/*
 * Simple synchronous serial port driver for ETRAX FS.
 *
 * Copyright (c) 2005 Axis Communications AB
 *
 * Author: Mikael Starvik
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/major.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/spinlock.h>

#include <asm/io.h>
#include <asm/arch/dma.h>
#include <asm/arch/pinmux.h>
#include <asm/arch/hwregs/reg_rdwr.h>
#include <asm/arch/hwregs/sser_defs.h>
#include <asm/arch/hwregs/dma_defs.h>
#include <asm/arch/hwregs/dma.h>
#include <asm/arch/hwregs/intr_vect_defs.h>
#include <asm/arch/hwregs/intr_vect.h>
#include <asm/arch/hwregs/reg_map.h>
#include <asm/sync_serial.h>

/* The receiver is a bit tricky beacuse of the continuous stream of data.*/
/*                                                                       */
/* Three DMA descriptors are linked together. Each DMA descriptor is     */
/* responsible for port->bufchunk of a common buffer.                    */
/*                                                                       */
/* +---------------------------------------------+                       */
/* |   +----------+   +----------+   +----------+ |                      */
/* +-> | Descr[0] |-->| Descr[1] |-->| Descr[2] |-+                      */
/*     +----------+   +----------+   +----------+                        */
/*         |            |              |                                 */
/*         v            v              v                                 */
/*   +-------------------------------------+                             */
/*   |        BUFFER                       |                             */
/*   +-------------------------------------+                             */
/*      |<- data_avail ->|                                               */
/*    readp          writep                                              */
/*                                                                       */
/* If the application keeps up the pace readp will be right after writep.*/
/* If the application can't keep the pace we have to throw away data.    */
/* The idea is that readp should be ready with the data pointed out by	 */
/* Descr[i] when the DMA has filled in Descr[i+1].                       */
/* Otherwise we will discard	                                         */
/* the rest of the data pointed out by Descr1 and set readp to the start */
/* of Descr2                                                             */

#define SYNC_SERIAL_MAJOR 125

/* IN_BUFFER_SIZE should be a multiple of 6 to make sure that 24 bit */
/* words can be handled */
#define IN_BUFFER_SIZE 12288
#define IN_DESCR_SIZE 256
#define NUM_IN_DESCR (IN_BUFFER_SIZE/IN_DESCR_SIZE)
#define OUT_BUFFER_SIZE 4096

#define DEFAULT_FRAME_RATE 0
#define DEFAULT_WORD_RATE 7

/* NOTE: Enabling some debug will likely cause overrun or underrun,
 * especially if manual mode is use.
 */
#define DEBUG(x)
#define DEBUGREAD(x)
#define DEBUGWRITE(x)
#define DEBUGPOLL(x)
#define DEBUGRXINT(x)
#define DEBUGTXINT(x)

typedef struct sync_port
{
	reg_scope_instances regi_sser;
	reg_scope_instances regi_dmain;
	reg_scope_instances regi_dmaout;

	char started; /* 1 if port has been started */
	char port_nbr; /* Port 0 or 1 */
	char busy; /* 1 if port is busy */

	char enabled;  /* 1 if port is enabled */
	char use_dma;  /* 1 if port uses dma */
	char tr_running;

	char init_irqs;
	int output;
	int input;

	volatile unsigned int out_count; /* Remaining bytes for current transfer */
	unsigned char* outp; /* Current position in out_buffer */
	volatile unsigned char* volatile readp;  /* Next byte to be read by application */
	volatile unsigned char* volatile writep; /* Next byte to be written by etrax */
	unsigned int in_buffer_size;
	unsigned int inbufchunk;
	unsigned char out_buffer[OUT_BUFFER_SIZE] __attribute__ ((aligned(32)));
	unsigned char in_buffer[IN_BUFFER_SIZE]__attribute__ ((aligned(32)));
	unsigned char flip[IN_BUFFER_SIZE] __attribute__ ((aligned(32)));
	struct dma_descr_data* next_rx_desc;
	struct dma_descr_data* prev_rx_desc;
	int full;

	dma_descr_data in_descr[NUM_IN_DESCR] __attribute__ ((__aligned__(16)));
	dma_descr_context in_context __attribute__ ((__aligned__(32)));
	dma_descr_data out_descr __attribute__ ((__aligned__(16)));
	dma_descr_context out_context __attribute__ ((__aligned__(32)));
	wait_queue_head_t out_wait_q;
	wait_queue_head_t in_wait_q;

	spinlock_t lock;
} sync_port;

static int etrax_sync_serial_init(void);
static void initialize_port(int portnbr);
static inline int sync_data_avail(struct sync_port *port);

static int sync_serial_open(struct inode *, struct file*);
static int sync_serial_release(struct inode*, struct file*);
static unsigned int sync_serial_poll(struct file *filp, poll_table *wait);

static int sync_serial_ioctl(struct inode*, struct file*,
			     unsigned int cmd, unsigned long arg);
static ssize_t sync_serial_write(struct file * file, const char * buf,
				 size_t count, loff_t *ppos);
static ssize_t sync_serial_read(struct file *file, char *buf,
				size_t count, loff_t *ppos);

#if (defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT0) && \
     defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL0_DMA)) || \
    (defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT1) && \
     defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL1_DMA))
#define SYNC_SER_DMA
#endif

static void send_word(sync_port* port);
static void start_dma(struct sync_port *port, const char* data, int count);
static void start_dma_in(sync_port* port);
#ifdef SYNC_SER_DMA
static irqreturn_t tr_interrupt(int irq, void *dev_id, struct pt_regs * regs);
static irqreturn_t rx_interrupt(int irq, void *dev_id, struct pt_regs * regs);
#endif

#if (defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT0) && \
     !defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL0_DMA)) || \
    (defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT1) && \
     !defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL1_DMA))
#define SYNC_SER_MANUAL
#endif
#ifdef SYNC_SER_MANUAL
static irqreturn_t manual_interrupt(int irq, void *dev_id, struct pt_regs * regs);
#endif

/* The ports */
static struct sync_port ports[]=
{
	{
		.regi_sser             = regi_sser0,
		.regi_dmaout           = regi_dma4,
		.regi_dmain            = regi_dma5,
#if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL0_DMA)
                .use_dma               = 1,
#else
                .use_dma               = 0,
#endif
	},
	{
		.regi_sser             = regi_sser1,
		.regi_dmaout           = regi_dma6,
		.regi_dmain            = regi_dma7,
#if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL1_DMA)
                .use_dma               = 1,
#else
                .use_dma               = 0,
#endif
	}
};

#define NUMBER_OF_PORTS (sizeof(ports)/sizeof(sync_port))

static struct file_operations sync_serial_fops = {
	.owner   = THIS_MODULE,
	.write   = sync_serial_write,
	.read    = sync_serial_read,
	.poll    = sync_serial_poll,
	.ioctl   = sync_serial_ioctl,
	.open    = sync_serial_open,
	.release = sync_serial_release
};

static int __init etrax_sync_serial_init(void)
{
	ports[0].enabled = 0;
	ports[1].enabled = 0;

	if (register_chrdev(SYNC_SERIAL_MAJOR,"sync serial", &sync_serial_fops) <0 )
	{
		printk("unable to get major for synchronous serial port\n");
		return -EBUSY;
	}

	/* Initialize Ports */
#if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT0)
	if (crisv32_pinmux_alloc_fixed(pinmux_sser0))
	{
		printk("Unable to allocate pins for syncrhronous serial port 0\n");
		return -EIO;
	}
	ports[0].enabled = 1;
	initialize_port(0);
#endif

#if defined(CONFIG_ETRAX_SYNCHRONOUS_SERIAL_PORT1)
	if (crisv32_pinmux_alloc_fixed(pinmux_sser1))
	{
		printk("Unable to allocate pins for syncrhronous serial port 0\n");
		return -EIO;
	}
	ports[1].enabled = 1;
	initialize_port(1);
#endif

	printk("ETRAX FS synchronous serial port driver\n");
	return 0;
}

static void __init initialize_port(int portnbr)
{
	struct sync_port* port = &ports[portnbr];
	reg_sser_rw_cfg cfg = {0};
	reg_sser_rw_frm_cfg frm_cfg = {0};
	reg_sser_rw_tr_cfg tr_cfg = {0};
	reg_sser_rw_rec_cfg rec_cfg = {0};

	DEBUG(printk("Init sync serial port %d\n", portnbr));

	port->port_nbr = portnbr;
	port->init_irqs = 1;

	port->outp = port->out_buffer;
	port->output = 1;
	port->input = 0;

	port->readp = port->flip;
	port->writep = port->flip;
	port->in_buffer_size = IN_BUFFER_SIZE;
	port->inbufchunk = IN_DESCR_SIZE;
	port->next_rx_desc = &port->in_descr[0];
	port->prev_rx_desc = &port->in_descr[NUM_IN_DESCR-1];
	port->prev_rx_desc->eol = 1;

	init_waitqueue_head(&port->out_wait_q);
	init_waitqueue_head(&port->in_wait_q);

	spin_lock_init(&port->lock);

	cfg.out_clk_src = regk_sser_intern_clk;
	cfg.out_clk_pol = regk_sser_pos;
	cfg.clk_od_mode = regk_sser_no;
	cfg.clk_dir = regk_sser_out;
	cfg.gate_clk = regk_sser_no;
	cfg.base_freq = regk_sser_f29_493;
	cfg.clk_div = 256;
	REG_WR(sser, port->regi_sser, rw_cfg, cfg);

	frm_cfg.wordrate = DEFAULT_WORD_RATE;
	frm_cfg.type = regk_sser_edge;
	frm_cfg.frame_pin_dir = regk_sser_out;
	frm_cfg.frame_pin_use = regk_sser_frm;
	frm_cfg.status_pin_dir = regk_sser_in;
	frm_cfg.status_pin_use = regk_sser_hold;
	frm_cfg.out_on = regk_sser_tr;
	frm_cfg.tr_delay = 1;
	REG_WR(sser, port->regi_sser, rw_frm_cfg, frm_cfg);

	tr_cfg.urun_stop = regk_sser_no;
	tr_cfg.sample_size = 7;
	tr_cfg.sh_dir = regk_sser_msbfirst;
	tr_cfg.use_dma = port->use_dma ? regk_sser_yes : regk_sser_no;
	tr_cfg.rate_ctrl = regk_sser_bulk;
	tr_cfg.data_pin_use = regk_sser_dout;
	tr_cfg.bulk_wspace = 1;
	REG_WR(sser, port->regi_sser, rw_tr_cfg, tr_cfg);

	rec_cfg.sample_size = 7;
	rec_cfg.sh_dir = regk_sser_msbfirst;
	rec_cfg.use_dma = port->use_dma ? regk_sser_yes : regk_sser_no;
	rec_cfg.fifo_thr = regk_sser_inf;
	REG_WR(sser, port->regi_sser, rw_rec_cfg, rec_cfg);
}

static inline int sync_data_avail(struct sync_port *port)
{
	int avail;
	unsigned char *start;
	unsigned char *end;

	start = (unsigned char*)port->readp; /* cast away volatile */
	end = (unsigned char*)port->writep;  /* cast away volatile */
	/* 0123456789  0123456789
	 *  -----      -    -----
	 *  ^rp  ^wp    ^wp ^rp
	 */

  	if (end >= start)
		avail = end - start;
	else
		avail = port->in_buffer_size - (start - end);
	return avail;
}

static inline int sync_data_avail_to_end(struct sync_port *port)
{
	int avail;
	unsigned char *start;
	unsigned char *end;

	start = (unsigned char*)port->readp; /* cast away volatile */
	end = (unsigned char*)port->writep;  /* cast away volatile */
	/* 0123456789  0123456789
	 *  -----           -----
	 *  ^rp  ^wp    ^wp ^rp
	 */

  	if (end >= start)
		avail = end - start;
	else
		avail = port->flip + port->in_buffer_size - start;
	return avail;
}

static int sync_serial_open(struct inode *inode, struct file *file)
{
	int dev = iminor(inode);
	sync_port* port;
	reg_dma_rw_cfg cfg = {.en = regk_dma_yes};
	reg_dma_rw_intr_mask intr_mask = {.data = regk_dma_yes};

	DEBUG(printk("Open sync serial port %d\n", dev));

	if (dev < 0 || dev >= NUMBER_OF_PORTS || !ports[dev].enabled)
	{
		DEBUG(printk("Invalid minor %d\n", dev));
		return -ENODEV;
	}
	port = &ports[dev];
	/* Allow open this device twice (assuming one reader and one writer) */
	if (port->busy == 2)
	{
		DEBUG(printk("Device is busy.. \n"));
		return -EBUSY;
	}
	if (port->init_irqs) {
		if (port->use_dma) {
			if (port == &ports[0]){
#ifdef SYNC_SER_DMA
				if(request_irq(DMA4_INTR_VECT,
					       tr_interrupt,
					       0,
					       "synchronous serial 0 dma tr",
					       &ports[0])) {
					printk(KERN_CRIT "Can't allocate sync serial port 0 IRQ");
					return -EBUSY;
				} else if(request_irq(DMA5_INTR_VECT,
						      rx_interrupt,
						      0,
						      "synchronous serial 1 dma rx",
						      &ports[0])) {
					free_irq(DMA4_INTR_VECT, &port[0]);
					printk(KERN_CRIT "Can't allocate sync serial port 0 IRQ");
					return -EBUSY;
				} else if (crisv32_request_dma(SYNC_SER0_TX_DMA_NBR,
                                                               "synchronous serial 0 dma tr",
                                                               DMA_VERBOSE_ON_ERROR,
                                                               0,
                                                               dma_sser0)) {
					free_irq(DMA4_INTR_VECT, &port[0]);
					free_irq(DMA5_INTR_VECT, &port[0]);
					printk(KERN_CRIT "Can't allocate sync serial port 0 TX DMA channel");
					return -EBUSY;
				} else if (crisv32_request_dma(SYNC_SER0_RX_DMA_NBR,
                                                               "synchronous serial 0 dma rec",
                                                               DMA_VERBOSE_ON_ERROR,
                                                               0,
                                                               dma_sser0)) {
					crisv32_free_dma(SYNC_SER0_TX_DMA_NBR);
					free_irq(DMA4_INTR_VECT, &port[0]);
					free_irq(DMA5_INTR_VECT, &port[0]);
					printk(KERN_CRIT "Can't allocate sync serial port 1 RX DMA channel");
					return -EBUSY;
				}
#endif
			}
			else if (port == &ports[1]){
#ifdef SYNC_SER_DMA
				if (request_irq(DMA6_INTR_VECT,
						tr_interrupt,
						0,
						"synchronous serial 1 dma tr",
						&ports[1])) {
					printk(KERN_CRIT "Can't allocate sync serial port 1 IRQ");
					return -EBUSY;
				} else if (request_irq(DMA7_INTR_VECT,
						       rx_interrupt,
						       0,
						       "synchronous serial 1 dma rx",
						       &ports[1])) {
					free_irq(DMA6_INTR_VECT, &ports[1]);
					printk(KERN_CRIT "Can't allocate sync serial port 3 IRQ");
					return -EBUSY;
				} else if (crisv32_request_dma(SYNC_SER1_TX_DMA_NBR,
                                                               "synchronous serial 1 dma tr",
                                                               DMA_VERBOSE_ON_ERROR,
                                                               0,
                                                               dma_sser1)) {
					free_irq(21, &ports[1]);
					free_irq(20, &ports[1]);
					printk(KERN_CRIT "Can't allocate sync serial port 3 TX DMA channel");
					return -EBUSY;
				} else if (crisv32_request_dma(SYNC_SER1_RX_DMA_NBR,
							    "synchronous serial 3 dma rec",
							    DMA_VERBOSE_ON_ERROR,
							    0,
							    dma_sser1)) {
					crisv32_free_dma(SYNC_SER1_TX_DMA_NBR);
					free_irq(DMA6_INTR_VECT, &ports[1]);
					free_irq(DMA7_INTR_VECT, &ports[1]);
					printk(KERN_CRIT "Can't allocate sync serial port 3 RX DMA channel");
					return -EBUSY;
				}
#endif
			}

                        /* Enable DMAs */
			REG_WR(dma, port->regi_dmain, rw_cfg, cfg);
			REG_WR(dma, port->regi_dmaout, rw_cfg, cfg);
			/* Enable DMA IRQs */
			REG_WR(dma, port->regi_dmain, rw_intr_mask, intr_mask);
			REG_WR(dma, port->regi_dmaout, rw_intr_mask, intr_mask);
			/* Set up wordsize = 2 for DMAs. */
			DMA_WR_CMD (port->regi_dmain, regk_dma_set_w_size1);
			DMA_WR_CMD (port->regi_dmaout, regk_dma_set_w_size1);

			start_dma_in(port);
			port->init_irqs = 0;
		} else { /* !port->use_dma */
#ifdef SYNC_SER_MANUAL
			if (port == &ports[0]) {
				if (request_irq(SSER0_INTR_VECT,
						manual_interrupt,
						0,
						"synchronous serial manual irq",
						&ports[0])) {
					printk("Can't allocate sync serial manual irq");
					return -EBUSY;
				}
			} else if (port == &ports[1]) {
				if (request_irq(SSER1_INTR_VECT,
						manual_interrupt,
						0,
						"synchronous serial manual irq",
						&ports[1])) {
					printk(KERN_CRIT "Can't allocate sync serial manual irq");
					return -EBUSY;
				}
			}
			port->init_irqs = 0;
#else
			panic("sync_serial: Manual mode not supported.\n");
#endif /* SYNC_SER_MANUAL */
		}
	} /* port->init_irqs */

	port->busy++;
	return 0;
}

static int sync_serial_release(struct inode *inode, struct file *file)
{
	int dev = iminor(inode);
	sync_port* port;

	if (dev < 0 || dev >= NUMBER_OF_PORTS || !ports[dev].enabled)
	{
		DEBUG(printk("Invalid minor %d\n", dev));
		return -ENODEV;
	}
	port = &ports[dev];
	if (port->busy)
		port->busy--;
	if (!port->busy)
          /* XXX */ ;
	return 0;
}

static unsigned int sync_serial_poll(struct file *file, poll_table *wait)
{
	int dev = iminor(file->f_path.dentry->d_inode);
	unsigned int mask = 0;
	sync_port* port;
	DEBUGPOLL( static unsigned int prev_mask = 0; );

	port = &ports[dev];
	poll_wait(file, &port->out_wait_q, wait);
	poll_wait(file, &port->in_wait_q, wait);
	/* Some room to write */
	if (port->out_count < OUT_BUFFER_SIZE)
		mask |=  POLLOUT | POLLWRNORM;
	/* At least an inbufchunk of data */
	if (sync_data_avail(port) >= port->inbufchunk)
		mask |= POLLIN | POLLRDNORM;

	DEBUGPOLL(if (mask != prev_mask)
	      printk("sync_serial_poll: mask 0x%08X %s %s\n", mask,
		     mask&POLLOUT?"POLLOUT":"", mask&POLLIN?"POLLIN":"");
	      prev_mask = mask;
	      );
	return mask;
}

static int sync_serial_ioctl(struct inode *inode, struct file *file,
		  unsigned int cmd, unsigned long arg)
{
	int return_val = 0;
	int dev = iminor(file->f_path.dentry->d_inode);
	sync_port* port;
	reg_sser_rw_tr_cfg tr_cfg;
	reg_sser_rw_rec_cfg rec_cfg;
	reg_sser_rw_frm_cfg frm_cfg;
	reg_sser_rw_cfg gen_cfg;
	reg_sser_rw_intr_mask intr_mask;

	if (dev < 0 || dev >= NUMBER_OF_PORTS || !ports[dev].enabled)
	{
		DEBUG(printk("Invalid minor %d\n", dev));
		return -1;
	}
        port = &ports[dev];
	spin_lock_irq(&port->lock);

	tr_cfg = REG_RD(sser, port->regi_sser, rw_tr_cfg);
	rec_cfg = REG_RD(sser, port->regi_sser, rw_rec_cfg);
	frm_cfg = REG_RD(sser, port->regi_sser, rw_frm_cfg);
	gen_cfg = REG_RD(sser, port->regi_sser, rw_cfg);
	intr_mask = REG_RD(sser, port->regi_sser, rw_intr_mask);

	switch(cmd)
	{
	case SSP_SPEED:
		if (GET_SPEED(arg) == CODEC)
		{
			gen_cfg.base_freq = regk_sser_f32;
			/* FREQ = 0 => 4 MHz => clk_div = 7*/
			gen_cfg.clk_div = 6 + (1 << GET_FREQ(arg));
		}
		else
		{
			gen_cfg.base_freq = regk_sser_f29_493;
			switch (GET_SPEED(arg))
			{
				case SSP150:
					gen_cfg.clk_div = 29493000 / (150 * 8) - 1;
					break;
				case SSP300:
					gen_cfg.clk_div = 29493000 / (300 * 8) - 1;
					break;
				case SSP600:
					gen_cfg.clk_div = 29493000 / (600 * 8) - 1;
					break;
				case SSP1200:
					gen_cfg.clk_div = 29493000 / (1200 * 8) - 1;
					break;
				case SSP2400:
					gen_cfg.clk_div = 29493000 / (2400 * 8) - 1;
					break;
				case SSP4800:
					gen_cfg.clk_div = 29493000 / (4800 * 8) - 1;
					break;
				case SSP9600:
					gen_cfg.clk_div = 29493000 / (9600 * 8) - 1;
					break;
				case SSP19200:
					gen_cfg.clk_div = 29493000 / (19200 * 8) - 1;
					break;
				case SSP28800:
					gen_cfg.clk_div = 29493000 / (28800 * 8) - 1;
					break;
				case SSP57600:
					gen_cfg.clk_div = 29493000 / (57600 * 8) - 1;
					break;
				case SSP115200:
					gen_cfg.clk_div = 29493000 / (115200 * 8) - 1;
					break;
				case SSP230400:
					gen_cfg.clk_div = 29493000 / (230400 * 8) - 1;
					break;
				case SSP460800:
					gen_cfg.clk_div = 29493000 / (460800 * 8) - 1;
					break;
				case SSP921600:
					gen_cfg.clk_div = 29493000 / (921600 * 8) - 1;
					break;
				case SSP3125000:
					gen_cfg.base_freq = regk_sser_f100;
					gen_cfg.clk_div = 100000000 / (3125000 * 8) - 1;
					break;

			}
		}
		frm_cfg.wordrate = GET_WORD_RATE(arg);

		break;
	case SSP_MODE:
		switch(arg)
		{
			case MASTER_OUTPUT:
				port->output = 1;
				port->input = 0;
				gen_cfg.clk_dir = regk_sser_out;
				break;
			case SLAVE_OUTPUT:
				port->output = 1;
				port->input = 0;
				gen_cfg.clk_dir = regk_sser_in;
				break;
			case MASTER_INPUT:
				port->output = 0;
				port->input = 1;
				gen_cfg.clk_dir = regk_sser_out;
				break;
			case SLAVE_INPUT:
				port->output = 0;
				port->input = 1;
				gen_cfg.clk_dir = regk_sser_in;
				break;
			case MASTER_BIDIR:
				port->output = 1;
				port->input = 1;
				gen_cfg.clk_dir = regk_sser_out;
				break;
			case SLAVE_BIDIR:
				port->output = 1;
				port->input = 1;
				gen_cfg.clk_dir = regk_sser_in;
				break;
			default:
				spin_unlock_irq(&port->lock);
				return -EINVAL;

		}
		if (!port->use_dma || (arg == MASTER_OUTPUT || arg == SLAVE_OUTPUT))
			intr_mask.rdav = regk_sser_yes;
		break;
	case SSP_FRAME_SYNC:
		if (arg & NORMAL_SYNC)
			frm_cfg.tr_delay = 1;
		else if (arg & EARLY_SYNC)
			frm_cfg.tr_delay = 0;

		tr_cfg.bulk_wspace = frm_cfg.tr_delay;
		frm_cfg.early_wend = regk_sser_yes;
		if (arg & BIT_SYNC)
			frm_cfg.type = regk_sser_edge;
		else if (arg & WORD_SYNC)
			frm_cfg.type = regk_sser_level;
		else if (arg & EXTENDED_SYNC)
			frm_cfg.early_wend = regk_sser_no;

		if (arg & SYNC_ON)
			frm_cfg.frame_pin_use = regk_sser_frm;
		else if (arg & SYNC_OFF)
			frm_cfg.frame_pin_use = regk_sser_gio0;

		if (arg & WORD_SIZE_8)
			rec_cfg.sample_size = tr_cfg.sample_size = 7;
		else if (arg & WORD_SIZE_12)
			rec_cfg.sample_size = tr_cfg.sample_size = 11;
		else if (arg & WORD_SIZE_16)
			rec_cfg.sample_size = tr_cfg.sample_size = 15;
		else if (arg & WORD_SIZE_24)
			rec_cfg.sample_size = tr_cfg.sample_size = 23;
		else if (arg & WORD_SIZE_32)
			rec_cfg.sample_size = tr_cfg.sample_size = 31;

		if (arg & BIT_ORDER_MSB)
			rec_cfg.sh_dir = tr_cfg.sh_dir = regk_sser_msbfirst;
		else if (arg & BIT_ORDER_LSB)
			rec_cfg.sh_dir = tr_cfg.sh_dir = regk_sser_lsbfirst;

		if (arg & FLOW_CONTROL_ENABLE)
			rec_cfg.fifo_thr = regk_sser_thr16;
		else if (arg & FLOW_CONTROL_DISABLE)
			rec_cfg.fifo_thr = regk_sser_inf;

		if (arg & CLOCK_NOT_GATED)
			gen_cfg.gate_clk = regk_sser_no;
		else if (arg & CLOCK_GATED)
			gen_cfg.gate_clk = regk_sser_yes;

		break;
	case SSP_IPOLARITY:
		/* NOTE!! negedge is considered NORMAL */
		if (arg & CLOCK_NORMAL)
			rec_cfg.clk_pol = regk_sser_neg;
		else if (arg & CLOCK_INVERT)
			rec_cfg.clk_pol = regk_sser_pos;

		if (arg & FRAME_NORMAL)
			frm_cfg.level = regk_sser_pos_hi;
		else if (arg & FRAME_INVERT)
			frm_cfg.level = regk_sser_neg_lo;

		if (arg & STATUS_NORMAL)
			gen_cfg.hold_pol = regk_sser_pos;
		else if (arg & STATUS_INVERT)
			gen_cfg.hold_pol = regk_sser_neg;
		break;
	case SSP_OPOLARITY:
		if (arg & CLOCK_NORMAL)
			gen_cfg.out_clk_pol = regk_sser_neg;
		else if (arg & CLOCK_INVERT)
			gen_cfg.out_clk_pol = regk_sser_pos;

		if (arg & FRAME_NORMAL)
			frm_cfg.level = regk_sser_pos_hi;
		else if (arg & FRAME_INVERT)
			frm_cfg.level = regk_sser_neg_lo;

		if (arg & STATUS_NORMAL)
			gen_cfg.hold_pol = regk_sser_pos;
		else if (arg & STATUS_INVERT)
			gen_cfg.hold_pol = regk_sser_neg;
		break;
	case SSP_SPI:
		rec_cfg.fifo_thr = regk_sser_inf;
		rec_cfg.sh_dir = tr_cfg.sh_dir = regk_sser_msbfirst;
		rec_cfg.sample_size = tr_cfg.sample_size = 7;
		frm_cfg.frame_pin_use = regk_sser_frm;
		frm_cfg.type = regk_sser_level;
		frm_cfg.tr_delay = 1;
		frm_cfg.level = regk_sser_neg_lo;
		if (arg & SPI_SLAVE)
		{
			rec_cfg.clk_pol = regk_sser_neg;
			gen_cfg.clk_dir = regk_sser_in;
			port->input = 1;
			port->output = 0;
		}
		else
		{
			gen_cfg.out_clk_pol = regk_sser_pos;
			port->input = 0;
			port->output = 1;
			gen_cfg.clk_dir = regk_sser_out;
		}
		break;
	case SSP_INBUFCHUNK:
		break;
	default:
		return_val = -1;
	}


	if (port->started)
	{
		tr_cfg.tr_en = port->output;
		rec_cfg.rec_en = port->input;
	}

	REG_WR(sser, port->regi_sser, rw_tr_cfg, tr_cfg);
	REG_WR(sser, port->regi_sser, rw_rec_cfg, rec_cfg);
	REG_WR(sser, port->regi_sser, rw_frm_cfg, frm_cfg);
	REG_WR(sser, port->regi_sser, rw_intr_mask, intr_mask);
	REG_WR(sser, port->regi_sser, rw_cfg, gen_cfg);

	spin_unlock_irq(&port->lock);
	return return_val;
}

static ssize_t sync_serial_write(struct file * file, const char * buf,
                                 size_t count, loff_t *ppos)
{
	int dev = iminor(file->f_path.dentry->d_inode);
	DECLARE_WAITQUEUE(wait, current);
	sync_port *port;
	unsigned long c, c1;
	unsigned long free_outp;
	unsigned long outp;
	unsigned long out_buffer;
	unsigned long flags;

	if (dev < 0 || dev >= NUMBER_OF_PORTS || !ports[dev].enabled)
	{
		DEBUG(printk("Invalid minor %d\n", dev));
		return -ENODEV;
	}
	port = &ports[dev];

	DEBUGWRITE(printk("W d%d c %lu (%d/%d)\n", port->port_nbr, count, port->out_count, OUT_BUFFER_SIZE));
	/* Space to end of buffer */
	/*
	 * out_buffer <c1>012345<-   c    ->OUT_BUFFER_SIZE
	 *            outp^    +out_count
	                        ^free_outp
	 * out_buffer 45<-     c      ->0123OUT_BUFFER_SIZE
	 *             +out_count   outp^
	 *              free_outp
	 *
	 */

	/* Read variables that may be updated by interrupts */
	spin_lock_irqsave(&port->lock, flags);
	count = count > OUT_BUFFER_SIZE - port->out_count ? OUT_BUFFER_SIZE  - port->out_count : count;
	outp = (unsigned long)port->outp;
	free_outp = outp + port->out_count;
	spin_unlock_irqrestore(&port->lock, flags);
	out_buffer = (unsigned long)port->out_buffer;

	/* Find out where and how much to write */
	if (free_outp >= out_buffer + OUT_BUFFER_SIZE)
		free_outp -= OUT_BUFFER_SIZE;
	if (free_outp >= outp)
		c = out_buffer + OUT_BUFFER_SIZE - free_outp;
	else
		c = outp - free_outp;
	if (c > count)
		c = count;

//	DEBUGWRITE(printk("w op %08lX fop %08lX c %lu\n", outp, free_outp, c));
	if (copy_from_user((void*)free_outp, buf, c))
		return -EFAULT;

	if (c != count) {
		buf += c;
		c1 = count - c;
		DEBUGWRITE(printk("w2 fi %lu c %lu c1 %lu\n", free_outp-out_buffer, c, c1));
		if (copy_from_user((void*)out_buffer, buf, c1))
			return -EFAULT;
	}
	spin_lock_irqsave(&port->lock, flags);
	port->out_count += count;
	spin_unlock_irqrestore(&port->lock, flags);

	/* Make sure transmitter/receiver is running */
	if (!port->started)
	{
		reg_sser_rw_cfg cfg = REG_RD(sser, port->regi_sser, rw_cfg);
		reg_sser_rw_tr_cfg tr_cfg = REG_RD(sser, port->regi_sser, rw_tr_cfg);
		reg_sser_rw_rec_cfg rec_cfg = REG_RD(sser, port->regi_sser, rw_rec_cfg);
		cfg.en = regk_sser_yes;
		tr_cfg.tr_en = port->output;
		rec_cfg.rec_en = port->input;
		REG_WR(sser, port->regi_sser, rw_cfg, cfg);
		REG_WR(sser, port->regi_sser, rw_tr_cfg, tr_cfg);
		REG_WR(sser, port->regi_sser, rw_rec_cfg, rec_cfg);
		port->started = 1;
	}

	if (file->f_flags & O_NONBLOCK)	{
		spin_lock_irqsave(&port->lock, flags);
		if (!port->tr_running) {
			if (!port->use_dma) {
				reg_sser_rw_intr_mask intr_mask;
				intr_mask = REG_RD(sser, port->regi_sser, rw_intr_mask);
				/* Start sender by writing data */
				send_word(port);
				/* and enable transmitter ready IRQ */
				intr_mask.trdy = 1;
				REG_WR(sser, port->regi_sser, rw_intr_mask, intr_mask);
			} else {
				start_dma(port, (unsigned char* volatile )port->outp, c);
			}
		}
		spin_unlock_irqrestore(&port->lock, flags);
		DEBUGWRITE(printk("w d%d c %lu NB\n",
				  port->port_nbr, count));
		return count;
	}

	/* Sleep until all sent */

	add_wait_queue(&port->out_wait_q, &wait);
	set_current_state(TASK_INTERRUPTIBLE);
	spin_lock_irqsave(&port->lock, flags);
	if (!port->tr_running) {
		if (!port->use_dma) {
			reg_sser_rw_intr_mask intr_mask;
			intr_mask = REG_RD(sser, port->regi_sser, rw_intr_mask);
			/* Start sender by writing data */
			send_word(port);
			/* and enable transmitter ready IRQ */
			intr_mask.trdy = 1;
			REG_WR(sser, port->regi_sser, rw_intr_mask, intr_mask);
		} else {
			start_dma(port, port->outp, c);
		}
	}
	spin_unlock_irqrestore(&port->lock, flags);
	schedule();
	set_current_state(TASK_RUNNING);
	remove_wait_queue(&port->out_wait_q, &wait);
	if (signal_pending(current))
	{
		return -EINTR;
	}
	DEBUGWRITE(printk("w d%d c %lu\n", port->port_nbr, count));
	return count;
}

static ssize_t sync_serial_read(struct file * file, char * buf,
				size_t count, loff_t *ppos)
{
	int dev = iminor(file->f_path.dentry->d_inode);
	int avail;
	sync_port *port;
	unsigned char* start;
	unsigned char* end;
	unsigned long flags;

	if (dev < 0 || dev >= NUMBER_OF_PORTS || !ports[dev].enabled)
	{
		DEBUG(printk("Invalid minor %d\n", dev));
		return -ENODEV;
	}
	port = &ports[dev];

	DEBUGREAD(printk("R%d c %d ri %lu wi %lu /%lu\n", dev, count, port->readp - port->flip, port->writep - port->flip, port->in_buffer_size));

	if (!port->started)
	{
		reg_sser_rw_cfg cfg = REG_RD(sser, port->regi_sser, rw_cfg);
		reg_sser_rw_tr_cfg tr_cfg = REG_RD(sser, port->regi_sser, rw_tr_cfg);
		reg_sser_rw_rec_cfg rec_cfg = REG_RD(sser, port->regi_sser, rw_rec_cfg);
		cfg.en = regk_sser_yes;
		tr_cfg.tr_en = regk_sser_yes;
		rec_cfg.rec_en = regk_sser_yes;
		REG_WR(sser, port->regi_sser, rw_cfg, cfg);
		REG_WR(sser, port->regi_sser, rw_tr_cfg, tr_cfg);
		REG_WR(sser, port->regi_sser, rw_rec_cfg, rec_cfg);
		port->started = 1;
	}


	/* Calculate number of available bytes */
	/* Save pointers to avoid that they are modified by interrupt */
	spin_lock_irqsave(&port->lock, flags);
	start = (unsigned char*)port->readp; /* cast away volatile */
	end = (unsigned char*)port->writep;  /* cast away volatile */
	spin_unlock_irqrestore(&port->lock, flags);
	while ((start == end) && !port->full) /* No data */
	{
		if (file->f_flags & O_NONBLOCK)
		{
			return -EAGAIN;
		}

		interruptible_sleep_on(&port->in_wait_q);
		if (signal_pending(current))
		{
			return -EINTR;
		}
		spin_lock_irqsave(&port->lock, flags);
		start = (unsigned char*)port->readp; /* cast away volatile */
		end = (unsigned char*)port->writep;  /* cast away volatile */
		spin_unlock_irqrestore(&port->lock, flags);
	}

	/* Lazy read, never return wrapped data. */
	if (port->full)
		avail = port->in_buffer_size;
	else if (end > start)
		avail = end - start;
	else
		avail = port->flip + port->in_buffer_size - start;

	count = count > avail ? avail : count;
	if (copy_to_user(buf, start, count))
		return -EFAULT;
	/* Disable interrupts while updating readp */
	spin_lock_irqsave(&port->lock, flags);
	port->readp += count;
	if (port->readp >= port->flip + port->in_buffer_size) /* Wrap? */
		port->readp = port->flip;
	port->full = 0;
	spin_unlock_irqrestore(&port->lock, flags);
	DEBUGREAD(printk("r %d\n", count));
	return count;
}

static void send_word(sync_port* port)
{
	reg_sser_rw_tr_cfg tr_cfg = REG_RD(sser, port->regi_sser, rw_tr_cfg);
	reg_sser_rw_tr_data tr_data =  {0};

	switch(tr_cfg.sample_size)
	{
	 case 8:
		 port->out_count--;
		 tr_data.data = *port->outp++;
		 REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
		 if (port->outp >= port->out_buffer + OUT_BUFFER_SIZE)
			 port->outp = port->out_buffer;
		 break;
	 case 12:
	 {
		int data = (*port->outp++) << 8;
		data |= *port->outp++;
		port->out_count-=2;
		tr_data.data = data;
		REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
		if (port->outp >= port->out_buffer + OUT_BUFFER_SIZE)
			port->outp = port->out_buffer;
	}
	break;
	case 16:
		port->out_count-=2;
		tr_data.data = *(unsigned short *)port->outp;
		REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
		port->outp+=2;
		if (port->outp >= port->out_buffer + OUT_BUFFER_SIZE)
			port->outp = port->out_buffer;
		break;
	case 24:
		port->out_count-=3;
		tr_data.data = *(unsigned short *)port->outp;
		REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
		port->outp+=2;
		tr_data.data = *port->outp++;
		REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
		if (port->outp >= port->out_buffer + OUT_BUFFER_SIZE)
			port->outp = port->out_buffer;
		break;
	case 32:
		port->out_count-=4;
		tr_data.data = *(unsigned short *)port->outp;
		REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
		port->outp+=2;
		tr_data.data = *(unsigned short *)port->outp;
		REG_WR(sser, port->regi_sser, rw_tr_data, tr_data);
		port->outp+=2;
		if (port->outp >= port->out_buffer + OUT_BUFFER_SIZE)
			port->outp = port->out_buffer;
		break;
	}
}


static void start_dma(struct sync_port* port, const char* data, int count)
{
	port->tr_running = 1;
	port->out_descr.buf = (char*)virt_to_phys((char*)data);
	port->out_descr.after = port->out_descr.buf + count;
	port->out_descr.eol = port->out_descr.intr = 1;

	port->out_context.saved_data = (dma_descr_data*)virt_to_phys(&port->out_descr);
	port->out_context.saved_data_buf = port->out_descr.buf;

	DMA_START_CONTEXT(port->regi_dmaout, virt_to_phys((char*)&port->out_context));
	DEBUGTXINT(printk("dma %08lX c %d\n", (unsigned long)data, count));
}

static void start_dma_in(sync_port* port)
{
	int i;
	char* buf;
	port->writep = port->flip;

	if (port->writep > port->flip + port->in_buffer_size)
	{
		panic("Offset too large in sync serial driver\n");
		return;
	}
	buf = (char*)virt_to_phys(port->in_buffer);
	for (i = 0; i < NUM_IN_DESCR; i++) {
		port->in_descr[i].buf = buf;
		port->in_descr[i].after = buf + port->inbufchunk;
		port->in_descr[i].intr = 1;
		port->in_descr[i].next = (dma_descr_data*)virt_to_phys(&port->in_descr[i+1]);
		port->in_descr[i].buf = buf;
		buf += port->inbufchunk;
	}
	/* Link the last descriptor to the first */
	port->in_descr[i-1].next = (dma_descr_data*)virt_to_phys(&port->in_descr[0]);
	port->in_descr[i-1].eol = regk_sser_yes;
	port->next_rx_desc = &port->in_descr[0];
	port->prev_rx_desc = &port->in_descr[NUM_IN_DESCR - 1];
	port->in_context.saved_data = (dma_descr_data*)virt_to_phys(&port->in_descr[0]);
	port->in_context.saved_data_buf = port->in_descr[0].buf;
	DMA_START_CONTEXT(port->regi_dmain, virt_to_phys(&port->in_context));
}

#ifdef SYNC_SER_DMA
static irqreturn_t tr_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	reg_dma_r_masked_intr masked;
	reg_dma_rw_ack_intr ack_intr = {.data = regk_dma_yes};
	int i;
	struct dma_descr_data *descr;
	unsigned int sentl;
	int found = 0;

	for (i = 0; i < NUMBER_OF_PORTS; i++)
	{
		sync_port *port = &ports[i];
		if (!port->enabled  || !port->use_dma )
			continue;

		masked = REG_RD(dma, port->regi_dmaout, r_masked_intr);

		if (masked.data) /* IRQ active for the port? */
		{
			found = 1;
			/* Clear IRQ */
			REG_WR(dma, port->regi_dmaout, rw_ack_intr, ack_intr);
			descr = &port->out_descr;
			sentl = descr->after - descr->buf;
			port->out_count -= sentl;
			port->outp += sentl;
			if (port->outp >= port->out_buffer + OUT_BUFFER_SIZE)
				port->outp = port->out_buffer;
			if (port->out_count)  {
				int c;
				c = port->out_buffer + OUT_BUFFER_SIZE - port->outp;
				if (c > port->out_count)
					c = port->out_count;
				DEBUGTXINT(printk("tx_int DMAWRITE %i %i\n", sentl, c));
				start_dma(port, port->outp, c);
			} else  {
				DEBUGTXINT(printk("tx_int DMA stop %i\n", sentl));
				port->tr_running = 0;
			}
			wake_up_interruptible(&port->out_wait_q); /* wake up the waiting process */
		}
	}
	return IRQ_RETVAL(found);
} /* tr_interrupt */

static irqreturn_t rx_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	reg_dma_r_masked_intr masked;
	reg_dma_rw_ack_intr ack_intr = {.data = regk_dma_yes};

	int i;
	int found = 0;

	for (i = 0; i < NUMBER_OF_PORTS; i++)
	{
		sync_port *port = &ports[i];

		if (!port->enabled || !port->use_dma )
			continue;

		masked = REG_RD(dma, port->regi_dmain, r_masked_intr);

		if (masked.data) /* Descriptor interrupt */
		{
			found = 1;
			while (REG_RD(dma, port->regi_dmain, rw_data) !=
			       virt_to_phys(port->next_rx_desc)) {

				if (port->writep + port->inbufchunk > port->flip + port->in_buffer_size) {
					int first_size = port->flip + port->in_buffer_size - port->writep;
					memcpy((char*)port->writep, phys_to_virt((unsigned)port->next_rx_desc->buf), first_size);
					memcpy(port->flip, phys_to_virt((unsigned)port->next_rx_desc->buf+first_size), port->inbufchunk - first_size);
					port->writep = port->flip + port->inbufchunk - first_size;
				} else {
					memcpy((char*)port->writep,
					       phys_to_virt((unsigned)port->next_rx_desc->buf),
					       port->inbufchunk);
					port->writep += port->inbufchunk;
					if (port->writep >= port->flip + port->in_buffer_size)
						port->writep = port->flip;
				}
                                if (port->writep == port->readp)
                                {
				  port->full = 1;
                                }

				port->next_rx_desc->eol = 0;
				port->prev_rx_desc->eol = 1;
				port->prev_rx_desc = phys_to_virt((unsigned)port->next_rx_desc);
				port->next_rx_desc = phys_to_virt((unsigned)port->next_rx_desc->next);
				wake_up_interruptible(&port->in_wait_q); /* wake up the waiting process */
				DMA_CONTINUE(port->regi_dmain);
				REG_WR(dma, port->regi_dmain, rw_ack_intr, ack_intr);

			}
		}
	}
	return IRQ_RETVAL(found);
} /* rx_interrupt */
#endif /* SYNC_SER_DMA */

#ifdef SYNC_SER_MANUAL
static irqreturn_t manual_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	int i;
	int found = 0;
	reg_sser_r_masked_intr masked;

	for (i = 0; i < NUMBER_OF_PORTS; i++)
	{
		sync_port* port = &ports[i];

		if (!port->enabled || port->use_dma)
		{
			continue;
		}

		masked = REG_RD(sser, port->regi_sser, r_masked_intr);
		if (masked.rdav)	/* Data received? */
		{
			reg_sser_rw_rec_cfg rec_cfg = REG_RD(sser, port->regi_sser, rw_rec_cfg);
			reg_sser_r_rec_data data = REG_RD(sser, port->regi_sser, r_rec_data);
			found = 1;
			/* Read data */
			switch(rec_cfg.sample_size)
			{
			case 8:
				*port->writep++ = data.data & 0xff;
				break;
			case 12:
				*port->writep = (data.data & 0x0ff0) >> 4;
				*(port->writep + 1) = data.data & 0x0f;
				port->writep+=2;
				break;
			case 16:
				*(unsigned short*)port->writep = data.data;
				port->writep+=2;
				break;
			case 24:
				*(unsigned int*)port->writep = data.data;
				port->writep+=3;
				break;
			case 32:
				*(unsigned int*)port->writep = data.data;
				port->writep+=4;
				break;
			}

			if (port->writep >= port->flip + port->in_buffer_size) /* Wrap? */
				port->writep = port->flip;
			if (port->writep == port->readp) {
				/* receive buffer overrun, discard oldest data
				 */
				port->readp++;
				if (port->readp >= port->flip + port->in_buffer_size) /* Wrap? */
					port->readp = port->flip;
			}
			if (sync_data_avail(port) >= port->inbufchunk)
				wake_up_interruptible(&port->in_wait_q); /* Wake up application */
		}

		if (masked.trdy) /* Transmitter ready? */
		{
			found = 1;
			if (port->out_count > 0) /* More data to send */
				send_word(port);
			else /* transmission finished */
			{
				reg_sser_rw_intr_mask intr_mask;
				intr_mask = REG_RD(sser, port->regi_sser, rw_intr_mask);
				intr_mask.trdy = 0;
				REG_WR(sser, port->regi_sser, rw_intr_mask, intr_mask);
				wake_up_interruptible(&port->out_wait_q); /* Wake up application */
			}
		}
	}
	return IRQ_RETVAL(found);
}
#endif

module_init(etrax_sync_serial_init);