[PATCH v2 06/29] mtd: Add support for reading MTD devices via the nvmem API
From: Boris Brezillon <hidden>
Date: 2018-08-17 16:27:37
Also in:
linux-doc, linux-i2c, linux-omap, lkml, netdev
Hi Bartosz, On Fri, 10 Aug 2018 10:05:03 +0200 Bartosz Golaszewski [off-list ref] wrote:
From: Alban Bedel <albeu@free.fr> 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. Signed-off-by: Alban Bedel <albeu@free.fr> [Bartosz: - use the managed variant of nvmem_register(), - set the nvmem name] Signed-off-by: Bartosz Golaszewski <redacted>
What happened to the 2 other patches of Alban's series? I'd really like the DT case to be handled/agreed on in the same patchset, but IIRC, Alban and Srinivas disagreed on how this should be represented. I hope this time we'll come to an agreement, because the MTD <-> NVMEM glue has been floating around for quite some time... Regards, Boris
quoted hunk ↗ jump to hunk
--- drivers/mtd/Kconfig | 1 + drivers/mtd/mtdcore.c | 50 +++++++++++++++++++++++++++++++++++++++++ include/linux/mtd/mtd.h | 2 ++ 3 files changed, 53 insertions(+)diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig index 46ab7feec6b6..f5549482d0df 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 optiondiff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 42395df06be9..a57302eaceb5 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c@@ -488,6 +488,49 @@ 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.owner = THIS_MODULE; + config.name = mtd->name; + 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.priv = mtd; + + mtd->nvmem = devm_nvmem_register(&mtd->dev, &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 +613,11 @@ 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 +643,8 @@ 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);diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h index a86c4fa93115..8121c6582285 100644 --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h@@ -25,6 +25,7 @@ #include <linux/notifier.h> #include <linux/device.h> #include <linux/of.h> +#include <linux/nvmem-provider.h> #include <mtd/mtd-abi.h>@@ -339,6 +340,7 @@ 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,