xref: /openbmc/linux/drivers/ata/sata_via.c (revision 827634ad)
1 /*
2  *  sata_via.c - VIA Serial ATA controllers
3  *
4  *  Maintained by:  Tejun Heo <tj@kernel.org>
5  * 		   Please ALWAYS copy linux-ide@vger.kernel.org
6  *		   on emails.
7  *
8  *  Copyright 2003-2004 Red Hat, Inc.  All rights reserved.
9  *  Copyright 2003-2004 Jeff Garzik
10  *
11  *
12  *  This program is free software; you can redistribute it and/or modify
13  *  it under the terms of the GNU General Public License as published by
14  *  the Free Software Foundation; either version 2, or (at your option)
15  *  any later version.
16  *
17  *  This program is distributed in the hope that it will be useful,
18  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
19  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
20  *  GNU General Public License for more details.
21  *
22  *  You should have received a copy of the GNU General Public License
23  *  along with this program; see the file COPYING.  If not, write to
24  *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
25  *
26  *
27  *  libata documentation is available via 'make {ps|pdf}docs',
28  *  as Documentation/DocBook/libata.*
29  *
30  *  Hardware documentation available under NDA.
31  *
32  *
33  *
34  */
35 
36 #include <linux/kernel.h>
37 #include <linux/module.h>
38 #include <linux/pci.h>
39 #include <linux/blkdev.h>
40 #include <linux/delay.h>
41 #include <linux/device.h>
42 #include <scsi/scsi.h>
43 #include <scsi/scsi_cmnd.h>
44 #include <scsi/scsi_host.h>
45 #include <linux/libata.h>
46 
47 #define DRV_NAME	"sata_via"
48 #define DRV_VERSION	"2.6"
49 
50 /*
51  * vt8251 is different from other sata controllers of VIA.  It has two
52  * channels, each channel has both Master and Slave slot.
53  */
54 enum board_ids_enum {
55 	vt6420,
56 	vt6421,
57 	vt8251,
58 };
59 
60 enum {
61 	SATA_CHAN_ENAB		= 0x40, /* SATA channel enable */
62 	SATA_INT_GATE		= 0x41, /* SATA interrupt gating */
63 	SATA_NATIVE_MODE	= 0x42, /* Native mode enable */
64 	PATA_UDMA_TIMING	= 0xB3, /* PATA timing for DMA/ cable detect */
65 	PATA_PIO_TIMING		= 0xAB, /* PATA timing register */
66 
67 	PORT0			= (1 << 1),
68 	PORT1			= (1 << 0),
69 	ALL_PORTS		= PORT0 | PORT1,
70 
71 	NATIVE_MODE_ALL		= (1 << 7) | (1 << 6) | (1 << 5) | (1 << 4),
72 
73 	SATA_EXT_PHY		= (1 << 6), /* 0==use PATA, 1==ext phy */
74 };
75 
76 static int svia_init_one(struct pci_dev *pdev, const struct pci_device_id *ent);
77 static int svia_scr_read(struct ata_link *link, unsigned int sc_reg, u32 *val);
78 static int svia_scr_write(struct ata_link *link, unsigned int sc_reg, u32 val);
79 static int vt8251_scr_read(struct ata_link *link, unsigned int scr, u32 *val);
80 static int vt8251_scr_write(struct ata_link *link, unsigned int scr, u32 val);
81 static void svia_tf_load(struct ata_port *ap, const struct ata_taskfile *tf);
82 static void svia_noop_freeze(struct ata_port *ap);
83 static int vt6420_prereset(struct ata_link *link, unsigned long deadline);
84 static void vt6420_bmdma_start(struct ata_queued_cmd *qc);
85 static int vt6421_pata_cable_detect(struct ata_port *ap);
86 static void vt6421_set_pio_mode(struct ata_port *ap, struct ata_device *adev);
87 static void vt6421_set_dma_mode(struct ata_port *ap, struct ata_device *adev);
88 
89 static const struct pci_device_id svia_pci_tbl[] = {
90 	{ PCI_VDEVICE(VIA, 0x5337), vt6420 },
91 	{ PCI_VDEVICE(VIA, 0x0591), vt6420 }, /* 2 sata chnls (Master) */
92 	{ PCI_VDEVICE(VIA, 0x3149), vt6420 }, /* 2 sata chnls (Master) */
93 	{ PCI_VDEVICE(VIA, 0x3249), vt6421 }, /* 2 sata chnls, 1 pata chnl */
94 	{ PCI_VDEVICE(VIA, 0x5372), vt6420 },
95 	{ PCI_VDEVICE(VIA, 0x7372), vt6420 },
96 	{ PCI_VDEVICE(VIA, 0x5287), vt8251 }, /* 2 sata chnls (Master/Slave) */
97 	{ PCI_VDEVICE(VIA, 0x9000), vt8251 },
98 
99 	{ }	/* terminate list */
100 };
101 
102 static struct pci_driver svia_pci_driver = {
103 	.name			= DRV_NAME,
104 	.id_table		= svia_pci_tbl,
105 	.probe			= svia_init_one,
106 #ifdef CONFIG_PM_SLEEP
107 	.suspend		= ata_pci_device_suspend,
108 	.resume			= ata_pci_device_resume,
109 #endif
110 	.remove			= ata_pci_remove_one,
111 };
112 
113 static struct scsi_host_template svia_sht = {
114 	ATA_BMDMA_SHT(DRV_NAME),
115 };
116 
117 static struct ata_port_operations svia_base_ops = {
118 	.inherits		= &ata_bmdma_port_ops,
119 	.sff_tf_load		= svia_tf_load,
120 };
121 
122 static struct ata_port_operations vt6420_sata_ops = {
123 	.inherits		= &svia_base_ops,
124 	.freeze			= svia_noop_freeze,
125 	.prereset		= vt6420_prereset,
126 	.bmdma_start		= vt6420_bmdma_start,
127 };
128 
129 static struct ata_port_operations vt6421_pata_ops = {
130 	.inherits		= &svia_base_ops,
131 	.cable_detect		= vt6421_pata_cable_detect,
132 	.set_piomode		= vt6421_set_pio_mode,
133 	.set_dmamode		= vt6421_set_dma_mode,
134 };
135 
136 static struct ata_port_operations vt6421_sata_ops = {
137 	.inherits		= &svia_base_ops,
138 	.scr_read		= svia_scr_read,
139 	.scr_write		= svia_scr_write,
140 };
141 
142 static struct ata_port_operations vt8251_ops = {
143 	.inherits		= &svia_base_ops,
144 	.hardreset		= sata_std_hardreset,
145 	.scr_read		= vt8251_scr_read,
146 	.scr_write		= vt8251_scr_write,
147 };
148 
149 static const struct ata_port_info vt6420_port_info = {
150 	.flags		= ATA_FLAG_SATA,
151 	.pio_mask	= ATA_PIO4,
152 	.mwdma_mask	= ATA_MWDMA2,
153 	.udma_mask	= ATA_UDMA6,
154 	.port_ops	= &vt6420_sata_ops,
155 };
156 
157 static struct ata_port_info vt6421_sport_info = {
158 	.flags		= ATA_FLAG_SATA,
159 	.pio_mask	= ATA_PIO4,
160 	.mwdma_mask	= ATA_MWDMA2,
161 	.udma_mask	= ATA_UDMA6,
162 	.port_ops	= &vt6421_sata_ops,
163 };
164 
165 static struct ata_port_info vt6421_pport_info = {
166 	.flags		= ATA_FLAG_SLAVE_POSS,
167 	.pio_mask	= ATA_PIO4,
168 	/* No MWDMA */
169 	.udma_mask	= ATA_UDMA6,
170 	.port_ops	= &vt6421_pata_ops,
171 };
172 
173 static struct ata_port_info vt8251_port_info = {
174 	.flags		= ATA_FLAG_SATA | ATA_FLAG_SLAVE_POSS,
175 	.pio_mask	= ATA_PIO4,
176 	.mwdma_mask	= ATA_MWDMA2,
177 	.udma_mask	= ATA_UDMA6,
178 	.port_ops	= &vt8251_ops,
179 };
180 
181 MODULE_AUTHOR("Jeff Garzik");
182 MODULE_DESCRIPTION("SCSI low-level driver for VIA SATA controllers");
183 MODULE_LICENSE("GPL");
184 MODULE_DEVICE_TABLE(pci, svia_pci_tbl);
185 MODULE_VERSION(DRV_VERSION);
186 
187 static int svia_scr_read(struct ata_link *link, unsigned int sc_reg, u32 *val)
188 {
189 	if (sc_reg > SCR_CONTROL)
190 		return -EINVAL;
191 	*val = ioread32(link->ap->ioaddr.scr_addr + (4 * sc_reg));
192 	return 0;
193 }
194 
195 static int svia_scr_write(struct ata_link *link, unsigned int sc_reg, u32 val)
196 {
197 	if (sc_reg > SCR_CONTROL)
198 		return -EINVAL;
199 	iowrite32(val, link->ap->ioaddr.scr_addr + (4 * sc_reg));
200 	return 0;
201 }
202 
203 static int vt8251_scr_read(struct ata_link *link, unsigned int scr, u32 *val)
204 {
205 	static const u8 ipm_tbl[] = { 1, 2, 6, 0 };
206 	struct pci_dev *pdev = to_pci_dev(link->ap->host->dev);
207 	int slot = 2 * link->ap->port_no + link->pmp;
208 	u32 v = 0;
209 	u8 raw;
210 
211 	switch (scr) {
212 	case SCR_STATUS:
213 		pci_read_config_byte(pdev, 0xA0 + slot, &raw);
214 
215 		/* read the DET field, bit0 and 1 of the config byte */
216 		v |= raw & 0x03;
217 
218 		/* read the SPD field, bit4 of the configure byte */
219 		if (raw & (1 << 4))
220 			v |= 0x02 << 4;
221 		else
222 			v |= 0x01 << 4;
223 
224 		/* read the IPM field, bit2 and 3 of the config byte */
225 		v |= ipm_tbl[(raw >> 2) & 0x3];
226 		break;
227 
228 	case SCR_ERROR:
229 		/* devices other than 5287 uses 0xA8 as base */
230 		WARN_ON(pdev->device != 0x5287);
231 		pci_read_config_dword(pdev, 0xB0 + slot * 4, &v);
232 		break;
233 
234 	case SCR_CONTROL:
235 		pci_read_config_byte(pdev, 0xA4 + slot, &raw);
236 
237 		/* read the DET field, bit0 and bit1 */
238 		v |= ((raw & 0x02) << 1) | (raw & 0x01);
239 
240 		/* read the IPM field, bit2 and bit3 */
241 		v |= ((raw >> 2) & 0x03) << 8;
242 		break;
243 
244 	default:
245 		return -EINVAL;
246 	}
247 
248 	*val = v;
249 	return 0;
250 }
251 
252 static int vt8251_scr_write(struct ata_link *link, unsigned int scr, u32 val)
253 {
254 	struct pci_dev *pdev = to_pci_dev(link->ap->host->dev);
255 	int slot = 2 * link->ap->port_no + link->pmp;
256 	u32 v = 0;
257 
258 	switch (scr) {
259 	case SCR_ERROR:
260 		/* devices other than 5287 uses 0xA8 as base */
261 		WARN_ON(pdev->device != 0x5287);
262 		pci_write_config_dword(pdev, 0xB0 + slot * 4, val);
263 		return 0;
264 
265 	case SCR_CONTROL:
266 		/* set the DET field */
267 		v |= ((val & 0x4) >> 1) | (val & 0x1);
268 
269 		/* set the IPM field */
270 		v |= ((val >> 8) & 0x3) << 2;
271 
272 		pci_write_config_byte(pdev, 0xA4 + slot, v);
273 		return 0;
274 
275 	default:
276 		return -EINVAL;
277 	}
278 }
279 
280 /**
281  *	svia_tf_load - send taskfile registers to host controller
282  *	@ap: Port to which output is sent
283  *	@tf: ATA taskfile register set
284  *
285  *	Outputs ATA taskfile to standard ATA host controller.
286  *
287  *	This is to fix the internal bug of via chipsets, which will
288  *	reset the device register after changing the IEN bit on ctl
289  *	register.
290  */
291 static void svia_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
292 {
293 	struct ata_taskfile ttf;
294 
295 	if (tf->ctl != ap->last_ctl)  {
296 		ttf = *tf;
297 		ttf.flags |= ATA_TFLAG_DEVICE;
298 		tf = &ttf;
299 	}
300 	ata_sff_tf_load(ap, tf);
301 }
302 
303 static void svia_noop_freeze(struct ata_port *ap)
304 {
305 	/* Some VIA controllers choke if ATA_NIEN is manipulated in
306 	 * certain way.  Leave it alone and just clear pending IRQ.
307 	 */
308 	ap->ops->sff_check_status(ap);
309 	ata_bmdma_irq_clear(ap);
310 }
311 
312 /**
313  *	vt6420_prereset - prereset for vt6420
314  *	@link: target ATA link
315  *	@deadline: deadline jiffies for the operation
316  *
317  *	SCR registers on vt6420 are pieces of shit and may hang the
318  *	whole machine completely if accessed with the wrong timing.
319  *	To avoid such catastrophe, vt6420 doesn't provide generic SCR
320  *	access operations, but uses SStatus and SControl only during
321  *	boot probing in controlled way.
322  *
323  *	As the old (pre EH update) probing code is proven to work, we
324  *	strictly follow the access pattern.
325  *
326  *	LOCKING:
327  *	Kernel thread context (may sleep)
328  *
329  *	RETURNS:
330  *	0 on success, -errno otherwise.
331  */
332 static int vt6420_prereset(struct ata_link *link, unsigned long deadline)
333 {
334 	struct ata_port *ap = link->ap;
335 	struct ata_eh_context *ehc = &ap->link.eh_context;
336 	unsigned long timeout = jiffies + (HZ * 5);
337 	u32 sstatus, scontrol;
338 	int online;
339 
340 	/* don't do any SCR stuff if we're not loading */
341 	if (!(ap->pflags & ATA_PFLAG_LOADING))
342 		goto skip_scr;
343 
344 	/* Resume phy.  This is the old SATA resume sequence */
345 	svia_scr_write(link, SCR_CONTROL, 0x300);
346 	svia_scr_read(link, SCR_CONTROL, &scontrol); /* flush */
347 
348 	/* wait for phy to become ready, if necessary */
349 	do {
350 		ata_msleep(link->ap, 200);
351 		svia_scr_read(link, SCR_STATUS, &sstatus);
352 		if ((sstatus & 0xf) != 1)
353 			break;
354 	} while (time_before(jiffies, timeout));
355 
356 	/* open code sata_print_link_status() */
357 	svia_scr_read(link, SCR_STATUS, &sstatus);
358 	svia_scr_read(link, SCR_CONTROL, &scontrol);
359 
360 	online = (sstatus & 0xf) == 0x3;
361 
362 	ata_port_info(ap,
363 		      "SATA link %s 1.5 Gbps (SStatus %X SControl %X)\n",
364 		      online ? "up" : "down", sstatus, scontrol);
365 
366 	/* SStatus is read one more time */
367 	svia_scr_read(link, SCR_STATUS, &sstatus);
368 
369 	if (!online) {
370 		/* tell EH to bail */
371 		ehc->i.action &= ~ATA_EH_RESET;
372 		return 0;
373 	}
374 
375  skip_scr:
376 	/* wait for !BSY */
377 	ata_sff_wait_ready(link, deadline);
378 
379 	return 0;
380 }
381 
382 static void vt6420_bmdma_start(struct ata_queued_cmd *qc)
383 {
384 	struct ata_port *ap = qc->ap;
385 	if ((qc->tf.command == ATA_CMD_PACKET) &&
386 	    (qc->scsicmd->sc_data_direction == DMA_TO_DEVICE)) {
387 		/* Prevents corruption on some ATAPI burners */
388 		ata_sff_pause(ap);
389 	}
390 	ata_bmdma_start(qc);
391 }
392 
393 static int vt6421_pata_cable_detect(struct ata_port *ap)
394 {
395 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
396 	u8 tmp;
397 
398 	pci_read_config_byte(pdev, PATA_UDMA_TIMING, &tmp);
399 	if (tmp & 0x10)
400 		return ATA_CBL_PATA40;
401 	return ATA_CBL_PATA80;
402 }
403 
404 static void vt6421_set_pio_mode(struct ata_port *ap, struct ata_device *adev)
405 {
406 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
407 	static const u8 pio_bits[] = { 0xA8, 0x65, 0x65, 0x31, 0x20 };
408 	pci_write_config_byte(pdev, PATA_PIO_TIMING - adev->devno,
409 			      pio_bits[adev->pio_mode - XFER_PIO_0]);
410 }
411 
412 static void vt6421_set_dma_mode(struct ata_port *ap, struct ata_device *adev)
413 {
414 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
415 	static const u8 udma_bits[] = { 0xEE, 0xE8, 0xE6, 0xE4, 0xE2, 0xE1, 0xE0, 0xE0 };
416 	pci_write_config_byte(pdev, PATA_UDMA_TIMING - adev->devno,
417 			      udma_bits[adev->dma_mode - XFER_UDMA_0]);
418 }
419 
420 static const unsigned int svia_bar_sizes[] = {
421 	8, 4, 8, 4, 16, 256
422 };
423 
424 static const unsigned int vt6421_bar_sizes[] = {
425 	16, 16, 16, 16, 32, 128
426 };
427 
428 static void __iomem *svia_scr_addr(void __iomem *addr, unsigned int port)
429 {
430 	return addr + (port * 128);
431 }
432 
433 static void __iomem *vt6421_scr_addr(void __iomem *addr, unsigned int port)
434 {
435 	return addr + (port * 64);
436 }
437 
438 static void vt6421_init_addrs(struct ata_port *ap)
439 {
440 	void __iomem * const * iomap = ap->host->iomap;
441 	void __iomem *reg_addr = iomap[ap->port_no];
442 	void __iomem *bmdma_addr = iomap[4] + (ap->port_no * 8);
443 	struct ata_ioports *ioaddr = &ap->ioaddr;
444 
445 	ioaddr->cmd_addr = reg_addr;
446 	ioaddr->altstatus_addr =
447 	ioaddr->ctl_addr = (void __iomem *)
448 		((unsigned long)(reg_addr + 8) | ATA_PCI_CTL_OFS);
449 	ioaddr->bmdma_addr = bmdma_addr;
450 	ioaddr->scr_addr = vt6421_scr_addr(iomap[5], ap->port_no);
451 
452 	ata_sff_std_ports(ioaddr);
453 
454 	ata_port_pbar_desc(ap, ap->port_no, -1, "port");
455 	ata_port_pbar_desc(ap, 4, ap->port_no * 8, "bmdma");
456 }
457 
458 static int vt6420_prepare_host(struct pci_dev *pdev, struct ata_host **r_host)
459 {
460 	const struct ata_port_info *ppi[] = { &vt6420_port_info, NULL };
461 	struct ata_host *host;
462 	int rc;
463 
464 	rc = ata_pci_bmdma_prepare_host(pdev, ppi, &host);
465 	if (rc)
466 		return rc;
467 	*r_host = host;
468 
469 	rc = pcim_iomap_regions(pdev, 1 << 5, DRV_NAME);
470 	if (rc) {
471 		dev_err(&pdev->dev, "failed to iomap PCI BAR 5\n");
472 		return rc;
473 	}
474 
475 	host->ports[0]->ioaddr.scr_addr = svia_scr_addr(host->iomap[5], 0);
476 	host->ports[1]->ioaddr.scr_addr = svia_scr_addr(host->iomap[5], 1);
477 
478 	return 0;
479 }
480 
481 static int vt6421_prepare_host(struct pci_dev *pdev, struct ata_host **r_host)
482 {
483 	const struct ata_port_info *ppi[] =
484 		{ &vt6421_sport_info, &vt6421_sport_info, &vt6421_pport_info };
485 	struct ata_host *host;
486 	int i, rc;
487 
488 	*r_host = host = ata_host_alloc_pinfo(&pdev->dev, ppi, ARRAY_SIZE(ppi));
489 	if (!host) {
490 		dev_err(&pdev->dev, "failed to allocate host\n");
491 		return -ENOMEM;
492 	}
493 
494 	rc = pcim_iomap_regions(pdev, 0x3f, DRV_NAME);
495 	if (rc) {
496 		dev_err(&pdev->dev, "failed to request/iomap PCI BARs (errno=%d)\n",
497 			rc);
498 		return rc;
499 	}
500 	host->iomap = pcim_iomap_table(pdev);
501 
502 	for (i = 0; i < host->n_ports; i++)
503 		vt6421_init_addrs(host->ports[i]);
504 
505 	rc = dma_set_mask(&pdev->dev, ATA_DMA_MASK);
506 	if (rc)
507 		return rc;
508 	rc = dma_set_coherent_mask(&pdev->dev, ATA_DMA_MASK);
509 	if (rc)
510 		return rc;
511 
512 	return 0;
513 }
514 
515 static int vt8251_prepare_host(struct pci_dev *pdev, struct ata_host **r_host)
516 {
517 	const struct ata_port_info *ppi[] = { &vt8251_port_info, NULL };
518 	struct ata_host *host;
519 	int i, rc;
520 
521 	rc = ata_pci_bmdma_prepare_host(pdev, ppi, &host);
522 	if (rc)
523 		return rc;
524 	*r_host = host;
525 
526 	rc = pcim_iomap_regions(pdev, 1 << 5, DRV_NAME);
527 	if (rc) {
528 		dev_err(&pdev->dev, "failed to iomap PCI BAR 5\n");
529 		return rc;
530 	}
531 
532 	/* 8251 hosts four sata ports as M/S of the two channels */
533 	for (i = 0; i < host->n_ports; i++)
534 		ata_slave_link_init(host->ports[i]);
535 
536 	return 0;
537 }
538 
539 static void svia_configure(struct pci_dev *pdev, int board_id)
540 {
541 	u8 tmp8;
542 
543 	pci_read_config_byte(pdev, PCI_INTERRUPT_LINE, &tmp8);
544 	dev_info(&pdev->dev, "routed to hard irq line %d\n",
545 		 (int) (tmp8 & 0xf0) == 0xf0 ? 0 : tmp8 & 0x0f);
546 
547 	/* make sure SATA channels are enabled */
548 	pci_read_config_byte(pdev, SATA_CHAN_ENAB, &tmp8);
549 	if ((tmp8 & ALL_PORTS) != ALL_PORTS) {
550 		dev_dbg(&pdev->dev, "enabling SATA channels (0x%x)\n",
551 			(int)tmp8);
552 		tmp8 |= ALL_PORTS;
553 		pci_write_config_byte(pdev, SATA_CHAN_ENAB, tmp8);
554 	}
555 
556 	/* make sure interrupts for each channel sent to us */
557 	pci_read_config_byte(pdev, SATA_INT_GATE, &tmp8);
558 	if ((tmp8 & ALL_PORTS) != ALL_PORTS) {
559 		dev_dbg(&pdev->dev, "enabling SATA channel interrupts (0x%x)\n",
560 			(int) tmp8);
561 		tmp8 |= ALL_PORTS;
562 		pci_write_config_byte(pdev, SATA_INT_GATE, tmp8);
563 	}
564 
565 	/* make sure native mode is enabled */
566 	pci_read_config_byte(pdev, SATA_NATIVE_MODE, &tmp8);
567 	if ((tmp8 & NATIVE_MODE_ALL) != NATIVE_MODE_ALL) {
568 		dev_dbg(&pdev->dev,
569 			"enabling SATA channel native mode (0x%x)\n",
570 			(int) tmp8);
571 		tmp8 |= NATIVE_MODE_ALL;
572 		pci_write_config_byte(pdev, SATA_NATIVE_MODE, tmp8);
573 	}
574 
575 	/*
576 	 * vt6420/1 has problems talking to some drives.  The following
577 	 * is the fix from Joseph Chan <JosephChan@via.com.tw>.
578 	 *
579 	 * When host issues HOLD, device may send up to 20DW of data
580 	 * before acknowledging it with HOLDA and the host should be
581 	 * able to buffer them in FIFO.  Unfortunately, some WD drives
582 	 * send up to 40DW before acknowledging HOLD and, in the
583 	 * default configuration, this ends up overflowing vt6421's
584 	 * FIFO, making the controller abort the transaction with
585 	 * R_ERR.
586 	 *
587 	 * Rx52[2] is the internal 128DW FIFO Flow control watermark
588 	 * adjusting mechanism enable bit and the default value 0
589 	 * means host will issue HOLD to device when the left FIFO
590 	 * size goes below 32DW.  Setting it to 1 makes the watermark
591 	 * 64DW.
592 	 *
593 	 * https://bugzilla.kernel.org/show_bug.cgi?id=15173
594 	 * http://article.gmane.org/gmane.linux.ide/46352
595 	 * http://thread.gmane.org/gmane.linux.kernel/1062139
596 	 */
597 	if (board_id == vt6420 || board_id == vt6421) {
598 		pci_read_config_byte(pdev, 0x52, &tmp8);
599 		tmp8 |= 1 << 2;
600 		pci_write_config_byte(pdev, 0x52, tmp8);
601 	}
602 }
603 
604 static int svia_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
605 {
606 	unsigned int i;
607 	int rc;
608 	struct ata_host *host = NULL;
609 	int board_id = (int) ent->driver_data;
610 	const unsigned *bar_sizes;
611 
612 	ata_print_version_once(&pdev->dev, DRV_VERSION);
613 
614 	rc = pcim_enable_device(pdev);
615 	if (rc)
616 		return rc;
617 
618 	if (board_id == vt6421)
619 		bar_sizes = &vt6421_bar_sizes[0];
620 	else
621 		bar_sizes = &svia_bar_sizes[0];
622 
623 	for (i = 0; i < ARRAY_SIZE(svia_bar_sizes); i++)
624 		if ((pci_resource_start(pdev, i) == 0) ||
625 		    (pci_resource_len(pdev, i) < bar_sizes[i])) {
626 			dev_err(&pdev->dev,
627 				"invalid PCI BAR %u (sz 0x%llx, val 0x%llx)\n",
628 				i,
629 				(unsigned long long)pci_resource_start(pdev, i),
630 				(unsigned long long)pci_resource_len(pdev, i));
631 			return -ENODEV;
632 		}
633 
634 	switch (board_id) {
635 	case vt6420:
636 		rc = vt6420_prepare_host(pdev, &host);
637 		break;
638 	case vt6421:
639 		rc = vt6421_prepare_host(pdev, &host);
640 		break;
641 	case vt8251:
642 		rc = vt8251_prepare_host(pdev, &host);
643 		break;
644 	default:
645 		rc = -EINVAL;
646 	}
647 	if (rc)
648 		return rc;
649 
650 	svia_configure(pdev, board_id);
651 
652 	pci_set_master(pdev);
653 	return ata_host_activate(host, pdev->irq, ata_bmdma_interrupt,
654 				 IRQF_SHARED, &svia_sht);
655 }
656 
657 module_pci_driver(svia_pci_driver);
658