ncr5380.c

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#ifndef NDEBUG
#define NDEBUG (NDEBUG_RESTART_SELECT | NDEBUG_ABORT)
#endif
/* 
 * NCR 5380 generic driver routines.  These should make it *trivial*
 *      to implement 5380 SCSI drivers under Linux with a non-trantor
 *      architecture.
 *
 *      Note that these routines also work with NR53c400 family chips.
 *
 * Copyright 1993, Drew Eckhardt
 *      Visionary Computing 
 *      (Unix and Linux consulting and custom programming)
 *      [e-mail]
 *      [phone]
 *
 * DISTRIBUTION RELEASE 6. 
 *
 * For more information, please consult 
 *
 * NCR 5380 Family
 * SCSI Protocol Controller
 * Databook
 *
 * NCR Microelectronics
 * 1635 Aeroplaza Drive
 * Colorado Springs, CO 80916
 * 1+ [phone]
 * 1+ [phone]
 */

/*
 * $Log: NCR5380.c,v $

 * Revision 1.10 1998/9/2	Alan Cox
 *				([e-mail])
 * Fixed up the timer lockups reported so far. Things still suck. Looking 
 * forward to 2.3 and per device request queues. Then it'll be possible to
 * SMP thread this beast and improve life no end.
 
 * Revision 1.9  1997/7/27	Ronald van Cuijlenborg
 *				([e-mail] or [e-mail])
 * (hopefully) fixed and enhanced USLEEP
 * added support for DTC3181E card (for Mustek scanner)
 *

 * Revision 1.8			Ingmar Baumgart
 *				([e-mail])
 * added support for NCR53C400a card
 *

 * Revision 1.7  1996/3/2       Ray Van Tassle ([e-mail])
 * added proc_info
 * added support needed for DTC 3180/3280
 * fixed a couple of bugs
 *

 * Revision 1.5  1994/01/19  09:14:57  drew
 * Fixed udelay() hack that was being used on DATAOUT phases
 * instead of a proper wait for the final handshake.
 *
 * Revision 1.4  1994/01/19  06:44:25  drew
 * *** empty log message ***
 *
 * Revision 1.3  1994/01/19  05:24:40  drew
 * Added support for TCR LAST_BYTE_SENT bit.
 *
 * Revision 1.2  1994/01/15  06:14:11  drew
 * REAL DMA support, bug fixes.
 *
 * Revision 1.1  1994/01/15  06:00:54  drew
 * Initial revision
 *
 */

/*
 * Further development / testing that should be done : 
 * 1.  Cleanup the NCR5380_transfer_dma function and DMA operation complete
 *     code so that everything does the same thing that's done at the 
 *     end of a pseudo-DMA read operation.
 *
 * 2.  Fix REAL_DMA (interrupt driven, polled works fine) -
 *     basically, transfer size needs to be reduced by one 
 *     and the last byte read as is done with PSEUDO_DMA.
 * 
 * 4.  Test SCSI-II tagged queueing (I have no devices which support 
 *      tagged queueing)
 *
 * 5.  Test linked command handling code after Eric is ready with 
 *      the high level code.
 */

#if (NDEBUG & NDEBUG_LISTS)
#define LIST(x,y) {printk("LINE:%d   Adding %p to %p\n", __LINE__, (void*)(x), (void*)(y)); if ((x)==(y)) udelay(5); }
#define REMOVE(w,x,y,z) {printk("LINE:%d   Removing: %p->%p  %p->%p \n", __LINE__, (void*)(w), (void*)(x), (void*)(y), (void*)(z)); if ((x)==(y)) udelay(5); }
#else
#define LIST(x,y)
#define REMOVE(w,x,y,z)
#endif

#ifndef notyet
#undef LINKED
#undef REAL_DMA
#endif

#ifdef REAL_DMA_POLL
#undef READ_OVERRUNS
#define READ_OVERRUNS
#endif

#ifdef BOARD_REQUIRES_NO_DELAY
#define io_recovery_delay(x)
#else
#define io_recovery_delay(x)	udelay(x)
#endif

/*
 * Design
 * Issues :
 *
 * The other Linux SCSI drivers were written when Linux was Intel PC-only,
 * and specifically for each board rather than each chip.  This makes their
 * adaptation to platforms like the Mac (Some of which use NCR5380's)
 * more difficult than it has to be.
 *
 * Also, many of the SCSI drivers were written before the command queuing
 * routines were implemented, meaning their implementations of queued 
 * commands were hacked on rather than designed in from the start.
 *
 * When I designed the Linux SCSI drivers I figured that 
 * while having two different SCSI boards in a system might be useful
 * for debugging things, two of the same type wouldn't be used.
 * Well, I was wrong and a number of users have mailed me about running
 * multiple high-performance SCSI boards in a server.
 *
 * Finally, when I get questions from users, I have no idea what 
 * revision of my driver they are running.
 *
 * This driver attempts to address these problems :
 * This is a generic 5380 driver.  To use it on a different platform, 
 * one simply writes appropriate system specific macros (ie, data
 * transfer - some PC's will use the I/O bus, 68K's must use 
 * memory mapped) and drops this file in their 'C' wrapper.
 *
 * As far as command queueing, two queues are maintained for 
 * each 5380 in the system - commands that haven't been issued yet,
 * and commands that are currently executing.  This means that an 
 * unlimited number of commands may be queued, letting 
 * more commands propagate from the higher driver levels giving higher 
 * throughput.  Note that both I_T_L and I_T_L_Q nexuses are supported, 
 * allowing multiple commands to propagate all the way to a SCSI-II device 
 * while a command is already executing.
 *
 * To solve the multiple-boards-in-the-same-system problem, 
 * there is a separate instance structure for each instance
 * of a 5380 in the system.  So, multiple NCR5380 drivers will
 * be able to coexist with appropriate changes to the high level
 * SCSI code.  
 *
 * A NCR5380_PUBLIC_REVISION macro is provided, with the release
 * number (updated for each public release) printed by the 
 * NCR5380_print_options command, which should be called from the 
 * wrapper detect function, so that I know what release of the driver
 * users are using.
 *
 * Issues specific to the NCR5380 : 
 *
 * When used in a PIO or pseudo-dma mode, the NCR5380 is a braindead 
 * piece of hardware that requires you to sit in a loop polling for 
 * the REQ signal as long as you are connected.  Some devices are 
 * brain dead (ie, many TEXEL CD ROM drives) and won't disconnect 
 * while doing long seek operations.
 * 
 * The workaround for this is to keep track of devices that have
 * disconnected.  If the device hasn't disconnected, for commands that
 * should disconnect, we do something like 
 *
 * while (!REQ is asserted) { sleep for N usecs; poll for M usecs }
 * 
 * Some tweaking of N and M needs to be done.  An algorithm based 
 * on "time to data" would give the best results as long as short time
 * to datas (ie, on the same track) were considered, however these 
 * broken devices are the exception rather than the rule and I'd rather
 * spend my time optimizing for the normal case.
 *
 * Architecture :
 *
 * At the heart of the design is a coroutine, NCR5380_main,
 * which is started when not running by the interrupt handler,
 * timer, and queue command function.  It attempts to establish
 * I_T_L or I_T_L_Q nexuses by removing the commands from the 
 * issue queue and calling NCR5380_select() if a nexus 
 * is not established. 
 *
 * Once a nexus is established, the NCR5380_information_transfer()
 * phase goes through the various phases as instructed by the target.
 * if the target goes into MSG IN and sends a DISCONNECT message,
 * the command structure is placed into the per instance disconnected
 * queue, and NCR5380_main tries to find more work.  If the target is 
 * idle for too long, the system will try to sleep.
 *
 * If a command has disconnected, eventually an interrupt will trigger,
 * calling NCR5380_intr()  which will in turn call NCR5380_reselect
 * to reestablish a nexus.  This will run main if necessary.
 *
 * On command termination, the done function will be called as 
 * appropriate.
 *
 * SCSI pointers are maintained in the SCp field of SCSI command 
 * structures, being initialized after the command is connected
 * in NCR5380_select, and set as appropriate in NCR5380_information_transfer.
 * Note that in violation of the standard, an implicit SAVE POINTERS operation
 * is done, since some BROKEN disks fail to issue an explicit SAVE POINTERS.
 */

/*
 * Using this file :
 * This file a skeleton Linux SCSI driver for the NCR 5380 series
 * of chips.  To use it, you write an architecture specific functions 
 * and macros and include this file in your driver.
 *
 * These macros control options : 
 * AUTOPROBE_IRQ - if defined, the NCR5380_probe_irq() function will be 
 *      defined.
 * 
 * AUTOSENSE - if defined, REQUEST SENSE will be performed automatically
 *      for commands that return with a CHECK CONDITION status. 
 *
 * DIFFERENTIAL - if defined, NCR53c81 chips will use external differential
 *      transceivers. 
 *
 * DONT_USE_INTR - if defined, never use interrupts, even if we probe or
 *      override-configure an IRQ.
 *
 * LIMIT_TRANSFERSIZE - if defined, limit the pseudo-dma transfers to 512
 *      bytes at a time.  Since interrupts are disabled by default during
 *      these transfers, we might need this to give reasonable interrupt
 *      service time if the transfer size gets too large.
 *
 * LINKED - if defined, linked commands are supported.
 *
 * PSEUDO_DMA - if defined, PSEUDO DMA is used during the data transfer phases.
 *
 * REAL_DMA - if defined, REAL DMA is used during the data transfer phases.
 *
 * REAL_DMA_POLL - if defined, REAL DMA is used but the driver doesn't
 *      rely on phase mismatch and EOP interrupts to determine end 
 *      of phase.
 *
 * UNSAFE - leave interrupts enabled during pseudo-DMA transfers.  You
 *          only really want to use this if you're having a problem with
 *          dropped characters during high speed communications, and even
 *          then, you're going to be better off twiddling with transfersize
 *          in the high level code.
 *
 * Defaults for these will be provided although the user may want to adjust 
 * these to allocate CPU resources to the SCSI driver or "real" code.
 * 
 * USLEEP_SLEEP - amount of time, in jiffies, to sleep
 *
 * USLEEP_POLL - amount of time, in jiffies, to poll
 *
 * These macros MUST be defined :
 * NCR5380_local_declare() - declare any local variables needed for your
 *      transfer routines.
 *
 * NCR5380_setup(instance) - initialize any local variables needed from a given
 *      instance of the host adapter for NCR5380_{read,write,pread,pwrite}
 * 
 * NCR5380_read(register)  - read from the specified register
 *
 * NCR5380_write(register, value) - write to the specific register 
 *
 * NCR5380_implementation_fields  - additional fields needed for this 
 *      specific implementation of the NCR5380
 *
 * Either real DMA *or* pseudo DMA may be implemented
 * REAL functions : 
 * NCR5380_REAL_DMA should be defined if real DMA is to be used.
 * Note that the DMA setup functions should return the number of bytes 
 *      that they were able to program the controller for.
 *
 * Also note that generic i386/PC versions of these macros are 
 *      available as NCR5380_i386_dma_write_setup,
 *      NCR5380_i386_dma_read_setup, and NCR5380_i386_dma_residual.
 *
 * NCR5380_dma_write_setup(instance, src, count) - initialize
 * NCR5380_dma_read_setup(instance, dst, count) - initialize
 * NCR5380_dma_residual(instance); - residual count
 *
 * PSEUDO functions :
 * NCR5380_pwrite(instance, src, count)
 * NCR5380_pread(instance, dst, count);
 *
 * If nothing specific to this implementation needs doing (ie, with external
 * hardware), you must also define 
 *  
 * NCR5380_queue_command
 * NCR5380_reset
 * NCR5380_abort
 * NCR5380_proc_info
 *
 * to be the global entry points into the specific driver, ie 
 * #define NCR5380_queue_command t128_queue_command.
 *
 * If this is not done, the routines will be defined as static functions
 * with the NCR5380* names and the user must provide a globally
 * accessible wrapper function.
 *
 * The generic driver is initialized by calling NCR5380_init(instance),
 * after setting the appropriate host specific fields and ID.  If the 
 * driver wishes to autoprobe for an IRQ line, the NCR5380_probe_irq(instance,
 * possible) function may be used.  Before the specific driver initialization
 * code finishes, NCR5380_print_options should be called.
 */

static int do_abort(struct Scsi_Host *host);
static void do_reset(struct Scsi_Host *host);
static struct Scsi_Host *first_instance = NULL;
static Scsi_Host_Template *the_template = NULL;
static struct timer_list usleep_timer;

/*
 *	initialize_SCp		-	init the scsi pointer field
 *	@cmd: command block to set up
 *
 *	Set up the internal fields in the SCSI command.
 */

static __inline__ void initialize_SCp(Scsi_Cmnd * cmd)
{
	/* 
	 * Initialize the Scsi Pointer field so that all of the commands in the 
	 * various queues are valid.
	 */

	if (cmd->use_sg) {
		cmd->SCp.buffer = (struct scatterlist *) cmd->buffer;
		cmd->SCp.buffers_residual = cmd->use_sg - 1;
		cmd->SCp.ptr = (char *) cmd->SCp.buffer->address;
		cmd->SCp.this_residual = cmd->SCp.buffer->length;
	} else {
		cmd->SCp.buffer = NULL;
		cmd->SCp.buffers_residual = 0;
		cmd->SCp.ptr = (char *) cmd->request_buffer;
		cmd->SCp.this_residual = cmd->request_bufflen;
	}
}

#include <linux/delay.h>

#ifdef NDEBUG
static struct {
	unsigned char mask;
	const char *name;
} signals[] = { 
	{SR_DBP, "PARITY"}, 
	{SR_RST, "RST"}, 
	{SR_BSY, "BSY"}, 
	{SR_REQ, "REQ"}, 
	{SR_MSG, "MSG"}, 
	{SR_CD, "CD"}, 
	{SR_IO, "IO"}, 
	{SR_SEL, "SEL"}, 
	{0, NULL}
}, 
basrs[] = {
	{BASR_ATN, "ATN"}, 
	{BASR_ACK, "ACK"}, 
	{0, NULL}
}, 
icrs[] = { 
	{ICR_ASSERT_RST, "ASSERT RST"}, 
	{ICR_ASSERT_ACK, "ASSERT ACK"}, 
	{ICR_ASSERT_BSY, "ASSERT BSY"}, 
	{ICR_ASSERT_SEL, "ASSERT SEL"}, 
	{ICR_ASSERT_ATN, "ASSERT ATN"}, 
	{ICR_ASSERT_DATA, "ASSERT DATA"}, 
	{0, NULL}
}, 
mrs[] = { 
	{MR_BLOCK_DMA_MODE, "MODE BLOCK DMA"}, 
	{MR_TARGET, "MODE TARGET"}, 
	{MR_ENABLE_PAR_CHECK, "MODE PARITY CHECK"}, 
	{MR_ENABLE_PAR_INTR, "MODE PARITY INTR"}, 
	{MR_MONITOR_BSY, "MODE MONITOR BSY"}, 
	{MR_DMA_MODE, "MODE DMA"}, 
	{MR_ARBITRATE, "MODE ARBITRATION"}, 
	{0, NULL}
};

/**
 *	NCR5380_print	-	print scsi bus signals
 *	@instance:	adapter state to dump
 *
 *	Print the SCSI bus signals for debugging purposes
 *
 *	Locks: none
 */

static void NCR5380_print(struct Scsi_Host *instance)
{
	NCR5380_local_declare();
	unsigned long flags;
	unsigned char status, data, basr, mr, icr, i;
	NCR5380_setup(instance);
	/* FIXME - this needs proper locking */
	save_flags(flags);
	cli();