From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Thu, 05 Jun 2025 09:49:43 +0200 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uN5M7-003w8p-0d for lore@lore.pengutronix.de; Thu, 05 Jun 2025 09:49:43 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1uN5M5-0007lu-Da for lore@pengutronix.de; Thu, 05 Jun 2025 09:49:43 +0200 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=skRTK8qkOL8h78bM8bXrlt179Ep5VRcqDUTZzkTQhDo=; b=gJ6CBsPiVh/JtaY9h5IZ1UQ+vL oG7L/vp5CTYRsOhb57XqcYNF1WbqObEz6a8mu4yyQz3iRBybBcEwAHRIHj5OYfr0/++hCul0Ys5Br 3GNg+xuZkzWSvD0407VTR7SlUZt1gau7YiU5KRRTUWLSP+V8ZIBH3jXbDLK1JE5TZ6lGrEe8MRcWR ouM/3H/TnDrFHGzcc3uJry4nI6HKzPZJGfJrstJvYnGMW83tf7LLuYUqjU2DNdR1o4ilgwsO/83nW /cKEa61PDMA8YdqHIehrQ89Q988Hc70Mj5AyILcBoLnax1oZDxi4AiQzVBrIIQ+ODdRsnNes7uuHG Paiwqzyw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uN5La-0000000Ez87-1eES; Thu, 05 Jun 2025 07:49:10 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uN5Jk-0000000Eyrz-1eTG for barebox@lists.infradead.org; Thu, 05 Jun 2025 07:47:24 +0000 Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1uN5Ji-00065S-DY; Thu, 05 Jun 2025 09:47:14 +0200 Received: from dude04.red.stw.pengutronix.de ([2a0a:edc0:0:1101:1d::ac]) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uN5Ji-001v7z-0E; Thu, 05 Jun 2025 09:47:14 +0200 Received: from ore by dude04.red.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1uN5Jh-00HUuD-3D; Thu, 05 Jun 2025 09:47:13 +0200 From: Oleksij Rempel To: barebox@lists.infradead.org Cc: Oleksij Rempel Date: Thu, 5 Jun 2025 09:47:06 +0200 Message-Id: <20250605074713.4170334-3-o.rempel@pengutronix.de> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250605074713.4170334-1-o.rempel@pengutronix.de> References: <20250605074713.4170334-1-o.rempel@pengutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250605_004716_605328_F32DC440 X-CRM114-Status: GOOD ( 23.82 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-4.9 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: [PATCH v2 2/9] nvmem: rmem: add write and protect support X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) Add reg_write and reg_protect operations to the rmem NVMEM driver. This makes rmem devices writable (they were previously read-only via the NVMEM interface due to lacking reg_write) and allows specific regions to be marked read-only. The primary motivation is to improve testing of NVMEM consumer code that handles write protection, by enabling rmem to emulate such hardware, particularly in sandbox environments. Key changes: - reg_write implemented: Enables writes. Writes to protected regions return -EROFS. - reg_protect implemented: - PROTECT_DISABLE_WRITE: Marks range read-only. - PROTECT_ENABLE_WRITE: Makes range writable. - Probe function updated for new ops and list initialization. Signed-off-by: Oleksij Rempel --- changes v2: - use a bitmap instead of lists of ranges. --- drivers/nvmem/rmem.c | 195 +++++++++++++++++++++++++++++++++++++++++++ include/driver.h | 3 + 2 files changed, 198 insertions(+) diff --git a/drivers/nvmem/rmem.c b/drivers/nvmem/rmem.c index afa0dd78c8f4..fd7389cd39e3 100644 --- a/drivers/nvmem/rmem.c +++ b/drivers/nvmem/rmem.c @@ -11,6 +11,10 @@ struct rmem { struct device *dev; const struct resource *mem; + size_t total_size; + /* Bitmap: 1 bit per byte of rmem. 1=protected, 0=writable. */ + unsigned char *protection_bitmap; + size_t protection_bitmap_bytes; }; static int rmem_read(void *context, unsigned int offset, @@ -21,6 +25,190 @@ static int rmem_read(void *context, unsigned int offset, bytes, offset, 0); } +/** + * rmem_is_byte_protected() - Check if a specific byte is write-protected. + * @rmem: Pointer to the rmem private data. + * @offset: Offset of the byte to check. + * + * Helper function to consult the protection bitmap. + * + * Return: True if the byte at @offset is protected, false otherwise. + */ +static inline bool rmem_is_byte_protected(const struct rmem *rmem, + unsigned int offset) +{ + unsigned char bit_mask; + unsigned int byte_idx; + + byte_idx = offset / 8; + bit_mask = 1U << (offset % 8); + return (rmem->protection_bitmap[byte_idx] & bit_mask) != 0; +} + +/** + * rmem_do_protect_byte() - Mark a specific byte as write-protected. + * @rmem: Pointer to the rmem private data. + * @offset: Offset of the byte to protect. + * + * Helper function to set a bit in the protection bitmap. Assumes @offset + * is valid and rmem->protection_bitmap is allocated. + */ +static inline void rmem_do_protect_byte(struct rmem *rmem, unsigned int offset) +{ + unsigned char bit_mask = 1U << (offset % 8); + unsigned int byte_idx = offset / 8; + + rmem->protection_bitmap[byte_idx] |= bit_mask; +} + +/** + * rmem_do_unprotect_byte() - Mark a specific byte as writable. + * @rmem: Pointer to the rmem private data. + * @offset: Offset of the byte to unprotect. + * + * Helper function to clear a bit in the protection bitmap. Assumes @offset + * is valid and rmem->protection_bitmap is allocated. + */ +static inline void rmem_do_unprotect_byte(struct rmem *rmem, + unsigned int offset) +{ + unsigned int byte_idx = offset / 8; + unsigned char bit_mask = 1U << (offset % 8); + + rmem->protection_bitmap[byte_idx] &= ~bit_mask; +} + +/** + * rmem_write() - Write data to the NVMEM device. + * @context: Pointer to the rmem private data (struct rmem). + * @offset: Offset within the NVMEM device to write to. + * @val: Buffer containing the data to write. + * @bytes: Number of bytes to write. + * + * This function is called by the NVMEM core to write data to the + * reserved memory region. It first checks the protection bitmap to ensure + * the target range is not write-protected. If writable, it uses the + * custom 'mem_copy' function. + * Specific error codes include -EROFS if protected or -EINVAL for bad params. + * + * Return: 0 on success, or a negative error code on failure. + */ +static int rmem_write(void *context, unsigned int offset, const void *val, + size_t bytes) +{ + struct rmem *rmem = context; + unsigned int i; + + for (i = 0; i < bytes; ++i) { + if (rmem_is_byte_protected(rmem, offset + i)) { + dev_warn(rmem->dev, + "Write [0x%x, len %zu] denied at 0x%x (protected)\n", + offset, bytes, offset + i); + return -EROFS; + } + } + + /* + * The last two arguments to mem_copy (0, 0) are specific to + * the custom mem_copy implementation. + */ + return mem_copy(rmem->dev, (void *)rmem->mem->start + offset, val, + bytes, 0, 0); +} + +/** + * rmem_set_protection_bits() - Mark a memory range as read-only. + * @rmem: Pointer to the rmem private data. + * @offset: Starting offset of the range to protect. + * @bytes: Length of the range to protect in bytes. + * + * Sets the corresponding bits in the protection_bitmap to mark the + * specified memory range as write-protected (read-only). + * + * Return: 0 on success, or a negative error code on failure. + */ +static int rmem_set_protection_bits(struct rmem *rmem, unsigned int offset, + size_t bytes) +{ + unsigned int end_offset = offset + bytes; + unsigned int i; + + for (i = offset; i < end_offset; ++i) + rmem_do_protect_byte(rmem, i); + + dev_info(rmem->dev, "Protected range [0x%x, len %zu]\n", offset, + bytes); + return 0; +} + +/** + * rmem_clear_protection_bits() - Mark a memory range as writable. + * @rmem: Pointer to the rmem private data. + * @offset: Starting offset of the range to unprotect. + * @bytes: Length of the range to unprotect in bytes. + * + * Clears the corresponding bits in the protection_bitmap to mark the + * specified memory range as writable. + * + * Return: 0 on success, or a negative error code on failure. + */ +static int rmem_clear_protection_bits(struct rmem *rmem, unsigned int offset, + size_t bytes) +{ + unsigned int end_offset = offset + bytes; + unsigned int i; + + for (i = offset; i < end_offset; ++i) + rmem_do_unprotect_byte(rmem, i); + + dev_info(rmem->dev, "Unprotected range [0x%x, len %zu]\n", offset, + bytes); + return 0; +} + +/** + * rmem_protect() - NVMEM callback to change protection status of a range. + * @context: Pointer to the rmem private data (struct rmem). + * @offset: Starting offset of the range. + * @bytes: Length of the range in bytes. + * @prot_mode: Protection mode to apply (PROTECT_DISABLE_WRITE or + * PROTECT_ENABLE_WRITE). + * + * This function is called by the NVMEM core to enable or disable + * write protection for a specified memory range. + * + * Return: 0 on success, or a negative error code on failure. + */ +static int rmem_protect(void *context, unsigned int offset, size_t bytes, + int prot_mode) +{ + struct rmem *rmem = context; + int ret; + + switch (prot_mode) { + case PROTECT_DISABLE_WRITE: /* Make read-only */ + ret = rmem_set_protection_bits(rmem, offset, bytes); + break; + case PROTECT_ENABLE_WRITE: /* Make writable */ + ret = rmem_clear_protection_bits(rmem, offset, bytes); + break; + default: + dev_warn(rmem->dev, "%s: Invalid protection mode %d\n", + __func__, prot_mode); + ret = -EINVAL; + break; + } + + if (ret) + return ret; + + dev_dbg(rmem->dev, + "Protection op complete [0x%x, len %zu], mode %d\n", offset, + bytes, prot_mode); + + return 0; +} + static int rmem_probe(struct device *dev) { struct nvmem_config config = { }; @@ -41,7 +229,14 @@ static int rmem_probe(struct device *dev) config.priv = priv; config.name = "rmem"; config.size = resource_size(mem); + priv->total_size = config.size; + + priv->protection_bitmap_bytes = DIV_ROUND_UP(priv->total_size, 8); + priv->protection_bitmap = xzalloc(priv->protection_bitmap_bytes); + config.reg_read = rmem_read; + config.reg_write = rmem_write; + config.reg_protect = rmem_protect; return PTR_ERR_OR_ZERO(nvmem_register(&config)); } diff --git a/include/driver.h b/include/driver.h index e9a919f9bbb5..8e738f076c30 100644 --- a/include/driver.h +++ b/include/driver.h @@ -431,6 +431,9 @@ int platform_driver_register(struct driver *drv); int platform_device_register(struct device *new_device); +#define PROTECT_ENABLE_WRITE 0 +#define PROTECT_DISABLE_WRITE 1 + struct cdev_operations { /*! Called in response of reading from this device. Required */ ssize_t (*read)(struct cdev*, void* buf, size_t count, loff_t offset, ulong flags); -- 2.39.5