xref: /openbmc/linux/drivers/i2c/busses/scx200_acb.c (revision 4eb5928d)
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 
30 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
31 MODULE_DESCRIPTION("NatSemi SCx200 ACCESS.bus Driver");
32 MODULE_ALIAS("platform:cs5535-smb");
33 MODULE_LICENSE("GPL");
34 
35 #define MAX_DEVICES 4
36 static int base[MAX_DEVICES] = { 0x820, 0x840 };
37 module_param_hw_array(base, int, ioport, NULL, 0);
38 MODULE_PARM_DESC(base, "Base addresses for the ACCESS.bus controllers");
39 
40 #define POLL_TIMEOUT	(HZ/5)
41 
42 enum 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 
52 static 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 */
63 struct 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 
101 static 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 
217 static 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 
247 static 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 
268 static 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 
364 static 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) */
372 static const struct i2c_algorithm scx200_acb_algorithm = {
373 	.smbus_xfer	= scx200_acb_smbus_xfer,
374 	.functionality	= scx200_acb_func,
375 };
376 
377 static struct scx200_acb_iface *scx200_acb_list;
378 static DEFINE_MUTEX(scx200_acb_list_mutex);
379 
380 static 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 
415 static 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 | I2C_CLASS_SPD;
431 	adapter->dev.parent = dev;
432 
433 	mutex_init(&iface->mutex);
434 
435 	return iface;
436 }
437 
438 static 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 
469 static 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 
497 static 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 		dev_err(&pdev->dev, "can't fetch device resource info\n");
505 		return -ENODEV;
506 	}
507 
508 	iface = scx200_create_dev("CS5535", res->start, 0, &pdev->dev);
509 	if (!iface)
510 		return -EIO;
511 
512 	dev_info(&pdev->dev, "SCx200 device '%s' registered\n",
513 			iface->adapter.name);
514 	platform_set_drvdata(pdev, iface);
515 
516 	return 0;
517 }
518 
519 static void scx200_cleanup_iface(struct scx200_acb_iface *iface)
520 {
521 	i2c_del_adapter(&iface->adapter);
522 	release_region(iface->base, 8);
523 	kfree(iface);
524 }
525 
526 static int scx200_remove(struct platform_device *pdev)
527 {
528 	struct scx200_acb_iface *iface;
529 
530 	iface = platform_get_drvdata(pdev);
531 	scx200_cleanup_iface(iface);
532 
533 	return 0;
534 }
535 
536 static struct platform_driver scx200_pci_driver = {
537 	.driver = {
538 		.name = "cs5535-smb",
539 	},
540 	.probe = scx200_probe,
541 	.remove = scx200_remove,
542 };
543 
544 static const struct pci_device_id scx200_isa[] = {
545 	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SCx200_BRIDGE) },
546 	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SC1100_BRIDGE) },
547 	{ 0, }
548 };
549 
550 static __init void scx200_scan_isa(void)
551 {
552 	int i;
553 
554 	if (!pci_dev_present(scx200_isa))
555 		return;
556 
557 	for (i = 0; i < MAX_DEVICES; ++i) {
558 		if (base[i] == 0)
559 			continue;
560 
561 		/* XXX: should we care about failures? */
562 		scx200_create_dev("SCx200", base[i], i, NULL);
563 	}
564 }
565 
566 static int __init scx200_acb_init(void)
567 {
568 	pr_debug("NatSemi SCx200 ACCESS.bus Driver\n");
569 
570 	/* First scan for ISA-based devices */
571 	scx200_scan_isa();	/* XXX: should we care about errors? */
572 
573 	/* If at least one bus was created, init must succeed */
574 	if (scx200_acb_list)
575 		return 0;
576 
577 	/* No ISA devices; register the platform driver for PCI-based devices */
578 	return platform_driver_register(&scx200_pci_driver);
579 }
580 
581 static void __exit scx200_acb_cleanup(void)
582 {
583 	struct scx200_acb_iface *iface;
584 
585 	platform_driver_unregister(&scx200_pci_driver);
586 
587 	mutex_lock(&scx200_acb_list_mutex);
588 	while ((iface = scx200_acb_list) != NULL) {
589 		scx200_acb_list = iface->next;
590 		mutex_unlock(&scx200_acb_list_mutex);
591 
592 		scx200_cleanup_iface(iface);
593 
594 		mutex_lock(&scx200_acb_list_mutex);
595 	}
596 	mutex_unlock(&scx200_acb_list_mutex);
597 }
598 
599 module_init(scx200_acb_init);
600 module_exit(scx200_acb_cleanup);
601