvmem_bin_attr_get_umode(nvmem); } =20 +static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry, + const char *id, int index); + +static ssize_t nvmem_cell_attr_read(struct file *filp, struct kobject *kob= j, + struct bin_attribute *attr, char *buf, + loff_t pos, size_t count) +{ + struct nvmem_cell_entry *entry; + struct nvmem_cell *cell =3D NULL; + size_t cell_sz, read_len; + void *content; + + entry =3D attr->private; + cell =3D nvmem_create_cell(entry, entry->name, 0); + if (IS_ERR(cell)) + return PTR_ERR(cell); + + if (!cell) + return -EINVAL; + + content =3D nvmem_cell_read(cell, &cell_sz); + if (IS_ERR(content)) { + read_len =3D PTR_ERR(content); + goto destroy_cell; + } + + read_len =3D min_t(unsigned int, cell_sz - pos, count); + memcpy(buf, content + pos, read_len); + kfree(content); + +destroy_cell: + kfree_const(cell->id); + kfree(cell); + + return read_len; +} + /* default read/write permissions */ static struct bin_attribute bin_attr_rw_nvmem =3D { .attr =3D { @@ -346,8 +383,14 @@ static const struct attribute_group nvmem_bin_group = =3D { .is_bin_visible =3D nvmem_bin_attr_is_visible, }; =20 +/* Cell attributes will be dynamically allocated */ +static struct attribute_group nvmem_cells_group =3D { + .name =3D "cells", +}; + static const struct attribute_group *nvmem_dev_groups[] =3D { &nvmem_bin_group, + &nvmem_cells_group, NULL, }; =20 @@ -406,6 +449,58 @@ static void nvmem_sysfs_remove_compat(struct nvmem_dev= ice *nvmem, device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom); } =20 +static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem) +{ + struct bin_attribute **cells_attrs, *attrs; + struct nvmem_cell_entry *entry; + unsigned int ncells =3D 0, i =3D 0; + int ret =3D 0; + + mutex_lock(&nvmem_mutex); + + if (list_empty(&nvmem->cells)) + goto unlock_mutex; + + /* Allocate an array of attributes with a sentinel */ + ncells =3D list_count_nodes(&nvmem->cells); + cells_attrs =3D devm_kcalloc(&nvmem->dev, ncells + 1, + sizeof(struct bin_attribute *), GFP_KERNEL); + if (!cells_attrs) { + ret =3D -ENOMEM; + goto unlock_mutex; + } + + attrs =3D devm_kcalloc(&nvmem->dev, ncells, sizeof(struct bin_attribute),= GFP_KERNEL); + if (!attrs) { + ret =3D -ENOMEM; + goto unlock_mutex; + } + + /* Initialize each attribute to take the name and size of the cell */ + list_for_each_entry(entry, &nvmem->cells, node) { + sysfs_bin_attr_init(&attrs[i]); + attrs[i].attr.name =3D devm_kstrdup(&nvmem->dev, entry->name, GFP_KERNEL= ); + attrs[i].attr.mode =3D 0444; + attrs[i].size =3D entry->bytes; + attrs[i].read =3D &nvmem_cell_attr_read; + attrs[i].private =3D entry; + if (!attrs[i].attr.name) { + ret =3D -ENOMEM; + goto unlock_mutex; + } + + cells_attrs[i] =3D &attrs[i]; + i++; + } + + nvmem_cells_group.bin_attrs =3D cells_attrs; + +unlock_mutex: + mutex_unlock(&nvmem_mutex); + + return ret; +} + #else /* CONFIG_NVMEM_SYSFS */ =20 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem, @@ -1006,6 +1101,12 @@ struct nvmem_device *nvmem_register(const struct nvm= em_config *config) if (rval) goto err_remove_cells; =20 +#ifdef CONFIG_NVMEM_SYSFS + rval =3D nvmem_populate_sysfs_cells(nvmem); + if (rval) + goto err_remove_cells; +#endif + dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); =20 rval =3D device_add(&nvmem->dev); --=20 2.34.1