From patchwork Tue May 23 10:02:39 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miquel Raynal X-Patchwork-Id: 97949 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b0ea:0:b0:3b6:4342:cba0 with SMTP id b10csp2024431vqo; Tue, 23 May 2023 03:09:45 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6ogtQw/e8tLDO7k2fgI509pCz8VdMm8vRWo6UCzxomX6r9znteP3LpAFbeCnl4HZJ0vcl+ X-Received: by 2002:a05:6a20:3d02:b0:109:bdaf:6b47 with SMTP id y2-20020a056a203d0200b00109bdaf6b47mr16261845pzi.49.1684836585463; Tue, 23 May 2023 03:09:45 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1684836585; cv=none; d=google.com; s=arc-20160816; b=r5uQGP2tQuPuMF3P44sBRjzjoMGnIWh6SVRagFdj+UFSLSYw95JE7fzgz1x5WU66hh RQFLutSB4dfy/JXIScsPJjKB31M2xF4o+MgQ6n+6Q6PajmsZwpkYCflqMYfNqXNZTFjX ZSTanuY79h9UK54g0+Nzf7M+aHLnmPBcftryioXkb0g+kbrFTjlwnlYVib+0S7J9SAgF 7mUj2w6fP3vW/v3LDMXtPssJTfXFFOD+dbh3ttbtBXIL6lPTfWDGCLOVgltMCdroP3l0 xJSU+iut4p0qhUBMro/mag4mWuAaJhHPBoKJ3wEX7V+fOTAl1m09UzdEBkSC2XCzeJdU /azQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=W5M/vHgzuPPKaMo5s10MhzrRN3WWq1fY96XvfFQ3nlE=; b=qOWXNqCbC8/fcjr5okkukWMGRZ2HXds0pNhqOUF30Yve4ipKOV2iVzrVziWFqu06+m IfIrHOkV3Gv9RTpA59WZbL4tOKba3J22r+SvAraNlY/aUt0ccomb97YjC4tPaHF1vQxC A/SFeIq36wyh84ZnLyQqLda4pBz9A8nkMgukymjJdu81WohgFxc5/8NZyTrHtYE7ZFt3 oVW4780kppzp2tgYTX0qfMOQmgUeV7rYRpAIrQUZzvUDfY62JFVHrHGTyQvsE5YHZCTZ RFjzgCTof3srqZF1ZJPv6xq+tJ41zSNUoXj6lY5ppBIpSJwYmY/5LslqdASePwj8bMg1 yIrA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@bootlin.com header.s=gm1 header.b=YeqwowiJ; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 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 (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id b24-20020a639318000000b0050bede17e7bsi5978732pge.347.2023.05.23.03.09.30; Tue, 23 May 2023 03:09:45 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@bootlin.com header.s=gm1 header.b=YeqwowiJ; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=bootlin.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229921AbjEWKDA (ORCPT + 99 others); Tue, 23 May 2023 06:03:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236316AbjEWKCv (ORCPT ); Tue, 23 May 2023 06:02:51 -0400 Received: from relay8-d.mail.gandi.net (relay8-d.mail.gandi.net [217.70.183.201]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 539EC126 for ; Tue, 23 May 2023 03:02:44 -0700 (PDT) Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 1D6351BF205; Tue, 23 May 2023 10:02:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1684836162; 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=W5M/vHgzuPPKaMo5s10MhzrRN3WWq1fY96XvfFQ3nlE=; b=YeqwowiJ0aVl/brGpwQk1/8hi9PNM7WuD/z6nzr759He76pNZrB9RQtpWdq/Js4SGfWkKA Z8BPIjub1xWK39MaRo3NtcjizsE3BJhSYVEiHjzFmiDtn0skvlt09APzxAuxSa12mKa7nS HzyaMirNlPtZ63WIVyM+BIhagBgXcF71GusghkOYf9a0q55/OpsEh/zU4w6YWluoIw2j9x r1mBF/gCcThjgFOc5OLKxIFsHiTqHRjKx4jAuPRHPLsetDvVnGzRdHCAK5OGIni1VEiH1f 43F24UOjTUCtyRb4dzJKkMFSP4hi6ahuQLfbhsYpQ9a5ozmOBrkWAde4KzQeGA== From: Miquel Raynal To: Srinivas Kandagatla Cc: Greg Kroah-Hartman , Luka Perkov , Robert Marko , Thomas Petazzoni , , Miquel Raynal Subject: [PATCH 2/2] nvmem: core: Expose cells through sysfs Date: Tue, 23 May 2023 12:02:39 +0200 Message-Id: <20230523100239.307574-3-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230523100239.307574-1-miquel.raynal@bootlin.com> References: <20230523100239.307574-1-miquel.raynal@bootlin.com> MIME-Version: 1.0 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_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE,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-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1766679207347672242?= X-GMAIL-MSGID: =?utf-8?q?1766679207347672242?= 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 without re-writing the parser logic in userland. The current implementation only adds the 'cells' attributes if cells are found within the device, otherwise the folder does not appear. 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. Of course the relevant NVMEM sysfs Kconfig option must be enabled for this support to be compiled-in. 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 --- drivers/nvmem/core.c | 135 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 131 insertions(+), 4 deletions(-) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 342cd380b420..234b2f232854 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -325,6 +325,61 @@ 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; + struct nvmem_device *nvmem; + size_t cell_sz, read_len; + struct device *dev; + void *content; + + if (attr->private) + dev = attr->private; + else + dev = kobj_to_dev(kobj); + nvmem = to_nvmem_device(dev); + + mutex_lock(&nvmem_mutex); + list_for_each_entry(entry, &nvmem->cells, node) { + if (strncmp(entry->name, attr->attr.name, XATTR_NAME_MAX)) + continue; + + cell = nvmem_create_cell(entry, entry->name, 0); + if (IS_ERR(cell)) { + mutex_unlock(&nvmem_mutex); + return PTR_ERR(cell); + } + + break; + } + mutex_unlock(&nvmem_mutex); + + if (!cell) + return -EINVAL; + + content = nvmem_cell_read(cell, &cell_sz); + if (IS_ERR(content)) { + count = 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 = { @@ -346,8 +401,14 @@ 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, /* Reserved for exposing cells, if any */ NULL, }; @@ -406,6 +467,66 @@ static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem, device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom); } +static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem) +{ + struct bin_attribute **cells_attrs, *attrs; + struct nvmem_cell_entry *entry; + unsigned int ncells = 0, i = 0; + int ret = 0; + + mutex_lock(&nvmem_mutex); + + /* Allocate an array of attributes */ + list_for_each_entry(entry, &nvmem->cells, node) + ncells++; + + if (!ncells) + goto unlock_mutex; + + 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 have the name of a cell */ + list_for_each_entry(entry, &nvmem->cells, node) { + sysfs_bin_attr_init(&attrs[i]); + attrs[i].attr.name = kstrdup(entry->name, GFP_KERNEL); + attrs[i].attr.mode = 0444; + attrs[i].size = entry->bytes; + attrs[i].read = &nvmem_cell_attr_read; + if (!attrs[i].attr.name) { + ret = -ENOMEM; + goto unlock_mutex; + } + + cells_attrs[i] = &attrs[i]; + i++; + } + + nvmem_cells_group.bin_attrs = cells_attrs; + + /* Fill the attribute group structure with the cells member */ + for (i = 0;; i++) + if (!nvmem_dev_groups[i]) + break; + nvmem_dev_groups[i] = &nvmem_cells_group; + +unlock_mutex: + mutex_unlock(&nvmem_mutex); + + return ret; +} + #else /* CONFIG_NVMEM_SYSFS */ static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem, @@ -976,16 +1097,22 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) if (rval) goto err_remove_cells; + rval = nvmem_add_cells_from_layout(nvmem); + if (rval) + goto err_remove_cells; + +#ifdef CONFIG_NVMEM_SYSFS + rval = nvmem_populate_sysfs_cells(nvmem); + if (rval) + goto err_remove_cells; +#endif + dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); rval = device_add(&nvmem->dev); if (rval) goto err_remove_cells; - rval = nvmem_add_cells_from_layout(nvmem); - if (rval) - goto err_remove_cells; - blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem); return nvmem;