/*
 * Copyright (c) 2009 Lukas Mejdrech
 * Copyright (c) 2011 Martin Decky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This code is based upon the NE2000 driver for MINIX,
 * distributed according to a BSD-style license.
 *
 * Copyright (c) 1987, 1997, 2006 Vrije Universiteit
 * Copyright (c) 1992, 1994 Philip Homburg
 * Copyright (c) 1996 G. Falzoni
 *
 */

/** @addtogroup ne2000
 *  @{
 */

/** @file
 *
 * NE2000 (based on DP8390) network interface core implementation.
 * Only the basic NE2000 PIO (ISA) interface is supported, remote
 * DMA is completely absent from this code for simplicity.
 *
 */

#include <assert.h>
#include <byteorder.h>
#include <errno.h>
#include <libarch/ddi.h>
#include <net/packet.h>
#include <packet_client.h>
#include "dp8390.h"

/** Page size */
#define DP_PAGE  256

/** 6 * DP_PAGE >= 1514 bytes */
#define SQ_PAGES  6

/* NE2000 implementation. */

/** NE2000 Data Register */
#define NE2K_DATA  0x0010

/** NE2000 Reset register */
#define NE2K_RESET  0x001f

/** NE2000 data start */
#define NE2K_START  0x4000

/** NE2000 data size */
#define NE2K_SIZE  0x4000

/** NE2000 retry count */
#define NE2K_RETRY  0x1000

/** NE2000 error messages rate limiting */
#define NE2K_ERL  10

/** Minimum Ethernet packet size in bytes */
#define ETH_MIN_PACK_SIZE  60

/** Maximum Ethernet packet size in bytes */
#define ETH_MAX_PACK_SIZE_TAGGED  1518

/** Type definition of the receive header
 *
 */
typedef struct {
	/** Copy of RSR */
	uint8_t status;
	
	/** Pointer to next packet */
	uint8_t next;
	
	/** Receive Byte Count Low */
	uint8_t rbcl;
	
	/** Receive Byte Count High */
	uint8_t rbch;
} recv_header_t;

/** Read a memory block word by word.
 *
 * @param[in]  port Source address.
 * @param[out] buf  Destination buffer.
 * @param[in]  size Memory block size in bytes.
 *
 */
static void pio_read_buf_16(void *port, void *buf, size_t size)
{
	size_t i;
	
	for (i = 0; (i << 1) < size; i++)
		*((uint16_t *) buf + i) = pio_read_16((ioport16_t *) (port));
}

/** Write a memory block word by word.
 *
 * @param[in] port Destination address.
 * @param[in] buf  Source buffer.
 * @param[in] size Memory block size in bytes.
 *
 */
static void pio_write_buf_16(void *port, void *buf, size_t size)
{
	size_t i;
	
	for (i = 0; (i << 1) < size; i++)
		pio_write_16((ioport16_t *) port, *((uint16_t *) buf + i));
}

static void ne2k_download(ne2k_t *ne2k, void *buf, size_t addr, size_t size)
{
	size_t esize = size & ~1;
	
	pio_write_8(ne2k->port + DP_RBCR0, esize & 0xff);
	pio_write_8(ne2k->port + DP_RBCR1, (esize >> 8) & 0xff);
	pio_write_8(ne2k->port + DP_RSAR0, addr & 0xff);
	pio_write_8(ne2k->port + DP_RSAR1, (addr >> 8) & 0xff);
	pio_write_8(ne2k->port + DP_CR, CR_DM_RR | CR_PS_P0 | CR_STA);
	
	if (esize != 0) {
		pio_read_buf_16(ne2k->data_port, buf, esize);
		size -= esize;
		buf += esize;
	}
	
	if (size) {
		assert(size == 1);
		
		uint16_t word = pio_read_16(ne2k->data_port);
		memcpy(buf, &word, 1);
	}
}

static void ne2k_upload(ne2k_t *ne2k, void *buf, size_t addr, size_t size)
{
	size_t esize = size & ~1;
	
	pio_write_8(ne2k->port + DP_RBCR0, esize & 0xff);
	pio_write_8(ne2k->port + DP_RBCR1, (esize >> 8) & 0xff);
	pio_write_8(ne2k->port + DP_RSAR0, addr & 0xff);
	pio_write_8(ne2k->port + DP_RSAR1, (addr >> 8) & 0xff);
	pio_write_8(ne2k->port + DP_CR, CR_DM_RW | CR_PS_P0 | CR_STA);
	
	if (esize != 0) {
		pio_write_buf_16(ne2k->data_port, buf, esize);
		size -= esize;
		buf += esize;
	}
	
	if (size) {
		assert(size == 1);
		
		uint16_t word = 0;
		
		memcpy(&word, buf, 1);
		pio_write_16(ne2k->data_port, word);
	}
}

static void ne2k_init(ne2k_t *ne2k)
{
	unsigned int i;
	
	/* Reset the ethernet card */
	uint8_t val = pio_read_8(ne2k->port + NE2K_RESET);
	usleep(2000);
	pio_write_8(ne2k->port + NE2K_RESET, val);
	usleep(2000);
	
	/* Reset the DP8390 */
	pio_write_8(ne2k->port + DP_CR, CR_STP | CR_DM_ABORT);
	for (i = 0; i < NE2K_RETRY; i++) {
		if (pio_read_8(ne2k->port + DP_ISR) != 0)
			break;
	}
}

/** Probe and initialize the network interface.
 *
 * @param[in,out] ne2k Network interface structure.
 * @param[in]     port Device address.
 * @param[in]     irq  Device interrupt vector.
 *
 * @return EOK on success.
 * @return EXDEV if the network interface was not recognized.
 *
 */
int ne2k_probe(ne2k_t *ne2k, void *port, int irq)
{
	unsigned int i;
	
	/* General initialization */
	ne2k->port = port;
	ne2k->data_port = ne2k->port + NE2K_DATA;
	ne2k->irq = irq;
	ne2k->probed = false;
	ne2k->up = false;
	
	ne2k_init(ne2k);
	
	/* Check if the DP8390 is really there */
	uint8_t val = pio_read_8(ne2k->port + DP_CR);
	if ((val & (CR_STP | CR_DM_ABORT)) != (CR_STP | CR_DM_ABORT))
		return EXDEV;
	
	/* Disable the receiver and init TCR and DCR */
	pio_write_8(ne2k->port + DP_RCR, RCR_MON);
	pio_write_8(ne2k->port + DP_TCR, TCR_NORMAL);
	pio_write_8(ne2k->port + DP_DCR, DCR_WORDWIDE | DCR_8BYTES | DCR_BMS);
	
	/* Setup a transfer to get the MAC address */
	pio_write_8(ne2k->port + DP_RBCR0, ETH_ADDR << 1);
	pio_write_8(ne2k->port + DP_RBCR1, 0);
	pio_write_8(ne2k->port + DP_RSAR0, 0);
	pio_write_8(ne2k->port + DP_RSAR1, 0);
	pio_write_8(ne2k->port + DP_CR, CR_DM_RR | CR_PS_P0 | CR_STA);
	
	for (i = 0; i < ETH_ADDR; i++)
		ne2k->mac[i] = pio_read_16(ne2k->data_port);
	
	ne2k->probed = true;
	return EOK;
}

/** Start the network interface.
 *
 * @param[in,out] ne2k Network interface structure.
 *
 * @return EOK on success.
 * @return EXDEV if the network interface is disabled.
 *
 */
int ne2k_up(ne2k_t *ne2k)
{
	if (!ne2k->probed)
		return EXDEV;
	
	ne2k_init(ne2k);
	
	/*
	 * Setup send queue. Use the first
	 * SQ_PAGES of NE2000 memory for the send
	 * buffer.
	 */
	ne2k->sq.dirty = false;
	ne2k->sq.page = NE2K_START / DP_PAGE;
	fibril_mutex_initialize(&ne2k->sq_mutex);
	fibril_condvar_initialize(&ne2k->sq_cv);
	
	/*
	 * Setup receive ring buffer. Use all the rest
	 * of the NE2000 memory (except the first SQ_PAGES
	 * reserved for the send buffer) for the receive
	 * ring buffer.
	 */
	ne2k->start_page = ne2k->sq.page + SQ_PAGES;
	ne2k->stop_page = ne2k->sq.page + NE2K_SIZE / DP_PAGE;
	
	/*
	 * Initialization of the DP8390 following the mandatory procedure
	 * in reference manual ("DP8390D/NS32490D NIC Network Interface
	 * Controller", National Semiconductor, July 1995, Page 29).
	 */
	
	/* Step 1: */
	pio_write_8(ne2k->port + DP_CR, CR_PS_P0 | CR_STP | CR_DM_ABORT);
	
	/* Step 2: */
	pio_write_8(ne2k->port + DP_DCR, DCR_WORDWIDE | DCR_8BYTES | DCR_BMS);
	
	/* Step 3: */
	pio_write_8(ne2k->port + DP_RBCR0, 0);
	pio_write_8(ne2k->port + DP_RBCR1, 0);
	
	/* Step 4: */
	pio_write_8(ne2k->port + DP_RCR, RCR_AB);
	
	/* Step 5: */
	pio_write_8(ne2k->port + DP_TCR, TCR_INTERNAL);
	
	/* Step 6: */
	pio_write_8(ne2k->port + DP_BNRY, ne2k->start_page);
	pio_write_8(ne2k->port + DP_PSTART, ne2k->start_page);
	pio_write_8(ne2k->port + DP_PSTOP, ne2k->stop_page);
	
	/* Step 7: */
	pio_write_8(ne2k->port + DP_ISR, 0xff);
	
	/* Step 8: */
	pio_write_8(ne2k->port + DP_IMR,
	    IMR_PRXE | IMR_PTXE | IMR_RXEE | IMR_TXEE | IMR_OVWE | IMR_CNTE);
	
	/* Step 9: */
	pio_write_8(ne2k->port + DP_CR, CR_PS_P1 | CR_DM_ABORT | CR_STP);
	
	pio_write_8(ne2k->port + DP_PAR0, ne2k->mac[0]);
	pio_write_8(ne2k->port + DP_PAR1, ne2k->mac[1]);
	pio_write_8(ne2k->port + DP_PAR2, ne2k->mac[2]);
	pio_write_8(ne2k->port + DP_PAR3, ne2k->mac[3]);
	pio_write_8(ne2k->port + DP_PAR4, ne2k->mac[4]);
	pio_write_8(ne2k->port + DP_PAR5, ne2k->mac[5]);
	
	pio_write_8(ne2k->port + DP_MAR0, 0xff);
	pio_write_8(ne2k->port + DP_MAR1, 0xff);
	pio_write_8(ne2k->port + DP_MAR2, 0xff);
	pio_write_8(ne2k->port + DP_MAR3, 0xff);
	pio_write_8(ne2k->port + DP_MAR4, 0xff);
	pio_write_8(ne2k->port + DP_MAR5, 0xff);
	pio_write_8(ne2k->port + DP_MAR6, 0xff);
	pio_write_8(ne2k->port + DP_MAR7, 0xff);
	
	pio_write_8(ne2k->port + DP_CURR, ne2k->start_page + 1);
	
	/* Step 10: */
	pio_write_8(ne2k->port + DP_CR, CR_PS_P0 | CR_DM_ABORT | CR_STA);
	
	/* Step 11: */
	pio_write_8(ne2k->port + DP_TCR, TCR_NORMAL);
	
	/* Reset counters by reading */
	pio_read_8(ne2k->port + DP_CNTR0);
	pio_read_8(ne2k->port + DP_CNTR1);
	pio_read_8(ne2k->port + DP_CNTR2);
	
	/* Finish the initialization */
	ne2k->up = true;
	return EOK;
}

/** Stop the network interface.
 *
 * @param[in,out] ne2k Network interface structure.
 *
 */
void ne2k_down(ne2k_t *ne2k)
{
	if ((ne2k->probed) && (ne2k->up)) {
		pio_write_8(ne2k->port + DP_CR, CR_STP | CR_DM_ABORT);
		ne2k_init(ne2k);
		ne2k->up = false;
	}
}

/** Send a frame.
 *
 * @param[in,out] ne2k   Network interface structure.
 * @param[in]     packet Frame to be sent.
 *
 */
void ne2k_send(ne2k_t *ne2k, packet_t *packet)
{
	assert(ne2k->probed);
	assert(ne2k->up);
	
	fibril_mutex_lock(&ne2k->sq_mutex);
	
	while (ne2k->sq.dirty)
		fibril_condvar_wait(&ne2k->sq_cv, &ne2k->sq_mutex);
	
	void *buf = packet_get_data(packet);
	size_t size = packet_get_data_length(packet);
	
	if ((size < ETH_MIN_PACK_SIZE) || (size > ETH_MAX_PACK_SIZE_TAGGED)) {
		fprintf(stderr, "%s: Frame dropped (invalid size %zu bytes)\n",
		    NAME, size);
		return;
	}
	
	/* Upload the frame to the ethernet card */
	ne2k_upload(ne2k, buf, ne2k->sq.page * DP_PAGE, size);
	ne2k->sq.dirty = true;
	ne2k->sq.size = size;
	
	/* Initialize the transfer */
	pio_write_8(ne2k->port + DP_TPSR, ne2k->sq.page);
	pio_write_8(ne2k->port + DP_TBCR0, size & 0xff);
	pio_write_8(ne2k->port + DP_TBCR1, (size >> 8) & 0xff);
	pio_write_8(ne2k->port + DP_CR, CR_TXP | CR_STA);
	
	fibril_mutex_unlock(&ne2k->sq_mutex);
}

static void ne2k_reset(ne2k_t *ne2k)
{
	unsigned int i;
	
	/* Stop the chip */
	pio_write_8(ne2k->port + DP_CR, CR_STP | CR_DM_ABORT);
	pio_write_8(ne2k->port + DP_RBCR0, 0);
	pio_write_8(ne2k->port + DP_RBCR1, 0);
	
	for (i = 0; i < NE2K_RETRY; i++) {
		if ((pio_read_8(ne2k->port + DP_ISR) & ISR_RST) != 0)
			break;
	}
	
	pio_write_8(ne2k->port + DP_TCR, TCR_1EXTERNAL | TCR_OFST);
	pio_write_8(ne2k->port + DP_CR, CR_STA | CR_DM_ABORT);
	pio_write_8(ne2k->port + DP_TCR, TCR_NORMAL);
	
	/* Acknowledge the ISR_RDC (remote DMA) interrupt */
	for (i = 0; i < NE2K_RETRY; i++) {
		if ((pio_read_8(ne2k->port + DP_ISR) & ISR_RDC) != 0)
			break;
	}
	
	uint8_t val = pio_read_8(ne2k->port + DP_ISR);
	pio_write_8(ne2k->port + DP_ISR, val & ~ISR_RDC);
	
	/*
	 * Reset the transmit ring. If we were transmitting a frame,
	 * we pretend that the packet is processed. Higher layers will
	 * retransmit if the packet wasn't actually sent.
	 */
	fibril_mutex_lock(&ne2k->sq_mutex);
	ne2k->sq.dirty = false;
	fibril_mutex_unlock(&ne2k->sq_mutex);
}

static frame_t *ne2k_receive_frame(ne2k_t *ne2k, uint8_t page, size_t length)
{
	frame_t *frame = (frame_t *) malloc(sizeof(frame_t));
	if (frame == NULL)
		return NULL;
	
	link_initialize(&frame->link);
	
	frame->packet = netif_packet_get_1(length);
	if (frame->packet == NULL) {
		free(frame);
		return NULL;
	}
	
	void *buf = packet_suffix(frame->packet, length);
	bzero(buf, length);
	uint8_t last = page + length / DP_PAGE;
	
	if (last >= ne2k->stop_page) {
		size_t left = (ne2k->stop_page - page) * DP_PAGE
		    - sizeof(recv_header_t);
		
		ne2k_download(ne2k, buf, page * DP_PAGE + sizeof(recv_header_t),
		    left);
		ne2k_download(ne2k, buf + left, ne2k->start_page * DP_PAGE,
		    length - left);
	} else
		ne2k_download(ne2k, buf, page * DP_PAGE + sizeof(recv_header_t),
		    length);
	
	ne2k->stats.receive_packets++;
	return frame;
}

static link_t *ne2k_receive(ne2k_t *ne2k)
{
	/*
	 * Allocate memory for the list of received frames.
	 * If the allocation fails here we still receive the
	 * frames from the network, but they will be lost.
	 */
	link_t *frames = (link_t *) malloc(sizeof(link_t));
	if (frames != NULL)
		list_initialize(frames);
	
	while (true) {
		uint8_t boundary = pio_read_8(ne2k->port + DP_BNRY) + 1;
		
		if (boundary == ne2k->stop_page)
			boundary = ne2k->start_page;
		
		pio_write_8(ne2k->port + DP_CR, CR_PS_P1 | CR_STA);
		uint8_t current = pio_read_8(ne2k->port + DP_CURR);
		pio_write_8(ne2k->port + DP_CR, CR_PS_P0 | CR_STA);
		
		if (current == boundary)
			/* No more frames to process */
			break;
		
		recv_header_t header;
		size_t size = sizeof(header);
		size_t offset = boundary * DP_PAGE;
		
		/* Get the frame header */
		pio_write_8(ne2k->port + DP_RBCR0, size & 0xff);
		pio_write_8(ne2k->port + DP_RBCR1, (size >> 8) & 0xff);
		pio_write_8(ne2k->port + DP_RSAR0, offset & 0xff);
		pio_write_8(ne2k->port + DP_RSAR1, (offset >> 8) & 0xff);
		pio_write_8(ne2k->port + DP_CR, CR_DM_RR | CR_PS_P0 | CR_STA);
		
		pio_read_buf_16(ne2k->data_port, (void *) &header, size);
		
		size_t length =
		    (((size_t) header.rbcl) | (((size_t) header.rbch) << 8)) - size;
		uint8_t next = header.next;
		
		if ((length < ETH_MIN_PACK_SIZE)
		    || (length > ETH_MAX_PACK_SIZE_TAGGED)) {
			fprintf(stderr, "%s: Rant frame (%zu bytes)\n", NAME, length);
			next = current;
		} else if ((header.next < ne2k->start_page)
		    || (header.next > ne2k->stop_page)) {
			fprintf(stderr, "%s: Malformed next frame %u\n", NAME,
			    header.next);
			next = current;
		} else if (header.status & RSR_FO) {
			/*
			 * This is very serious, so we issue a warning and
			 * reset the buffers.
			 */
			fprintf(stderr, "%s: FIFO overrun\n", NAME);
			ne2k->overruns++;
			next = current;
		} else if ((header.status & RSR_PRX) && (ne2k->up)) {
			if (frames != NULL) {
				frame_t *frame = ne2k_receive_frame(ne2k, boundary, length);
				if (frame != NULL)
					list_append(&frame->link, frames);
			}
		}
		
		/*
		 * Update the boundary pointer
		 * to the value of the page
		 * prior to the next packet to
		 * be processed.
		 */
		if (next == ne2k->start_page)
			next = ne2k->stop_page - 1;
		else
			next--;
		
		pio_write_8(ne2k->port + DP_BNRY, next);
	}
	
	return frames;
}

link_t *ne2k_interrupt(ne2k_t *ne2k, uint8_t isr, uint8_t tsr)
{
	/* List of received frames */
	link_t *frames = NULL;
	
	if (isr & (ISR_PTX | ISR_TXE)) {
		if (isr & ISR_TXE)
			ne2k->stats.send_errors++;
		else {
			if (tsr & TSR_PTX)
				ne2k->stats.send_packets++;
			
			if (tsr & TSR_COL)
				ne2k->stats.collisions++;
			
			if (tsr & TSR_ABT)
				ne2k->stats.send_aborted_errors++;
			
			if (tsr & TSR_CRS)
				ne2k->stats.send_carrier_errors++;
			
			if (tsr & TSR_FU) {
				ne2k->underruns++;
				if (ne2k->underruns < NE2K_ERL)
					fprintf(stderr, "%s: FIFO underrun\n", NAME);
			}
			
			if (tsr & TSR_CDH) {
				ne2k->stats.send_heartbeat_errors++;
				if (ne2k->stats.send_heartbeat_errors < NE2K_ERL)
					fprintf(stderr, "%s: CD heartbeat failure\n", NAME);
			}
			
			if (tsr & TSR_OWC)
				ne2k->stats.send_window_errors++;
		}
		
		fibril_mutex_lock(&ne2k->sq_mutex);
		
		if (ne2k->sq.dirty) {
			/* Prepare the buffer for next packet */
			ne2k->sq.dirty = false;
			ne2k->sq.size = 0;
			
			/* Signal a next frame to be sent */
			fibril_condvar_broadcast(&ne2k->sq_cv);
		} else {
			ne2k->misses++;
			if (ne2k->misses < NE2K_ERL)
				fprintf(stderr, "%s: Spurious PTX interrupt\n", NAME);
		}
		
		fibril_mutex_unlock(&ne2k->sq_mutex);
	}
	
	if (isr & ISR_RXE)
		ne2k->stats.receive_errors++;
	
	if (isr & ISR_CNT) {
		ne2k->stats.receive_crc_errors +=
		    pio_read_8(ne2k->port + DP_CNTR0);
		ne2k->stats.receive_frame_errors +=
		    pio_read_8(ne2k->port + DP_CNTR1);
		ne2k->stats.receive_missed_errors +=
		    pio_read_8(ne2k->port + DP_CNTR2);
	}
	
	if (isr & ISR_PRX)
		frames = ne2k_receive(ne2k);
	
	if (isr & ISR_RST) {
		/*
		 * The chip is stopped, and all arrived
		 * frames are delivered.
		 */
		ne2k_reset(ne2k);
	}
	
	/* Unmask interrupts to be processed in the next round */
	pio_write_8(ne2k->port + DP_IMR,
	    IMR_PRXE | IMR_PTXE | IMR_RXEE | IMR_TXEE | IMR_OVWE | IMR_CNTE);
	
	return frames;
}

/** @}
 */