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[2620:137:e000::1:20]) by mx.google.com with ESMTP id va16-20020a17090711d000b0099b6becb10fsi9233407ejb.449.2023.08.01.11.52.41; Tue, 01 Aug 2023 11:53:18 -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=Ecjzjrj3; 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 S231849AbjHASVq (ORCPT + 99 others); Tue, 1 Aug 2023 14:21:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37342 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231718AbjHASVn (ORCPT ); Tue, 1 Aug 2023 14:21:43 -0400 Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [217.70.183.196]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE2E92683 for ; Tue, 1 Aug 2023 11:21:37 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 6A062E0004; Tue, 1 Aug 2023 18:21:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1690914096; 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; bh=wdDMxoqOMQfXcZRg2HYBz4LvEZlaPzTlh754krjIucs=; b=Ecjzjrj31Gn9nP+f7b0byMHCCQSYkixJ6uZNr2+jbOTpUyEzdPp/BJvePUfQedsRs0mqsB 11LVFeqhebQzk5u1X7etkrvEL/u2HphOGFSWjJq2VFdMrzArU5/jRawJwGR8yLdgAs/eZR qLzUdmtsyVWR8Bu3wS25diIDC0jlPoUwUjJZO/xF6FuqG5TZy/yU0OA5Sfp4ewYbs+PoOe wpfd93D/NGWx7YBPv3GQl1ksXdWJOyfwWc8Q69bFjz7Ks/gjUzZ3nKPGOlURzwZnc/GFFQ 8jVRihzJm8wZj3HEN3IZfgWaaEIhJPChM2Ll1/NACk5oAGg/LHCOK4UcrRqVDQ== From: Miquel Raynal To: Srinivas Kandagatla Cc: Greg Kroah-Hartman , Thomas Petazzoni , Robert Marko , Luka Perkov , Michael Walle , , Randy Dunlap , Chen-Yu Tsai , Daniel Golle , =?utf-8?b?UmFmYcWCIE1pxYJlY2tp?= , Miquel Raynal Subject: [PATCH v7 0/7] NVMEM cells in sysfs Date: Tue, 1 Aug 2023 20:21:25 +0200 Message-Id: <20230801182132.1058707-1-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-GND-Sasl: miquel.raynal@bootlin.com X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED, RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_PASS,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: INBOX X-GMAIL-THRID: 1773053933403580271 X-GMAIL-MSGID: 1773053933403580271 Hello, As part of a previous effort, support for dynamic NVMEM layouts was brought into mainline, helping a lot in getting information from NVMEM devices at non-static locations. One common example of NVMEM cell is the MAC address that must be used. Sometimes the cell content is mainly (or only) useful to the kernel, and sometimes it is not. Users might also want to know the content of cells such as: the manufacturing place and date, the hardware version, the unique ID, etc. Two possibilities in this case: either the users re-implement their own parser to go through the whole device and search for the information they want, or the kernel can expose the content of the cells if deemed relevant. This second approach sounds way more relevant than the first one to avoid useless code duplication, so here is a series bringing NVMEM cells content to the user through sysfs. Here is a real life example with a Marvell Armada 7040 TN48m switch: $ nvmem=/sys/bus/nvmem/devices/1-00563/ $ for i in `ls -1 $nvmem/cells/*`; do basename $i; hexdump -C $i | head -n1; done country-code 00000000 54 57 |TW| crc32 00000000 bb cd 51 98 |..Q.| device-version 00000000 02 |.| diag-version 00000000 56 31 2e 30 2e 30 |V1.0.0| label-revision 00000000 44 31 |D1| mac-address 00000000 18 be 92 13 9a 00 |......| manufacture-date 00000000 30 32 2f 32 34 2f 32 30 32 31 20 31 38 3a 35 39 |02/24/2021 18:59| manufacturer 00000000 44 4e 49 |DNI| num-macs 00000000 00 40 |.@| onie-version 00000000 32 30 32 30 2e 31 31 2d 56 30 31 |2020.11-V01| platform-name 00000000 38 38 46 37 30 34 30 2f 38 38 46 36 38 32 30 |88F7040/88F6820| product-name 00000000 54 4e 34 38 4d 2d 50 2d 44 4e |TN48M-P-DN| serial-number 00000000 54 4e 34 38 31 50 32 54 57 32 30 34 32 30 33 32 |TN481P2TW2042032| vendor 00000000 44 4e 49 |DNI| This layout with a cells/ folder containing one file per cell has been legitimately challenged by John Thomson. I am not against the idea of having a sub-folder per cell but I did not find a relevant way to do that so for know I did not change the sysfs organization. If someone really wants this other layout, please provide a code snipped which I can integrate. Here are two limitations: * It is currently not possible to know whether the cell contains ASCII or binary data, so by default all cells are exposed in binary form. * For now the implementation focuses on the read aspect. Technically speaking, in some cases, it could be acceptable to write the cells, I guess, but for now read-only files sound more than enough. A writable path can be added later anyway. Changes in v7: * Rework the layouts registration mechanism to use the platform devices logic. * Fix the two issues reported by Daniel Golle and Chen-Yu Tsai, one of them consist in suffixing '@' to the cell name to create the sysfs files in order to be sure they are all unique. * Update the doc. Changes in v6: * ABI documentation style fixes reported by Randy Dunlap: s|cells/ folder|"cells" folder| Missing period at the end of the final note. s|Ex::|Example::| * Remove spurious patch from the previous resubmission. Resending v5: * I forgot the mailing list in my former submission, both are absolutely identical otherwise. Changes in v5: * Rebased on last -rc1, fixing a conflict and skipping the first two patches already taken by Greg. * Collected tags from Greg. * Split the nvmem patch into two, one which just moves the cells creation and the other which adds the cells. Changes in v4: * Use a core helper to count the number of cells in a list. * Provide sysfs attributes a private member which is the entry itself to avoid the need for looking up the nvmem device and then looping over all the cells to find the right one. Changes in v3: * Patch 1 is new: fix a style issue which bothered me when reading the core. * Patch 2 is new: Don't error out when an attribute group does not contain any attributes, it's easier for developers to handle "empty" directories this way. It avoids strange/bad solutions to be implemented and does not cost much. * Drop the is_visible hook as it is no longer needed. * Stop allocating an empty attribute array to comply with the sysfs core checks (this check has been altered in the first commits). * Fix a missing tab in the ABI doc. Changes in v2: * Do not mention the cells might become writable in the future in the ABI documentation. * Fix a wrong return value reported by Dan and kernel test robot. * Implement .is_bin_visible(). * Avoid overwriting the list of attribute groups, but keep the cells attribute group writable as we need to populate it at run time. * Improve the commit messages. * Give a real life example in the cover letter. Miquel Raynal (7): nvmem: core: Create all cells before adding the nvmem device nvmem: core: Do not open-code existing functions nvmem: core: Track the registered devices nvmem: core: Notify when a new layout is registered nvmem: core: Rework layouts to become platform devices ABI: sysfs-nvmem-cells: Expose cells through sysfs nvmem: core: Expose cells through sysfs Documentation/ABI/testing/sysfs-nvmem-cells | 21 ++ drivers/nvmem/core.c | 269 +++++++++++++++++--- drivers/nvmem/layouts/onie-tlv.c | 39 ++- drivers/nvmem/layouts/sl28vpd.c | 39 ++- include/linux/nvmem-consumer.h | 2 + include/linux/nvmem-provider.h | 11 +- 6 files changed, 328 insertions(+), 53 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-nvmem-cells