xref: /openbmc/linux/drivers/ata/sata_via.c (revision 63dc02bd)
1 /*
2  *  sata_via.c - VIA Serial ATA controllers
3  *
4  *  Maintained by:  Jeff Garzik <jgarzik@pobox.com>
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/init.h>
40 #include <linux/blkdev.h>
41 #include <linux/delay.h>
42 #include <linux/device.h>
43 #include <scsi/scsi.h>
44 #include <scsi/scsi_cmnd.h>
45 #include <scsi/scsi_host.h>
46 #include <linux/libata.h>
47 
48 #define DRV_NAME	"sata_via"
49 #define DRV_VERSION	"2.6"
50 
51 /*
52  * vt8251 is different from other sata controllers of VIA.  It has two
53  * channels, each channel has both Master and Slave slot.
54  */
55 enum board_ids_enum {
56 	vt6420,
57 	vt6421,
58 	vt8251,
59 };
60 
61 enum {
62 	SATA_CHAN_ENAB		= 0x40, /* SATA channel enable */
63 	SATA_INT_GATE		= 0x41, /* SATA interrupt gating */
64 	SATA_NATIVE_MODE	= 0x42, /* Native mode enable */
65 	PATA_UDMA_TIMING	= 0xB3, /* PATA timing for DMA/ cable detect */
66 	PATA_PIO_TIMING		= 0xAB, /* PATA timing register */
67 
68 	PORT0			= (1 << 1),
69 	PORT1			= (1 << 0),
70 	ALL_PORTS		= PORT0 | PORT1,
71 
72 	NATIVE_MODE_ALL		= (1 << 7) | (1 << 6) | (1 << 5) | (1 << 4),
73 
74 	SATA_EXT_PHY		= (1 << 6), /* 0==use PATA, 1==ext phy */
75 };
76 
77 static int svia_init_one(struct pci_dev *pdev, const struct pci_device_id *ent);
78 static int svia_scr_read(struct ata_link *link, unsigned int sc_reg, u32 *val);
79 static int svia_scr_write(struct ata_link *link, unsigned int sc_reg, u32 val);
80 static int vt8251_scr_read(struct ata_link *link, unsigned int scr, u32 *val);
81 static int vt8251_scr_write(struct ata_link *link, unsigned int scr, u32 val);
82 static void svia_tf_load(struct ata_port *ap, const struct ata_taskfile *tf);
83 static void svia_noop_freeze(struct ata_port *ap);
84 static int vt6420_prereset(struct ata_link *link, unsigned long deadline);
85 static void vt6420_bmdma_start(struct ata_queued_cmd *qc);
86 static int vt6421_pata_cable_detect(struct ata_port *ap);
87 static void vt6421_set_pio_mode(struct ata_port *ap, struct ata_device *adev);
88 static void vt6421_set_dma_mode(struct ata_port *ap, struct ata_device *adev);
89 
90 static const struct pci_device_id svia_pci_tbl[] = {
91 	{ PCI_VDEVICE(VIA, 0x5337), vt6420 },
92 	{ PCI_VDEVICE(VIA, 0x0591), vt6420 }, /* 2 sata chnls (Master) */
93 	{ PCI_VDEVICE(VIA, 0x3149), vt6420 }, /* 2 sata chnls (Master) */
94 	{ PCI_VDEVICE(VIA, 0x3249), vt6421 }, /* 2 sata chnls, 1 pata chnl */
95 	{ PCI_VDEVICE(VIA, 0x5372), vt6420 },
96 	{ PCI_VDEVICE(VIA, 0x7372), vt6420 },
97 	{ PCI_VDEVICE(VIA, 0x5287), vt8251 }, /* 2 sata chnls (Master/Slave) */
98 	{ PCI_VDEVICE(VIA, 0x9000), vt8251 },
99 
100 	{ }	/* terminate list */
101 };
102 
103 static struct pci_driver svia_pci_driver = {
104 	.name			= DRV_NAME,
105 	.id_table		= svia_pci_tbl,
106 	.probe			= svia_init_one,
107 #ifdef CONFIG_PM
108 	.suspend		= ata_pci_device_suspend,
109 	.resume			= ata_pci_device_resume,
110 #endif
111 	.remove			= ata_pci_remove_one,
112 };
113 
114 static struct scsi_host_template svia_sht = {
115 	ATA_BMDMA_SHT(DRV_NAME),
116 };
117 
118 static struct ata_port_operations svia_base_ops = {
119 	.inherits		= &ata_bmdma_port_ops,
120 	.sff_tf_load		= svia_tf_load,
121 };
122 
123 static struct ata_port_operations vt6420_sata_ops = {
124 	.inherits		= &svia_base_ops,
125 	.freeze			= svia_noop_freeze,
126 	.prereset		= vt6420_prereset,
127 	.bmdma_start		= vt6420_bmdma_start,
128 };
129 
130 static struct ata_port_operations vt6421_pata_ops = {
131 	.inherits		= &svia_base_ops,
132 	.cable_detect		= vt6421_pata_cable_detect,
133 	.set_piomode		= vt6421_set_pio_mode,
134 	.set_dmamode		= vt6421_set_dma_mode,
135 };
136 
137 static struct ata_port_operations vt6421_sata_ops = {
138 	.inherits		= &svia_base_ops,
139 	.scr_read		= svia_scr_read,
140 	.scr_write		= svia_scr_write,
141 };
142 
143 static struct ata_port_operations vt8251_ops = {
144 	.inherits		= &svia_base_ops,
145 	.hardreset		= sata_std_hardreset,
146 	.scr_read		= vt8251_scr_read,
147 	.scr_write		= vt8251_scr_write,
148 };
149 
150 static const struct ata_port_info vt6420_port_info = {
151 	.flags		= ATA_FLAG_SATA,
152 	.pio_mask	= ATA_PIO4,
153 	.mwdma_mask	= ATA_MWDMA2,
154 	.udma_mask	= ATA_UDMA6,
155 	.port_ops	= &vt6420_sata_ops,
156 };
157 
158 static struct ata_port_info vt6421_sport_info = {
159 	.flags		= ATA_FLAG_SATA,
160 	.pio_mask	= ATA_PIO4,
161 	.mwdma_mask	= ATA_MWDMA2,
162 	.udma_mask	= ATA_UDMA6,
163 	.port_ops	= &vt6421_sata_ops,
164 };
165 
166 static struct ata_port_info vt6421_pport_info = {
167 	.flags		= ATA_FLAG_SLAVE_POSS,
168 	.pio_mask	= ATA_PIO4,
169 	/* No MWDMA */
170 	.udma_mask	= ATA_UDMA6,
171 	.port_ops	= &vt6421_pata_ops,
172 };
173 
174 static struct ata_port_info vt8251_port_info = {
175 	.flags		= ATA_FLAG_SATA | ATA_FLAG_SLAVE_POSS,
176 	.pio_mask	= ATA_PIO4,
177 	.mwdma_mask	= ATA_MWDMA2,
178 	.udma_mask	= ATA_UDMA6,
179 	.port_ops	= &vt8251_ops,
180 };
181 
182 MODULE_AUTHOR("Jeff Garzik");
183 MODULE_DESCRIPTION("SCSI low-level driver for VIA SATA controllers");
184 MODULE_LICENSE("GPL");
185 MODULE_DEVICE_TABLE(pci, svia_pci_tbl);
186 MODULE_VERSION(DRV_VERSION);
187 
188 static int svia_scr_read(struct ata_link *link, unsigned int sc_reg, u32 *val)
189 {
190 	if (sc_reg > SCR_CONTROL)
191 		return -EINVAL;
192 	*val = ioread32(link->ap->ioaddr.scr_addr + (4 * sc_reg));
193 	return 0;
194 }
195 
196 static int svia_scr_write(struct ata_link *link, unsigned int sc_reg, u32 val)
197 {
198 	if (sc_reg > SCR_CONTROL)
199 		return -EINVAL;
200 	iowrite32(val, link->ap->ioaddr.scr_addr + (4 * sc_reg));
201 	return 0;
202 }
203 
204 static int vt8251_scr_read(struct ata_link *link, unsigned int scr, u32 *val)
205 {
206 	static const u8 ipm_tbl[] = { 1, 2, 6, 0 };
207 	struct pci_dev *pdev = to_pci_dev(link->ap->host->dev);
208 	int slot = 2 * link->ap->port_no + link->pmp;
209 	u32 v = 0;
210 	u8 raw;
211 
212 	switch (scr) {
213 	case SCR_STATUS:
214 		pci_read_config_byte(pdev, 0xA0 + slot, &raw);
215 
216 		/* read the DET field, bit0 and 1 of the config byte */
217 		v |= raw & 0x03;
218 
219 		/* read the SPD field, bit4 of the configure byte */
220 		if (raw & (1 << 4))
221 			v |= 0x02 << 4;
222 		else
223 			v |= 0x01 << 4;
224 
225 		/* read the IPM field, bit2 and 3 of the config byte */
226 		v |= ipm_tbl[(raw >> 2) & 0x3];
227 		break;
228 
229 	case SCR_ERROR:
230 		/* devices other than 5287 uses 0xA8 as base */
231 		WARN_ON(pdev->device != 0x5287);
232 		pci_read_config_dword(pdev, 0xB0 + slot * 4, &v);
233 		break;
234 
235 	case SCR_CONTROL:
236 		pci_read_config_byte(pdev, 0xA4 + slot, &raw);
237 
238 		/* read the DET field, bit0 and bit1 */
239 		v |= ((raw & 0x02) << 1) | (raw & 0x01);
240 
241 		/* read the IPM field, bit2 and bit3 */
242 		v |= ((raw >> 2) & 0x03) << 8;
243 		break;
244 
245 	default:
246 		return -EINVAL;
247 	}
248 
249 	*val = v;
250 	return 0;
251 }
252 
253 static int vt8251_scr_write(struct ata_link *link, unsigned int scr, u32 val)
254 {
255 	struct pci_dev *pdev = to_pci_dev(link->ap->host->dev);
256 	int slot = 2 * link->ap->port_no + link->pmp;
257 	u32 v = 0;
258 
259 	switch (scr) {
260 	case SCR_ERROR:
261 		/* devices other than 5287 uses 0xA8 as base */
262 		WARN_ON(pdev->device != 0x5287);
263 		pci_write_config_dword(pdev, 0xB0 + slot * 4, val);
264 		return 0;
265 
266 	case SCR_CONTROL:
267 		/* set the DET field */
268 		v |= ((val & 0x4) >> 1) | (val & 0x1);
269 
270 		/* set the IPM field */
271 		v |= ((val >> 8) & 0x3) << 2;
272 
273 		pci_write_config_byte(pdev, 0xA4 + slot, v);
274 		return 0;
275 
276 	default:
277 		return -EINVAL;
278 	}
279 }
280 
281 /**
282  *	svia_tf_load - send taskfile registers to host controller
283  *	@ap: Port to which output is sent
284  *	@tf: ATA taskfile register set
285  *
286  *	Outputs ATA taskfile to standard ATA host controller.
287  *
288  *	This is to fix the internal bug of via chipsets, which will
289  *	reset the device register after changing the IEN bit on ctl
290  *	register.
291  */
292 static void svia_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
293 {
294 	struct ata_taskfile ttf;
295 
296 	if (tf->ctl != ap->last_ctl)  {
297 		ttf = *tf;
298 		ttf.flags |= ATA_TFLAG_DEVICE;
299 		tf = &ttf;
300 	}
301 	ata_sff_tf_load(ap, tf);
302 }
303 
304 static void svia_noop_freeze(struct ata_port *ap)
305 {
306 	/* Some VIA controllers choke if ATA_NIEN is manipulated in
307 	 * certain way.  Leave it alone and just clear pending IRQ.
308 	 */
309 	ap->ops->sff_check_status(ap);
310 	ata_bmdma_irq_clear(ap);
311 }
312 
313 /**
314  *	vt6420_prereset - prereset for vt6420
315  *	@link: target ATA link
316  *	@deadline: deadline jiffies for the operation
317  *
318  *	SCR registers on vt6420 are pieces of shit and may hang the
319  *	whole machine completely if accessed with the wrong timing.
320  *	To avoid such catastrophe, vt6420 doesn't provide generic SCR
321  *	access operations, but uses SStatus and SControl only during
322  *	boot probing in controlled way.
323  *
324  *	As the old (pre EH update) probing code is proven to work, we
325  *	strictly follow the access pattern.
326  *
327  *	LOCKING:
328  *	Kernel thread context (may sleep)
329  *
330  *	RETURNS:
331  *	0 on success, -errno otherwise.
332  */
333 static int vt6420_prereset(struct ata_link *link, unsigned long deadline)
334 {
335 	struct ata_port *ap = link->ap;
336 	struct ata_eh_context *ehc = &ap->link.eh_context;
337 	unsigned long timeout = jiffies + (HZ * 5);
338 	u32 sstatus, scontrol;
339 	int online;
340 
341 	/* don't do any SCR stuff if we're not loading */
342 	if (!(ap->pflags & ATA_PFLAG_LOADING))
343 		goto skip_scr;
344 
345 	/* Resume phy.  This is the old SATA resume sequence */
346 	svia_scr_write(link, SCR_CONTROL, 0x300);
347 	svia_scr_read(link, SCR_CONTROL, &scontrol); /* flush */
348 
349 	/* wait for phy to become ready, if necessary */
350 	do {
351 		ata_msleep(link->ap, 200);
352 		svia_scr_read(link, SCR_STATUS, &sstatus);
353 		if ((sstatus & 0xf) != 1)
354 			break;
355 	} while (time_before(jiffies, timeout));
356 
357 	/* open code sata_print_link_status() */
358 	svia_scr_read(link, SCR_STATUS, &sstatus);
359 	svia_scr_read(link, SCR_CONTROL, &scontrol);
360 
361 	online = (sstatus & 0xf) == 0x3;
362 
363 	ata_port_info(ap,
364 		      "SATA link %s 1.5 Gbps (SStatus %X SControl %X)\n",
365 		      online ? "up" : "down", sstatus, scontrol);
366 
367 	/* SStatus is read one more time */
368 	svia_scr_read(link, SCR_STATUS, &sstatus);
369 
370 	if (!online) {
371 		/* tell EH to bail */
372 		ehc->i.action &= ~ATA_EH_RESET;
373 		return 0;
374 	}
375 
376  skip_scr:
377 	/* wait for !BSY */
378 	ata_sff_wait_ready(link, deadline);
379 
380 	return 0;
381 }
382 
383 static void vt6420_bmdma_start(struct ata_queued_cmd *qc)
384 {
385 	struct ata_port *ap = qc->ap;
386 	if ((qc->tf.command == ATA_CMD_PACKET) &&
387 	    (qc->scsicmd->sc_data_direction == DMA_TO_DEVICE)) {
388 		/* Prevents corruption on some ATAPI burners */
389 		ata_sff_pause(ap);
390 	}
391 	ata_bmdma_start(qc);
392 }
393 
394 static int vt6421_pata_cable_detect(struct ata_port *ap)
395 {
396 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
397 	u8 tmp;
398 
399 	pci_read_config_byte(pdev, PATA_UDMA_TIMING, &tmp);
400 	if (tmp & 0x10)
401 		return ATA_CBL_PATA40;
402 	return ATA_CBL_PATA80;
403 }
404 
405 static void vt6421_set_pio_mode(struct ata_port *ap, struct ata_device *adev)
406 {
407 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
408 	static const u8 pio_bits[] = { 0xA8, 0x65, 0x65, 0x31, 0x20 };
409 	pci_write_config_byte(pdev, PATA_PIO_TIMING - adev->devno,
410 			      pio_bits[adev->pio_mode - XFER_PIO_0]);
411 }
412 
413 static void vt6421_set_dma_mode(struct ata_port *ap, struct ata_device *adev)
414 {
415 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
416 	static const u8 udma_bits[] = { 0xEE, 0xE8, 0xE6, 0xE4, 0xE2, 0xE1, 0xE0, 0xE0 };
417 	pci_write_config_byte(pdev, PATA_UDMA_TIMING - adev->devno,
418 			      udma_bits[adev->dma_mode - XFER_UDMA_0]);
419 }
420 
421 static const unsigned int svia_bar_sizes[] = {
422 	8, 4, 8, 4, 16, 256
423 };
424 
425 static const unsigned int vt6421_bar_sizes[] = {
426 	16, 16, 16, 16, 32, 128
427 };
428 
429 static void __iomem *svia_scr_addr(void __iomem *addr, unsigned int port)
430 {
431 	return addr + (port * 128);
432 }
433 
434 static void __iomem *vt6421_scr_addr(void __iomem *addr, unsigned int port)
435 {
436 	return addr + (port * 64);
437 }
438 
439 static void vt6421_init_addrs(struct ata_port *ap)
440 {
441 	void __iomem * const * iomap = ap->host->iomap;
442 	void __iomem *reg_addr = iomap[ap->port_no];
443 	void __iomem *bmdma_addr = iomap[4] + (ap->port_no * 8);
444 	struct ata_ioports *ioaddr = &ap->ioaddr;
445 
446 	ioaddr->cmd_addr = reg_addr;
447 	ioaddr->altstatus_addr =
448 	ioaddr->ctl_addr = (void __iomem *)
449 		((unsigned long)(reg_addr + 8) | ATA_PCI_CTL_OFS);
450 	ioaddr->bmdma_addr = bmdma_addr;
451 	ioaddr->scr_addr = vt6421_scr_addr(iomap[5], ap->port_no);
452 
453 	ata_sff_std_ports(ioaddr);
454 
455 	ata_port_pbar_desc(ap, ap->port_no, -1, "port");
456 	ata_port_pbar_desc(ap, 4, ap->port_no * 8, "bmdma");
457 }
458 
459 static int vt6420_prepare_host(struct pci_dev *pdev, struct ata_host **r_host)
460 {
461 	const struct ata_port_info *ppi[] = { &vt6420_port_info, NULL };
462 	struct ata_host *host;
463 	int rc;
464 
465 	rc = ata_pci_bmdma_prepare_host(pdev, ppi, &host);
466 	if (rc)
467 		return rc;
468 	*r_host = host;
469 
470 	rc = pcim_iomap_regions(pdev, 1 << 5, DRV_NAME);
471 	if (rc) {
472 		dev_err(&pdev->dev, "failed to iomap PCI BAR 5\n");
473 		return rc;
474 	}
475 
476 	host->ports[0]->ioaddr.scr_addr = svia_scr_addr(host->iomap[5], 0);
477 	host->ports[1]->ioaddr.scr_addr = svia_scr_addr(host->iomap[5], 1);
478 
479 	return 0;
480 }
481 
482 static int vt6421_prepare_host(struct pci_dev *pdev, struct ata_host **r_host)
483 {
484 	const struct ata_port_info *ppi[] =
485 		{ &vt6421_sport_info, &vt6421_sport_info, &vt6421_pport_info };
486 	struct ata_host *host;
487 	int i, rc;
488 
489 	*r_host = host = ata_host_alloc_pinfo(&pdev->dev, ppi, ARRAY_SIZE(ppi));
490 	if (!host) {
491 		dev_err(&pdev->dev, "failed to allocate host\n");
492 		return -ENOMEM;
493 	}
494 
495 	rc = pcim_iomap_regions(pdev, 0x3f, DRV_NAME);
496 	if (rc) {
497 		dev_err(&pdev->dev, "failed to request/iomap PCI BARs (errno=%d)\n",
498 			rc);
499 		return rc;
500 	}
501 	host->iomap = pcim_iomap_table(pdev);
502 
503 	for (i = 0; i < host->n_ports; i++)
504 		vt6421_init_addrs(host->ports[i]);
505 
506 	rc = pci_set_dma_mask(pdev, ATA_DMA_MASK);
507 	if (rc)
508 		return rc;
509 	rc = pci_set_consistent_dma_mask(pdev, ATA_DMA_MASK);
510 	if (rc)
511 		return rc;
512 
513 	return 0;
514 }
515 
516 static int vt8251_prepare_host(struct pci_dev *pdev, struct ata_host **r_host)
517 {
518 	const struct ata_port_info *ppi[] = { &vt8251_port_info, NULL };
519 	struct ata_host *host;
520 	int i, rc;
521 
522 	rc = ata_pci_bmdma_prepare_host(pdev, ppi, &host);
523 	if (rc)
524 		return rc;
525 	*r_host = host;
526 
527 	rc = pcim_iomap_regions(pdev, 1 << 5, DRV_NAME);
528 	if (rc) {
529 		dev_err(&pdev->dev, "failed to iomap PCI BAR 5\n");
530 		return rc;
531 	}
532 
533 	/* 8251 hosts four sata ports as M/S of the two channels */
534 	for (i = 0; i < host->n_ports; i++)
535 		ata_slave_link_init(host->ports[i]);
536 
537 	return 0;
538 }
539 
540 static void svia_configure(struct pci_dev *pdev, int board_id)
541 {
542 	u8 tmp8;
543 
544 	pci_read_config_byte(pdev, PCI_INTERRUPT_LINE, &tmp8);
545 	dev_info(&pdev->dev, "routed to hard irq line %d\n",
546 		 (int) (tmp8 & 0xf0) == 0xf0 ? 0 : tmp8 & 0x0f);
547 
548 	/* make sure SATA channels are enabled */
549 	pci_read_config_byte(pdev, SATA_CHAN_ENAB, &tmp8);
550 	if ((tmp8 & ALL_PORTS) != ALL_PORTS) {
551 		dev_dbg(&pdev->dev, "enabling SATA channels (0x%x)\n",
552 			(int)tmp8);
553 		tmp8 |= ALL_PORTS;
554 		pci_write_config_byte(pdev, SATA_CHAN_ENAB, tmp8);
555 	}
556 
557 	/* make sure interrupts for each channel sent to us */
558 	pci_read_config_byte(pdev, SATA_INT_GATE, &tmp8);
559 	if ((tmp8 & ALL_PORTS) != ALL_PORTS) {
560 		dev_dbg(&pdev->dev, "enabling SATA channel interrupts (0x%x)\n",
561 			(int) tmp8);
562 		tmp8 |= ALL_PORTS;
563 		pci_write_config_byte(pdev, SATA_INT_GATE, tmp8);
564 	}
565 
566 	/* make sure native mode is enabled */
567 	pci_read_config_byte(pdev, SATA_NATIVE_MODE, &tmp8);
568 	if ((tmp8 & NATIVE_MODE_ALL) != NATIVE_MODE_ALL) {
569 		dev_dbg(&pdev->dev,
570 			"enabling SATA channel native mode (0x%x)\n",
571 			(int) tmp8);
572 		tmp8 |= NATIVE_MODE_ALL;
573 		pci_write_config_byte(pdev, SATA_NATIVE_MODE, tmp8);
574 	}
575 
576 	/*
577 	 * vt6420/1 has problems talking to some drives.  The following
578 	 * is the fix from Joseph Chan <JosephChan@via.com.tw>.
579 	 *
580 	 * When host issues HOLD, device may send up to 20DW of data
581 	 * before acknowledging it with HOLDA and the host should be
582 	 * able to buffer them in FIFO.  Unfortunately, some WD drives
583 	 * send up to 40DW before acknowledging HOLD and, in the
584 	 * default configuration, this ends up overflowing vt6421's
585 	 * FIFO, making the controller abort the transaction with
586 	 * R_ERR.
587 	 *
588 	 * Rx52[2] is the internal 128DW FIFO Flow control watermark
589 	 * adjusting mechanism enable bit and the default value 0
590 	 * means host will issue HOLD to device when the left FIFO
591 	 * size goes below 32DW.  Setting it to 1 makes the watermark
592 	 * 64DW.
593 	 *
594 	 * https://bugzilla.kernel.org/show_bug.cgi?id=15173
595 	 * http://article.gmane.org/gmane.linux.ide/46352
596 	 * http://thread.gmane.org/gmane.linux.kernel/1062139
597 	 */
598 	if (board_id == vt6420 || board_id == vt6421) {
599 		pci_read_config_byte(pdev, 0x52, &tmp8);
600 		tmp8 |= 1 << 2;
601 		pci_write_config_byte(pdev, 0x52, tmp8);
602 	}
603 }
604 
605 static int svia_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
606 {
607 	unsigned int i;
608 	int rc;
609 	struct ata_host *host = NULL;
610 	int board_id = (int) ent->driver_data;
611 	const unsigned *bar_sizes;
612 
613 	ata_print_version_once(&pdev->dev, DRV_VERSION);
614 
615 	rc = pcim_enable_device(pdev);
616 	if (rc)
617 		return rc;
618 
619 	if (board_id == vt6421)
620 		bar_sizes = &vt6421_bar_sizes[0];
621 	else
622 		bar_sizes = &svia_bar_sizes[0];
623 
624 	for (i = 0; i < ARRAY_SIZE(svia_bar_sizes); i++)
625 		if ((pci_resource_start(pdev, i) == 0) ||
626 		    (pci_resource_len(pdev, i) < bar_sizes[i])) {
627 			dev_err(&pdev->dev,
628 				"invalid PCI BAR %u (sz 0x%llx, val 0x%llx)\n",
629 				i,
630 				(unsigned long long)pci_resource_start(pdev, i),
631 				(unsigned long long)pci_resource_len(pdev, i));
632 			return -ENODEV;
633 		}
634 
635 	switch (board_id) {
636 	case vt6420:
637 		rc = vt6420_prepare_host(pdev, &host);
638 		break;
639 	case vt6421:
640 		rc = vt6421_prepare_host(pdev, &host);
641 		break;
642 	case vt8251:
643 		rc = vt8251_prepare_host(pdev, &host);
644 		break;
645 	default:
646 		rc = -EINVAL;
647 	}
648 	if (rc)
649 		return rc;
650 
651 	svia_configure(pdev, board_id);
652 
653 	pci_set_master(pdev);
654 	return ata_host_activate(host, pdev->irq, ata_bmdma_interrupt,
655 				 IRQF_SHARED, &svia_sht);
656 }
657 
658 static int __init svia_init(void)
659 {
660 	return pci_register_driver(&svia_pci_driver);
661 }
662 
663 static void __exit svia_exit(void)
664 {
665 	pci_unregister_driver(&svia_pci_driver);
666 }
667 
668 module_init(svia_init);
669 module_exit(svia_exit);
670