drivers: eth: Refactor generation of random mac into help function

Rather than having each driver have its own slightly different way of
generating a random mac address, add a helper function that they all can
call so we do it one way.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>

drivers/ethernet/eth.h

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2020 Linaro Ltd
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_DRIVERS_ETHERNET_ETH_H_
+#define ZEPHYR_DRIVERS_ETHERNET_ETH_H_
+
+#include <zephyr/types.h>
+
+static inline void gen_random_mac(u8_t *mac_addr, u8_t b0, u8_t b1, u8_t b2)
+{
+	u32_t entropy;
+
+	entropy = sys_rand32_get();
+
+	mac_addr[0] = b0;
+	mac_addr[1] = b1;
+	mac_addr[2] = b2;
+
+	/* Set MAC address locally administered, unicast (LAA) */
+	mac_addr[0] |= 0x02;
+
+	mac_addr[3] = (entropy >> 16) & 0xff;
+	mac_addr[4] = (entropy >>  8) & 0xff;
+	mac_addr[5] = (entropy >>  0) & 0xff;
+}
+
+#endif /* ZEPHYR_DRIVERS_ETHERNET_ETH_H_ */

drivers/ethernet/eth_gecko.c

@@ -29,6 +29,7 @@ LOG_MODULE_REGISTER(eth_gecko, CONFIG_ETHERNET_LOG_LEVEL);
 #include "phy_gecko.h"
 #include "eth_gecko_priv.h"
 
+#include "eth.h"
 
 static u8_t dma_tx_buffer[ETH_TX_BUF_COUNT][ETH_TX_BUF_SIZE]
 __aligned(ETH_BUF_ALIGNMENT);
@@ -490,21 +491,7 @@ static int eth_init(struct device *dev)
 #if defined(CONFIG_ETH_GECKO_RANDOM_MAC)
 static void generate_random_mac(u8_t mac_addr[6])
 {
-	u32_t entropy;
+	gen_random_mac(mac_addr, SILABS_OUI_B0, SILABS_OUI_B1, SILABS_OUI_B2);
-
-	entropy = sys_rand32_get();
-
-	/* SiLabs' OUI */
-	mac_addr[0] = SILABS_OUI_B0;
-	mac_addr[1] = SILABS_OUI_B1;
-	mac_addr[2] = SILABS_OUI_B2;
-
-	mac_addr[3] = entropy >> 0;
-	mac_addr[4] = entropy >> 8;
-	mac_addr[5] = entropy >> 16;
-
-	/* Set MAC address locally administered, unicast (LAA) */
-	mac_addr[0] |= 0x02;
 }
 #endif
 

drivers/ethernet/eth_liteeth.c

@@ -22,6 +22,8 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 
 #include <sys/printk.h>
 
+#include "eth.h"
+
 /* flags */
 #define LITEETH_EV_TX		0x1
 #define LITEETH_EV_RX		0x1
@@ -177,15 +179,7 @@ static void eth_irq_handler(struct device *port)
 
 #ifdef CONFIG_ETH_LITEETH_0_RANDOM_MAC
 static void generate_mac(u8_t *mac_addr)
-{
+	gen_random_mac(mac_addr, 0x10, 0xe2, 0xd5);
-	u32_t entropy;
-
-	entropy = sys_rand32_get();
-
-	mac_addr[3] = entropy >> 8;
-	mac_addr[4] = entropy >> 16;
-	/* Locally administered, unicast */
-	mac_addr[5] = ((entropy >> 0) & 0xfc) | 0x02;
 }
 #endif
 

drivers/ethernet/eth_mcux.c

@@ -43,6 +43,8 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 #include <drivers/clock_control.h>
 #endif
 
+#include "eth.h"
+
 #define FREESCALE_OUI_B0 0x00
 #define FREESCALE_OUI_B1 0x04
 #define FREESCALE_OUI_B2 0x9f
@@ -880,15 +882,8 @@ static void eth_callback(ENET_Type *base, enet_handle_t *handle,
     defined(CONFIG_ETH_MCUX_1_RANDOM_MAC)
 static void generate_random_mac(u8_t *mac_addr)
 {
-	u32_t entropy;
+	gen_random_mac(mac_addr, FREESCALE_OUI_B0,
-
+		       FREESCALE_OUI_B1, FREESCALE_OUI_B2);
-	entropy = sys_rand32_get();
-
-	mac_addr[0] |= 0x02; /* force LAA bit */
-
-	mac_addr[3] = entropy >> 8;
-	mac_addr[4] = entropy >> 16;
-	mac_addr[5] = entropy >> 0;
 }
 #endif
 

drivers/ethernet/eth_native_posix.c

@@ -35,6 +35,7 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 #include <net/lldp.h>
 
 #include "eth_native_posix_priv.h"
+#include "eth.h"
 
 #define NET_BUF_TIMEOUT K_MSEC(100)
 
@@ -415,12 +416,10 @@ static void eth_iface_init(struct net_if *iface)
 
 #if defined(CONFIG_ETH_NATIVE_POSIX_RANDOM_MAC)
 	/* 00-00-5E-00-53-xx Documentation RFC 7042 */
-	ctx->mac_addr[0] = 0x00;
+	gen_random_mac(ctx->mac_addr, 0x00, 0x00, 0x5E);
-	ctx->mac_addr[1] = 0x00;
+
-	ctx->mac_addr[2] = 0x5E;
 	ctx->mac_addr[3] = 0x00;
 	ctx->mac_addr[4] = 0x53;
-	ctx->mac_addr[5] = sys_rand32_get();
 
 	/* The TUN/TAP setup script will by default set the MAC address of host
 	 * interface to 00:00:5E:00:53:FF so do not allow that.

drivers/ethernet/eth_sam_gmac.c

@@ -1800,17 +1800,7 @@ static void get_mac_addr_from_i2c_eeprom(u8_t mac_addr[6])
 #if defined(CONFIG_ETH_SAM_GMAC_RANDOM_MAC)
 static void generate_random_mac(u8_t mac_addr[6])
 {
-	u32_t entropy;
+	gen_random_mac(mac_addr, ATMEL_OUI_B0, ATMEL_OUI_B1, ATMEL_OUI_B2);
-
-	entropy = sys_rand32_get();
-
-	mac_addr[0] = ATMEL_OUI_B0 | 0x02; /* force LAA bit */
-	mac_addr[1] = ATMEL_OUI_B1;
-	mac_addr[2] = ATMEL_OUI_B2;
-
-	mac_addr[3] = entropy >> 8;
-	mac_addr[4] = entropy >> 16;
-	mac_addr[5] = entropy >> 0;
 }
 #endif
 

drivers/ethernet/eth_stm32_hal.c

@@ -24,6 +24,7 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 #include <drivers/clock_control.h>
 #include <drivers/clock_control/stm32_clock_control.h>
 
+#include "eth.h"
 #include "eth_stm32_hal_priv.h"
 
 #if defined(CONFIG_ETH_STM32_HAL_USE_DTCM_FOR_DMA_BUFFER) && \
@@ -362,15 +363,7 @@ void HAL_ETH_RxCpltCallback(ETH_HandleTypeDef *heth_handle)
 #if defined(CONFIG_ETH_STM32_HAL_RANDOM_MAC)
 static void generate_mac(u8_t *mac_addr)
 {
-	u32_t entropy;
+	gen_random_mac(mac_addr, ST_OUI_B0, ST_OUI_B1, ST_OUI_B2);
-
-	entropy = sys_rand32_get();
-
-	mac_addr[0] |= 0x02; /* force LAA bit */
-
-	mac_addr[3] = entropy >> 16;
-	mac_addr[4] = entropy >> 8;
-	mac_addr[5] = entropy >> 0;
 }
 #endif