1/*
2    Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
3
4    National Semiconductor SCx200 ACCESS.bus support
5    Also supports the AMD CS5535 and AMD CS5536
6
7    Based on i2c-keywest.c which is:
8        Copyright (c) 2001 Benjamin Herrenschmidt <benh@kernel.crashing.org>
9        Copyright (c) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
10
11    This program is free software; you can redistribute it and/or
12    modify it under the terms of the GNU General Public License as
13    published by the Free Software Foundation; either version 2 of the
14    License, or (at your option) any later version.
15
16    This program is distributed in the hope that it will be useful,
17    but WITHOUT ANY WARRANTY; without even the implied warranty of
18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
19    General Public License for more details.
20*/
21
22#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23
24#include <linux/module.h>
25#include <linux/errno.h>
26#include <linux/kernel.h>
27#include <linux/init.h>
28#include <linux/i2c.h>
29#include <linux/pci.h>
30#include <linux/platform_device.h>
31#include <linux/delay.h>
32#include <linux/mutex.h>
33#include <linux/slab.h>
34#include <linux/io.h>
35
36#include <linux/scx200.h>
37
38MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
39MODULE_DESCRIPTION("NatSemi SCx200 ACCESS.bus Driver");
40MODULE_ALIAS("platform:cs5535-smb");
41MODULE_LICENSE("GPL");
42
43#define MAX_DEVICES 4
44static int base[MAX_DEVICES] = { 0x820, 0x840 };
45module_param_array(base, int, NULL, 0);
46MODULE_PARM_DESC(base, "Base addresses for the ACCESS.bus controllers");
47
48#define POLL_TIMEOUT	(HZ/5)
49
50enum scx200_acb_state {
51	state_idle,
52	state_address,
53	state_command,
54	state_repeat_start,
55	state_quick,
56	state_read,
57	state_write,
58};
59
60static const char *scx200_acb_state_name[] = {
61	"idle",
62	"address",
63	"command",
64	"repeat_start",
65	"quick",
66	"read",
67	"write",
68};
69
70/* Physical interface */
71struct scx200_acb_iface {
72	struct scx200_acb_iface *next;
73	struct i2c_adapter adapter;
74	unsigned base;
75	struct mutex mutex;
76
77	/* State machine data */
78	enum scx200_acb_state state;
79	int result;
80	u8 address_byte;
81	u8 command;
82	u8 *ptr;
83	char needs_reset;
84	unsigned len;
85};
86
87/* Register Definitions */
88#define ACBSDA		(iface->base + 0)
89#define ACBST		(iface->base + 1)
90#define    ACBST_SDAST		0x40 /* SDA Status */
91#define    ACBST_BER		0x20
92#define    ACBST_NEGACK		0x10 /* Negative Acknowledge */
93#define    ACBST_STASTR		0x08 /* Stall After Start */
94#define    ACBST_MASTER		0x02
95#define ACBCST		(iface->base + 2)
96#define    ACBCST_BB		0x02
97#define ACBCTL1		(iface->base + 3)
98#define    ACBCTL1_STASTRE	0x80
99#define    ACBCTL1_NMINTE	0x40
100#define    ACBCTL1_ACK		0x10
101#define    ACBCTL1_STOP		0x02
102#define    ACBCTL1_START	0x01
103#define ACBADDR		(iface->base + 4)
104#define ACBCTL2		(iface->base + 5)
105#define    ACBCTL2_ENABLE	0x01
106
107/************************************************************************/
108
109static void scx200_acb_machine(struct scx200_acb_iface *iface, u8 status)
110{
111	const char *errmsg;
112
113	dev_dbg(&iface->adapter.dev, "state %s, status = 0x%02x\n",
114		scx200_acb_state_name[iface->state], status);
115
116	if (status & ACBST_BER) {
117		errmsg = "bus error";
118		goto error;
119	}
120	if (!(status & ACBST_MASTER)) {
121		errmsg = "not master";
122		goto error;
123	}
124	if (status & ACBST_NEGACK) {
125		dev_dbg(&iface->adapter.dev, "negative ack in state %s\n",
126			scx200_acb_state_name[iface->state]);
127
128		iface->state = state_idle;
129		iface->result = -ENXIO;
130
131		outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
132		outb(ACBST_STASTR | ACBST_NEGACK, ACBST);
133
134		/* Reset the status register */
135		outb(0, ACBST);
136		return;
137	}
138
139	switch (iface->state) {
140	case state_idle:
141		dev_warn(&iface->adapter.dev, "interrupt in idle state\n");
142		break;
143
144	case state_address:
145		/* Do a pointer write first */
146		outb(iface->address_byte & ~1, ACBSDA);
147
148		iface->state = state_command;
149		break;
150
151	case state_command:
152		outb(iface->command, ACBSDA);
153
154		if (iface->address_byte & 1)
155			iface->state = state_repeat_start;
156		else
157			iface->state = state_write;
158		break;
159
160	case state_repeat_start:
161		outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);
162		/* fallthrough */
163
164	case state_quick:
165		if (iface->address_byte & 1) {
166			if (iface->len == 1)
167				outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);
168			else
169				outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);
170			outb(iface->address_byte, ACBSDA);
171
172			iface->state = state_read;
173		} else {
174			outb(iface->address_byte, ACBSDA);
175
176			iface->state = state_write;
177		}
178		break;
179
180	case state_read:
181		/* Set ACK if _next_ byte will be the last one */
182		if (iface->len == 2)
183			outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);
184		else
185			outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);
186
187		if (iface->len == 1) {
188			iface->result = 0;
189			iface->state = state_idle;
190			outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
191		}
192
193		*iface->ptr++ = inb(ACBSDA);
194		--iface->len;
195
196		break;
197
198	case state_write:
199		if (iface->len == 0) {
200			iface->result = 0;
201			iface->state = state_idle;
202			outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
203			break;
204		}
205
206		outb(*iface->ptr++, ACBSDA);
207		--iface->len;
208
209		break;
210	}
211
212	return;
213
214 error:
215	dev_err(&iface->adapter.dev,
216		"%s in state %s (addr=0x%02x, len=%d, status=0x%02x)\n", errmsg,
217		scx200_acb_state_name[iface->state], iface->address_byte,
218		iface->len, status);
219
220	iface->state = state_idle;
221	iface->result = -EIO;
222	iface->needs_reset = 1;
223}
224
225static void scx200_acb_poll(struct scx200_acb_iface *iface)
226{
227	u8 status;
228	unsigned long timeout;
229
230	timeout = jiffies + POLL_TIMEOUT;
231	while (1) {
232		status = inb(ACBST);
233
234		/* Reset the status register to avoid the hang */
235		outb(0, ACBST);
236
237		if ((status & (ACBST_SDAST|ACBST_BER|ACBST_NEGACK)) != 0) {
238			scx200_acb_machine(iface, status);
239			return;
240		}
241		if (time_after(jiffies, timeout))
242			break;
243		cpu_relax();
244		cond_resched();
245	}
246
247	dev_err(&iface->adapter.dev, "timeout in state %s\n",
248		scx200_acb_state_name[iface->state]);
249
250	iface->state = state_idle;
251	iface->result = -EIO;
252	iface->needs_reset = 1;
253}
254
255static void scx200_acb_reset(struct scx200_acb_iface *iface)
256{
257	/* Disable the ACCESS.bus device and Configure the SCL
258	   frequency: 16 clock cycles */
259	outb(0x70, ACBCTL2);
260	/* Polling mode */
261	outb(0, ACBCTL1);
262	/* Disable slave address */
263	outb(0, ACBADDR);
264	/* Enable the ACCESS.bus device */
265	outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);
266	/* Free STALL after START */
267	outb(inb(ACBCTL1) & ~(ACBCTL1_STASTRE | ACBCTL1_NMINTE), ACBCTL1);
268	/* Send a STOP */
269	outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
270	/* Clear BER, NEGACK and STASTR bits */
271	outb(ACBST_BER | ACBST_NEGACK | ACBST_STASTR, ACBST);
272	/* Clear BB bit */
273	outb(inb(ACBCST) | ACBCST_BB, ACBCST);
274}
275
276static s32 scx200_acb_smbus_xfer(struct i2c_adapter *adapter,
277				 u16 address, unsigned short flags,
278				 char rw, u8 command, int size,
279				 union i2c_smbus_data *data)
280{
281	struct scx200_acb_iface *iface = i2c_get_adapdata(adapter);
282	int len;
283	u8 *buffer;
284	u16 cur_word;
285	int rc;
286
287	switch (size) {
288	case I2C_SMBUS_QUICK:
289		len = 0;
290		buffer = NULL;
291		break;
292
293	case I2C_SMBUS_BYTE:
294		len = 1;
295		buffer = rw ? &data->byte : &command;
296		break;
297
298	case I2C_SMBUS_BYTE_DATA:
299		len = 1;
300		buffer = &data->byte;
301		break;
302
303	case I2C_SMBUS_WORD_DATA:
304		len = 2;
305		cur_word = cpu_to_le16(data->word);
306		buffer = (u8 *)&cur_word;
307		break;
308
309	case I2C_SMBUS_I2C_BLOCK_DATA:
310		len = data->block[0];
311		if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
312			return -EINVAL;
313		buffer = &data->block[1];
314		break;
315
316	default:
317		return -EINVAL;
318	}
319
320	dev_dbg(&adapter->dev,
321		"size=%d, address=0x%x, command=0x%x, len=%d, read=%d\n",
322		size, address, command, len, rw);
323
324	if (!len && rw == I2C_SMBUS_READ) {
325		dev_dbg(&adapter->dev, "zero length read\n");
326		return -EINVAL;
327	}
328
329	mutex_lock(&iface->mutex);
330
331	iface->address_byte = (address << 1) | rw;
332	iface->command = command;
333	iface->ptr = buffer;
334	iface->len = len;
335	iface->result = -EINVAL;
336	iface->needs_reset = 0;
337
338	outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);
339
340	if (size == I2C_SMBUS_QUICK || size == I2C_SMBUS_BYTE)
341		iface->state = state_quick;
342	else
343		iface->state = state_address;
344
345	while (iface->state != state_idle)
346		scx200_acb_poll(iface);
347
348	if (iface->needs_reset)
349		scx200_acb_reset(iface);
350
351	rc = iface->result;
352
353	mutex_unlock(&iface->mutex);
354
355	if (rc == 0 && size == I2C_SMBUS_WORD_DATA && rw == I2C_SMBUS_READ)
356		data->word = le16_to_cpu(cur_word);
357
358#ifdef DEBUG
359	dev_dbg(&adapter->dev, "transfer done, result: %d", rc);
360	if (buffer) {
361		int i;
362		printk(" data:");
363		for (i = 0; i < len; ++i)
364			printk(" %02x", buffer[i]);
365	}
366	printk("\n");
367#endif
368
369	return rc;
370}
371
372static u32 scx200_acb_func(struct i2c_adapter *adapter)
373{
374	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
375	       I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
376	       I2C_FUNC_SMBUS_I2C_BLOCK;
377}
378
379/* For now, we only handle combined mode (smbus) */
380static const struct i2c_algorithm scx200_acb_algorithm = {
381	.smbus_xfer	= scx200_acb_smbus_xfer,
382	.functionality	= scx200_acb_func,
383};
384
385static struct scx200_acb_iface *scx200_acb_list;
386static DEFINE_MUTEX(scx200_acb_list_mutex);
387
388static int scx200_acb_probe(struct scx200_acb_iface *iface)
389{
390	u8 val;
391
392	/* Disable the ACCESS.bus device and Configure the SCL
393	   frequency: 16 clock cycles */
394	outb(0x70, ACBCTL2);
395
396	if (inb(ACBCTL2) != 0x70) {
397		pr_debug("ACBCTL2 readback failed\n");
398		return -ENXIO;
399	}
400
401	outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);
402
403	val = inb(ACBCTL1);
404	if (val) {
405		pr_debug("disabled, but ACBCTL1=0x%02x\n", val);
406		return -ENXIO;
407	}
408
409	outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);
410
411	outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);
412
413	val = inb(ACBCTL1);
414	if ((val & ACBCTL1_NMINTE) != ACBCTL1_NMINTE) {
415		pr_debug("enabled, but NMINTE won't be set, ACBCTL1=0x%02x\n",
416			 val);
417		return -ENXIO;
418	}
419
420	return 0;
421}
422
423static struct scx200_acb_iface *scx200_create_iface(const char *text,
424		struct device *dev, int index)
425{
426	struct scx200_acb_iface *iface;
427	struct i2c_adapter *adapter;
428
429	iface = kzalloc(sizeof(*iface), GFP_KERNEL);
430	if (!iface)
431		return NULL;
432
433	adapter = &iface->adapter;
434	i2c_set_adapdata(adapter, iface);
435	snprintf(adapter->name, sizeof(adapter->name), "%s ACB%d", text, index);
436	adapter->owner = THIS_MODULE;
437	adapter->algo = &scx200_acb_algorithm;
438	adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
439	adapter->dev.parent = dev;
440
441	mutex_init(&iface->mutex);
442
443	return iface;
444}
445
446static int scx200_acb_create(struct scx200_acb_iface *iface)
447{
448	struct i2c_adapter *adapter;
449	int rc;
450
451	adapter = &iface->adapter;
452
453	rc = scx200_acb_probe(iface);
454	if (rc) {
455		pr_warn("probe failed\n");
456		return rc;
457	}
458
459	scx200_acb_reset(iface);
460
461	if (i2c_add_adapter(adapter) < 0) {
462		pr_err("failed to register\n");
463		return -ENODEV;
464	}
465
466	if (!adapter->dev.parent) {
467		/* If there's no dev, we're tracking (ISA) ifaces manually */
468		mutex_lock(&scx200_acb_list_mutex);
469		iface->next = scx200_acb_list;
470		scx200_acb_list = iface;
471		mutex_unlock(&scx200_acb_list_mutex);
472	}
473
474	return 0;
475}
476
477static struct scx200_acb_iface *scx200_create_dev(const char *text,
478		unsigned long base, int index, struct device *dev)
479{
480	struct scx200_acb_iface *iface;
481	int rc;
482
483	iface = scx200_create_iface(text, dev, index);
484
485	if (iface == NULL)
486		return NULL;
487
488	if (!request_region(base, 8, iface->adapter.name)) {
489		pr_err("can't allocate io 0x%lx-0x%lx\n", base, base + 8 - 1);
490		goto errout_free;
491	}
492
493	iface->base = base;
494	rc = scx200_acb_create(iface);
495
496	if (rc == 0)
497		return iface;
498
499	release_region(base, 8);
500 errout_free:
501	kfree(iface);
502	return NULL;
503}
504
505static int scx200_probe(struct platform_device *pdev)
506{
507	struct scx200_acb_iface *iface;
508	struct resource *res;
509
510	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
511	if (!res) {
512		dev_err(&pdev->dev, "can't fetch device resource info\n");
513		return -ENODEV;
514	}
515
516	iface = scx200_create_dev("CS5535", res->start, 0, &pdev->dev);
517	if (!iface)
518		return -EIO;
519
520	dev_info(&pdev->dev, "SCx200 device '%s' registered\n",
521			iface->adapter.name);
522	platform_set_drvdata(pdev, iface);
523
524	return 0;
525}
526
527static void scx200_cleanup_iface(struct scx200_acb_iface *iface)
528{
529	i2c_del_adapter(&iface->adapter);
530	release_region(iface->base, 8);
531	kfree(iface);
532}
533
534static int scx200_remove(struct platform_device *pdev)
535{
536	struct scx200_acb_iface *iface;
537
538	iface = platform_get_drvdata(pdev);
539	scx200_cleanup_iface(iface);
540
541	return 0;
542}
543
544static struct platform_driver scx200_pci_driver = {
545	.driver = {
546		.name = "cs5535-smb",
547	},
548	.probe = scx200_probe,
549	.remove = scx200_remove,
550};
551
552static const struct pci_device_id scx200_isa[] = {
553	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SCx200_BRIDGE) },
554	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SC1100_BRIDGE) },
555	{ 0, }
556};
557
558static __init void scx200_scan_isa(void)
559{
560	int i;
561
562	if (!pci_dev_present(scx200_isa))
563		return;
564
565	for (i = 0; i < MAX_DEVICES; ++i) {
566		if (base[i] == 0)
567			continue;
568
569		/* XXX: should we care about failures? */
570		scx200_create_dev("SCx200", base[i], i, NULL);
571	}
572}
573
574static int __init scx200_acb_init(void)
575{
576	pr_debug("NatSemi SCx200 ACCESS.bus Driver\n");
577
578	/* First scan for ISA-based devices */
579	scx200_scan_isa();	/* XXX: should we care about errors? */
580
581	/* If at least one bus was created, init must succeed */
582	if (scx200_acb_list)
583		return 0;
584
585	/* No ISA devices; register the platform driver for PCI-based devices */
586	return platform_driver_register(&scx200_pci_driver);
587}
588
589static void __exit scx200_acb_cleanup(void)
590{
591	struct scx200_acb_iface *iface;
592
593	platform_driver_unregister(&scx200_pci_driver);
594
595	mutex_lock(&scx200_acb_list_mutex);
596	while ((iface = scx200_acb_list) != NULL) {
597		scx200_acb_list = iface->next;
598		mutex_unlock(&scx200_acb_list_mutex);
599
600		scx200_cleanup_iface(iface);
601
602		mutex_lock(&scx200_acb_list_mutex);
603	}
604	mutex_unlock(&scx200_acb_list_mutex);
605}
606
607module_init(scx200_acb_init);
608module_exit(scx200_acb_cleanup);
609