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 <[email protected]> --- arch/arm/boards/novena/board.c | 88 ++++++++++++++++++++++++++++++++++ arch/arm/dts/imx6q-novena.dts | 15 ++++++ 2 files changed, 103 insertions(+) diff --git a/arch/arm/boards/novena/board.c b/arch/arm/boards/novena/board.c index e247f8b8c3..24cde1c0d4 100644 --- a/arch/arm/boards/novena/board.c +++ b/arch/arm/boards/novena/board.c @@ -3,9 +3,97 @@ #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"); + 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_probe(struct device *dev) { + novena_try_eeprom(); + return 0; } 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
