From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 581FAC982E6 for ; Sun, 20 Sep 2026 11:10:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=KeFrxtRlpViVLqlhGyy1ctRdSRe1o39pSIdnoxihDCU=; b=ivXnDAX9Zyvn9y6kLVoAr32U12 yBIsARzOnpRfjpbEQWgTHv1zNm7CHJKhgElX0URx8d2u3DiEj3DrblZ4yaDsBo2xURERWK1zz86Rd Md2YJLwIikG6zWPOgTchRAORX0qn5XVGzdoXeZkcaFqd8mztTnjnDFmLl/jHGzYCRKVjKHCd5G50Y FynqZq6k+T/JUqQkYW3/4kD5V24vkXCq1ReB5liNL0bq17VTA3fRr07QM9BvonJUgpmiKVc9kpydN iSKqrJvTGZ9oEVjQkNrMINOIPc5mv1xHZNVFkIb+BMpmRta5vMOmJp/fMnf8baYPcstQSXgUcrtbh uqrZygzA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x8FR6-0000000HJRE-0Og4; Sun, 20 Sep 2026 11:10:20 +0000 Received: from linkmauve.fr ([82.65.109.163]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x8FQu-0000000HJML-3pMg; Sun, 20 Sep 2026 11:10:13 +0000 Received: by linkmauve.fr (Postfix, from userid 1000) id 83CB47189A5B; Sun, 20 Sep 2026 13:10:03 +0200 (CEST) From: Link Mauve To: Srinivas Kandagatla Cc: Link Mauve , Sasha Finkelstein , Andy Shevchenko , Neil Armstrong , Kevin Hilman , Jerome Brunet , Martin Blumenstingl , Sven Peter , Janne Grunau , Neal Gompa , Frank Li , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Vladimir Zapolskiy , =?UTF-8?q?Andr=C3=A9=20Draszik?= , Orson Zhai , Baolin Wang , Chunyan Zhang , Maxime Coquelin , Alexandre Torgue , Kalyani Akula , Michal Simek , Miguel Ojeda , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?UTF-8?q?Onur=20=C3=96zkan?= , Johan Hovold , Ronald Claveau , Daniel Lezcano , linux-arm-kernel@lists.infradead.org, linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org, asahi@lists.linux.dev, imx@lists.linux.dev, linux-arm-msm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, rust-for-linux@vger.kernel.org Subject: [PATCH v6 2/4] nvmem: core: deprecate reg_write callback with reg_write_const Date: Sun, 20 Sep 2026 13:09:55 +0200 Message-ID: <20260920111000.2404131-3-linkmauve@linkmauve.fr> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260920111000.2404131-1-linkmauve@linkmauve.fr> References: <20260920111000.2404131-1-linkmauve@linkmauve.fr> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260920_041009_110966_54CFEFAD X-CRM114-Status: GOOD ( 17.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This callback used to take a mutable void * for no reason, which causes the compiler to be unaware that the val buffer should never be modified by the callback. This was found while drafting the nvmem-provider Rust abstraction. Signed-off-by: Link Mauve --- drivers/nvmem/core.c | 26 +++++++++++++++++--------- drivers/nvmem/internals.h | 1 + include/linux/nvmem-provider.h | 6 +++++- 3 files changed, 23 insertions(+), 10 deletions(-) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 0556d140170a..a484d424119f 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -66,19 +66,22 @@ static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset, } static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset, - void *val, size_t bytes) + const void *val, size_t bytes) { struct nvmem_operations *ops = nvmem->ops; int ret, wr_ok; - if (!ops->reg_write) + if (!ops->reg_write && !ops->reg_write_const) return -EOPNOTSUPP; ret = gpiod_set_value_cansleep(nvmem->wp_gpio, 0); if (ret) return ret; - wr_ok = ops->reg_write(nvmem->priv, offset, val, bytes); + if (ops->reg_write_const) + wr_ok = ops->reg_write_const(nvmem->priv, offset, val, bytes); + else + wr_ok = ops->reg_write(nvmem->priv, offset, (void *)val, bytes); ret = gpiod_set_value_cansleep(nvmem->wp_gpio, 1); if (ret) @@ -299,7 +302,7 @@ static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem) if (!nvmem->read_only) mode |= 0200; - if (!ops->reg_write) + if (!ops->reg_write && !ops->reg_write_const) mode &= ~0200; if (!ops->reg_read) @@ -336,13 +339,13 @@ static umode_t nvmem_attr_is_visible(struct kobject *kobj, struct nvmem_operations *ops = nvmem->ops; /* - * If the device has no .reg_write operation, do not allow - * configuration as read-write. + * If the device has no .reg_write or .reg_write_const operation, do + * not allow configuration as read-write. * If the device is set as read-only by configuration, it * can be forced into read-write mode using the 'force_ro' * attribute. */ - if (attr == &dev_attr_force_ro.attr && !ops->reg_write) + if (attr == &dev_attr_force_ro.attr && !ops->reg_write && !ops->reg_write_const) return 0; /* Attribute not visible */ return attr->mode; @@ -893,7 +896,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) if (!config->dev) return ERR_PTR(-EINVAL); - if (!config->reg_read && !config->reg_write) + if (!config->reg_read && !config->reg_write && !config->reg_write_const) return ERR_PTR(-EINVAL); nvmem = kzalloc_obj(*nvmem); @@ -937,6 +940,11 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) ops->reg_read = config->reg_read; ops->reg_write = config->reg_write; + ops->reg_write_const = config->reg_write_const; + + if (ops->reg_write) + dev_warn(&nvmem->dev, "Usage of reg_write in nvmem is deprecated, please " + "migrate to reg_write_const.\n"); nvmem->owner = config->owner; if (!nvmem->owner && config->dev->driver) @@ -972,7 +980,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) goto err_put_device; nvmem->read_only = device_property_present(config->dev, "read-only") || - config->read_only || !ops->reg_write; + config->read_only || (!ops->reg_write && !ops->reg_write_const); #ifdef CONFIG_NVMEM_SYSFS nvmem->dev.groups = nvmem_dev_groups; diff --git a/drivers/nvmem/internals.h b/drivers/nvmem/internals.h index 4e610deeaa7b..c1766f8fa482 100644 --- a/drivers/nvmem/internals.h +++ b/drivers/nvmem/internals.h @@ -11,6 +11,7 @@ struct nvmem_operations { nvmem_reg_read_t reg_read; nvmem_reg_write_t reg_write; + nvmem_reg_write_const_t reg_write_const; }; struct nvmem_device { diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h index 6063fe5b7784..e944530999b4 100644 --- a/include/linux/nvmem-provider.h +++ b/include/linux/nvmem-provider.h @@ -20,6 +20,8 @@ typedef int (*nvmem_reg_read_t)(void *priv, unsigned int offset, void *val, size_t bytes); typedef int (*nvmem_reg_write_t)(void *priv, unsigned int offset, void *val, size_t bytes); +typedef int (*nvmem_reg_write_const_t)(void *priv, unsigned int offset, + const void *val, size_t bytes); /* used for vendor specific post processing of cell data */ typedef int (*nvmem_cell_post_process_t)(void *priv, const char *id, int index, unsigned int offset, void *buf, @@ -93,7 +95,8 @@ struct nvmem_cell_info { * @root_only: Device is accessibly to root only. * @of_node: If given, this will be used instead of the parent's of_node. * @reg_read: Callback to read data; return zero if successful. - * @reg_write: Callback to write data; return zero if successful. + * @reg_write: **DEPRECATED** - please use reg_write_const instead. + * @reg_write_const: Callback to write data; return zero if successful. * @size: Device size. * @word_size: Minimum read/write access granularity. * @stride: Minimum read/write access stride. @@ -128,6 +131,7 @@ struct nvmem_config { struct device_node *of_node; nvmem_reg_read_t reg_read; nvmem_reg_write_t reg_write; + nvmem_reg_write_const_t reg_write_const; int size; int word_size; int stride; -- 2.55.0