--- /dev/null
+From f955dc14450695564926711cf9fa8e1d5d854302 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Wed, 15 Jun 2022 21:43:00 +0200
+Subject: [PATCH] nvmem: add driver handling U-Boot environment variables
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+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
+
+Current Linux's NVMEM sysfs API allows reading whole NVMEM data block.
+It can be used by user-space tools for reading U-Boot env vars block
+without the hassle of finding its location. Parsing will still need to
+be re-done there.
+
+Kernel-parsed NVMEM cells can be read however by Linux drivers. This may
+be useful for Ethernet drivers for reading device MAC address which is
+often stored as U-Boot env variable.
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
+Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+---
+
+--- a/drivers/nvmem/Kconfig
++++ b/drivers/nvmem/Kconfig
+@@ -300,4 +300,17 @@ 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 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.
++
++ Currently this drivers works only with env variables on top of MTD.
++
++ If compiled as module it will be called nvmem_u-boot-env.
++
+ endif
+--- a/drivers/nvmem/Makefile
++++ b/drivers/nvmem/Makefile
+@@ -61,3 +61,5 @@ obj-$(CONFIG_NVMEM_RMEM) += nvmem-rmem.
+ nvmem-rmem-y := rmem.o
+ obj-$(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
+--- /dev/null
++++ b/drivers/nvmem/u-boot-env.c
+@@ -0,0 +1,218 @@
++// 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;
++
++ struct mtd_info *mtd;
++
++ /* Cells */
++ struct nvmem_cell_info *cells;
++ int ncells;
++};
++
++struct u_boot_env_image_single {
++ __le32 crc32;
++ uint8_t data[];
++} __packed;
++
++struct u_boot_env_image_redundant {
++ __le32 crc32;
++ u8 mark;
++ uint8_t data[];
++} __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, 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 %zu 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->mtd->size, GFP_KERNEL);
++ if (!buf) {
++ err = -ENOMEM;
++ goto err_out;
++ }
++
++ err = mtd_read(priv->mtd, 0, priv->mtd->size, &bytes, buf);
++ if ((err && !mtd_is_bitflip(err)) || bytes != priv->mtd->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->mtd->size - crc32_data_offset;
++ data_len = priv->mtd->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->mtd->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 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;
++ struct u_boot_env *priv;
++ int err;
++
++ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
++ if (!priv)
++ return -ENOMEM;
++ priv->dev = dev;
++
++ priv->format = (uintptr_t)of_device_get_match_data(dev);
++
++ priv->mtd = of_get_mtd_device_by_node(np);
++ if (IS_ERR(priv->mtd)) {
++ dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np);
++ 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->mtd->size;
++
++ return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
++}
++
++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 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);
projects / openwrt / staging / svanheule.git / blobdiff