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[23.128.96.34]) by mx.google.com with ESMTPS id l8-20020a170903244800b001c62502d9fasi118510pls.343.2023.10.04.15.23.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Oct 2023 15:23:20 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.34 as permitted sender) client-ip=23.128.96.34; Authentication-Results: mx.google.com; dkim=pass header.i=@bootlin.com header.s=gm1 header.b=CPLsLqOe; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.34 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=bootlin.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by howler.vger.email (Postfix) with ESMTP id 236ED84DB7AE; Wed, 4 Oct 2023 15:23:20 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at howler.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233464AbjJDWXO (ORCPT + 19 others); Wed, 4 Oct 2023 18:23:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232667AbjJDWXE (ORCPT ); Wed, 4 Oct 2023 18:23:04 -0400 Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::225]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36D93DC; Wed, 4 Oct 2023 15:22:59 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id A07521C0009; Wed, 4 Oct 2023 22:22:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1696458177; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MJSnkDzDxHMCQetZ/+skPNzc1TJhICAJggt8E2GoXhw=; b=CPLsLqOebwAUKFkOPiza6wA07lk29WukSFnS52exZjJL4ZU7H3NOxXhGZ8B+dOhM2iAT0V wHiWFeTKF/DYA1w7OJWouhLys9jF7I3roD/dXL9rIp1TXlyaecPGfi2opEgyYqL3wv8e9Y pZG+qU/5Y9Dv32w+TpUSkRhyv6HCZnj2lGBRQ+ZxmD7c8XnmsKKx3UfJmZ/ZMJFLsYe88K XnP1uSLb59r5cRFbFdp75vhL9vwJDhUNWsJzxO8RJ9Y90bx4qy++VvTPgWsi6Ihf98bS4U slEAIz97JW2UyXSwfc47Lpju1WPB2PzBVlPmqWpX57VKMgl5jWprM2IVuzZaJQ== From: Miquel Raynal To: Srinivas Kandagatla , Greg Kroah-Hartman Cc: Michael Walle , =?utf-8?b?UmFmYcWCIE1pxYJlY2tp?= , Rob Herring , Frank Rowand , devicetree@vger.kernel.org, , Robert Marko , Thomas Petazzoni , Luka Perkov , Randy Dunlap , Chen-Yu Tsai , Daniel Golle , Miquel Raynal Subject: [PATCH v11 7/7] nvmem: core: Expose cells through sysfs Date: Thu, 5 Oct 2023 00:22:36 +0200 Message-Id: <20231004222236.411248-8-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231004222236.411248-1-miquel.raynal@bootlin.com> References: <20231004222236.411248-1-miquel.raynal@bootlin.com> MIME-Version: 1.0 X-GND-Sasl: miquel.raynal@bootlin.com X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_PASS, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (howler.vger.email [0.0.0.0]); Wed, 04 Oct 2023 15:23:20 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1778865354472416076 X-GMAIL-MSGID: 1778865354472416076 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. Signed-off-by: Miquel Raynal Tested-by: Rafał Miłecki --- drivers/nvmem/core.c | 116 ++++++++++++++++++++++++++++++++++++++ drivers/nvmem/internals.h | 1 + 2 files changed, 117 insertions(+) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 1f311c899ae1..bb29cfe11334 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -303,6 +303,43 @@ static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj, return nvmem_bin_attr_get_umode(nvmem); } +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 *kobj, + struct bin_attribute *attr, char *buf, + loff_t pos, size_t count) +{ + struct nvmem_cell_entry *entry; + struct nvmem_cell *cell = NULL; + size_t cell_sz, read_len; + void *content; + + entry = attr->private; + cell = nvmem_create_cell(entry, entry->name, 0); + if (IS_ERR(cell)) + return PTR_ERR(cell); + + if (!cell) + return -EINVAL; + + content = nvmem_cell_read(cell, &cell_sz); + if (IS_ERR(content)) { + read_len = PTR_ERR(content); + goto destroy_cell; + } + + read_len = 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 = { .attr = { @@ -324,11 +361,21 @@ static const struct attribute_group nvmem_bin_group = { .is_bin_visible = nvmem_bin_attr_is_visible, }; +/* Cell attributes will be dynamically allocated */ +static struct attribute_group nvmem_cells_group = { + .name = "cells", +}; + static const struct attribute_group *nvmem_dev_groups[] = { &nvmem_bin_group, NULL, }; +static const struct attribute_group *nvmem_cells_groups[] = { + &nvmem_cells_group, + NULL, +}; + static struct bin_attribute bin_attr_nvmem_eeprom_compat = { .attr = { .name = "eeprom", @@ -384,6 +431,69 @@ static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem, device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom); } +static int nvmem_dev_populate_sysfs_cells(struct device *dev, void *data) +{ + struct nvmem_device *nvmem = to_nvmem_device(dev); + struct bin_attribute **cells_attrs, *attrs; + struct nvmem_cell_entry *entry; + unsigned int ncells = 0, i = 0; + int ret = 0; + + mutex_lock(&nvmem_mutex); + + if (list_empty(&nvmem->cells) || nvmem->sysfs_cells_populated) { + nvmem_cells_group.bin_attrs = NULL; + goto unlock_mutex; + } + + /* Allocate an array of attributes with a sentinel */ + ncells = list_count_nodes(&nvmem->cells); + cells_attrs = devm_kcalloc(&nvmem->dev, ncells + 1, + sizeof(struct bin_attribute *), GFP_KERNEL); + if (!cells_attrs) { + ret = -ENOMEM; + goto unlock_mutex; + } + + attrs = devm_kcalloc(&nvmem->dev, ncells, sizeof(struct bin_attribute), GFP_KERNEL); + if (!attrs) { + ret = -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 = devm_kasprintf(&nvmem->dev, GFP_KERNEL, + "%s@%x", entry->name, + entry->offset); + attrs[i].attr.mode = 0444; + attrs[i].size = entry->bytes; + attrs[i].read = &nvmem_cell_attr_read; + attrs[i].private = entry; + if (!attrs[i].attr.name) { + ret = -ENOMEM; + goto unlock_mutex; + } + + cells_attrs[i] = &attrs[i]; + i++; + } + + nvmem_cells_group.bin_attrs = cells_attrs; + + ret = devm_device_add_groups(&nvmem->dev, nvmem_cells_groups); + if (ret) + goto unlock_mutex; + + nvmem->sysfs_cells_populated = true; + +unlock_mutex: + mutex_unlock(&nvmem_mutex); + + return ret; +} + #else /* CONFIG_NVMEM_SYSFS */ static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem, @@ -2151,6 +2261,12 @@ static int nvmem_notifier_call(struct notifier_block *notifier, if (ret) return notifier_from_errno(ret); +#ifdef CONFIG_NVMEM_SYSFS + ret = nvmem_for_each_dev(nvmem_dev_populate_sysfs_cells); + if (ret) + return notifier_from_errno(ret); +#endif + return NOTIFY_OK; } diff --git a/drivers/nvmem/internals.h b/drivers/nvmem/internals.h index eb73b59d1fd9..baa1c173be1c 100644 --- a/drivers/nvmem/internals.h +++ b/drivers/nvmem/internals.h @@ -30,6 +30,7 @@ struct nvmem_device { struct gpio_desc *wp_gpio; struct nvmem_layout *layout; void *priv; + bool sysfs_cells_populated; }; int nvmem_layout_bus_register(void);