diff mbox series

[2/2] nvmem: add driver handling U-Boot environment variables

Message ID 20220406143225.28107-2-zajec5@gmail.com (mailing list archive)
State New, archived
Headers show
Series [1/2] mtd: call of_platform_populate() for MTD partitions | expand

Commit Message

Rafał Miłecki April 6, 2022, 2:32 p.m. UTC
From: Rafał Miłecki <rafal@milecki.pl>

U-Boot stores its setup as environment variables. It's a list of
key-value pairs stored on flash device with a custom header.

This commit adds an NVMEM driver that:
1. Provides NVMEM access to environment vars binary data
2. Extracts variables as NVMEM cells

It can be used for:
1. Accessing env variables from user-space
2. Reading NVMEM cells by Linux drivers

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 MAINTAINERS                |   1 +
 drivers/nvmem/Kconfig      |  12 ++
 drivers/nvmem/Makefile     |   2 +
 drivers/nvmem/u-boot-env.c | 236 +++++++++++++++++++++++++++++++++++++
 4 files changed, 251 insertions(+)
 create mode 100644 drivers/nvmem/u-boot-env.c

Comments

Miquel Raynal April 11, 2022, 8:59 a.m. UTC | #1
On Wed, 2022-04-06 at 14:32:25 UTC, =?utf-8?b?UmFmYcWCIE1pxYJlY2tp?= wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> U-Boot stores its setup as environment variables. It's a list of
> key-value pairs stored on flash device with a custom header.
> 
> This commit adds an NVMEM driver that:
> 1. Provides NVMEM access to environment vars binary data
> 2. Extracts variables as NVMEM cells
> 
> It can be used for:
> 1. Accessing env variables from user-space
> 2. Reading NVMEM cells by Linux drivers
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel
Srinivas Kandagatla April 11, 2022, 9:45 a.m. UTC | #2
On 11/04/2022 09:59, Miquel Raynal wrote:
> On Wed, 2022-04-06 at 14:32:25 UTC, =?utf-8?b?UmFmYcWCIE1pxYJlY2tp?= wrote:
>> From: Rafał Miłecki <rafal@milecki.pl>
>>
>> U-Boot stores its setup as environment variables. It's a list of
>> key-value pairs stored on flash device with a custom header.
>>
>> This commit adds an NVMEM driver that:
>> 1. Provides NVMEM access to environment vars binary data
>> 2. Extracts variables as NVMEM cells
>>
>> It can be used for:
>> 1. Accessing env variables from user-space
>> 2. Reading NVMEM cells by Linux drivers
>>
>> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> 
> Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Hi Miquel,

Any reason why this nvmem driver is taken via mtd tree?

This is going to conflict with other nvmem patches that are touching 
KConfig and Makefile


--srini
> 
> Miquel
Miquel Raynal April 11, 2022, 10:04 a.m. UTC | #3
Hi Srinivas,

srinivas.kandagatla@linaro.org wrote on Mon, 11 Apr 2022 10:45:53 +0100:

> On 11/04/2022 09:59, Miquel Raynal wrote:
> > On Wed, 2022-04-06 at 14:32:25 UTC, =?utf-8?b?UmFmYcWCIE1pxYJlY2tp?= wrote:  
> >> From: Rafał Miłecki <rafal@milecki.pl>
> >>
> >> U-Boot stores its setup as environment variables. It's a list of
> >> key-value pairs stored on flash device with a custom header.
> >>
> >> This commit adds an NVMEM driver that:
> >> 1. Provides NVMEM access to environment vars binary data
> >> 2. Extracts variables as NVMEM cells
> >>
> >> It can be used for:
> >> 1. Accessing env variables from user-space
> >> 2. Reading NVMEM cells by Linux drivers
> >>
> >> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>  
> > 
> > Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.  
> 
> Hi Miquel,
> 
> Any reason why this nvmem driver is taken via mtd tree?
> 
> This is going to conflict with other nvmem patches that are touching KConfig and Makefile

Sorry I selected it by mistake. I'll let you take it through nvmem
unless there is still something missing on your side?

Anyway, it's now dropped from mtd.

Thanks,
Miquèl
Srinivas Kandagatla April 11, 2022, 10:18 a.m. UTC | #4
On 06/04/2022 15:32, Rafał Miłecki wrote:
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index 555aa77a574d..17a78b1ba077 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -324,4 +324,16 @@ config NVMEM_SUNPLUS_OCOTP
>   	  This driver can also be built as a module. If so, the module
>   	  will be called nvmem-sunplus-ocotp.
>   
> +config NVMEM_U_BOOT_ENV
> +	tristate "U-Boot environment variables support"
> +	depends on ARCH_BCM4908 || COMPILE_TEST

This nvmem provider seems more generic, so why ARCH_BCM4908 dependency here?


--srini
> +	depends on OF && MTD
> +	select CRC32
> +	help
> +	  U-Boot stores its setup as environment variables. This driver adds
> +	  support for verifying & exporting such data. It also exposes variables
> +	  as NVMEM cells so they can be referenced by other drivers.
> +
> +	  If compiled as module it will be called nvmem_u-boot-env.
> +
>   endif
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 4cb7fd127e68..122bf4230507 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20121,6 +20121,7 @@  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 555aa77a574d..17a78b1ba077 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -324,4 +324,16 @@  config NVMEM_SUNPLUS_OCOTP
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem-sunplus-ocotp.
 
+config NVMEM_U_BOOT_ENV
+	tristate "U-Boot environment variables support"
+	depends on ARCH_BCM4908 || COMPILE_TEST
+	depends on OF && MTD
+	select CRC32
+	help
+	  U-Boot stores its setup as environment variables. This driver adds
+	  support for verifying & exporting such data. It also exposes variables
+	  as NVMEM cells so they can be referenced by other drivers.
+
+	  If compiled as module it will be called nvmem_u-boot-env.
+
 endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 891958e29d25..84c8d75e59cf 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -65,3 +65,5 @@  obj-$(CONFIG_NVMEM_LAYERSCAPE_SFP)	+= nvmem-layerscape-sfp.o
 nvmem-layerscape-sfp-y		:= layerscape-sfp.o
 obj-$(CONFIG_NVMEM_SUNPLUS_OCOTP)	+= nvmem_sunplus_ocotp.o
 nvmem_sunplus_ocotp-y		:= sunplus-ocotp.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..c7945d7d5750
--- /dev/null
+++ b/drivers/nvmem/u-boot-env.c
@@ -0,0 +1,236 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 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_SINGLE,
+	U_BOOT_FORMAT_REDUNDANT,
+};
+
+struct u_boot_env {
+	struct device *dev;
+	enum u_boot_env_format format;
+
+	/* Parent device */
+	struct mtd_info *mtd;
+	size_t offset;
+	size_t size;
+
+	/* Cells */
+	struct nvmem_cell_info *cells;
+	int ncells;
+};
+
+struct u_boot_env_image_single {
+	__le32 crc32;
+	uint8_t data[0];
+} __packed;
+
+struct u_boot_env_image_redundant {
+	__le32 crc32;
+	u8 mark;
+	uint8_t data[0];
+} __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 -EIO;
+	}
+
+	return 0;
+}
+
+static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf,
+				size_t data_offset, size_t data_len)
+{
+	struct device *dev = priv->dev;
+	char *data = buf + data_offset;
+	char *var, *value, *eq;
+	int idx;
+
+	priv->ncells = 0;
+	for (var = data; var < data + 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 < data + 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 - 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;
+	size_t crc32_data_offset;
+	size_t crc32_data_len;
+	size_t crc32_offset;
+	size_t data_offset;
+	size_t data_len;
+	uint32_t crc32;
+	uint32_t calc;
+	size_t bytes;
+	uint8_t *buf;
+	int err;
+
+	buf = kcalloc(1, priv->size, GFP_KERNEL);
+	if (!buf) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	err = mtd_read(priv->mtd, priv->offset, priv->size, &bytes, buf);
+	if ((err && !mtd_is_bitflip(err)) || bytes != priv->size) {
+		dev_err(dev, "Failed to read from mtd: %d\n", err);
+		goto err_kfree;
+	}
+
+	switch (priv->format) {
+	case U_BOOT_FORMAT_SINGLE:
+		crc32_offset = offsetof(struct u_boot_env_image_single, crc32);
+		crc32_data_offset = offsetof(struct u_boot_env_image_single, data);
+		data_offset = offsetof(struct u_boot_env_image_single, data);
+		break;
+	case U_BOOT_FORMAT_REDUNDANT:
+		crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32);
+		crc32_data_offset = offsetof(struct u_boot_env_image_redundant, mark);
+		data_offset = offsetof(struct u_boot_env_image_redundant, data);
+		break;
+	}
+	crc32 = le32_to_cpu(*(uint32_t *)(buf + crc32_offset));
+	crc32_data_len = priv->size - crc32_data_offset;
+	data_len = priv->size - data_offset;
+
+	calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L;
+	if (calc != crc32) {
+		dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);
+		err = -EINVAL;
+		goto err_kfree;
+	}
+
+	buf[priv->size - 1] = '\0';
+	err = u_boot_env_add_cells(priv, buf, data_offset, data_len);
+	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_SINGLE, },
+	{ .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
+	{ .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
+	{},
+};
+
+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,
+	},
+};
+module_platform_driver(u_boot_env_driver);
+
+MODULE_AUTHOR("Rafał Miłecki");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);