path: root/arch/cris/arch-v32/drivers/sync_serial.c

/*
 * Simple synchronous serial port driver for ETRAX FS and Artpec-3.
 *
 * 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/mutex.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 <dma.h>
#include <pinmux.h>
#include <hwregs/reg_rdwr.h>
#include <hwregs/sser_defs.h>
#include <hwregs/dma_defs.h>
#include <hwregs/dma.h>
#include <hwregs/intr_vect_defs.h>
#include <hwregs/intr_vect.h>
#include <hwregs/reg_map.h>
#include <asm/sync_serial.h>


/* The receiver is a bit tricky because 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 NBR_IN_DESCR (IN_BUFFER_SIZE/IN_DESCR_SIZE)

#define OUT_BUFFER_SIZE 1024*8
#define NBR_OUT_DESCR 8

#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)
#define DEBUGTRDMA(x)
#define DEBUGOUTBUF(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