The Novena has an EEPROM used for storing information about the board,
including the Ethernet MAC address.
The reference for the EEPROM fields is the novena-eeprom source code.
Signed-off-by: John Watts <contact@xxxxxxxxxx>
---
arch/arm/boards/novena/board.c | 68 ++++++++++++++++++++++++++++++++++
arch/arm/dts/imx6q-novena.dts | 15 ++++++++
2 files changed, 83 insertions(+)
diff --git a/arch/arm/boards/novena/board.c b/arch/arm/boards/novena/board.c
index 186f91093f..0341117c46 100644
--- a/arch/arm/boards/novena/board.c
+++ b/arch/arm/boards/novena/board.c
@@ -2,12 +2,80 @@
// SPDX-FileCopyrightText: 2023 John Watts
#include <common.h>
+#include <fs.h>
+#include <libfile.h>
+#include <net.h>
+
+struct novena_eeprom {
+ uint8_t signature[6]; /* 'Novena' */
+ uint8_t version; /* 1 or 2, not checked */
+ uint8_t page_size; /* v2 only: EEPROM read/write page */
+ uint32_t serial; /* 32-bit serial number */
+ uint8_t mac[6]; /* Gigabit MAC address */
+ uint16_t features; /* features */
+ /* ... extra fields omitted ... */
+} __packed;
+
+static struct novena_eeprom *novena_read_eeprom(void)
+{
+ size_t read;
+ loff_t max = sizeof(struct novena_eeprom);
+ void *eeprom;
+
+ int rc = read_file_2("/dev/eeprom0", &read, &eeprom, max);
+
+ if (rc < 0 && rc != -EFBIG) {
+ pr_err("Unable to read Novena EEPROM: %s\n", strerror(-rc));
+ return NULL;
+ } else if (read != max) {
+ pr_err("Short read from Novena EEPROM?\n");
+ return NULL;
+ } else {
+ return eeprom;
+ }
+}
+
+static bool novena_check_eeprom(struct novena_eeprom *eeprom)
+{
+ char *sig = eeprom->signature;
+ size_t size = sizeof(eeprom->signature);
+
+ if (memcmp("Novena", sig, size) != 0) {
+ pr_err("Unknown Novena EEPROM signature\n");
+ return false;
+ }
+
+ return true;
+}
+
+static void novena_set_mac(struct novena_eeprom *eeprom)
+{
+ struct device_node *dnode;
+
+ dnode = of_find_node_by_alias(of_get_root_node(), "ethernet0");
+ if (dnode)
+ of_eth_register_ethaddr(dnode, eeprom->mac);
+ else
+ pr_err("Unable to find ethernet node\n");
+}
+
+static void novena_try_eeprom(void)
+{
+ struct novena_eeprom *eeprom = novena_read_eeprom();
+
+ if (!eeprom || !novena_check_eeprom(eeprom))
+ return;
+
+ novena_set_mac(eeprom);
+}
static int novena_device_init(void)
{
if (!of_machine_is_compatible("kosagi,imx6q-novena"))
return 0;
+ novena_try_eeprom();
+
return 0;
}
device_initcall(novena_device_init);
diff --git a/arch/arm/dts/imx6q-novena.dts b/arch/arm/dts/imx6q-novena.dts
index 07471cb132..095dcde0d5 100644
--- a/arch/arm/dts/imx6q-novena.dts
+++ b/arch/arm/dts/imx6q-novena.dts
@@ -2,3 +2,18 @@
// SPDX-FileCopyrightText: 2023 John Watts
#include <arm/imx6q-novena.dts>
+
+/ {
+ aliases {
+ eeprom0 = &eeprom;
+ };
+};
+
+&i2c3 {
+ eeprom: eeprom@56 {
+ compatible = "24c512";
+ reg = <0x56>;
+ pagesize = <128>;
+ status = "okay";
+ };
+};
--
2.39.0
