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Date: Tue, 7 Mar 2017 09:26:04 +0100
From: Alban <albeu@...e.fr>
To: linux-kernel@...r.kernel.org
Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
Maxime Ripard <maxime.ripard@...e-electrons.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
David Woodhouse <dwmw2@...radead.org>,
Brian Norris <computersforpeace@...il.com>,
Boris Brezillon <boris.brezillon@...e-electrons.com>,
Marek Vasut <marek.vasut@...il.com>,
Richard Weinberger <richard@....at>,
Cyrille Pitchen <cyrille.pitchen@...el.com>,
devicetree@...r.kernel.org, linux-mtd@...ts.infradead.org,
Moritz Fischer <moritz.fischer@...us.com>,
Alban <albeu@...e.fr>
Subject: [PATCH v2 2/2] mtd: Add support for reading MTD devices via the nvmem API
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@...e.fr>
---
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@...e.fr>
+ *
+ * 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@...e.fr>");
+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@...e.fr>
+ *
+ * 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
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