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Miller" , Grygorii Strashko , Srinivas Kandagatla , Andrew Lunn , Florian Fainelli , Rob Herring , Frank Rowand , Wolfram Sang Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org, linux-mtd@lists.infradead.org, netdev@vger.kernel.org, linux-omap@vger.kernel.org, devicetree@vger.kernel.org, Alban Bedel , Bartosz Golaszewski Subject: [PATCH v2 02/25] mtd: add support for reading MTD devices via the nvmem API Date: Tue, 13 Nov 2018 15:01:10 +0100 Message-Id: <20181113140133.17385-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181113140133.17385-1-brgl@bgdev.pl> References: <20181113140133.17385-1-brgl@bgdev.pl> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alban Bedel Allow drivers that use the nvmem API to read data stored on MTD devices. For this the mtd devices are registered as read-only NVMEM providers. We don't support device tree systems for now. Signed-off-by: Alban Bedel [Bartosz: - include linux/nvmem-provider.h - set the name of the nvmem provider - set no_of_node to true in nvmem_config - don't check the return value of nvmem_unregister() - it cannot fail - tweaked the commit message] Signed-off-by: Bartosz Golaszewski --- drivers/mtd/Kconfig | 1 + drivers/mtd/mtdcore.c | 56 +++++++++++++++++++++++++++++++++++++++++ include/linux/mtd/mtd.h | 2 ++ 3 files changed, 59 insertions(+) diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig index c77f537323ec..efbe7a6f1d8f 100644 --- a/drivers/mtd/Kconfig +++ b/drivers/mtd/Kconfig @@ -1,5 +1,6 @@ menuconfig MTD tristate "Memory Technology Device (MTD) support" + imply NVMEM help Memory Technology Devices are flash, RAM and similar chips, often used for solid state file systems on embedded devices. This option diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 97ac219c082e..5f1053d995b0 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -41,6 +41,7 @@ #include #include #include +#include #include #include @@ -488,6 +489,50 @@ int mtd_pairing_groups(struct mtd_info *mtd) } EXPORT_SYMBOL_GPL(mtd_pairing_groups); +static int mtd_nvmem_reg_read(void *priv, unsigned int offset, + void *val, size_t bytes) +{ + struct mtd_info *mtd = priv; + size_t retlen; + int err; + + err = mtd_read(mtd, offset, bytes, &retlen, val); + if (err && err != -EUCLEAN) + return err; + + return retlen == bytes ? 0 : -EIO; +} + +static int mtd_nvmem_add(struct mtd_info *mtd) +{ + struct nvmem_config config = {}; + + config.dev = &mtd->dev; + config.name = mtd->name; + config.owner = THIS_MODULE; + config.reg_read = mtd_nvmem_reg_read; + config.size = mtd->size; + config.word_size = 1; + config.stride = 1; + config.read_only = true; + config.root_only = true; + config.no_of_node = true; + config.priv = mtd; + + mtd->nvmem = nvmem_register(&config); + if (IS_ERR(mtd->nvmem)) { + /* Just ignore if there is no NVMEM support in the kernel */ + if (PTR_ERR(mtd->nvmem) == -ENOSYS) { + mtd->nvmem = NULL; + } else { + dev_err(&mtd->dev, "Failed to register NVMEM device\n"); + return PTR_ERR(mtd->nvmem); + } + } + + return 0; +} + static struct dentry *dfs_dir_mtd; /** @@ -570,6 +615,11 @@ int add_mtd_device(struct mtd_info *mtd) if (error) goto fail_added; + /* Add the nvmem provider */ + error = mtd_nvmem_add(mtd); + if (error) + goto fail_nvmem_add; + if (!IS_ERR_OR_NULL(dfs_dir_mtd)) { mtd->dbg.dfs_dir = debugfs_create_dir(dev_name(&mtd->dev), dfs_dir_mtd); if (IS_ERR_OR_NULL(mtd->dbg.dfs_dir)) { @@ -595,6 +645,8 @@ int add_mtd_device(struct mtd_info *mtd) __module_get(THIS_MODULE); return 0; +fail_nvmem_add: + device_unregister(&mtd->dev); fail_added: of_node_put(mtd_get_of_node(mtd)); idr_remove(&mtd_idr, i); @@ -637,6 +689,10 @@ int del_mtd_device(struct mtd_info *mtd) mtd->index, mtd->name, mtd->usecount); ret = -EBUSY; } else { + /* Try to remove the NVMEM provider */ + if (mtd->nvmem) + nvmem_unregister(mtd->nvmem); + device_unregister(&mtd->dev); idr_remove(&mtd_idr, mtd->index); diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h index cd0be91bdefa..545070c2ee64 100644 --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -25,6 +25,7 @@ #include #include #include +#include #include @@ -341,6 +342,7 @@ struct mtd_info { struct device dev; int usecount; struct mtd_debug_info dbg; + struct nvmem_device *nvmem; }; int mtd_ooblayout_ecc(struct mtd_info *mtd, int section, -- 2.19.1