[PATCH V2 1/3] mtd: core: call devm_of_platform_populate() for MTD devices

[PATCH V2 1/3] mtd: core: call devm_of_platform_populate() for MTD devices

[Rafał Miłecki]

From: Rafał Miłecki <rafal@milecki.pl>

This adds support for bindings present in MTD devices (applies to
partitions too) nodes. The purpose of this change is to allow drivers
handle MTD device (partition) data. Some partitions may contain info
that requires parsing & processing.

An example can be U-Boot partition that contains block with environment
variables somehwere in a middle. That block should be described in DT
and parsed by a specific driver.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 drivers/mtd/mtdcore.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 70f492dce158..07b75e6ca111 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -19,6 +19,7 @@
 #include <linux/ioctl.h>
 #include <linux/init.h>
 #include <linux/of.h>
+#include <linux/of_platform.h>
 #include <linux/proc_fs.h>
 #include <linux/idr.h>
 #include <linux/backing-dev.h>
@@ -690,6 +691,9 @@ int add_mtd_device(struct mtd_info *mtd)
 		not->add(mtd);
 
 	mutex_unlock(&mtd_table_mutex);
+
+	devm_of_platform_populate(&mtd->dev);
+
 	/* We _know_ we aren't being removed, because
 	   our caller is still holding us here. So none
 	   of this try_ nonsense, and no bitching about it
-- 
2.31.1

[PATCH V2 2/3] dt-bindings: nvmem: add U-Boot environment variables binding

[Rafał Miłecki]

From: Rafał Miłecki <rafal@milecki.pl>

This binding allows describing a (part of) MTD device (partition) that
contains a block with environment variables. Operating system usually
needs to parse that block to read variables values that may affect
booting process & device configuration.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
V2: s/u,boot/u-boot/
---
 .../devicetree/bindings/nvmem/u-boot,env.yaml | 56 +++++++++++++++++++
 MAINTAINERS                                   |  5 ++
 2 files changed, 61 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/u-boot,env.yaml

diff --git a/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml b/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
new file mode 100644
index 000000000000..e3296e005ffd
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/nvmem/u-boot,env.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: U-Boot environment variables
+
+description: |
+  U-Boot uses environment variables to store device parameters and
+  configuration. They may be used for booting process, setup or keeping end user
+  interesting info.
+
+  Data is stored on flash partition in a U-Boot specific format (CRC32 and NUL
+  separated key-value pairs).
+
+  This binding allows specifying data location and format (default one or vendor
+  specific).
+
+maintainers:
+  - Rafał Miłecki <rafal@milecki.pl>
+
+allOf:
+  - $ref: nvmem.yaml#
+
+properties:
+  compatible:
+    enum:
+      - u-boot,env
+      - brcm,env
+
+  reg:
+    maxItems: 1
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    partitions {
+        compatible = "fixed-partitions";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        partition@0 {
+            label = "uboot";
+            reg = <0x0 0x100000>;
+
+            #address-cells = <1>;
+            #size-cells = <1>;
+
+            nvmem@10000 {
+                compatible = "u-boot,env";
+                reg = <0x10000 0x10000>;
+            };
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 67558097bb66..271c29c84c7d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19624,6 +19624,11 @@ W:	http://linuxtv.org
 T:	git git://linuxtv.org/media_tree.git
 F:	drivers/media/pci/tw686x/
 
+U-BOOT ENVIRONMENT VARIABLES
+M:	Rafał Miłecki <rafal@milecki.pl>
+S:	Maintained
+F:	Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
+
 UACCE ACCELERATOR FRAMEWORK
 M:	Zhangfei Gao <zhangfei.gao@linaro.org>
 M:	Zhou Wang <wangzhou1@hisilicon.com>
-- 
2.31.1

[PATCH V2 3/3] nvmem: add driver handling U-Boot environment variables

[Rafał Miłecki]

From: Rafał Miłecki <rafal@milecki.pl>

U-Boot binary contains a block of environment variables (NVMEM) that
should be parsed and exposed as NVMEM cells.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
V2: Drop debugging dev_info() call
    Fix variable type mismatch
---
 MAINTAINERS                |   1 +
 drivers/nvmem/Kconfig      |  10 ++
 drivers/nvmem/Makefile     |   2 +
 drivers/nvmem/u-boot-env.c | 235 +++++++++++++++++++++++++++++++++++++
 4 files changed, 248 insertions(+)
 create mode 100644 drivers/nvmem/u-boot-env.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 271c29c84c7d..cc9bdeb33b64 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19628,6 +19628,7 @@ U-BOOT ENVIRONMENT VARIABLES
 M:	Rafał Miłecki <rafal@milecki.pl>
 S:	Maintained
 F:	Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
+F:	drivers/nvmem/u-boot-env.c
 
 UACCE ACCELERATOR FRAMEWORK
 M:	Zhangfei Gao <zhangfei.gao@linaro.org>
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index da414617a54d..af9115852412 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -300,4 +300,14 @@ config NVMEM_BRCM_NVRAM
 	  This driver provides support for Broadcom's NVRAM that can be accessed
 	  using I/O mapping.
 
+config NVMEM_U_BOOT_ENV
+	tristate "U-Boot environment variables support"
+	depends on ARCH_BCM4908 || COMPILE_TEST
+	depends on OF
+	help
+	  This driver adds support for parsing U-Boot environment variables
+	  stored on flash partition.
+
+	  If compiled as module it will be called nvmem_u-boot-env.
+
 endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index dcbbde35b6a8..772904cdebdb 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -61,3 +61,5 @@ obj-$(CONFIG_NVMEM_RMEM) 	+= nvmem-rmem.o
 nvmem-rmem-y			:= rmem.o
 obj-$(CONFIG_NVMEM_BRCM_NVRAM)	+= nvmem_brcm_nvram.o
 nvmem_brcm_nvram-y		:= brcm_nvram.o
+obj-$(CONFIG_NVMEM_U_BOOT_ENV)	+= nvmem_u-boot-env.o
+nvmem_u-boot-env-y		:= u-boot-env.o
diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c
new file mode 100644
index 000000000000..42626c552d37
--- /dev/null
+++ b/drivers/nvmem/u-boot-env.c
@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
+ */
+
+#include <linux/crc32.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+enum u_boot_env_format {
+	U_BOOT_FORMAT_DEFAULT,
+	U_BOOT_FORMAT_BRCM,
+};
+
+struct u_boot_env {
+	struct device *dev;
+	enum u_boot_env_format format;
+	struct mtd_info *mtd;
+	size_t offset;
+	size_t size;
+	struct nvmem_cell_info *cells;
+	int ncells;
+};
+
+struct u_boot_env_image {
+	__le32 crc32;
+	uint8_t data[0];
+} __packed;
+
+struct u_boot_brcm_header {
+	__le32 unk;
+	__le32 len;
+} __packed;
+
+static int u_boot_env_read(void *context, unsigned int offset, void *val,
+			   size_t bytes)
+{
+	struct u_boot_env *priv = context;
+	struct device *dev = priv->dev;
+	size_t bytes_read;
+	int err;
+
+	err = mtd_read(priv->mtd, priv->offset + offset, bytes, &bytes_read, val);
+	if (err && !mtd_is_bitflip(err)) {
+		dev_err(dev, "Failed to read from mtd: %d\n", err);
+		return err;
+	}
+
+	if (bytes_read != bytes) {
+		dev_err(dev, "Failed to read %zd bytes\n", bytes);
+		return err;
+	}
+
+	return 0;
+}
+
+static int u_boot_env_add_cells(struct u_boot_env *priv, size_t data_offset,
+				uint8_t *data, size_t len)
+{
+	struct device *dev = priv->dev;
+	char *var, *value, *eq;
+	int idx;
+
+	priv->ncells = 0;
+	for (var = data; var < (char *)data + len && *var; var += strlen(var) + 1)
+		priv->ncells++;
+
+	priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
+	if (!priv->cells)
+		return -ENOMEM;
+
+	for (var = data, idx = 0;
+	     var < (char *)data + len && *var;
+	     var = value + strlen(value) + 1, idx++) {
+		eq = strchr(var, '=');
+		if (!eq)
+			break;
+		*eq = '\0';
+		value = eq + 1;
+
+		priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
+		if (!priv->cells[idx].name)
+			return -ENOMEM;
+		priv->cells[idx].offset = data_offset + value - (char *)data;
+		priv->cells[idx].bytes = strlen(value);
+	}
+
+	if (WARN_ON(idx != priv->ncells))
+		priv->ncells = idx;
+
+	return 0;
+}
+
+static int u_boot_env_parse(struct u_boot_env *priv)
+{
+	struct device *dev = priv->dev;
+	struct u_boot_env_image *image;
+	size_t image_offset;
+	size_t image_len;
+	uint32_t crc32;
+	size_t bytes;
+	uint8_t *buf;
+	int err;
+
+	image_offset = 0;
+	image_len = priv->size;
+	if (priv->format == U_BOOT_FORMAT_BRCM) {
+		struct u_boot_brcm_header header;
+
+		err = mtd_read(priv->mtd, priv->offset, sizeof(header), &bytes,
+			       (uint8_t *)&header);
+		if (err && !mtd_is_bitflip(err)) {
+			dev_err(dev, "Failed to read from mtd: %d\n", err);
+			return err;
+		}
+
+		image_offset = sizeof(header);
+		image_len = le32_to_cpu(header.len);
+	}
+
+	buf = kcalloc(1, image_len, GFP_KERNEL);
+	if (!buf) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+	image = (struct u_boot_env_image *)buf;
+
+	err = mtd_read(priv->mtd, priv->offset + image_offset, image_len, &bytes, buf);
+	if (err && !mtd_is_bitflip(err)) {
+		dev_err(dev, "Failed to read from mtd: %d\n", err);
+		goto err_kfree;
+	}
+
+	crc32 = crc32(~0, buf + 4, image_len - 4) ^ ~0L;
+	if (crc32 != le32_to_cpu(image->crc32)) {
+		dev_err(dev, "Invalid calculated CRC32: 0x%08x\n", crc32);
+		err = -EINVAL;
+		goto err_kfree;
+	}
+
+	buf[image_len - 1] = '\0';
+	err = u_boot_env_add_cells(priv, image_offset + sizeof(*image),
+				   buf + sizeof(*image),
+				   image_len - sizeof(*image));
+	if (err)
+		dev_err(dev, "Failed to add cells: %d\n", err);
+
+err_kfree:
+	kfree(buf);
+err_out:
+	return err;
+}
+
+static const struct of_device_id u_boot_env_of_match_table[] = {
+	{ .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_DEFAULT, },
+	{ .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BRCM, },
+	{},
+};
+
+static int u_boot_env_probe(struct platform_device *pdev)
+{
+	struct nvmem_config config = {
+		.name = "u-boot-env",
+		.reg_read = u_boot_env_read,
+	};
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	const struct of_device_id *of_id;
+	struct u_boot_env *priv;
+	const char *label;
+	int err;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	priv->dev = dev;
+
+	of_id = of_match_device(u_boot_env_of_match_table, dev);
+	if (!of_id)
+		return -EINVAL;
+	priv->format = (uintptr_t)of_id->data;
+
+	if (of_property_read_u32(np, "reg", (u32 *)&priv->offset) ||
+	    of_property_read_u32_index(np, "reg", 1, (u32 *)&priv->size)) {
+		dev_err(dev, "Failed to read \"reg\" property\n");
+		return -EINVAL;
+	}
+
+	label = of_get_property(np->parent, "label", NULL);
+	if (!label)
+		label = np->parent->name;
+
+	priv->mtd = get_mtd_device_nm(label);
+	if (IS_ERR(priv->mtd)) {
+		dev_err(dev, "Failed to find \"%s\" MTD device: %ld\n", label, PTR_ERR(priv->mtd));
+		return PTR_ERR(priv->mtd);
+	}
+
+	err = u_boot_env_parse(priv);
+	if (err)
+		return err;
+
+	config.dev = dev;
+	config.cells = priv->cells;
+	config.ncells = priv->ncells;
+	config.priv = priv;
+	config.size = priv->size;
+
+	return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
+}
+
+static struct platform_driver u_boot_env_driver = {
+	.probe = u_boot_env_probe,
+	.driver = {
+		.name = "u_boot_env",
+		.of_match_table = u_boot_env_of_match_table,
+	},
+};
+
+static int __init u_boot_env_init(void)
+{
+	return platform_driver_register(&u_boot_env_driver);
+}
+
+subsys_initcall_sync(u_boot_env_init);
+
+MODULE_AUTHOR("Rafał Miłecki");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);
-- 
2.31.1

Re: [PATCH V2 3/3] nvmem: add driver handling U-Boot environment variables

[kernel test robot]

Hi "Rafał,

I love your patch! Yet something to improve:

[auto build test ERROR on robh/for-next]
[also build test ERROR on mtd/mtd/next mtd/mtd/fixes linus/master v5.16-rc8]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Rafa-Mi-ecki/mtd-core-call-devm_of_platform_populate-for-MTD-devices/20211230-170531
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
config: nios2-randconfig-r013-20220105 (https://download.01.org/0day-ci/archive/20220105/202201051502.yOxThsL0-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/52f6be4712d04b927cd356dd95940bd76f1f5b97
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Rafa-Mi-ecki/mtd-core-call-devm_of_platform_populate-for-MTD-devices/20211230-170531
        git checkout 52f6be4712d04b927cd356dd95940bd76f1f5b97
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=nios2 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   nios2-linux-ld: drivers/nvmem/u-boot-env.o: in function `u_boot_env_read':
   u-boot-env.c:(.text+0x2c): undefined reference to `mtd_read'
   u-boot-env.c:(.text+0x2c): relocation truncated to fit: R_NIOS2_CALL26 against `mtd_read'
   nios2-linux-ld: drivers/nvmem/u-boot-env.o: in function `u_boot_env_parse':
   u-boot-env.c:(.text+0x2d4): undefined reference to `mtd_read'
   u-boot-env.c:(.text+0x2d4): relocation truncated to fit: R_NIOS2_CALL26 against `mtd_read'
>> nios2-linux-ld: u-boot-env.c:(.text+0x314): undefined reference to `mtd_read'
   u-boot-env.c:(.text+0x314): relocation truncated to fit: R_NIOS2_CALL26 against `mtd_read'
   nios2-linux-ld: drivers/nvmem/u-boot-env.o: in function `u_boot_env_probe':
   u-boot-env.c:(.text+0x4ec): undefined reference to `get_mtd_device_nm'
   u-boot-env.c:(.text+0x4ec): relocation truncated to fit: R_NIOS2_CALL26 against `get_mtd_device_nm'

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

Re: [PATCH V2 3/3] nvmem: add driver handling U-Boot environment variables

[kernel test robot]

Hi "Rafał,

I love your patch! Yet something to improve:

[auto build test ERROR on robh/for-next]
[also build test ERROR on mtd/mtd/next mtd/mtd/fixes linus/master v5.16-rc8 next-20220105]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Rafa-Mi-ecki/mtd-core-call-devm_of_platform_populate-for-MTD-devices/20211230-170531
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
config: hexagon-randconfig-r013-20220105 (https://download.01.org/0day-ci/archive/20220105/202201051949.ZpWQfrvi-lkp@intel.com/config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project d5b6e30ed3acad794dd0aec400e617daffc6cc3d)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/52f6be4712d04b927cd356dd95940bd76f1f5b97
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Rafa-Mi-ecki/mtd-core-call-devm_of_platform_populate-for-MTD-devices/20211230-170531
        git checkout 52f6be4712d04b927cd356dd95940bd76f1f5b97
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "mtd_read" [drivers/nvmem/nvmem_u-boot-env.ko] undefined!
>> ERROR: modpost: "get_mtd_device_nm" [drivers/nvmem/nvmem_u-boot-env.ko] undefined!
ERROR: modpost: "__raw_readsl" [drivers/i3c/master/svc-i3c-master.ko] undefined!
ERROR: modpost: "__raw_writesl" [drivers/i3c/master/dw-i3c-master.ko] undefined!
ERROR: modpost: "__raw_readsl" [drivers/i3c/master/dw-i3c-master.ko] undefined!
ERROR: modpost: "__raw_writesl" [drivers/i3c/master/i3c-master-cdns.ko] undefined!
ERROR: modpost: "__raw_readsl" [drivers/i3c/master/i3c-master-cdns.ko] undefined!

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

Re: [PATCH V2 3/3] nvmem: add driver handling U-Boot environment variables

[kernel test robot]

Hi "Rafał,

I love your patch! Yet something to improve:

[auto build test ERROR on robh/for-next]
[also build test ERROR on mtd/mtd/next mtd/mtd/fixes linus/master v5.16-rc8]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Rafa-Mi-ecki/mtd-core-call-devm_of_platform_populate-for-MTD-devices/20211230-170531
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
config: arm64-randconfig-r003-20220105 (https://download.01.org/0day-ci/archive/20220105/202201052036.kcalPY98-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/52f6be4712d04b927cd356dd95940bd76f1f5b97
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Rafa-Mi-ecki/mtd-core-call-devm_of_platform_populate-for-MTD-devices/20211230-170531
        git checkout 52f6be4712d04b927cd356dd95940bd76f1f5b97
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arm64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   aarch64-linux-ld: Unexpected GOT/PLT entries detected!
   aarch64-linux-ld: Unexpected run-time procedure linkages detected!
   aarch64-linux-ld: drivers/nvmem/u-boot-env.o: in function `u_boot_env_read':
>> u-boot-env.c:(.text+0x4c): undefined reference to `mtd_read'
   aarch64-linux-ld: drivers/nvmem/u-boot-env.o: in function `u_boot_env_probe':
>> u-boot-env.c:(.text+0x3e0): undefined reference to `get_mtd_device_nm'
>> aarch64-linux-ld: u-boot-env.c:(.text+0x428): undefined reference to `mtd_read'
   aarch64-linux-ld: u-boot-env.c:(.text+0x494): undefined reference to `mtd_read'

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

Re: [PATCH V2 2/3] dt-bindings: nvmem: add U-Boot environment variables binding

[Rob Herring]

On Thu, Dec 30, 2021 at 10:04:48AM +0100, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> This binding allows describing a (part of) MTD device (partition) that
> contains a block with environment variables. Operating system usually
> needs to parse that block to read variables values that may affect
> booting process & device configuration.

What do the u-boot folks think about this binding? This needs an ack 
from a u-boot maintainer.

> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---
> V2: s/u,boot/u-boot/
> ---
>  .../devicetree/bindings/nvmem/u-boot,env.yaml | 56 +++++++++++++++++++
>  MAINTAINERS                                   |  5 ++
>  2 files changed, 61 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
> 
> diff --git a/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml b/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
> new file mode 100644
> index 000000000000..e3296e005ffd
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
> @@ -0,0 +1,56 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/nvmem/u-boot,env.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: U-Boot environment variables
> +
> +description: |
> +  U-Boot uses environment variables to store device parameters and
> +  configuration. They may be used for booting process, setup or keeping end user
> +  interesting info.
> +
> +  Data is stored on flash partition in a U-Boot specific format (CRC32 and NUL
> +  separated key-value pairs).
> +
> +  This binding allows specifying data location and format (default one or vendor
> +  specific).
> +
> +maintainers:
> +  - Rafał Miłecki <rafal@milecki.pl>
> +
> +allOf:
> +  - $ref: nvmem.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - u-boot,env
> +      - brcm,env
> +
> +  reg:
> +    maxItems: 1
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    partitions {
> +        compatible = "fixed-partitions";
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +
> +        partition@0 {
> +            label = "uboot";
> +            reg = <0x0 0x100000>;
> +
> +            #address-cells = <1>;
> +            #size-cells = <1>;
> +
> +            nvmem@10000 {

I think most existing cases define a partition for the u-boot env, but 
this looks like you have it nested with other u-boot related data? Is 
there any reason to nest the partitions? A compatible in a partition 
node should be enough.

> +                compatible = "u-boot,env";
> +                reg = <0x10000 0x10000>;
> +            };
> +        };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 67558097bb66..271c29c84c7d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19624,6 +19624,11 @@ W:	http://linuxtv.org
>  T:	git git://linuxtv.org/media_tree.git
>  F:	drivers/media/pci/tw686x/
>  
> +U-BOOT ENVIRONMENT VARIABLES
> +M:	Rafał Miłecki <rafal@milecki.pl>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
> +
>  UACCE ACCELERATOR FRAMEWORK
>  M:	Zhangfei Gao <zhangfei.gao@linaro.org>
>  M:	Zhou Wang <wangzhou1@hisilicon.com>
> -- 
> 2.31.1
> 
>