burn_ethaddr_to_efuses

nvmem-cell.dtsi

&emac {
        nvmem-cells = <&ethaddr>;
        nvmem-cell-names = "mac-address";
};


&sid {
	#address-cells = <1>;
	#size-cells = <1>;
	
        ethaddr: ethaddr@ec {
                reg = <0xec 0x06>;
        };	
}

sid.cpp

// MAP OF WRITABLE REGIONS
//
// Obtained by sequentially writing 0xff into each byte except
// - CHIPID field (read-only),
// - THERMAL_SENSOR field (already contaminated) and
// - LCJS field (writable but the value is affecting behavior)
//
// I guess the remaining unchanged bits become writable under
// some yet-to-be-found condition.
// I didn't observe any undesirable effect after setting
// the eFuses, can't guarantee there aren't any though.
// (Tried out on hundreds of chips)
//
// 00000000  /*                  CHIPID                    */
// 00000010  ff ff ff ff 00 00 00 00  ff ff ff ff ff ff ff ff
// 00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00 
// 00000030  00 00 00 00 /*   THERMAL_SENSOR   */ ff ff ff ff
// 00000040  ff ff ff ff 00 00 00 00  00 00 00 00 00 00 00 00  
// 00000050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
// 00000060  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
// 00000070  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
// 00000080  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
// 00000090  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
// 000000a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
// 000000b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
// 000000c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
// 000000d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
// 000000e0  00 00 00 00 00 00 00 00  00 00 00 00 ff ff ff ff
// 000000f0  ff ff ff ff  /* LCJS */  00 00 00 00 00 00 00 00

#include <cstdio>
#include <endian.h>
#include <cstring>
#include <cassert>

/* Forward declarations */
typedef struct _feldev_handle feldev_handle;
uint32_t fel_readl(feldev_handle *dev, uint32_t addr);
void fel_writel(feldev_handle *dev, uint32_t addr, uint32_t val);

constexpr uint8_t SID_ETH_MAC_OFFSET	0xec;
constexpr uint32_t EFUSES_MAGIC = 0xac00u;

extern "C" uint32_t read_sid(feldev_handle *dev, uint8_t address)
{
    uint32_t prctl = (address << 16) | EFUSES_MAGIC | 0x02u;
    fel_writel(dev, 0x01c14040, prctl);
    uint32_t data = fel_readl(dev, 0x01c14060);

    return be32toh(data);
}

extern "C" void write_sid(feldev_handle *dev, uint8_t address, uint32_t value)
{
    uint32_t prctl = (address << 16) | EFUSES_MAGIC | 0x01u;
	fel_writel(dev, 0x01c14050, htobe32(value));
	fel_writel(dev, 0x01c14040, prctl);
}

extern "C" void write_eth_mac(feldev_handle* handle, uint8_t* mac)
{
	uint32_t tmp;
	memcpy(&tmp, mac, 4);
	write_sid(handle, SID_ETH_MAC_OFFSET, tmp);
	memcpy(&tmp, mac + 4, 4);
	write_sid(handle, SID_ETH_MAC_OFFSET + 4, tmp);
}


extern "C" void print_eth_mac(feldev_handle *dev)
{
	uint8_t ether_addr[8];
	uint32_t tmp = read_sid(dev, SID_ETH_MAC_OFFSET);
	memcpy(ether_addr, &tmp, 4);
	tmp = read_sid(dev, SID_ETH_MAC_OFFSET + 4);
	memcpy(ether_addr + 4, &tmp, 4);

	printf("eth mac is %02X:%02X:%02X:%02X:%02X:%02X\n",
		ether_addr[0], ether_addr[1], ether_addr[2],
		ether_addr[3], ether_addr[4], ether_addr[5]
	);
}

stmmac-nvmem-consumer.patch

967142cf31f8b20eeec2d5633eeb29ad9104c4ccommit 967142cf31f8b20eeec2d5633eeb29ad9104c4c3
Author: Roman Beránek <roman.beranek@prusa3d.com>
Date:   Fri Nov 16 02:19:25 2018 +0100

    net: stmmac: enable MAC address to be read from a nvmem cell as is described in Documentation/devicetree/bindings/net/ethernet.txt

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 72da77b94ecd..8a7b804528ef 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -25,6 +25,7 @@
 #include <linux/of_net.h>
 #include <linux/of_device.h>
 #include <linux/of_mdio.h>
+#include <linux/nvmem-consumer.h>
 
 #include "stmmac.h"
 #include "stmmac_platform.h"
@@ -375,6 +376,22 @@ static int stmmac_dt_phy(struct plat_stmmacenet_data *plat,
 	return 0;
 }
 
+static void *stmmac_get_nvmem_address(struct device *dev)
+{
+	struct nvmem_cell *cell;
+	size_t cell_size;
+	char *mac;
+
+	cell = nvmem_cell_get(dev, "mac-address");
+	if (IS_ERR(cell))
+		return NULL;
+
+        mac = nvmem_cell_read(cell, &cell_size);
+        nvmem_cell_put(cell);
+
+        return mac;
+}
+
 /**
  * stmmac_probe_config_dt - parse device-tree driver parameters
  * @pdev: platform_device structure
@@ -389,13 +406,21 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 	struct device_node *np = pdev->dev.of_node;
 	struct plat_stmmacenet_data *plat;
 	struct stmmac_dma_cfg *dma_cfg;
+	const u8 *mac_addr;
 	int rc;
 
 	plat = devm_kzalloc(&pdev->dev, sizeof(*plat), GFP_KERNEL);
 	if (!plat)
 		return ERR_PTR(-ENOMEM);
 
+	/* U-boot passes a MAC address it found/generated for the
+	   interface as a "local-mac-address" attribute in the dt
+	   node. Here it is received.
+	*/
 	*mac = of_get_mac_address(np);

+		mac_addr = stmmac_get_nvmem_address(&pdev->dev);
+		if (mac_addr && is_valid_ether_addr(mac_addr))
+			*mac = mac_addr;

plat->interface = of_get_phy_mode(np);
 
 	/* Get max speed of operation from device tree */