[PATCH v2 2/2] mtd: Add support for reading MTD devices via the nvmem API
From: Alban
Date: Tue Mar 07 2017 - 03:31:31 EST
Allow drivers that use the nvmem API to read data stored on MTD devices.
Add an option to the MTD core that allow registering the MTD as
read-only NVMEM providers.
Signed-off-by: Alban <albeu@xxxxxxx>
---
Changelog:
v2: * Moved to the MTD core instead of using notifiers
* Fixed the Kconfig description
---
drivers/mtd/Kconfig | 9 +++++++
drivers/mtd/Makefile | 1 +
drivers/mtd/mtdcore.c | 13 +++++++++
drivers/mtd/mtdnvmem.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++
drivers/mtd/mtdnvmem.h | 25 +++++++++++++++++
include/linux/mtd/mtd.h | 4 +++
6 files changed, 124 insertions(+)
create mode 100644 drivers/mtd/mtdnvmem.c
create mode 100644 drivers/mtd/mtdnvmem.h
diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
index e83a279..5a34c6a 100644
--- a/drivers/mtd/Kconfig
+++ b/drivers/mtd/Kconfig
@@ -322,6 +322,15 @@ config MTD_PARTITIONED_MASTER
the parent of the partition device be the master device, rather than
what lies behind the master.
+config MTD_NVMEM
+ bool "Register MTD devices as NVMEM providers"
+ default y
+ depends on NVMEM || COMPILE_TEST
+ help
+ Provides support for reading config data from MTD devices. This can
+ be used by drivers to read device specific data such as MAC addresses
+ or calibration results.
+
source "drivers/mtd/chips/Kconfig"
source "drivers/mtd/maps/Kconfig"
diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile
index 99bb9a1..879a542 100644
--- a/drivers/mtd/Makefile
+++ b/drivers/mtd/Makefile
@@ -5,6 +5,7 @@
# Core functionality.
obj-$(CONFIG_MTD) += mtd.o
mtd-y := mtdcore.o mtdsuper.o mtdconcat.o mtdpart.o mtdchar.o
+mtd-$(CONFIG_MTD_NVMEM) += mtdnvmem.o
obj-$(CONFIG_MTD_OF_PARTS) += ofpart.o
obj-$(CONFIG_MTD_REDBOOT_PARTS) += redboot.o
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 66a9ded..bb88997 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -45,6 +45,7 @@
#include <linux/mtd/partitions.h>
#include "mtdcore.h"
+#include "mtdnvmem.h"
static struct backing_dev_info *mtd_bdi;
@@ -554,6 +555,11 @@ 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;
+
device_create(&mtd_class, mtd->dev.parent, MTD_DEVT(i) + 1, NULL,
"mtd%dro", i);
@@ -571,6 +577,8 @@ 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);
@@ -611,6 +619,11 @@ int del_mtd_device(struct mtd_info *mtd)
mtd->index, mtd->name, mtd->usecount);
ret = -EBUSY;
} else {
+ /* Try to remove the NVMEM provider */
+ ret = mtd_nvmem_remove(mtd);
+ if (ret)
+ goto out_error;
+
device_unregister(&mtd->dev);
idr_remove(&mtd_idr, mtd->index);
diff --git a/drivers/mtd/mtdnvmem.c b/drivers/mtd/mtdnvmem.c
new file mode 100644
index 0000000..d6bc402
--- /dev/null
+++ b/drivers/mtd/mtdnvmem.c
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2017 Alban Bedel <albeu@xxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+
+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;
+}
+
+int mtd_nvmem_add(struct mtd_info *mtd)
+{
+ struct device_node *np = dev_of_node(&mtd->dev);
+ struct nvmem_config config = {};
+
+ /* OF devices must have the nvmem-provider property */
+ if (np && !of_property_read_bool(np, "nvmem-provider"))
+ return 0;
+
+ config.dev = &mtd->dev;
+ 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.priv = mtd;
+
+ mtd->nvmem = nvmem_register(&config);
+ if (IS_ERR(mtd->nvmem)) {
+ dev_err(&mtd->dev, "Failed to register NVMEM device\n");
+ return PTR_ERR(mtd->nvmem);
+ }
+
+ return 0;
+}
+
+int mtd_nvmem_remove(struct mtd_info *mtd)
+{
+ int ret;
+
+ if (!mtd->nvmem)
+ return 0;
+
+ ret = nvmem_unregister(mtd->nvmem);
+ if (ret)
+ dev_err(&mtd->dev, "Failed to unregister NVMEM device\n");
+
+ return ret;
+}
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Alban Bedel <albeu@xxxxxxx>");
+MODULE_DESCRIPTION("Driver to read config data from MTD devices");
diff --git a/drivers/mtd/mtdnvmem.h b/drivers/mtd/mtdnvmem.h
new file mode 100644
index 0000000..a49d8bd
--- /dev/null
+++ b/drivers/mtd/mtdnvmem.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2017 Alban Bedel <albeu@xxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#ifndef MTD_NVMEM_H
+#define MTD_NVMEM_H 1
+
+struct mtd_info;
+
+#ifdef CONFIG_MTD_NVMEM
+int mtd_nvmem_add(struct mtd_info *mtd);
+int mtd_nvmem_remove(struct mtd_info *mtd);
+#else
+static inline int mtd_nvmem_add(struct mtd_info *mtd)
+{ return 0; }
+
+static inline int mtd_nvmem_remove(struct mtd_info *mtd)
+{ return 0; }
+#endif
+
+#endif /* MTD_NVMEM_H */
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index eebdc63..e06c6e6 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -205,6 +205,7 @@ struct mtd_pairing_scheme {
};
struct module; /* only needed for owner field in mtd_info */
+struct nvmem_device;
struct mtd_info {
u_char type;
@@ -351,6 +352,9 @@ struct mtd_info {
struct module *owner;
struct device dev;
int usecount;
+#if IS_ENABLED(CONFIG_MTD_NVMEM)
+ struct nvmem_device *nvmem;
+#endif
};
int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,
--
2.7.4