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GET /api/1.1/patches/2228333/?format=api
{ "id": 2228333, "url": "http://patchwork.ozlabs.org/api/1.1/patches/2228333/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-i2c/patch/20260426024507.597480-1-marex@nabladev.com/", "project": { "id": 35, "url": "http://patchwork.ozlabs.org/api/1.1/projects/35/?format=api", "name": "Linux I2C development", "link_name": "linux-i2c", "list_id": "linux-i2c.vger.kernel.org", "list_email": "linux-i2c@vger.kernel.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20260426024507.597480-1-marex@nabladev.com>", "date": "2026-04-26T02:44:32", "name": "[v2] nvmem: core: Default to read-only if wp-gpios present", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "ced4e04c017474b265e748a45550b399584793f0", "submitter": { "id": 91452, "url": "http://patchwork.ozlabs.org/api/1.1/people/91452/?format=api", "name": "Marek Vasut", "email": "marex@nabladev.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linux-i2c/patch/20260426024507.597480-1-marex@nabladev.com/mbox/", "series": [ { "id": 501499, "url": "http://patchwork.ozlabs.org/api/1.1/series/501499/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-i2c/list/?series=501499", "date": "2026-04-26T02:44:32", "name": "[v2] nvmem: core: Default to read-only if wp-gpios present", "version": 2, "mbox": "http://patchwork.ozlabs.org/series/501499/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2228333/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2228333/checks/", "tags": {}, "headers": { "Return-Path": "\n <linux-i2c+bounces-17179-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-i2c@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=nabladev.com header.i=@nabladev.com header.a=rsa-sha256\n header.s=dkim header.b=gJk3nKDC;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; helo=sea.lore.kernel.org;\n envelope-from=linux-i2c+bounces-17179-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)", "smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=nabladev.com header.i=@nabladev.com\n header.b=\"gJk3nKDC\"", "smtp.subspace.kernel.org;\n arc=none smtp.client-ip=178.251.229.89", "smtp.subspace.kernel.org;\n dmarc=pass (p=reject dis=none) header.from=nabladev.com", "smtp.subspace.kernel.org;\n spf=pass smtp.mailfrom=nabladev.com" ], "Received": [ "from sea.lore.kernel.org (sea.lore.kernel.org\n [IPv6:2600:3c0a:e001:db::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g39zW4vLbz1yHv\n\tfor <incoming@patchwork.ozlabs.org>; Sun, 26 Apr 2026 12:45:27 +1000 (AEST)", "from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby sea.lore.kernel.org (Postfix) with ESMTP id C781F301D04F\n\tfor <incoming@patchwork.ozlabs.org>; Sun, 26 Apr 2026 02:45:21 +0000 (UTC)", "from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id E154E221FBD;\n\tSun, 26 Apr 2026 02:45:19 +0000 (UTC)", "from mx.nabladev.com (mx.nabladev.com [178.251.229.89])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby smtp.subspace.kernel.org (Postfix) with ESMTPS id B3C12126C02;\n\tSun, 26 Apr 2026 02:45:17 +0000 (UTC)", "from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon)\n with ESMTPSA id 655AA114D3D;\n\tSun, 26 Apr 2026 04:45:14 +0200 (CEST)" ], "ARC-Seal": "i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1777171519; cv=none;\n b=dRuxRWhOmOlxcqN+ftiQ4BBxehf0WlntQQON1EKQuTq6rN1vxahbWQGQ5YCkNRuvh0AhoHOK6cdmkVP9ns7m7GfOrmUjCZT0DXM/63AzeGwiJwNsJBX8LQyzR7lrfqEVwBO4DkgVbb9g+21VnvFtPSdDCqCCw4vUmquyE7UDlDs=", "ARC-Message-Signature": "i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1777171519; c=relaxed/simple;\n\tbh=P6vg/u8mtaOqDTc++MuUp6HgFqxSPaUF8GiwXM2ZEw0=;\n\th=From:To:Cc:Subject:Date:Message-ID:MIME-Version;\n b=Kvoc7f+4/6CZsTTrtRFNO/75/oIKNR5v0SA2uCpz+8kCbhy++It0hc4tl7FIQFyfkyjQtxDkMeDIr4OCwQSRFMY95EZhVAQLXnXN+iLRxnc/0tj1XCeKS46m7mOl9xXl6vPkdN3gxk063lYB/iFvos9N9x4iosRE0OBUKFwmkSE=", "ARC-Authentication-Results": "i=1; smtp.subspace.kernel.org;\n dmarc=pass (p=reject dis=none) header.from=nabladev.com;\n spf=pass smtp.mailfrom=nabladev.com;\n dkim=pass (2048-bit key) header.d=nabladev.com header.i=@nabladev.com\n header.b=gJk3nKDC; arc=none smtp.client-ip=178.251.229.89", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=nabladev.com;\n\ts=dkim; t=1777171515; h=from:subject:date:message-id:to:cc:mime-version:\n\t content-transfer-encoding; bh=OCw1cmmN/s4IqyAwm6S/ENA1IUWW4c1JPYW+MdOnM6w=;\n\tb=gJk3nKDC0OQ5FIOvLERMM5dIY8XkXJSsCGm5gd0ljl36aByaPr4oo0mmHtDs43ym+00OIN\n\tSvqcjo7LF696g3B9CLdQucNrmMtmoT3vxK3h3c2tYQto/ib1muGj5MUM0zjWPFTwn/yhu7\n\t/o6GLXhvHZdLsgdRmy3ZXkgDFTjMPbjExmRDPO0EjxTTc8aYslugZNQieYED8kTLMnD/Ec\n\tJ6LAh3T+cR7TsqMYm3SR6GraNJokNy1Yr0V/NXx3B9BA0VzqpB5WwugEUFQqCLxgQ9f1jT\n\t5FtvRn+GZ7IUMumLrI5kUPU9Jj1G3w5pue4bWWx+ePHp01bFEQoAA+auh1u4dQ==", "From": "Marek Vasut <marex@nabladev.com>", "To": "linux-i2c@vger.kernel.org", "Cc": "Marek Vasut <marex@nabladev.com>,\n\tArnd Bergmann <arnd@arndb.de>,\n\tBartosz Golaszewski <brgl@kernel.org>,\n\tGreg Kroah-Hartman <gregkh@linuxfoundation.org>,\n\tSrinivas Kandagatla <srini@kernel.org>,\n\tlinux-kernel@vger.kernel.org", "Subject": "[PATCH v2] nvmem: core: Default to read-only if wp-gpios present", "Date": "Sun, 26 Apr 2026 04:44:32 +0200", "Message-ID": "<20260426024507.597480-1-marex@nabladev.com>", "X-Mailer": "git-send-email 2.53.0", "Precedence": "bulk", "X-Mailing-List": "linux-i2c@vger.kernel.org", "List-Id": "<linux-i2c.vger.kernel.org>", "List-Subscribe": "<mailto:linux-i2c+subscribe@vger.kernel.org>", "List-Unsubscribe": "<mailto:linux-i2c+unsubscribe@vger.kernel.org>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "X-Last-TLS-Session-Version": "TLSv1.3" }, "content": "In case the nvmem DT node contains \"wp-gpios\" DT property, the device\ncurrently defaults to read-write and the force_ro sysfs attribute reads\n0. Switch to the default read-only, which is both safer, and aligned\nwith eMMC HW BOOT partition force_ro sysfs attribute behavior, which\nalso defaults to read-only.\n\nThe adjustment of nvmem->read_only value to read-only in case wp-gpios\nDT property is present must be done only after the device_add() got\ncalled because device_add() does internally call nvmem_bin_attr_get_umode(),\nwhich configures the permissions of 'nvmem' bin attr based on the value\nof nvmem->read_only that is only parsed from DT property 'read-only',\nwithout any adjustment. This way, if DT property 'read-only' is present,\nthe 'nvmem' attribute is always read-only. Otherwise, if the device is\nwriteable, then 'nvmem' attribute is writeable, and nvmem->read_only\ndefaults to read-only, but can be switched to read-write at runtime via\nthe 'force_ro' attribute.\n\nThe updated behavior can be tested as follows:\n\nCurrent content:\n\"\n$ cat /sys/bus/nvmem/devices/logging7/force_ro\n1\n\n$ hexdump -C /sys/bus/nvmem/devices/logging7/nvmem\n00000000 66 6f 6f 0a ff ff ff ff\n\"\n\nWrite into default-read-only device:\n\"\n$ echo bar > /sys/bus/nvmem/devices/logging7/nvmem\nbash: echo: write error: Operation not permitted\n$ cat /sys/bus/nvmem/devices/logging7/force_ro\n1\n\"\n\nUnlock and write into device:\n\"\n$ echo 0 > /sys/bus/nvmem/devices/logging7/force_ro\n$ cat /sys/bus/nvmem/devices/logging7/force_ro\n0\n\n$ echo bar > /sys/bus/nvmem/devices/logging7/nvmem\n$ hexdump -C /sys/bus/nvmem/devices/logging7/nvmem\n00000000 62 61 72 0a ff ff ff ff\n\"\n\nRelock and write into device, fails because device is read-only again:\n\"\n$ echo 1 > /sys/bus/nvmem/devices/logging7/force_ro\n$ echo baz > /sys/bus/nvmem/devices/logging7/nvmem\nbash: echo: write error: Operation not permitted\n\n$ hexdump -C /sys/bus/nvmem/devices/logging7/nvmem\n00000000 62 61 72 0a ff ff ff ff\n\"\n\nSigned-off-by: Marek Vasut <marex@nabladev.com>\n---\nCc: Arnd Bergmann <arnd@arndb.de>\nCc: Bartosz Golaszewski <brgl@kernel.org>\nCc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nCc: Srinivas Kandagatla <srini@kernel.org>\nCc: linux-i2c@vger.kernel.org\nCc: linux-kernel@vger.kernel.org\n---\nV2: Simplify the implementation, make devices with wp-gpios default\n to read-only and let users unlock those devices via force_ro\n sysfs attribute, just like eMMC HW BOOT partitions\n---\n drivers/nvmem/core.c | 6 ++++++\n 1 file changed, 6 insertions(+)", "diff": "diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c\nindex 311cb2e5a5c02..0b1942e389113 100644\n--- a/drivers/nvmem/core.c\n+++ b/drivers/nvmem/core.c\n@@ -1019,6 +1019,12 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)\n \tif (rval)\n \t\tgoto err_remove_dev;\n \n+\t/* If the device has WP GPIO, default to read-only */\n+\tif (nvmem->wp_gpio) {\n+\t\tnvmem->read_only = true;\n+\t\tgpiod_set_value_cansleep(nvmem->wp_gpio, 1);\n+\t}\n+\n #ifdef CONFIG_NVMEM_SYSFS\n \trval = nvmem_populate_sysfs_cells(nvmem);\n \tif (rval)\n", "prefixes": [ "v2" ] }