From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx.nabladev.com (mx.nabladev.com [178.251.229.89]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6153E3D7D8A; Tue, 21 Apr 2026 14:08:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.251.229.89 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776780489; cv=none; b=QChikO2MgPJrfBx+LYJ+BvzOd7uzZSfpVz6kIQ9YzmEun8wp3Gie03wiJ2U1fFsHYBzk5YV+Cqm57UTBBaL2XTDkQLdDn5NJctkYABc+kmul8yNW6aY21sQ1Iywe5jUFRByFK8bdo/8Ul6zO5ql2VGC8M6IHw4zUuDBvQch39Xg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776780489; c=relaxed/simple; bh=U3S/azcYtoK8lqyCMrjeJ/KYEZqdHpjzdHxJ59k4dfM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=bTy2xQSItL8pwUlqY+fV2qaJkIXJcZu93yNvuvukwZxrz7Hps4o4A0PaaReCXg07oDczsnxdWS5qU0r02QBPYAytK+8zAycjIE6ddSz0nbCaddzb0msQShXGpP3VFfOiGKCAPPz50Dr+j99/xznFVD093BrGyEM6FFdkxcNgTws= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nabladev.com; spf=pass smtp.mailfrom=nabladev.com; dkim=pass (2048-bit key) header.d=nabladev.com header.i=@nabladev.com header.b=SKXpzINo; arc=none smtp.client-ip=178.251.229.89 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nabladev.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=nabladev.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=nabladev.com header.i=@nabladev.com header.b="SKXpzINo" Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 855D61147FA; Tue, 21 Apr 2026 16:07:57 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nabladev.com; s=dkim; t=1776780478; h=from:subject:date:message-id:to:cc:mime-version: content-transfer-encoding; bh=ONHip1GbFzvZ4cejM52KSuI+49tZZL0UydKXrafRDOQ=; b=SKXpzINoETov8u3ksehh8NnLGkKRkat+0/W/iCk6kpxpKqDThTVnyISyVYkZOvY3SBS8Pv 3tyV/6VCbGZ2GKw5DC4TW1wPLX5N3OPVgIoWAhESfDaeC1fAunBSAK3Nde8vufCTbu7xLI /r8dF46xPERu2Cu6s/jU0JFCNYCUdMLXZHq0y5nq9th70APWZY52ZdEYUmhz/jq9aM3WBh +bKHpqXhCCsjI5wHuUq8MVlvxbFgup1CDI47hhBWr4T2Vvh8gmNLjbi/pc99vzX1hO7Gqh KIvYzBhDRA7CukSE1+hylC1wCtrTvYaPeolxWjh2v9wn0EHl9s7S2phgzmSOJg== From: Marek Vasut To: linux-i2c@vger.kernel.org Cc: Marek Vasut , Arnd Bergmann , Bartosz Golaszewski , Greg Kroah-Hartman , Srinivas Kandagatla , linux-kernel@vger.kernel.org Subject: [PATCH] nvmem: core: eeprom: at24: Handle EEPROM with both read-only and wp-gpios Date: Tue, 21 Apr 2026 16:06:49 +0200 Message-ID: <20260421140755.54222-1-marex@nabladev.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Last-TLS-Session-Version: TLSv1.3 Handle special-case of AT24 EEPROM described in DT, which contains both "read-only" and "wp-gpios" properties. Interpret this configuration as default read-only, but with the possibility of unlock via force_ro sysfs attribute. For this to work, the nvmem core must keep the "nvmem" sysfs bin attr as read-write, any writes into the bin attr which occur while the device is read-only are blocked in bin_attr_nvmem_write(). The AT24 EEPROM driver must not mark the EEPROM as read-only if both "read-only" and "wp-gpios" DT properties are present. The updated behavior can be tested as follows: Current content: " $ hexdump -C /sys/bus/nvmem/devices/logging7/nvmem 00000000 66 6f 6f 0a ff ff ff ff " Write into default-read-only device: " $ echo bar > /sys/bus/nvmem/devices/logging7/nvmem bash: echo: write error: Operation not permitted $ cat /sys/bus/nvmem/devices/logging7/force_ro 1 " Unlock and write into device: " $ echo 0 > /sys/bus/nvmem/devices/logging7/force_ro $ cat /sys/bus/nvmem/devices/logging7/force_ro 0 $ echo bar > /sys/bus/nvmem/devices/logging7/nvmem $ hexdump -C /sys/bus/nvmem/devices/logging7/nvmem 00000000 62 61 72 0a ff ff ff ff " Relock and write into device, fails because device is read-only again: " $ echo 1 > /sys/bus/nvmem/devices/logging7/force_ro $ echo baz > /sys/bus/nvmem/devices/logging7/nvmem bash: echo: write error: Operation not permitted $ hexdump -C /sys/bus/nvmem/devices/logging7/nvmem 00000000 62 61 72 0a ff ff ff ff " Signed-off-by: Marek Vasut --- Cc: Arnd Bergmann Cc: Bartosz Golaszewski Cc: Greg Kroah-Hartman Cc: Srinivas Kandagatla Cc: linux-i2c@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- drivers/misc/eeprom/at24.c | 3 ++- drivers/nvmem/core.c | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index 0200288d3a7ab..9ef00b0ce83d2 100644 --- a/drivers/misc/eeprom/at24.c +++ b/drivers/misc/eeprom/at24.c @@ -627,7 +627,8 @@ static int at24_probe(struct i2c_client *client) page_size = 1; flags = cdata->flags; - if (device_property_present(dev, "read-only")) + if (device_property_present(dev, "read-only") && + !device_property_present(dev, "wp-gpios")) flags |= AT24_FLAG_READONLY; if (device_property_present(dev, "no-read-rollover")) flags |= AT24_FLAG_NO_RDROL; diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 311cb2e5a5c02..c0eedfe8d706c 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -282,6 +282,9 @@ static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem) if (!nvmem->root_only) mode |= 0044; + if (nvmem->read_only && nvmem->reg_write) + mode |= 0200; + if (!nvmem->read_only) mode |= 0200; -- 2.53.0