scx200_acb.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3    Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
  4
  5    National Semiconductor SCx200 ACCESS.bus support
  6    Also supports the AMD CS5535 and AMD CS5536
  7
  8    Based on i2c-keywest.c which is:
  9        Copyright (c) 2001 Benjamin Herrenschmidt <benh@kernel.crashing.org>
 10        Copyright (c) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
 11
 12*/
 13
 14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 15
 16#include <linux/module.h>
 17#include <linux/errno.h>
 18#include <linux/kernel.h>
 19#include <linux/init.h>
 20#include <linux/i2c.h>
 21#include <linux/pci.h>
 22#include <linux/platform_device.h>
 23#include <linux/delay.h>
 24#include <linux/mutex.h>
 25#include <linux/slab.h>
 26#include <linux/io.h>
 27
 28#include <linux/scx200.h>
 29
 30MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
 31MODULE_DESCRIPTION("NatSemi SCx200 ACCESS.bus Driver");
 32MODULE_ALIAS("platform:cs5535-smb");
 33MODULE_LICENSE("GPL");
 34
 35#define MAX_DEVICES 4
 36static int base[MAX_DEVICES] = { 0x820, 0x840 };
 37module_param_hw_array(base, int, ioport, NULL, 0);
 38MODULE_PARM_DESC(base, "Base addresses for the ACCESS.bus controllers");
 39
 40#define POLL_TIMEOUT	(HZ/5)
 41
 42enum scx200_acb_state {
 43	state_idle,
 44	state_address,
 45	state_command,
 46	state_repeat_start,
 47	state_quick,
 48	state_read,
 49	state_write,
 50};
 51
 52static const char *scx200_acb_state_name[] = {
 53	"idle",
 54	"address",
 55	"command",
 56	"repeat_start",
 57	"quick",
 58	"read",
 59	"write",
 60};
 61
 62/* Physical interface */
 63struct scx200_acb_iface {
 64	struct scx200_acb_iface *next;
 65	struct i2c_adapter adapter;
 66	unsigned base;
 67	struct mutex mutex;
 68
 69	/* State machine data */
 70	enum scx200_acb_state state;
 71	int result;
 72	u8 address_byte;
 73	u8 command;
 74	u8 *ptr;
 75	char needs_reset;
 76	unsigned len;
 77};
 78
 79/* Register Definitions */
 80#define ACBSDA		(iface->base + 0)
 81#define ACBST		(iface->base + 1)
 82#define    ACBST_SDAST		0x40 /* SDA Status */
 83#define    ACBST_BER		0x20
 84#define    ACBST_NEGACK		0x10 /* Negative Acknowledge */
 85#define    ACBST_STASTR		0x08 /* Stall After Start */
 86#define    ACBST_MASTER		0x02
 87#define ACBCST		(iface->base + 2)
 88#define    ACBCST_BB		0x02
 89#define ACBCTL1		(iface->base + 3)
 90#define    ACBCTL1_STASTRE	0x80
 91#define    ACBCTL1_NMINTE	0x40
 92#define    ACBCTL1_ACK		0x10
 93#define    ACBCTL1_STOP		0x02
 94#define    ACBCTL1_START	0x01
 95#define ACBADDR		(iface->base + 4)
 96#define ACBCTL2		(iface->base + 5)
 97#define    ACBCTL2_ENABLE	0x01
 98
 99/************************************************************************/
100
101static void scx200_acb_machine(struct scx200_acb_iface *iface, u8 status)
102{
103	const char *errmsg;
104
105	dev_dbg(&iface->adapter.dev, "state %s, status = 0x%02x\n",
106		scx200_acb_state_name[iface->state], status);
107
108	if (status & ACBST_BER) {
109		errmsg = "bus error";
110		goto error;
111	}
112	if (!(status & ACBST_MASTER)) {
113		errmsg = "not master";
114		goto error;
115	}
116	if (status & ACBST_NEGACK) {
117		dev_dbg(&iface->adapter.dev, "negative ack in state %s\n",
118			scx200_acb_state_name[iface->state]);
119
120		iface->state = state_idle;
121		iface->result = -ENXIO;
122
123		outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
124		outb(ACBST_STASTR | ACBST_NEGACK, ACBST);
125
126		/* Reset the status register */
127		outb(0, ACBST);
128		return;
129	}
130
131	switch (iface->state) {
132	case state_idle:
133		dev_warn(&iface->adapter.dev, "interrupt in idle state\n");
134		break;
135
136	case state_address:
137		/* Do a pointer write first */
138		outb(iface->address_byte & ~1, ACBSDA);
139
140		iface->state = state_command;
141		break;
142
143	case state_command:
144		outb(iface->command, ACBSDA);
145
146		if (iface->address_byte & 1)
147			iface->state = state_repeat_start;
148		else
149			iface->state = state_write;
150		break;
151
152	case state_repeat_start:
153		outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);
154		fallthrough;
155
156	case state_quick:
157		if (iface->address_byte & 1) {
158			if (iface->len == 1)
159				outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);
160			else
161				outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);
162			outb(iface->address_byte, ACBSDA);
163
164			iface->state = state_read;
165		} else {
166			outb(iface->address_byte, ACBSDA);
167
168			iface->state = state_write;
169		}
170		break;
171
172	case state_read:
173		/* Set ACK if _next_ byte will be the last one */
174		if (iface->len == 2)
175			outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);
176		else
177			outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);
178
179		if (iface->len == 1) {
180			iface->result = 0;
181			iface->state = state_idle;
182			outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
183		}
184
185		*iface->ptr++ = inb(ACBSDA);
186		--iface->len;
187
188		break;
189
190	case state_write:
191		if (iface->len == 0) {
192			iface->result = 0;
193			iface->state = state_idle;
194			outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
195			break;
196		}
197
198		outb(*iface->ptr++, ACBSDA);
199		--iface->len;
200
201		break;
202	}
203
204	return;
205
206 error:
207	dev_err(&iface->adapter.dev,
208		"%s in state %s (addr=0x%02x, len=%d, status=0x%02x)\n", errmsg,
209		scx200_acb_state_name[iface->state], iface->address_byte,
210		iface->len, status);
211
212	iface->state = state_idle;
213	iface->result = -EIO;
214	iface->needs_reset = 1;
215}
216
217static void scx200_acb_poll(struct scx200_acb_iface *iface)
218{
219	u8 status;
220	unsigned long timeout;
221
222	timeout = jiffies + POLL_TIMEOUT;
223	while (1) {
224		status = inb(ACBST);
225
226		/* Reset the status register to avoid the hang */
227		outb(0, ACBST);
228
229		if ((status & (ACBST_SDAST|ACBST_BER|ACBST_NEGACK)) != 0) {
230			scx200_acb_machine(iface, status);
231			return;
232		}
233		if (time_after(jiffies, timeout))
234			break;
235		cpu_relax();
236		cond_resched();
237	}
238
239	dev_err(&iface->adapter.dev, "timeout in state %s\n",
240		scx200_acb_state_name[iface->state]);
241
242	iface->state = state_idle;
243	iface->result = -EIO;
244	iface->needs_reset = 1;
245}
246
247static void scx200_acb_reset(struct scx200_acb_iface *iface)
248{
249	/* Disable the ACCESS.bus device and Configure the SCL
250	   frequency: 16 clock cycles */
251	outb(0x70, ACBCTL2);
252	/* Polling mode */
253	outb(0, ACBCTL1);
254	/* Disable slave address */
255	outb(0, ACBADDR);
256	/* Enable the ACCESS.bus device */
257	outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);
258	/* Free STALL after START */
259	outb(inb(ACBCTL1) & ~(ACBCTL1_STASTRE | ACBCTL1_NMINTE), ACBCTL1);
260	/* Send a STOP */
261	outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
262	/* Clear BER, NEGACK and STASTR bits */
263	outb(ACBST_BER | ACBST_NEGACK | ACBST_STASTR, ACBST);
264	/* Clear BB bit */
265	outb(inb(ACBCST) | ACBCST_BB, ACBCST);
266}
267
268static s32 scx200_acb_smbus_xfer(struct i2c_adapter *adapter,
269				 u16 address, unsigned short flags,
270				 char rw, u8 command, int size,
271				 union i2c_smbus_data *data)
272{
273	struct scx200_acb_iface *iface = i2c_get_adapdata(adapter);
274	int len;
275	u8 *buffer;
276	u16 cur_word;
277	int rc;
278
279	switch (size) {
280	case I2C_SMBUS_QUICK:
281		len = 0;
282		buffer = NULL;
283		break;
284
285	case I2C_SMBUS_BYTE:
286		len = 1;
287		buffer = rw ? &data->byte : &command;
288		break;
289
290	case I2C_SMBUS_BYTE_DATA:
291		len = 1;
292		buffer = &data->byte;
293		break;
294
295	case I2C_SMBUS_WORD_DATA:
296		len = 2;
297		cur_word = cpu_to_le16(data->word);
298		buffer = (u8 *)&cur_word;
299		break;
300
301	case I2C_SMBUS_I2C_BLOCK_DATA:
302		len = data->block[0];
303		if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
304			return -EINVAL;
305		buffer = &data->block[1];
306		break;
307
308	default:
309		return -EINVAL;
310	}
311
312	dev_dbg(&adapter->dev,
313		"size=%d, address=0x%x, command=0x%x, len=%d, read=%d\n",
314		size, address, command, len, rw);
315
316	if (!len && rw == I2C_SMBUS_READ) {
317		dev_dbg(&adapter->dev, "zero length read\n");
318		return -EINVAL;
319	}
320
321	mutex_lock(&iface->mutex);
322
323	iface->address_byte = (address << 1) | rw;
324	iface->command = command;
325	iface->ptr = buffer;
326	iface->len = len;
327	iface->result = -EINVAL;
328	iface->needs_reset = 0;
329
330	outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);
331
332	if (size == I2C_SMBUS_QUICK || size == I2C_SMBUS_BYTE)
333		iface->state = state_quick;
334	else
335		iface->state = state_address;
336
337	while (iface->state != state_idle)
338		scx200_acb_poll(iface);
339
340	if (iface->needs_reset)
341		scx200_acb_reset(iface);
342
343	rc = iface->result;
344
345	mutex_unlock(&iface->mutex);
346
347	if (rc == 0 && size == I2C_SMBUS_WORD_DATA && rw == I2C_SMBUS_READ)
348		data->word = le16_to_cpu(cur_word);
349
350#ifdef DEBUG
351	dev_dbg(&adapter->dev, "transfer done, result: %d", rc);
352	if (buffer) {
353		int i;
354		printk(" data:");
355		for (i = 0; i < len; ++i)
356			printk(" %02x", buffer[i]);
357	}
358	printk("\n");
359#endif
360
361	return rc;
362}
363
364static u32 scx200_acb_func(struct i2c_adapter *adapter)
365{
366	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
367	       I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
368	       I2C_FUNC_SMBUS_I2C_BLOCK;
369}
370
371/* For now, we only handle combined mode (smbus) */
372static const struct i2c_algorithm scx200_acb_algorithm = {
373	.smbus_xfer	= scx200_acb_smbus_xfer,
374	.functionality	= scx200_acb_func,
375};
376
377static struct scx200_acb_iface *scx200_acb_list;
378static DEFINE_MUTEX(scx200_acb_list_mutex);
379
380static int scx200_acb_probe(struct scx200_acb_iface *iface)
381{
382	u8 val;
383
384	/* Disable the ACCESS.bus device and Configure the SCL
385	   frequency: 16 clock cycles */
386	outb(0x70, ACBCTL2);
387
388	if (inb(ACBCTL2) != 0x70) {
389		pr_debug("ACBCTL2 readback failed\n");
390		return -ENXIO;
391	}
392
393	outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);
394
395	val = inb(ACBCTL1);
396	if (val) {
397		pr_debug("disabled, but ACBCTL1=0x%02x\n", val);
398		return -ENXIO;
399	}
400
401	outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);
402
403	outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);
404
405	val = inb(ACBCTL1);
406	if ((val & ACBCTL1_NMINTE) != ACBCTL1_NMINTE) {
407		pr_debug("enabled, but NMINTE won't be set, ACBCTL1=0x%02x\n",
408			 val);
409		return -ENXIO;
410	}
411
412	return 0;
413}
414
415static struct scx200_acb_iface *scx200_create_iface(const char *text,
416		struct device *dev, int index)
417{
418	struct scx200_acb_iface *iface;
419	struct i2c_adapter *adapter;
420
421	iface = kzalloc(sizeof(*iface), GFP_KERNEL);
422	if (!iface)
423		return NULL;
424
425	adapter = &iface->adapter;
426	i2c_set_adapdata(adapter, iface);
427	snprintf(adapter->name, sizeof(adapter->name), "%s ACB%d", text, index);
428	adapter->owner = THIS_MODULE;
429	adapter->algo = &scx200_acb_algorithm;
430	adapter->class = I2C_CLASS_HWMON;
431	adapter->dev.parent = dev;
432
433	mutex_init(&iface->mutex);
434
435	return iface;
436}
437
438static int scx200_acb_create(struct scx200_acb_iface *iface)
439{
440	struct i2c_adapter *adapter;
441	int rc;
442
443	adapter = &iface->adapter;
444
445	rc = scx200_acb_probe(iface);
446	if (rc) {
447		pr_warn("probe failed\n");
448		return rc;
449	}
450
451	scx200_acb_reset(iface);
452
453	if (i2c_add_adapter(adapter) < 0) {
454		pr_err("failed to register\n");
455		return -ENODEV;
456	}
457
458	if (!adapter->dev.parent) {
459		/* If there's no dev, we're tracking (ISA) ifaces manually */
460		mutex_lock(&scx200_acb_list_mutex);
461		iface->next = scx200_acb_list;
462		scx200_acb_list = iface;
463		mutex_unlock(&scx200_acb_list_mutex);
464	}
465
466	return 0;
467}
468
469static struct scx200_acb_iface *scx200_create_dev(const char *text,
470		unsigned long base, int index, struct device *dev)
471{
472	struct scx200_acb_iface *iface;
473	int rc;
474
475	iface = scx200_create_iface(text, dev, index);
476
477	if (iface == NULL)
478		return NULL;
479
480	if (!request_region(base, 8, iface->adapter.name)) {
481		pr_err("can't allocate io 0x%lx-0x%lx\n", base, base + 8 - 1);
482		goto errout_free;
483	}
484
485	iface->base = base;
486	rc = scx200_acb_create(iface);
487
488	if (rc == 0)
489		return iface;
490
491	release_region(base, 8);
492 errout_free:
493	kfree(iface);
494	return NULL;
495}
496
497static int scx200_probe(struct platform_device *pdev)
498{
499	struct scx200_acb_iface *iface;
500	struct resource *res;
501
502	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
503	if (!res)
504		return dev_err_probe(&pdev->dev, -ENODEV, "can't fetch device resource info\n");
505
506	iface = scx200_create_dev("CS5535", res->start, 0, &pdev->dev);
507	if (!iface)
508		return -EIO;
509
510	dev_info(&pdev->dev, "SCx200 device '%s' registered\n",
511			iface->adapter.name);
512	platform_set_drvdata(pdev, iface);
513
514	return 0;
515}
516
517static void scx200_cleanup_iface(struct scx200_acb_iface *iface)
518{
519	i2c_del_adapter(&iface->adapter);
520	release_region(iface->base, 8);
521	kfree(iface);
522}
523
524static void scx200_remove(struct platform_device *pdev)
525{
526	struct scx200_acb_iface *iface;
527
528	iface = platform_get_drvdata(pdev);
529	scx200_cleanup_iface(iface);
530}
531
532static struct platform_driver scx200_pci_driver = {
533	.driver = {
534		.name = "cs5535-smb",
535	},
536	.probe = scx200_probe,
537	.remove = scx200_remove,
538};
539
540static const struct pci_device_id scx200_isa[] = {
541	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SCx200_BRIDGE) },
542	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SC1100_BRIDGE) },
543	{ 0, }
544};
545
546static __init void scx200_scan_isa(void)
547{
548	int i;
549
550	if (!pci_dev_present(scx200_isa))
551		return;
552
553	for (i = 0; i < MAX_DEVICES; ++i) {
554		if (base[i] == 0)
555			continue;
556
557		/* XXX: should we care about failures? */
558		scx200_create_dev("SCx200", base[i], i, NULL);
559	}
560}
561
562static int __init scx200_acb_init(void)
563{
564	pr_debug("NatSemi SCx200 ACCESS.bus Driver\n");
565
566	/* First scan for ISA-based devices */
567	scx200_scan_isa();	/* XXX: should we care about errors? */
568
569	/* If at least one bus was created, init must succeed */
570	if (scx200_acb_list)
571		return 0;
572
573	/* No ISA devices; register the platform driver for PCI-based devices */
574	return platform_driver_register(&scx200_pci_driver);
575}
576
577static void __exit scx200_acb_cleanup(void)
578{
579	struct scx200_acb_iface *iface;
580
581	platform_driver_unregister(&scx200_pci_driver);
582
583	mutex_lock(&scx200_acb_list_mutex);
584	while ((iface = scx200_acb_list) != NULL) {
585		scx200_acb_list = iface->next;
586		mutex_unlock(&scx200_acb_list_mutex);
587
588		scx200_cleanup_iface(iface);
589
590		mutex_lock(&scx200_acb_list_mutex);
591	}
592	mutex_unlock(&scx200_acb_list_mutex);
593}
594
595module_init(scx200_acb_init);
596module_exit(scx200_acb_cleanup);