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 | 85 ++++++++++++++++++++++++++++++++++
arch/arm/dts/imx6q-novena.dts | 14 ++++++
2 files changed, 99 insertions(+)
diff --git a/arch/arm/boards/novena/board.c b/arch/arm/boards/novena/board.c
index e41ea10f8d..b6c59aff44 100644
--- a/arch/arm/boards/novena/board.c
+++ b/arch/arm/boards/novena/board.c
@@ -3,9 +3,94 @@
#include <common.h>
#include <deep-probe.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 void power_on_audio_codec(void)
+{
+ int rc = of_devices_ensure_probed_by_name("regulator-audio-codec");
+
+ if (rc < 0)
+ pr_err("Unable to power on audio codec: %s\n", strerror(-rc));
+}
+
+static struct novena_eeprom *novena_read_eeprom(void)
+{
+ size_t read;
+ loff_t max = sizeof(struct novena_eeprom);
+ void *eeprom;
+ int rc;
+
+ /*
+ * When powered off the audio codec pulls down the EEPROM's I2C line.
+ * Power it on so we can actually read data.
+ */
+ power_on_audio_codec();
+
+ rc = of_device_ensure_probed_by_alias("eeprom0");
+ if (rc < 0) {
+ pr_err("Unable to probe eeprom0: %s\n", strerror(-rc));
+ return NULL;
+ }
+
+ 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");
+ free(eeprom);
+ return NULL;
+ }
+
+ 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 int novena_probe(struct device *dev)
{
+ struct novena_eeprom *eeprom = novena_read_eeprom();
+
+ if (eeprom && novena_check_eeprom(eeprom))
+ novena_set_mac(eeprom);
+
+ free(eeprom);
+
return 0;
}
diff --git a/arch/arm/dts/imx6q-novena.dts b/arch/arm/dts/imx6q-novena.dts
index 12bade849c..c614ed3cbb 100644
--- a/arch/arm/dts/imx6q-novena.dts
+++ b/arch/arm/dts/imx6q-novena.dts
@@ -2,3 +2,17 @@
// SPDX-FileCopyrightText: 2023 John Watts <contact@xxxxxxxxxx>
#include <arm/imx6q-novena.dts>
+
+/ {
+ aliases {
+ eeprom0 = &eeprom;
+ };
+};
+
+&i2c3 {
+ eeprom: eeprom@56 {
+ compatible = "24c512";
+ reg = <0x56>;
+ pagesize = <128>;
+ };
+};
--
2.39.1
