Automotive Ethernet vs IT Ethernet

/* Automotive PHY startup: NXP TJA1100 100BASE-T1 */
/* Critical: link must be up before application tasks start */

#include "EthDrv.h"
#include "Eth_Phy.h"

#define PHY_ADDR         0x00u
#define PHY_TIMEOUT_MS   100u    /* OEM requirement: link up within 100 ms */

/* OPEN Alliance TC8 startup sequence */
Std_ReturnType EthPhy_Init(void)
{
    /* Step 1: Assert hardware reset (active low, hold 10 µs) */
    GPIO_ClearPin(ETH_PHY_RESET_PORT, ETH_PHY_RESET_PIN);
    Timer_DelayUs(10u);
    GPIO_SetPin(ETH_PHY_RESET_PORT, ETH_PHY_RESET_PIN);
    Timer_DelayUs(100u);  /* PHY internal reset time */

    /* Step 2: Verify PHY ID register */
    uint16_t phy_id1 = MDIO_Read(PHY_ADDR, MII_PHYSID1);  /* TJA1100: 0x0180 */
    uint16_t phy_id2 = MDIO_Read(PHY_ADDR, MII_PHYSID2);  /* TJA1100: 0xDC40 */
    if ((phy_id1 != 0x0180u) || ((phy_id2 & 0xFFF0u) != 0xDC40u)) {
        return E_NOT_OK;  /* wrong PHY or MDIO communication failure */
    }

    /* Step 3: Enable PHY (TJA1100: write CONFIG register to leave standby) */
    MDIO_Write(PHY_ADDR, TJA1100_EXTENDED_CTRL, TJA1100_LINK_CTRL_EN);

    /* Step 4: Wait for link up */
    uint32_t t_start = Timer_GetMs();
    while (Timer_GetMs() - t_start < PHY_TIMEOUT_MS) {
        uint16_t status = MDIO_Read(PHY_ADDR, MII_BMSR);
        if (status & BMSR_LSTATUS) {   /* link status bit */
            return E_OK;
        }
        Timer_DelayUs(1000u);
    }
    return E_NOT_OK;   /* link-up timeout: cable issue or remote PHY not ready */
}