/*
 * SBE 2T3E3 synchronous serial card driver for Linux
 *
 * Copyright (C) 2009-2010 Krzysztof Halasa <khc@pm.waw.pl>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 *
 * This code is based on a driver written by SBE Inc.
 */

#include <linux/interrupt.h>
#include <linux/netdevice.h>
#include "2t3e3.h"

void t3e3_init(struct channel *sc)
{
        cpld_init(sc);
        dc_reset(sc);
        dc_init(sc);
        exar7250_init(sc);
        exar7300_init(sc);
}

int t3e3_if_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct channel *sc = dev_to_priv(dev);
        u32 current_write, last_write;
        unsigned long flags;
        struct sk_buff *skb2;

        if (skb == NULL) {
                sc->s.out_errors++;
                return 0;
        }

        if (sc->p.transmitter_on != SBE_2T3E3_ON) {
                sc->s.out_errors++;
                sc->s.out_dropped++;
                dev_kfree_skb_any(skb);
                return 0;
        }

        if (sc->s.OOF && sc->p.loopback == SBE_2T3E3_LOOPBACK_NONE) {
                sc->s.out_dropped++;
                dev_kfree_skb_any(skb);
                return 0;
        }

        spin_lock_irqsave(&sc->ether.tx_lock, flags);

        current_write = sc->ether.tx_ring_current_write;
        for (skb2 = skb; skb2 != NULL; skb2 = NULL) {
                if (skb2->len) {
                        if ((sc->ether.tx_ring[current_write].tdes1 &
                             SBE_2T3E3_TX_DESC_BUFFER_1_SIZE) > 0)
                                break;
                        current_write = (current_write + 1) % SBE_2T3E3_TX_DESC_RING_SIZE;
                        /*
                         * Leave at least 1 tx desc free so that dc_intr_tx() can
                         * identify empty list
                         */
                        if (current_write == sc->ether.tx_ring_current_read)
                                break;
                }
        }
        if (skb2 != NULL) {
                netif_stop_queue(sc->dev);
                sc->ether.tx_full = 1;
                dev_dbg(&sc->pdev->dev, "SBE 2T3E3: out of descriptors\n");
                spin_unlock_irqrestore(&sc->ether.tx_lock, flags);
                return NETDEV_TX_BUSY;
        }

        current_write = last_write = sc->ether.tx_ring_current_write;
        dev_dbg(&sc->pdev->dev, "sending mbuf (current_write = %d)\n",
                current_write);

        for (skb2 = skb; skb2 != NULL; skb2 = NULL) {
                if (skb2->len) {
                        dev_dbg(&sc->pdev->dev,
                                "sending mbuf (len = %d, next = %p)\n",
                                skb2->len, NULL);

                        sc->ether.tx_free_cnt--;
                        sc->ether.tx_ring[current_write].tdes0 = 0;
                        sc->ether.tx_ring[current_write].tdes1 &=
                                SBE_2T3E3_TX_DESC_END_OF_RING |
                                SBE_2T3E3_TX_DESC_SECOND_ADDRESS_CHAINED;
/* DISABLE_PADDING sometimes gets lost somehow, hands off... */
                        sc->ether.tx_ring[current_write].tdes1 |=
                                SBE_2T3E3_TX_DESC_DISABLE_PADDING | skb2->len;

                        if (current_write == sc->ether.tx_ring_current_write) {
                                sc->ether.tx_ring[current_write].tdes1 |=
                                        SBE_2T3E3_TX_DESC_FIRST_SEGMENT;
                        } else {
                                sc->ether.tx_ring[current_write].tdes0 =
                                        SBE_2T3E3_TX_DESC_21143_OWN;
                        }

                        sc->ether.tx_ring[current_write].tdes2 = virt_to_phys(skb2->data);
                        sc->ether.tx_data[current_write] = NULL;

                        last_write = current_write;
                        current_write = (current_write + 1) % SBE_2T3E3_TX_DESC_RING_SIZE;
                }
        }

        sc->ether.tx_data[last_write] = skb;
        sc->ether.tx_ring[last_write].tdes1 |=
                SBE_2T3E3_TX_DESC_LAST_SEGMENT |
                SBE_2T3E3_TX_DESC_INTERRUPT_ON_COMPLETION;
        sc->ether.tx_ring[sc->ether.tx_ring_current_write].tdes0 |=
                SBE_2T3E3_TX_DESC_21143_OWN;
        sc->ether.tx_ring_current_write = current_write;

        dev_dbg(&sc->pdev->dev, "txput: tdes0 = %08X        tdes1 = %08X\n",
                sc->ether.tx_ring[last_write].tdes0,
                sc->ether.tx_ring[last_write].tdes1);

        dc_write(sc->addr, SBE_2T3E3_21143_REG_TRANSMIT_POLL_DEMAND,
                 0xffffffff);

        spin_unlock_irqrestore(&sc->ether.tx_lock, flags);
        return 0;
}


void t3e3_read_card_serial_number(struct channel *sc)
{
        u32 i;

        for (i = 0; i < 3; i++)
                sc->ether.card_serial_number[i] = t3e3_eeprom_read_word(sc, 10 + i);

        netdev_info(sc->dev, "SBE wanPMC-2T3E3 serial number: %04X%04X%04X\n",
                    sc->ether.card_serial_number[0],
                    sc->ether.card_serial_number[1],
                    sc->ether.card_serial_number[2]);
}

/*
  bit 0 led1 (green)
  bit 1 led1 (yellow)

  bit 2 led2 (green)
  bit 3 led2 (yellow)

  bit 4 led3 (green)
  bit 5 led3 (yellow)

  bit 6 led4 (green)
  bit 7 led4 (yellow)
*/

void update_led(struct channel *sc, int blinker)
{
        int leds;
        if (sc->s.LOS)
                leds = 0; /* led1 = off */
        else if (sc->s.OOF)
                leds = 2; /* led1 = yellow */
        else if ((blinker & 1) && sc->rcv_count) {
                leds = 0; /* led1 = off */
                sc->rcv_count = 0;
        } else
                leds = 1; /* led1 = green */
        cpld_write(sc, SBE_2T3E3_CPLD_REG_LEDR, leds);
        sc->leds = leds;
}