/*
 * (C) Copyright 2010
 * Reinhard Meyer, EMK Elektronik, reinhard.meyer@emk-elektronik.de
 * Martin Krause, Martin.Krause@tqs.de
 * reworked original enc28j60.c
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <common.h>
#include <net.h>
#include <spi.h>
#include <malloc.h>
#include <netdev.h>
#include <miiphy.h>
#include "enc28j60.h"

/*
 * IMPORTANT: spi_claim_bus() and spi_release_bus()
 * are called at begin and end of each of the following functions:
 * enc_miiphy_read(), enc_miiphy_write(), enc_write_hwaddr(),
 * enc_init(), enc_recv(), enc_send(), enc_halt()
 * ALL other functions assume that the bus has already been claimed!
 * Since NetReceive() might call enc_send() in return, the bus must be
 * released, NetReceive() called and claimed again.
 */

/*
 * Controller memory layout.
 * We only allow 1 frame for transmission and reserve the rest
 * for reception to handle as many broadcast packets as possible.
 * Also use the memory from 0x0000 for receiver buffer. See errata pt. 5
 * 0x0000 - 0x19ff 6656 bytes receive buffer
 * 0x1a00 - 0x1fff 1536 bytes transmit buffer =
 * control(1)+frame(1518)+status(7)+reserve(10).
 */
#define ENC_RX_BUF_START        0x0000
#define ENC_RX_BUF_END          0x19ff
#define ENC_TX_BUF_START        0x1a00
#define ENC_TX_BUF_END          0x1fff
#define ENC_MAX_FRM_LEN         1518
#define RX_RESET_COUNTER        1000

/*
 * For non data transfer functions, like phy read/write, set hwaddr, init
 * we do not need a full, time consuming init including link ready wait.
 * This enum helps to bring the chip through the minimum necessary inits.
 */
enum enc_initstate {none=0, setupdone, linkready};
typedef struct enc_device {
        struct eth_device       *dev;   /* back pointer */
        struct spi_slave        *slave;
        int                     rx_reset_counter;
        u16                     next_pointer;
        u8                      bank;   /* current bank in enc28j60 */
        enum enc_initstate      initstate;
} enc_dev_t;

/*
 * enc_bset:            set bits in a common register
 * enc_bclr:            clear bits in a common register
 *
 * making the reg parameter u8 will give a compile time warning if the
 * functions are called with a register not accessible in all Banks
 */
static void enc_bset(enc_dev_t *enc, const u8 reg, const u8 data)
{
        u8 dout[2];

        dout[0] = CMD_BFS(reg);
        dout[1] = data;
        spi_xfer(enc->slave, 2 * 8, dout, NULL,
                SPI_XFER_BEGIN | SPI_XFER_END);
}

static void enc_bclr(enc_dev_t *enc, const u8 reg, const u8 data)
{
        u8 dout[2];

        dout[0] = CMD_BFC(reg);
        dout[1] = data;
        spi_xfer(enc->slave, 2 * 8, dout, NULL,
                SPI_XFER_BEGIN | SPI_XFER_END);
}

/*
 * high byte of the register contains bank number:
 * 0: no bank switch necessary
 * 1: switch to bank 0
 * 2: switch to bank 1
 * 3: switch to bank 2
 * 4: switch to bank 3
 */
static void enc_set_bank(enc_dev_t *enc, const u16 reg)
{
        u8 newbank = reg >> 8;

        if (newbank == 0 || newbank == enc->bank)
                return;
        switch (newbank) {
        case 1:
                enc_bclr(enc, CTL_REG_ECON1,
                        ENC_ECON1_BSEL0 | ENC_ECON1_BSEL1);
                break;
        case 2:
                enc_bset(enc, CTL_REG_ECON1, ENC_ECON1_BSEL0);
                enc_bclr(enc, CTL_REG_ECON1, ENC_ECON1_BSEL1);
                break;
        case 3:
                enc_bclr(enc, CTL_REG_ECON1, ENC_ECON1_BSEL0);
                enc_bset(enc, CTL_REG_ECON1, ENC_ECON1_BSEL1);
                break;
        case 4:
                enc_bset(enc, CTL_REG_ECON1,
                        ENC_ECON1_BSEL0 | ENC_ECON1_BSEL1);
                break;
        }
        enc->bank = newbank;
}

/*
 * local functions to access SPI
 *
 * reg: register inside ENC28J60
 * data: 8/16 bits to write
 * c: number of retries
 *
 * enc_r8:              read 8 bits
 * enc_r16:             read 16 bits
 * enc_w8:              write 8 bits
 * enc_w16:             write 16 bits
 * enc_w8_retry:        write 8 bits, verify and retry
 * enc_rbuf:            read from ENC28J60 into buffer
 * enc_wbuf:            write from buffer into ENC28J60
 */

/*
 * MAC and MII registers need a 3 byte SPI transfer to read,
 * all other registers need a 2 byte SPI transfer.
 */
static int enc_reg2nbytes(const u16 reg)
{
        /* check if MAC or MII register */
        return ((reg >= CTL_REG_MACON1 && reg <= CTL_REG_MIRDH) ||
                (reg >= CTL_REG_MAADR1 && reg <= CTL_REG_MAADR4) ||
                (reg == CTL_REG_MISTAT)) ? 3 : 2;
}

/*
 * Read a byte register
 */
static u8 enc_r8(enc_dev_t *enc, const u16 reg)
{
        u8 dout[3];
        u8 din[3];
        int nbytes = enc_reg2nbytes(reg);

        enc_set_bank(enc, reg);
        dout[0] = CMD_RCR(reg);
        spi_xfer(enc->slave, nbytes * 8, dout, din,
                SPI_XFER_BEGIN | SPI_XFER_END);
        return din[nbytes-1];
}

/*
 * Read a L/H register pair and return a word.
 * Must be called with the L register's address.
 */
static u16 enc_r16(enc_dev_t *enc, const u16 reg)
{
        u8 dout[3];
        u8 din[3];
        u16 result;
        int nbytes = enc_reg2nbytes(reg);

        enc_set_bank(enc, reg);
        dout[0] = CMD_RCR(reg);
        spi_xfer(enc->slave, nbytes * 8, dout, din,
                SPI_XFER_BEGIN | SPI_XFER_END);
        result = din[nbytes-1];
        dout[0]++; /* next register */
        spi_xfer(enc->slave, nbytes * 8, dout, din,
                SPI_XFER_BEGIN | SPI_XFER_END);
        result |= din[nbytes-1] << 8;
        return result;
}

/*
 * Write a byte register
 */
static void enc_w8(enc_dev_t *enc, const u16 reg, const u8 data)
{
        u8 dout[2];

        enc_set_bank(enc, reg);
        dout[0] = CMD_WCR(reg);
        dout[1] = data;
        spi_xfer(enc->slave, 2 * 8, dout, NULL,
                SPI_XFER_BEGIN | SPI_XFER_END);
}

/*
 * Write a L/H register pair.
 * Must be called with the L register's address.
 */
static void enc_w16(enc_dev_t *enc, const u16 reg, const u16 data)
{
        u8 dout[2];

        enc_set_bank(enc, reg);
        dout[0] = CMD_WCR(reg);
        dout[1] = data;
        spi_xfer(enc->slave, 2 * 8, dout, NULL,
                SPI_XFER_BEGIN | SPI_XFER_END);
        dout[0]++; /* next register */
        dout[1] = data >> 8;
        spi_xfer(enc->slave, 2 * 8, dout, NULL,
                SPI_XFER_BEGIN | SPI_XFER_END);
}

/*
 * Write a byte register, verify and retry
 */
static void enc_w8_retry(enc_dev_t *enc, const u16 reg, const u8 data, const int c)
{
        u8 dout[2];
        u8 readback;
        int i;

        enc_set_bank(enc, reg);
        for (i = 0; i < c; i++) {
                dout[0] = CMD_WCR(reg);
                dout[1] = data;
                spi_xfer(enc->slave, 2 * 8, dout, NULL,
                        SPI_XFER_BEGIN | SPI_XFER_END);
                readback = enc_r8(enc, reg);
                if (readback == data)
                        break;
                /* wait 1ms */
                udelay(1000);
        }
        if (i == c) {
                printf("%s: write reg 0x%03x failed\n", enc->dev->name, reg);
        }
}

/*
 * Read ENC RAM into buffer
 */
static void enc_rbuf(enc_dev_t *enc, const u16 length, u8 *buf)
{
        u8 dout[1];

        dout[0] = CMD_RBM;
        spi_xfer(enc->slave, 8, dout, NULL, SPI_XFER_BEGIN);
        spi_xfer(enc->slave, length * 8, NULL, buf, SPI_XFER_END);
#ifdef DEBUG
        puts("Rx:\n");
        print_buffer(0, buf, 1, length, 0);
#endif
}

/*
 * Write buffer into ENC RAM
 */
static void enc_wbuf(enc_dev_t *enc, const u16 length, const u8 *buf, const u8 control)
{
        u8 dout[2];
        dout[0] = CMD_WBM;
        dout[1] = control;
        spi_xfer(enc->slave, 2 * 8, dout, NULL, SPI_XFER_BEGIN);
        spi_xfer(enc->slave, length * 8, buf, NULL, SPI_XFER_END);
#ifdef DEBUG
        puts("Tx:\n");
        print_buffer(0, buf, 1, length, 0);
#endif
}

/*
 * Try to claim the SPI bus.
 * Print error message on failure.
 */
static int enc_claim_bus(enc_dev_t *enc)
{
        int rc = spi_claim_bus(enc->slave);
        if (rc)
                printf("%s: failed to claim SPI bus\n", enc->dev->name);
        return rc;
}

/*
 * Release previously claimed SPI bus.
 * This function is mainly for symmetry to enc_claim_bus().
 * Let the toolchain decide to inline it...
 */
static void enc_release_bus(enc_dev_t *enc)
{
        spi_release_bus(enc->slave);
}

/*
 * Read PHY register
 */
static u16 enc_phy_read(enc_dev_t *enc, const u8 addr)
{
        uint64_t etime;
        u8 status;

        enc_w8(enc, CTL_REG_MIREGADR, addr);
        enc_w8(enc, CTL_REG_MICMD, ENC_MICMD_MIIRD);
        /* 1 second timeout - only happens on hardware problem */
        etime = get_ticks() + get_tbclk();
        /* poll MISTAT.BUSY bit until operation is complete */
        do
        {
                status = enc_r8(enc, CTL_REG_MISTAT);
        } while (get_ticks() <= etime && (status & ENC_MISTAT_BUSY));
        if (status & ENC_MISTAT_BUSY) {
                printf("%s: timeout reading phy\n", enc->dev->name);
                return 0;
        }
        enc_w8(enc, CTL_REG_MICMD, 0);
        return enc_r16(enc, CTL_REG_MIRDL);
}

/*
 * Write PHY register
 */
static void enc_phy_write(enc_dev_t *enc, const u8 addr, const u16 data)
{
        uint64_t etime;
        u8 status;

        enc_w8(enc, CTL_REG_MIREGADR, addr);
        enc_w16(enc, CTL_REG_MIWRL, data);
        /* 1 second timeout - only happens on hardware problem */
        etime = get_ticks() + get_tbclk();
        /* poll MISTAT.BUSY bit until operation is complete */
        do
        {
                status = enc_r8(enc, CTL_REG_MISTAT);
        } while (get_ticks() <= etime && (status & ENC_MISTAT_BUSY));
        if (status & ENC_MISTAT_BUSY) {
                printf("%s: timeout writing phy\n", enc->dev->name);
                return;
        }
}

/*
 * Verify link status, wait if necessary
 *
 * Note: with a 10 MBit/s only PHY there is no autonegotiation possible,
 * half/full duplex is a pure setup matter. For the time being, this driver
 * will setup in half duplex mode only.
 */
static int enc_phy_link_wait(enc_dev_t *enc)
{
        u16 status;
        int duplex;
        uint64_t etime;

#ifdef CONFIG_ENC_SILENTLINK
        /* check if we have a link, then just return */
        status = enc_phy_read(enc, PHY_REG_PHSTAT1);
        if (status & ENC_PHSTAT1_LLSTAT)
                return 0;
#endif

        /* wait for link with 1 second timeout */
        etime = get_ticks() + get_tbclk();
        while (get_ticks() <= etime) {
                status = enc_phy_read(enc, PHY_REG_PHSTAT1);
                if (status & ENC_PHSTAT1_LLSTAT) {
                        /* now we have a link */
                        status = enc_phy_read(enc, PHY_REG_PHSTAT2);
                        duplex = (status & ENC_PHSTAT2_DPXSTAT) ? 1 : 0;
                        printf("%s: link up, 10Mbps %s-duplex\n",
                                enc->dev->name, duplex ? "full" : "half");
                        return 0;
                }
                udelay(1000);
        }

        /* timeout occured */
        printf("%s: link down\n", enc->dev->name);
        return 1;
}

/*
 * This function resets the receiver only.
 */
static void enc_reset_rx(enc_dev_t *enc)
{
        u8 econ1;

        econ1 = enc_r8(enc, CTL_REG_ECON1);
        if ((econ1 & ENC_ECON1_RXRST) == 0) {
                enc_bset(enc, CTL_REG_ECON1, ENC_ECON1_RXRST);
                enc->rx_reset_counter = RX_RESET_COUNTER;
        }
}

/*
 * Reset receiver and reenable it.
 */
static void enc_reset_rx_call(enc_dev_t *enc)
{
        enc_bclr(enc, CTL_REG_ECON1, ENC_ECON1_RXRST);
        enc_bset(enc, CTL_REG_ECON1, ENC_ECON1_RXEN);
}

/*
 * Copy a packet from the receive ring and forward it to
 * the protocol stack.
 */
static void enc_receive(enc_dev_t *enc)
{
        u8 *packet = (u8 *)NetRxPackets[0];
        u16 pkt_len;
        u16 copy_len;
        u16 status;
        u8 pkt_cnt = 0;
        u16 rxbuf_rdpt;
        u8 hbuf[6];

        enc_w16(enc, CTL_REG_ERDPTL, enc->next_pointer);
        do {
                enc_rbuf(enc, 6, hbuf);
                enc->next_pointer = hbuf[0] | (hbuf[1] << 8);
                pkt_len = hbuf[2] | (hbuf[3] << 8);
                status = hbuf[4] | (hbuf[5] << 8);
                debug("next_pointer=$%04x pkt_len=%u status=$%04x\n",
                        enc->next_pointer, pkt_len, status);
                if (pkt_len <= ENC_MAX_FRM_LEN)
                        copy_len = pkt_len;
                else
                        copy_len = 0;
                if ((status & (1L << 7)) == 0) /* check Received Ok bit */
                        copy_len = 0;
                /* check if next pointer is resonable */
                if (enc->next_pointer >= ENC_TX_BUF_START)
                        copy_len = 0;
                if (copy_len > 0) {
                        enc_rbuf(enc, copy_len, packet);
                }
                /* advance read pointer to next pointer */
                enc_w16(enc, CTL_REG_ERDPTL, enc->next_pointer);
                /* decrease packet counter */
                enc_bset(enc, CTL_REG_ECON2, ENC_ECON2_PKTDEC);
                /*
                 * Only odd values should be written to ERXRDPTL,
                 * see errata B4 pt.13
                 */
                rxbuf_rdpt = enc->next_pointer - 1;
                if ((rxbuf_rdpt < enc_r16(enc, CTL_REG_ERXSTL)) ||
                        (rxbuf_rdpt > enc_r16(enc, CTL_REG_ERXNDL))) {
                        enc_w16(enc, CTL_REG_ERXRDPTL,
                                enc_r16(enc, CTL_REG_ERXNDL));
                } else {
                        enc_w16(enc, CTL_REG_ERXRDPTL, rxbuf_rdpt);
                }
                /* read pktcnt */
                pkt_cnt = enc_r8(enc, CTL_REG_EPKTCNT);
                if (copy_len == 0) {
                        (void)enc_r8(enc, CTL_REG_EIR);
                        enc_reset_rx(enc);
                        printf("%s: receive copy_len=0\n", enc->dev->name);
                        continue;
                }
                /*
                 * Because NetReceive() might call enc_send(), we need to
                 * release the SPI bus, call NetReceive(), reclaim the bus
                 */
                enc_release_bus(enc);
                NetReceive(packet, pkt_len);
                if (enc_claim_bus(enc))
                        return;
                (void)enc_r8(enc, CTL_REG_EIR);
        } while (pkt_cnt);
        /* Use EPKTCNT not EIR.PKTIF flag, see errata pt. 6 */
}

/*
 * Poll for completely received packets.
 */
static void enc_poll(enc_dev_t *enc)
{
        u8 eir_reg;
        u8 pkt_cnt;

#ifdef CONFIG_USE_IRQ
        /* clear global interrupt enable bit in enc28j60 */
        enc_bclr(enc, CTL_REG_EIE, ENC_EIE_INTIE);
#endif
        (void)enc_r8(enc, CTL_REG_ESTAT);
        eir_reg = enc_r8(enc, CTL_REG_EIR);
        if (eir_reg & ENC_EIR_TXIF) {
                /* clear TXIF bit in EIR */
                enc_bclr(enc, CTL_REG_EIR, ENC_EIR_TXIF);
        }
        /* We have to use pktcnt and not pktif bit, see errata pt. 6 */
        pkt_cnt = enc_r8(enc, CTL_REG_EPKTCNT);
        if (pkt_cnt > 0) {
                if ((eir_reg & ENC_EIR_PKTIF) == 0) {
                        debug("enc_poll: pkt cnt > 0, but pktif not set\n");
                }
                enc_receive(enc);
                /*
                 * clear PKTIF bit in EIR, this should not need to be done
                 * but it seems like we get problems if we do not
                 */
                enc_bclr(enc, CTL_REG_EIR, ENC_EIR_PKTIF);
        }
        if (eir_reg & ENC_EIR_RXERIF) {
                printf("%s: rx error\n", enc->dev->name);
                enc_bclr(enc, CTL_REG_EIR, ENC_EIR_RXERIF);
        }
        if (eir_reg & ENC_EIR_TXERIF) {
                printf("%s: tx error\n", enc->dev->name);
                enc_bclr(enc, CTL_REG_EIR, ENC_EIR_TXERIF);
        }
#ifdef CONFIG_USE_IRQ
        /* set global interrupt enable bit in enc28j60 */
        enc_bset(enc, CTL_REG_EIE, ENC_EIE_INTIE);
#endif
}

/*
 * Completely Reset the ENC
 */
static void enc_reset(enc_dev_t *enc)
{
        u8 dout[1];

        dout[0] = CMD_SRC;
        spi_xfer(enc->slave, 8, dout, NULL,
                SPI_XFER_BEGIN | SPI_XFER_END);
        /* sleep 1 ms. See errata pt. 2 */
        udelay(1000);
}

/*
 * Initialisation data for most of the ENC registers
 */
static const u16 enc_initdata[] = {
        /*
         * Setup the buffer space. The reset values are valid for the
         * other pointers.
         *
         * We shall not write to ERXST, see errata pt. 5. Instead we
         * have to make sure that ENC_RX_BUS_START is 0.
         */
        CTL_REG_ERXSTL, ENC_RX_BUF_START,
        CTL_REG_ERXSTH, ENC_RX_BUF_START >> 8,
        CTL_REG_ERXNDL, ENC_RX_BUF_END,
        CTL_REG_ERXNDH, ENC_RX_BUF_END >> 8,
        CTL_REG_ERDPTL, ENC_RX_BUF_START,
        CTL_REG_ERDPTH, ENC_RX_BUF_START >> 8,
        /*
         * Set the filter to receive only good-CRC, unicast and broadcast
         * frames.
         * Note: some DHCP servers return their answers as broadcasts!
         * So its unwise to remove broadcast from this. This driver
         * might incur receiver overruns with packet loss on a broadcast
         * flooded network.
         */
        CTL_REG_ERXFCON, ENC_RFR_BCEN | ENC_RFR_UCEN | ENC_RFR_CRCEN,

        /* enable MAC to receive frames */
        CTL_REG_MACON1,
                ENC_MACON1_MARXEN | ENC_MACON1_TXPAUS | ENC_MACON1_RXPAUS,

        /* configure pad, tx-crc and duplex */
        CTL_REG_MACON3,
                ENC_MACON3_PADCFG0 | ENC_MACON3_TXCRCEN |
                ENC_MACON3_FRMLNEN,

        /* Allow infinite deferals if the medium is continously busy */
        CTL_REG_MACON4, ENC_MACON4_DEFER,

        /* Late collisions occur beyond 63 bytes */
        CTL_REG_MACLCON2, 63,

        /*
         * Set (low byte) Non-Back-to_Back Inter-Packet Gap.
         * Recommended 0x12
         */
        CTL_REG_MAIPGL, 0x12,

        /*
         * Set (high byte) Non-Back-to_Back Inter-Packet Gap.
         * Recommended 0x0c for half-duplex. Nothing for full-duplex
         */
        CTL_REG_MAIPGH, 0x0C,

        /* set maximum frame length */
        CTL_REG_MAMXFLL, ENC_MAX_FRM_LEN,
        CTL_REG_MAMXFLH, ENC_MAX_FRM_LEN >> 8,

        /*
         * Set MAC back-to-back inter-packet gap.
         * Recommended 0x12 for half duplex
         * and 0x15 for full duplex.
         */
        CTL_REG_MABBIPG, 0x12,

        /* end of table */
        0xffff
};

/*
 * Wait for the XTAL oscillator to become ready
 */
static int enc_clock_wait(enc_dev_t *enc)
{
        uint64_t etime;

        /* one second timeout */
        etime = get_ticks() + get_tbclk();

        /*
         * Wait for CLKRDY to become set (i.e., check that we can
         * communicate with the ENC)
         */
        do
        {
                if (enc_r8(enc, CTL_REG_ESTAT) & ENC_ESTAT_CLKRDY)
                        return 0;
        } while (get_ticks() <= etime);

        printf("%s: timeout waiting for CLKRDY\n", enc->dev->name);
        return -1;
}

/*
 * Write the MAC address into the ENC
 */
static int enc_write_macaddr(enc_dev_t *enc)
{
        unsigned char *p = enc->dev->enetaddr;

        enc_w8_retry(enc, CTL_REG_MAADR5, *p++, 5);
        enc_w8_retry(enc, CTL_REG_MAADR4, *p++, 5);
        enc_w8_retry(enc, CTL_REG_MAADR3, *p++, 5);
        enc_w8_retry(enc, CTL_REG_MAADR2, *p++, 5);
        enc_w8_retry(enc, CTL_REG_MAADR1, *p++, 5);
        enc_w8_retry(enc, CTL_REG_MAADR0, *p, 5);
        return 0;
}

/*
 * Setup most of the ENC registers
 */
static int enc_setup(enc_dev_t *enc)
{
        u16 phid1 = 0;
        u16 phid2 = 0;
        const u16 *tp;

        /* reset enc struct values */
        enc->next_pointer = ENC_RX_BUF_START;
        enc->rx_reset_counter = RX_RESET_COUNTER;
        enc->bank = 0xff;       /* invalidate current bank in enc28j60 */

        /* verify PHY identification */
        phid1 = enc_phy_read(enc, PHY_REG_PHID1);
        phid2 = enc_phy_read(enc, PHY_REG_PHID2) & ENC_PHID2_MASK;
        if (phid1 != ENC_PHID1_VALUE || phid2 != ENC_PHID2_VALUE) {
                printf("%s: failed to identify PHY. Found %04x:%04x\n",
                        enc->dev->name, phid1, phid2);
                return -1;
        }

        /* now program registers */
        for (tp = enc_initdata; *tp != 0xffff; tp += 2)
                enc_w8_retry(enc, tp[0], tp[1], 10);

        /*
         * Prevent automatic loopback of data beeing transmitted by setting
         * ENC_PHCON2_HDLDIS
         */
        enc_phy_write(enc, PHY_REG_PHCON2, (1<<8));

        /*
         * LEDs configuration
         * LEDA: LACFG = 0100 -> display link status
         * LEDB: LBCFG = 0111 -> display TX & RX activity
         * STRCH = 1 -> LED pulses
         */
        enc_phy_write(enc, PHY_REG_PHLCON, 0x0472);

        /* Reset PDPXMD-bit => half duplex */
        enc_phy_write(enc, PHY_REG_PHCON1, 0);

#ifdef CONFIG_USE_IRQ
        /* enable interrupts */
        enc_bset(enc, CTL_REG_EIE, ENC_EIE_PKTIE);
        enc_bset(enc, CTL_REG_EIE, ENC_EIE_TXIE);
        enc_bset(enc, CTL_REG_EIE, ENC_EIE_RXERIE);
        enc_bset(enc, CTL_REG_EIE, ENC_EIE_TXERIE);
        enc_bset(enc, CTL_REG_EIE, ENC_EIE_INTIE);
#endif

        return 0;
}

/*
 * Check if ENC has been initialized.
 * If not, try to initialize it.
 * Remember initialized state in struct.
 */
static int enc_initcheck(enc_dev_t *enc, const enum enc_initstate requiredstate)
{
        if (enc->initstate >= requiredstate)
                return 0;

        if (enc->initstate < setupdone) {
                /* Initialize the ENC only */
                enc_reset(enc);
                /* if any of functions fails, skip the rest and return an error */
                if (enc_clock_wait(enc) || enc_setup(enc) || enc_write_macaddr(enc)) {
                        return -1;
                }
                enc->initstate = setupdone;
        }
        /* if that's all we need, return here */
        if (enc->initstate >= requiredstate)
                return 0;

        /* now wait for link ready condition */
        if (enc_phy_link_wait(enc)) {
                return -1;
        }
        enc->initstate = linkready;
        return 0;
}

#if defined(CONFIG_CMD_MII)
/*
 * Read a PHY register.
 *
 * This function is registered with miiphy_register().
 */
int enc_miiphy_read(const char *devname, u8 phy_adr, u8 reg, u16 *value)
{
        struct eth_device *dev = eth_get_dev_by_name(devname);
        enc_dev_t *enc;

        if (!dev || phy_adr != 0)
                return -1;

        enc = dev->priv;
        if (enc_claim_bus(enc))
                return -1;
        if (enc_initcheck(enc, setupdone)) {
                enc_release_bus(enc);
                return -1;
        }
        *value = enc_phy_read(enc, reg);
        enc_release_bus(enc);
        return 0;
}

/*
 * Write a PHY register.
 *
 * This function is registered with miiphy_register().
 */
int enc_miiphy_write(const char *devname, u8 phy_adr, u8 reg, u16 value)
{
        struct eth_device *dev = eth_get_dev_by_name(devname);
        enc_dev_t *enc;

        if (!dev || phy_adr != 0)
                return -1;

        enc = dev->priv;
        if (enc_claim_bus(enc))
                return -1;
        if (enc_initcheck(enc, setupdone)) {
                enc_release_bus(enc);
                return -1;
        }
        enc_phy_write(enc, reg, value);
        enc_release_bus(enc);
        return 0;
}
#endif

/*
 * Write hardware (MAC) address.
 *
 * This function entered into eth_device structure.
 */
static int enc_write_hwaddr(struct eth_device *dev)
{
        enc_dev_t *enc = dev->priv;

        if (enc_claim_bus(enc))
                return -1;
        if (enc_initcheck(enc, setupdone)) {
                enc_release_bus(enc);
                return -1;
        }
        enc_release_bus(enc);
        return 0;
}

/*
 * Initialize ENC28J60 for use.
 *
 * This function entered into eth_device structure.
 */
static int enc_init(struct eth_device *dev, bd_t *bis)
{
        enc_dev_t *enc = dev->priv;

        if (enc_claim_bus(enc))
                return -1;
        if (enc_initcheck(enc, linkready)) {
                enc_release_bus(enc);
                return -1;
        }
        /* enable receive */
        enc_bset(enc, CTL_REG_ECON1, ENC_ECON1_RXEN);
        enc_release_bus(enc);
        return 0;
}

/*
 * Check for received packets.
 *
 * This function entered into eth_device structure.
 */
static int enc_recv(struct eth_device *dev)
{
        enc_dev_t *enc = dev->priv;

        if (enc_claim_bus(enc))
                return -1;
        if (enc_initcheck(enc, linkready)) {
                enc_release_bus(enc);
                return -1;
        }
        /* Check for dead receiver */
        if (enc->rx_reset_counter > 0)
                enc->rx_reset_counter--;
        else
                enc_reset_rx_call(enc);
        enc_poll(enc);
        enc_release_bus(enc);
        return 0;
}

/*
 * Send a packet.
 *
 * This function entered into eth_device structure.
 *
 * Should we wait here until we have a Link? Or shall we leave that to
 * protocol retries?
 */
static int enc_send(
        struct eth_device *dev,
        void *packet,
        int length)
{
        enc_dev_t *enc = dev->priv;

        if (enc_claim_bus(enc))
                return -1;
        if (enc_initcheck(enc, linkready)) {
                enc_release_bus(enc);
                return -1;
        }
        /* setup transmit pointers */
        enc_w16(enc, CTL_REG_EWRPTL, ENC_TX_BUF_START);
        enc_w16(enc, CTL_REG_ETXNDL, length + ENC_TX_BUF_START);
        enc_w16(enc, CTL_REG_ETXSTL, ENC_TX_BUF_START);
        /* write packet to ENC */
        enc_wbuf(enc, length, (u8 *) packet, 0x00);
        /*
         * Check that the internal transmit logic has not been altered
         * by excessive collisions. Reset transmitter if so.
         * See Errata B4 12 and 14.
         */
        if (enc_r8(enc, CTL_REG_EIR) & ENC_EIR_TXERIF) {
                enc_bset(enc, CTL_REG_ECON1, ENC_ECON1_TXRST);
                enc_bclr(enc, CTL_REG_ECON1, ENC_ECON1_TXRST);
        }
        enc_bclr(enc, CTL_REG_EIR, (ENC_EIR_TXERIF | ENC_EIR_TXIF));
        /* start transmitting */
        enc_bset(enc, CTL_REG_ECON1, ENC_ECON1_TXRTS);
        enc_release_bus(enc);
        return 0;
}

/*
 * Finish use of ENC.
 *
 * This function entered into eth_device structure.
 */
static void enc_halt(struct eth_device *dev)
{
        enc_dev_t *enc = dev->priv;

        if (enc_claim_bus(enc))
                return;
        /* Just disable receiver */
        enc_bclr(enc, CTL_REG_ECON1, ENC_ECON1_RXEN);
        enc_release_bus(enc);
}

/*
 * This is the only exported function.
 *
 * It may be called several times with different bus:cs combinations.
 */
int enc28j60_initialize(unsigned int bus, unsigned int cs,
        unsigned int max_hz, unsigned int mode)
{
        struct eth_device *dev;
        enc_dev_t *enc;

        /* try to allocate, check and clear eth_device object */
        dev = malloc(sizeof(*dev));
        if (!dev) {
                return -1;
        }
        memset(dev, 0, sizeof(*dev));

        /* try to allocate, check and clear enc_dev_t object */
        enc = malloc(sizeof(*enc));
        if (!enc) {
                free(dev);
                return -1;
        }
        memset(enc, 0, sizeof(*enc));

        /* try to setup the SPI slave */
        enc->slave = spi_setup_slave(bus, cs, max_hz, mode);
        if (!enc->slave) {
                printf("enc28j60: invalid SPI device %i:%i\n", bus, cs);
                free(enc);
                free(dev);
                return -1;
        }

        enc->dev = dev;
        /* now fill the eth_device object */
        dev->priv = enc;
        dev->init = enc_init;
        dev->halt = enc_halt;
        dev->send = enc_send;
        dev->recv = enc_recv;
        dev->write_hwaddr = enc_write_hwaddr;
        sprintf(dev->name, "enc%i.%i", bus, cs);
        eth_register(dev);
#if defined(CONFIG_CMD_MII)
        miiphy_register(dev->name, enc_miiphy_read, enc_miiphy_write);
#endif
        return 0;
}