linux-kernel - [PATCH 4/4] nvmem: u-boot-env: post-process "ethaddr" env variable

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Message-Id: <20230222172245.6313-5-zajec5@gmail.com>
Date:   Wed, 22 Feb 2023 18:22:45 +0100
From:   Rafał Miłecki <zajec5@...il.com>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Michael Walle <michael@...le.cc>, gregkh@...uxfoundation.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, u-boot@...ts.denx.de,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: [PATCH 4/4] nvmem: u-boot-env: post-process "ethaddr" env variable

From: Rafał Miłecki <rafal@...ecki.pl>

U-Boot environment variables are stored in ASCII format so "ethaddr"
requires parsing into binary to make it work with Ethernet interfaces.

This includes support for indexes to support #nvmem-cell-cells = <1>.

Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
---
 drivers/nvmem/Kconfig      |  1 +
 drivers/nvmem/u-boot-env.c | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 189ea85bd67d..71322ea7cf53 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -346,6 +346,7 @@ config NVMEM_U_BOOT_ENV
 	tristate "U-Boot environment variables support"
 	depends on OF && MTD
 	select CRC32
+	select GENERIC_NET_UTILS
 	help
 	  U-Boot stores its setup as environment variables. This driver adds
 	  support for verifying & exporting such data. It also exposes variables
diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c
index 29b1d87a3c51..1f5d8aba98bf 100644
--- a/drivers/nvmem/u-boot-env.c
+++ b/drivers/nvmem/u-boot-env.c
@@ -4,6 +4,8 @@
  */
 
 #include <linux/crc32.h>
+#include <linux/etherdevice.h>
+#include <linux/if_ether.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/mtd/mtd.h>
@@ -70,6 +72,27 @@ static int u_boot_env_read(void *context, unsigned int offset, void *val,
 	return 0;
 }
 
+static int u_boot_env_read_post_process_ethaddr(void *context, const char *id, int index,
+						unsigned int offset, void **data, size_t *bytes)
+{
+	u8 mac[ETH_ALEN];
+
+	if (*bytes != 3 * ETH_ALEN - 1)
+		return -EINVAL;
+
+	if (!mac_pton(*data, mac))
+		return -EINVAL;
+
+	if (index)
+		eth_addr_add(mac, index);
+
+	/* We need *smaller* buffer so don't bother to krealloc() */
+	ether_addr_copy(*data, mac);
+	*bytes = ETH_ALEN;
+
+	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)
 {
@@ -101,6 +124,8 @@ static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf,
 		priv->cells[idx].offset = data_offset + value - data;
 		priv->cells[idx].bytes = strlen(value);
 		priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
+		if (!strcmp(var, "ethaddr"))
+			priv->cells[idx].read_post_process = u_boot_env_read_post_process_ethaddr;
 	}
 
 	if (WARN_ON(idx != priv->ncells))
-- 
2.34.1