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/drivers/scsi/atari_scsi.c

http://github.com/mirrors/linux
C | 896 lines | 527 code | 139 blank | 230 comment | 103 complexity | 35dcfce6fa8c9d4b5cbd16a245c0764a MD5 | raw file
  1/*
  2 * atari_scsi.c -- Device dependent functions for the Atari generic SCSI port
  3 *
  4 * Copyright 1994 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>
  5 *
  6 *   Loosely based on the work of Robert De Vries' team and added:
  7 *    - working real DMA
  8 *    - Falcon support (untested yet!)   ++bjoern fixed and now it works
  9 *    - lots of extensions and bug fixes.
 10 *
 11 * This file is subject to the terms and conditions of the GNU General Public
 12 * License.  See the file COPYING in the main directory of this archive
 13 * for more details.
 14 *
 15 */
 16
 17/*
 18 * Notes for Falcon SCSI DMA
 19 *
 20 * The 5380 device is one of several that all share the DMA chip. Hence
 21 * "locking" and "unlocking" access to this chip is required.
 22 *
 23 * Two possible schemes for ST DMA acquisition by atari_scsi are:
 24 * 1) The lock is taken for each command separately (i.e. can_queue == 1).
 25 * 2) The lock is taken when the first command arrives and released
 26 * when the last command is finished (i.e. can_queue > 1).
 27 *
 28 * The first alternative limits SCSI bus utilization, since interleaving
 29 * commands is not possible. The second gives better performance but is
 30 * unfair to other drivers needing to use the ST DMA chip. In order to
 31 * allow the IDE and floppy drivers equal access to the ST DMA chip
 32 * the default is can_queue == 1.
 33 */
 34
 35#include <linux/module.h>
 36#include <linux/types.h>
 37#include <linux/blkdev.h>
 38#include <linux/interrupt.h>
 39#include <linux/init.h>
 40#include <linux/nvram.h>
 41#include <linux/bitops.h>
 42#include <linux/wait.h>
 43#include <linux/platform_device.h>
 44
 45#include <asm/setup.h>
 46#include <asm/atarihw.h>
 47#include <asm/atariints.h>
 48#include <asm/atari_stdma.h>
 49#include <asm/atari_stram.h>
 50#include <asm/io.h>
 51
 52#include <scsi/scsi_host.h>
 53
 54#define DMA_MIN_SIZE                    32
 55
 56/* Definitions for the core NCR5380 driver. */
 57
 58#define NCR5380_implementation_fields   /* none */
 59
 60static u8 (*atari_scsi_reg_read)(unsigned int);
 61static void (*atari_scsi_reg_write)(unsigned int, u8);
 62
 63#define NCR5380_read(reg)               atari_scsi_reg_read(reg)
 64#define NCR5380_write(reg, value)       atari_scsi_reg_write(reg, value)
 65
 66#define NCR5380_queue_command           atari_scsi_queue_command
 67#define NCR5380_abort                   atari_scsi_abort
 68#define NCR5380_info                    atari_scsi_info
 69
 70#define NCR5380_dma_xfer_len            atari_scsi_dma_xfer_len
 71#define NCR5380_dma_recv_setup          atari_scsi_dma_recv_setup
 72#define NCR5380_dma_send_setup          atari_scsi_dma_send_setup
 73#define NCR5380_dma_residual            atari_scsi_dma_residual
 74
 75#define NCR5380_acquire_dma_irq(instance)      falcon_get_lock(instance)
 76#define NCR5380_release_dma_irq(instance)      falcon_release_lock()
 77
 78#include "NCR5380.h"
 79
 80
 81#define	IS_A_TT()	ATARIHW_PRESENT(TT_SCSI)
 82
 83#define	SCSI_DMA_WRITE_P(elt,val)				\
 84	do {							\
 85		unsigned long v = val;				\
 86		tt_scsi_dma.elt##_lo = v & 0xff;		\
 87		v >>= 8;					\
 88		tt_scsi_dma.elt##_lmd = v & 0xff;		\
 89		v >>= 8;					\
 90		tt_scsi_dma.elt##_hmd = v & 0xff;		\
 91		v >>= 8;					\
 92		tt_scsi_dma.elt##_hi = v & 0xff;		\
 93	} while(0)
 94
 95#define	SCSI_DMA_READ_P(elt)					\
 96	(((((((unsigned long)tt_scsi_dma.elt##_hi << 8) |	\
 97	     (unsigned long)tt_scsi_dma.elt##_hmd) << 8) |	\
 98	   (unsigned long)tt_scsi_dma.elt##_lmd) << 8) |	\
 99	 (unsigned long)tt_scsi_dma.elt##_lo)
100
101
102static inline void SCSI_DMA_SETADR(unsigned long adr)
103{
104	st_dma.dma_lo = (unsigned char)adr;
105	MFPDELAY();
106	adr >>= 8;
107	st_dma.dma_md = (unsigned char)adr;
108	MFPDELAY();
109	adr >>= 8;
110	st_dma.dma_hi = (unsigned char)adr;
111	MFPDELAY();
112}
113
114static inline unsigned long SCSI_DMA_GETADR(void)
115{
116	unsigned long adr;
117	adr = st_dma.dma_lo;
118	MFPDELAY();
119	adr |= (st_dma.dma_md & 0xff) << 8;
120	MFPDELAY();
121	adr |= (st_dma.dma_hi & 0xff) << 16;
122	MFPDELAY();
123	return adr;
124}
125
126static void atari_scsi_fetch_restbytes(void);
127
128static unsigned long	atari_dma_residual, atari_dma_startaddr;
129static short		atari_dma_active;
130/* pointer to the dribble buffer */
131static char		*atari_dma_buffer;
132/* precalculated physical address of the dribble buffer */
133static unsigned long	atari_dma_phys_buffer;
134/* != 0 tells the Falcon int handler to copy data from the dribble buffer */
135static char		*atari_dma_orig_addr;
136/* size of the dribble buffer; 4k seems enough, since the Falcon cannot use
137 * scatter-gather anyway, so most transfers are 1024 byte only. In the rare
138 * cases where requests to physical contiguous buffers have been merged, this
139 * request is <= 4k (one page). So I don't think we have to split transfers
140 * just due to this buffer size...
141 */
142#define	STRAM_BUFFER_SIZE	(4096)
143/* mask for address bits that can't be used with the ST-DMA */
144static unsigned long	atari_dma_stram_mask;
145#define STRAM_ADDR(a)	(((a) & atari_dma_stram_mask) == 0)
146
147static int setup_can_queue = -1;
148module_param(setup_can_queue, int, 0);
149static int setup_cmd_per_lun = -1;
150module_param(setup_cmd_per_lun, int, 0);
151static int setup_sg_tablesize = -1;
152module_param(setup_sg_tablesize, int, 0);
153static int setup_hostid = -1;
154module_param(setup_hostid, int, 0);
155static int setup_toshiba_delay = -1;
156module_param(setup_toshiba_delay, int, 0);
157
158
159static int scsi_dma_is_ignored_buserr(unsigned char dma_stat)
160{
161	int i;
162	unsigned long addr = SCSI_DMA_READ_P(dma_addr), end_addr;
163
164	if (dma_stat & 0x01) {
165
166		/* A bus error happens when DMA-ing from the last page of a
167		 * physical memory chunk (DMA prefetch!), but that doesn't hurt.
168		 * Check for this case:
169		 */
170
171		for (i = 0; i < m68k_num_memory; ++i) {
172			end_addr = m68k_memory[i].addr + m68k_memory[i].size;
173			if (end_addr <= addr && addr <= end_addr + 4)
174				return 1;
175		}
176	}
177	return 0;
178}
179
180
181static irqreturn_t scsi_tt_intr(int irq, void *dev)
182{
183	struct Scsi_Host *instance = dev;
184	struct NCR5380_hostdata *hostdata = shost_priv(instance);
185	int dma_stat;
186
187	dma_stat = tt_scsi_dma.dma_ctrl;
188
189	dsprintk(NDEBUG_INTR, instance, "NCR5380 interrupt, DMA status = %02x\n",
190	         dma_stat & 0xff);
191
192	/* Look if it was the DMA that has interrupted: First possibility
193	 * is that a bus error occurred...
194	 */
195	if (dma_stat & 0x80) {
196		if (!scsi_dma_is_ignored_buserr(dma_stat)) {
197			printk(KERN_ERR "SCSI DMA caused bus error near 0x%08lx\n",
198			       SCSI_DMA_READ_P(dma_addr));
199			printk(KERN_CRIT "SCSI DMA bus error -- bad DMA programming!");
200		}
201	}
202
203	/* If the DMA is active but not finished, we have the case
204	 * that some other 5380 interrupt occurred within the DMA transfer.
205	 * This means we have residual bytes, if the desired end address
206	 * is not yet reached. Maybe we have to fetch some bytes from the
207	 * rest data register, too. The residual must be calculated from
208	 * the address pointer, not the counter register, because only the
209	 * addr reg counts bytes not yet written and pending in the rest
210	 * data reg!
211	 */
212	if ((dma_stat & 0x02) && !(dma_stat & 0x40)) {
213		atari_dma_residual = hostdata->dma_len -
214			(SCSI_DMA_READ_P(dma_addr) - atari_dma_startaddr);
215
216		dprintk(NDEBUG_DMA, "SCSI DMA: There are %ld residual bytes.\n",
217			   atari_dma_residual);
218
219		if ((signed int)atari_dma_residual < 0)
220			atari_dma_residual = 0;
221		if ((dma_stat & 1) == 0) {
222			/*
223			 * After read operations, we maybe have to
224			 * transport some rest bytes
225			 */
226			atari_scsi_fetch_restbytes();
227		} else {
228			/*
229			 * There seems to be a nasty bug in some SCSI-DMA/NCR
230			 * combinations: If a target disconnects while a write
231			 * operation is going on, the address register of the
232			 * DMA may be a few bytes farer than it actually read.
233			 * This is probably due to DMA prefetching and a delay
234			 * between DMA and NCR.  Experiments showed that the
235			 * dma_addr is 9 bytes to high, but this could vary.
236			 * The problem is, that the residual is thus calculated
237			 * wrong and the next transfer will start behind where
238			 * it should.  So we round up the residual to the next
239			 * multiple of a sector size, if it isn't already a
240			 * multiple and the originally expected transfer size
241			 * was.  The latter condition is there to ensure that
242			 * the correction is taken only for "real" data
243			 * transfers and not for, e.g., the parameters of some
244			 * other command.  These shouldn't disconnect anyway.
245			 */
246			if (atari_dma_residual & 0x1ff) {
247				dprintk(NDEBUG_DMA, "SCSI DMA: DMA bug corrected, "
248					   "difference %ld bytes\n",
249					   512 - (atari_dma_residual & 0x1ff));
250				atari_dma_residual = (atari_dma_residual + 511) & ~0x1ff;
251			}
252		}
253		tt_scsi_dma.dma_ctrl = 0;
254	}
255
256	/* If the DMA is finished, fetch the rest bytes and turn it off */
257	if (dma_stat & 0x40) {
258		atari_dma_residual = 0;
259		if ((dma_stat & 1) == 0)
260			atari_scsi_fetch_restbytes();
261		tt_scsi_dma.dma_ctrl = 0;
262	}
263
264	NCR5380_intr(irq, dev);
265
266	return IRQ_HANDLED;
267}
268
269
270static irqreturn_t scsi_falcon_intr(int irq, void *dev)
271{
272	struct Scsi_Host *instance = dev;
273	struct NCR5380_hostdata *hostdata = shost_priv(instance);
274	int dma_stat;
275
276	/* Turn off DMA and select sector counter register before
277	 * accessing the status register (Atari recommendation!)
278	 */
279	st_dma.dma_mode_status = 0x90;
280	dma_stat = st_dma.dma_mode_status;
281
282	/* Bit 0 indicates some error in the DMA process... don't know
283	 * what happened exactly (no further docu).
284	 */
285	if (!(dma_stat & 0x01)) {
286		/* DMA error */
287		printk(KERN_CRIT "SCSI DMA error near 0x%08lx!\n", SCSI_DMA_GETADR());
288	}
289
290	/* If the DMA was active, but now bit 1 is not clear, it is some
291	 * other 5380 interrupt that finishes the DMA transfer. We have to
292	 * calculate the number of residual bytes and give a warning if
293	 * bytes are stuck in the ST-DMA fifo (there's no way to reach them!)
294	 */
295	if (atari_dma_active && (dma_stat & 0x02)) {
296		unsigned long transferred;
297
298		transferred = SCSI_DMA_GETADR() - atari_dma_startaddr;
299		/* The ST-DMA address is incremented in 2-byte steps, but the
300		 * data are written only in 16-byte chunks. If the number of
301		 * transferred bytes is not divisible by 16, the remainder is
302		 * lost somewhere in outer space.
303		 */
304		if (transferred & 15)
305			printk(KERN_ERR "SCSI DMA error: %ld bytes lost in "
306			       "ST-DMA fifo\n", transferred & 15);
307
308		atari_dma_residual = hostdata->dma_len - transferred;
309		dprintk(NDEBUG_DMA, "SCSI DMA: There are %ld residual bytes.\n",
310			   atari_dma_residual);
311	} else
312		atari_dma_residual = 0;
313	atari_dma_active = 0;
314
315	if (atari_dma_orig_addr) {
316		/* If the dribble buffer was used on a read operation, copy the DMA-ed
317		 * data to the original destination address.
318		 */
319		memcpy(atari_dma_orig_addr, phys_to_virt(atari_dma_startaddr),
320		       hostdata->dma_len - atari_dma_residual);
321		atari_dma_orig_addr = NULL;
322	}
323
324	NCR5380_intr(irq, dev);
325
326	return IRQ_HANDLED;
327}
328
329
330static void atari_scsi_fetch_restbytes(void)
331{
332	int nr;
333	char *src, *dst;
334	unsigned long phys_dst;
335
336	/* fetch rest bytes in the DMA register */
337	phys_dst = SCSI_DMA_READ_P(dma_addr);
338	nr = phys_dst & 3;
339	if (nr) {
340		/* there are 'nr' bytes left for the last long address
341		   before the DMA pointer */
342		phys_dst ^= nr;
343		dprintk(NDEBUG_DMA, "SCSI DMA: there are %d rest bytes for phys addr 0x%08lx",
344			   nr, phys_dst);
345		/* The content of the DMA pointer is a physical address!  */
346		dst = phys_to_virt(phys_dst);
347		dprintk(NDEBUG_DMA, " = virt addr %p\n", dst);
348		for (src = (char *)&tt_scsi_dma.dma_restdata; nr != 0; --nr)
349			*dst++ = *src++;
350	}
351}
352
353
354/* This function releases the lock on the DMA chip if there is no
355 * connected command and the disconnected queue is empty.
356 */
357
358static void falcon_release_lock(void)
359{
360	if (IS_A_TT())
361		return;
362
363	if (stdma_is_locked_by(scsi_falcon_intr))
364		stdma_release();
365}
366
367/* This function manages the locking of the ST-DMA.
368 * If the DMA isn't locked already for SCSI, it tries to lock it by
369 * calling stdma_lock(). But if the DMA is locked by the SCSI code and
370 * there are other drivers waiting for the chip, we do not issue the
371 * command immediately but tell the SCSI mid-layer to defer.
372 */
373
374static int falcon_get_lock(struct Scsi_Host *instance)
375{
376	if (IS_A_TT())
377		return 1;
378
379	if (stdma_is_locked_by(scsi_falcon_intr) &&
380	    instance->hostt->can_queue > 1)
381		return 1;
382
383	if (in_interrupt())
384		return stdma_try_lock(scsi_falcon_intr, instance);
385
386	stdma_lock(scsi_falcon_intr, instance);
387	return 1;
388}
389
390#ifndef MODULE
391static int __init atari_scsi_setup(char *str)
392{
393	/* Format of atascsi parameter is:
394	 *   atascsi=<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
395	 * Defaults depend on TT or Falcon, determined at run time.
396	 * Negative values mean don't change.
397	 */
398	int ints[8];
399
400	get_options(str, ARRAY_SIZE(ints), ints);
401
402	if (ints[0] < 1) {
403		printk("atari_scsi_setup: no arguments!\n");
404		return 0;
405	}
406	if (ints[0] >= 1)
407		setup_can_queue = ints[1];
408	if (ints[0] >= 2)
409		setup_cmd_per_lun = ints[2];
410	if (ints[0] >= 3)
411		setup_sg_tablesize = ints[3];
412	if (ints[0] >= 4)
413		setup_hostid = ints[4];
414	/* ints[5] (use_tagged_queuing) is ignored */
415	/* ints[6] (use_pdma) is ignored */
416	if (ints[0] >= 7)
417		setup_toshiba_delay = ints[7];
418
419	return 1;
420}
421
422__setup("atascsi=", atari_scsi_setup);
423#endif /* !MODULE */
424
425static unsigned long atari_scsi_dma_setup(struct NCR5380_hostdata *hostdata,
426					  void *data, unsigned long count,
427					  int dir)
428{
429	unsigned long addr = virt_to_phys(data);
430
431	dprintk(NDEBUG_DMA, "scsi%d: setting up dma, data = %p, phys = %lx, count = %ld, dir = %d\n",
432	        hostdata->host->host_no, data, addr, count, dir);
433
434	if (!IS_A_TT() && !STRAM_ADDR(addr)) {
435		/* If we have a non-DMAable address on a Falcon, use the dribble
436		 * buffer; 'orig_addr' != 0 in the read case tells the interrupt
437		 * handler to copy data from the dribble buffer to the originally
438		 * wanted address.
439		 */
440		if (dir)
441			memcpy(atari_dma_buffer, data, count);
442		else
443			atari_dma_orig_addr = data;
444		addr = atari_dma_phys_buffer;
445	}
446
447	atari_dma_startaddr = addr;	/* Needed for calculating residual later. */
448
449	/* Cache cleanup stuff: On writes, push any dirty cache out before sending
450	 * it to the peripheral. (Must be done before DMA setup, since at least
451	 * the ST-DMA begins to fill internal buffers right after setup. For
452	 * reads, invalidate any cache, may be altered after DMA without CPU
453	 * knowledge.
454	 *
455	 * ++roman: For the Medusa, there's no need at all for that cache stuff,
456	 * because the hardware does bus snooping (fine!).
457	 */
458	dma_cache_maintenance(addr, count, dir);
459
460	if (IS_A_TT()) {
461		tt_scsi_dma.dma_ctrl = dir;
462		SCSI_DMA_WRITE_P(dma_addr, addr);
463		SCSI_DMA_WRITE_P(dma_cnt, count);
464		tt_scsi_dma.dma_ctrl = dir | 2;
465	} else { /* ! IS_A_TT */
466
467		/* set address */
468		SCSI_DMA_SETADR(addr);
469
470		/* toggle direction bit to clear FIFO and set DMA direction */
471		dir <<= 8;
472		st_dma.dma_mode_status = 0x90 | dir;
473		st_dma.dma_mode_status = 0x90 | (dir ^ 0x100);
474		st_dma.dma_mode_status = 0x90 | dir;
475		udelay(40);
476		/* On writes, round up the transfer length to the next multiple of 512
477		 * (see also comment at atari_dma_xfer_len()). */
478		st_dma.fdc_acces_seccount = (count + (dir ? 511 : 0)) >> 9;
479		udelay(40);
480		st_dma.dma_mode_status = 0x10 | dir;
481		udelay(40);
482		/* need not restore value of dir, only boolean value is tested */
483		atari_dma_active = 1;
484	}
485
486	return count;
487}
488
489static inline int atari_scsi_dma_recv_setup(struct NCR5380_hostdata *hostdata,
490                                            unsigned char *data, int count)
491{
492	return atari_scsi_dma_setup(hostdata, data, count, 0);
493}
494
495static inline int atari_scsi_dma_send_setup(struct NCR5380_hostdata *hostdata,
496                                            unsigned char *data, int count)
497{
498	return atari_scsi_dma_setup(hostdata, data, count, 1);
499}
500
501static int atari_scsi_dma_residual(struct NCR5380_hostdata *hostdata)
502{
503	return atari_dma_residual;
504}
505
506
507#define	CMD_SURELY_BLOCK_MODE	0
508#define	CMD_SURELY_BYTE_MODE	1
509#define	CMD_MODE_UNKNOWN		2
510
511static int falcon_classify_cmd(struct scsi_cmnd *cmd)
512{
513	unsigned char opcode = cmd->cmnd[0];
514
515	if (opcode == READ_DEFECT_DATA || opcode == READ_LONG ||
516	    opcode == READ_BUFFER)
517		return CMD_SURELY_BYTE_MODE;
518	else if (opcode == READ_6 || opcode == READ_10 ||
519		 opcode == 0xa8 /* READ_12 */ || opcode == READ_REVERSE ||
520		 opcode == RECOVER_BUFFERED_DATA) {
521		/* In case of a sequential-access target (tape), special care is
522		 * needed here: The transfer is block-mode only if the 'fixed' bit is
523		 * set! */
524		if (cmd->device->type == TYPE_TAPE && !(cmd->cmnd[1] & 1))
525			return CMD_SURELY_BYTE_MODE;
526		else
527			return CMD_SURELY_BLOCK_MODE;
528	} else
529		return CMD_MODE_UNKNOWN;
530}
531
532
533/* This function calculates the number of bytes that can be transferred via
534 * DMA. On the TT, this is arbitrary, but on the Falcon we have to use the
535 * ST-DMA chip. There are only multiples of 512 bytes possible and max.
536 * 255*512 bytes :-( This means also, that defining READ_OVERRUNS is not
537 * possible on the Falcon, since that would require to program the DMA for
538 * n*512 - atari_read_overrun bytes. But it seems that the Falcon doesn't have
539 * the overrun problem, so this question is academic :-)
540 */
541
542static int atari_scsi_dma_xfer_len(struct NCR5380_hostdata *hostdata,
543                                   struct scsi_cmnd *cmd)
544{
545	int wanted_len = cmd->SCp.this_residual;
546	int possible_len, limit;
547
548	if (wanted_len < DMA_MIN_SIZE)
549		return 0;
550
551	if (IS_A_TT())
552		/* TT SCSI DMA can transfer arbitrary #bytes */
553		return wanted_len;
554
555	/* ST DMA chip is stupid -- only multiples of 512 bytes! (and max.
556	 * 255*512 bytes, but this should be enough)
557	 *
558	 * ++roman: Aaargl! Another Falcon-SCSI problem... There are some commands
559	 * that return a number of bytes which cannot be known beforehand. In this
560	 * case, the given transfer length is an "allocation length". Now it
561	 * can happen that this allocation length is a multiple of 512 bytes and
562	 * the DMA is used. But if not n*512 bytes really arrive, some input data
563	 * will be lost in the ST-DMA's FIFO :-( Thus, we have to distinguish
564	 * between commands that do block transfers and those that do byte
565	 * transfers. But this isn't easy... there are lots of vendor specific
566	 * commands, and the user can issue any command via the
567	 * SCSI_IOCTL_SEND_COMMAND.
568	 *
569	 * The solution: We classify SCSI commands in 1) surely block-mode cmd.s,
570	 * 2) surely byte-mode cmd.s and 3) cmd.s with unknown mode. In case 1)
571	 * and 3), the thing to do is obvious: allow any number of blocks via DMA
572	 * or none. In case 2), we apply some heuristic: Byte mode is assumed if
573	 * the transfer (allocation) length is < 1024, hoping that no cmd. not
574	 * explicitly known as byte mode have such big allocation lengths...
575	 * BTW, all the discussion above applies only to reads. DMA writes are
576	 * unproblematic anyways, since the targets aborts the transfer after
577	 * receiving a sufficient number of bytes.
578	 *
579	 * Another point: If the transfer is from/to an non-ST-RAM address, we
580	 * use the dribble buffer and thus can do only STRAM_BUFFER_SIZE bytes.
581	 */
582
583	if (cmd->sc_data_direction == DMA_TO_DEVICE) {
584		/* Write operation can always use the DMA, but the transfer size must
585		 * be rounded up to the next multiple of 512 (atari_dma_setup() does
586		 * this).
587		 */
588		possible_len = wanted_len;
589	} else {
590		/* Read operations: if the wanted transfer length is not a multiple of
591		 * 512, we cannot use DMA, since the ST-DMA cannot split transfers
592		 * (no interrupt on DMA finished!)
593		 */
594		if (wanted_len & 0x1ff)
595			possible_len = 0;
596		else {
597			/* Now classify the command (see above) and decide whether it is
598			 * allowed to do DMA at all */
599			switch (falcon_classify_cmd(cmd)) {
600			case CMD_SURELY_BLOCK_MODE:
601				possible_len = wanted_len;
602				break;
603			case CMD_SURELY_BYTE_MODE:
604				possible_len = 0; /* DMA prohibited */
605				break;
606			case CMD_MODE_UNKNOWN:
607			default:
608				/* For unknown commands assume block transfers if the transfer
609				 * size/allocation length is >= 1024 */
610				possible_len = (wanted_len < 1024) ? 0 : wanted_len;
611				break;
612			}
613		}
614	}
615
616	/* Last step: apply the hard limit on DMA transfers */
617	limit = (atari_dma_buffer && !STRAM_ADDR(virt_to_phys(cmd->SCp.ptr))) ?
618		    STRAM_BUFFER_SIZE : 255*512;
619	if (possible_len > limit)
620		possible_len = limit;
621
622	if (possible_len != wanted_len)
623		dprintk(NDEBUG_DMA, "DMA transfer now %d bytes instead of %d\n",
624		        possible_len, wanted_len);
625
626	return possible_len;
627}
628
629
630/* NCR5380 register access functions
631 *
632 * There are separate functions for TT and Falcon, because the access
633 * methods are quite different. The calling macros NCR5380_read and
634 * NCR5380_write call these functions via function pointers.
635 */
636
637static u8 atari_scsi_tt_reg_read(unsigned int reg)
638{
639	return tt_scsi_regp[reg * 2];
640}
641
642static void atari_scsi_tt_reg_write(unsigned int reg, u8 value)
643{
644	tt_scsi_regp[reg * 2] = value;
645}
646
647static u8 atari_scsi_falcon_reg_read(unsigned int reg)
648{
649	unsigned long flags;
650	u8 result;
651
652	reg += 0x88;
653	local_irq_save(flags);
654	dma_wd.dma_mode_status = (u_short)reg;
655	result = (u8)dma_wd.fdc_acces_seccount;
656	local_irq_restore(flags);
657	return result;
658}
659
660static void atari_scsi_falcon_reg_write(unsigned int reg, u8 value)
661{
662	unsigned long flags;
663
664	reg += 0x88;
665	local_irq_save(flags);
666	dma_wd.dma_mode_status = (u_short)reg;
667	dma_wd.fdc_acces_seccount = (u_short)value;
668	local_irq_restore(flags);
669}
670
671
672#include "NCR5380.c"
673
674static int atari_scsi_host_reset(struct scsi_cmnd *cmd)
675{
676	int rv;
677	unsigned long flags;
678
679	local_irq_save(flags);
680
681	/* Abort a maybe active DMA transfer */
682	if (IS_A_TT()) {
683		tt_scsi_dma.dma_ctrl = 0;
684	} else {
685		if (stdma_is_locked_by(scsi_falcon_intr))
686			st_dma.dma_mode_status = 0x90;
687		atari_dma_active = 0;
688		atari_dma_orig_addr = NULL;
689	}
690
691	rv = NCR5380_host_reset(cmd);
692
693	/* The 5380 raises its IRQ line while _RST is active but the ST DMA
694	 * "lock" has been released so this interrupt may end up handled by
695	 * floppy or IDE driver (if one of them holds the lock). The NCR5380
696	 * interrupt flag has been cleared already.
697	 */
698
699	local_irq_restore(flags);
700
701	return rv;
702}
703
704#define DRV_MODULE_NAME         "atari_scsi"
705#define PFX                     DRV_MODULE_NAME ": "
706
707static struct scsi_host_template atari_scsi_template = {
708	.module			= THIS_MODULE,
709	.proc_name		= DRV_MODULE_NAME,
710	.name			= "Atari native SCSI",
711	.info			= atari_scsi_info,
712	.queuecommand		= atari_scsi_queue_command,
713	.eh_abort_handler	= atari_scsi_abort,
714	.eh_host_reset_handler	= atari_scsi_host_reset,
715	.this_id		= 7,
716	.cmd_per_lun		= 2,
717	.dma_boundary		= PAGE_SIZE - 1,
718	.cmd_size		= NCR5380_CMD_SIZE,
719};
720
721static int __init atari_scsi_probe(struct platform_device *pdev)
722{
723	struct Scsi_Host *instance;
724	int error;
725	struct resource *irq;
726	int host_flags = 0;
727
728	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
729	if (!irq)
730		return -ENODEV;
731
732	if (ATARIHW_PRESENT(TT_SCSI)) {
733		atari_scsi_reg_read  = atari_scsi_tt_reg_read;
734		atari_scsi_reg_write = atari_scsi_tt_reg_write;
735	} else {
736		atari_scsi_reg_read  = atari_scsi_falcon_reg_read;
737		atari_scsi_reg_write = atari_scsi_falcon_reg_write;
738	}
739
740	if (ATARIHW_PRESENT(TT_SCSI)) {
741		atari_scsi_template.can_queue    = 16;
742		atari_scsi_template.sg_tablesize = SG_ALL;
743	} else {
744		atari_scsi_template.can_queue    = 1;
745		atari_scsi_template.sg_tablesize = 1;
746	}
747
748	if (setup_can_queue > 0)
749		atari_scsi_template.can_queue = setup_can_queue;
750
751	if (setup_cmd_per_lun > 0)
752		atari_scsi_template.cmd_per_lun = setup_cmd_per_lun;
753
754	/* Don't increase sg_tablesize on Falcon! */
755	if (ATARIHW_PRESENT(TT_SCSI) && setup_sg_tablesize > 0)
756		atari_scsi_template.sg_tablesize = setup_sg_tablesize;
757
758	if (setup_hostid >= 0) {
759		atari_scsi_template.this_id = setup_hostid & 7;
760	} else if (IS_REACHABLE(CONFIG_NVRAM)) {
761		/* Test if a host id is set in the NVRam */
762		if (ATARIHW_PRESENT(TT_CLK)) {
763			unsigned char b;
764			loff_t offset = 16;
765			ssize_t count = nvram_read(&b, 1, &offset);
766
767			/* Arbitration enabled? (for TOS)
768			 * If yes, use configured host ID
769			 */
770			if ((count == 1) && (b & 0x80))
771				atari_scsi_template.this_id = b & 7;
772		}
773	}
774
775	/* If running on a Falcon and if there's TT-Ram (i.e., more than one
776	 * memory block, since there's always ST-Ram in a Falcon), then
777	 * allocate a STRAM_BUFFER_SIZE byte dribble buffer for transfers
778	 * from/to alternative Ram.
779	 */
780	if (ATARIHW_PRESENT(ST_SCSI) && !ATARIHW_PRESENT(EXTD_DMA) &&
781	    m68k_realnum_memory > 1) {
782		atari_dma_buffer = atari_stram_alloc(STRAM_BUFFER_SIZE, "SCSI");
783		if (!atari_dma_buffer) {
784			pr_err(PFX "can't allocate ST-RAM double buffer\n");
785			return -ENOMEM;
786		}
787		atari_dma_phys_buffer = atari_stram_to_phys(atari_dma_buffer);
788		atari_dma_orig_addr = NULL;
789	}
790
791	instance = scsi_host_alloc(&atari_scsi_template,
792	                           sizeof(struct NCR5380_hostdata));
793	if (!instance) {
794		error = -ENOMEM;
795		goto fail_alloc;
796	}
797
798	instance->irq = irq->start;
799
800	host_flags |= IS_A_TT() ? 0 : FLAG_LATE_DMA_SETUP;
801	host_flags |= setup_toshiba_delay > 0 ? FLAG_TOSHIBA_DELAY : 0;
802
803	error = NCR5380_init(instance, host_flags);
804	if (error)
805		goto fail_init;
806
807	if (IS_A_TT()) {
808		error = request_irq(instance->irq, scsi_tt_intr, 0,
809		                    "NCR5380", instance);
810		if (error) {
811			pr_err(PFX "request irq %d failed, aborting\n",
812			       instance->irq);
813			goto fail_irq;
814		}
815		tt_mfp.active_edge |= 0x80;	/* SCSI int on L->H */
816
817		tt_scsi_dma.dma_ctrl = 0;
818		atari_dma_residual = 0;
819
820		/* While the read overruns (described by Drew Eckhardt in
821		 * NCR5380.c) never happened on TTs, they do in fact on the
822		 * Medusa (This was the cause why SCSI didn't work right for
823		 * so long there.) Since handling the overruns slows down
824		 * a bit, I turned the #ifdef's into a runtime condition.
825		 *
826		 * In principle it should be sufficient to do max. 1 byte with
827		 * PIO, but there is another problem on the Medusa with the DMA
828		 * rest data register. So read_overruns is currently set
829		 * to 4 to avoid having transfers that aren't a multiple of 4.
830		 * If the rest data bug is fixed, this can be lowered to 1.
831		 */
832		if (MACH_IS_MEDUSA) {
833			struct NCR5380_hostdata *hostdata =
834				shost_priv(instance);
835
836			hostdata->read_overruns = 4;
837		}
838	} else {
839		/* Nothing to do for the interrupt: the ST-DMA is initialized
840		 * already.
841		 */
842		atari_dma_residual = 0;
843		atari_dma_active = 0;
844		atari_dma_stram_mask = (ATARIHW_PRESENT(EXTD_DMA) ? 0x00000000
845					: 0xff000000);
846	}
847
848	NCR5380_maybe_reset_bus(instance);
849
850	error = scsi_add_host(instance, NULL);
851	if (error)
852		goto fail_host;
853
854	platform_set_drvdata(pdev, instance);
855
856	scsi_scan_host(instance);
857	return 0;
858
859fail_host:
860	if (IS_A_TT())
861		free_irq(instance->irq, instance);
862fail_irq:
863	NCR5380_exit(instance);
864fail_init:
865	scsi_host_put(instance);
866fail_alloc:
867	if (atari_dma_buffer)
868		atari_stram_free(atari_dma_buffer);
869	return error;
870}
871
872static int __exit atari_scsi_remove(struct platform_device *pdev)
873{
874	struct Scsi_Host *instance = platform_get_drvdata(pdev);
875
876	scsi_remove_host(instance);
877	if (IS_A_TT())
878		free_irq(instance->irq, instance);
879	NCR5380_exit(instance);
880	scsi_host_put(instance);
881	if (atari_dma_buffer)
882		atari_stram_free(atari_dma_buffer);
883	return 0;
884}
885
886static struct platform_driver atari_scsi_driver = {
887	.remove = __exit_p(atari_scsi_remove),
888	.driver = {
889		.name	= DRV_MODULE_NAME,
890	},
891};
892
893module_platform_driver_probe(atari_scsi_driver, atari_scsi_probe);
894
895MODULE_ALIAS("platform:" DRV_MODULE_NAME);
896MODULE_LICENSE("GPL");