aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/ipmi/ipmi_kcs_sm.c
blob: cf82fedae09975272fd6517b1fa5346eff95a814 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
/*
 * ipmi_kcs_sm.c
 *
 * State machine for handling IPMI KCS interfaces.
 *
 * Author: MontaVista Software, Inc.
 *         Corey Minyard <minyard@mvista.com>
 *         source@mvista.com
 *
 * Copyright 2002 MontaVista Software Inc.
 *
 *  This program is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License as published by the
 *  Free Software Foundation; either version 2 of the License, or (at your
 *  option) any later version.
 *
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 *  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 *  OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 *  TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 *  USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 * This state machine is taken from the state machine in the IPMI spec,
 * pretty much verbatim.  If you have questions about the states, see
 * that document.
 */

#include <linux/kernel.h> /* For printk. */
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/string.h>
#include <linux/jiffies.h>
#include <linux/ipmi_msgdefs.h>		/* for completion codes */
#include "ipmi_si_sm.h"

/* kcs_debug is a bit-field
 *	KCS_DEBUG_ENABLE -	turned on for now
 *	KCS_DEBUG_MSG    -	commands and their responses
 *	KCS_DEBUG_STATES -	state machine
 */
#define KCS_DEBUG_STATES	4
#define KCS_DEBUG_MSG		2
#define	KCS_DEBUG_ENABLE	1

static int kcs_debug;
module_param(kcs_debug, int, 0644);
MODULE_PARM_DESC(kcs_debug, "debug bitmask, 1=enable, 2=messages, 4=states");

/* The states the KCS driver may be in. */
enum kcs_states {
	/* The KCS interface is currently doing nothing. */
	KCS_IDLE,

	/*
	 * We are starting an operation.  The data is in the output
	 * buffer, but nothing has been done to the interface yet.  This
	 * was added to the state machine in the spec to wait for the
	 * initial IBF.
	 */
	KCS_START_OP,

	/* We have written a write cmd to the interface. */
	KCS_WAIT_WRITE_START,

	/* We are writing bytes to the interface. */
	KCS_WAIT_WRITE,

	/*
	 * We have written the write end cmd to the interface, and
	 * still need to write the last byte.
	 */
	KCS_WAIT_WRITE_END,

	/* We are waiting to read data from the interface. */
	KCS_WAIT_READ,

	/*
	 * State to transition to the error handler, this was added to
	 * the state machine in the spec to be sure IBF was there.
	 */
	KCS_ERROR0,

	/*
	 * First stage error handler, wait for the interface to
	 * respond.
	 */
	KCS_ERROR1,

	/*
	 * The abort cmd has been written, wait for the interface to
	 * respond.
	 */
	KCS_ERROR2,

	/*
	 * We wrote some data to the interface, wait for it to switch
	 * to read mode.
	 */
	KCS_ERROR3,

	/* The hardware failed to follow the state machine. */
	KCS_HOSED
};

#define MAX_KCS_READ_SIZE IPMI_MAX_MSG_LENGTH
#define MAX_KCS_WRITE_SIZE IPMI_MAX_MSG_LENGTH

/* Timeouts in microseconds. */
#define IBF_RETRY_TIMEOUT 1000000
#define OBF_RETRY_TIMEOUT 1000000
#define MAX_ERROR_RETRIES 10
#define ERROR0_OBF_WAIT_JIFFIES (2*HZ)

struct si_sm_data {
	enum kcs_states  state;
	struct si_sm_io *io;
	unsigned char    write_data[MAX_KCS_WRITE_SIZE];
	int              write_pos;
	int              write_count;
	int              orig_write_count;
	unsigned char    read_data[MAX_KCS_READ_SIZE];
	int              read_pos;
	int	         truncated;

	unsigned int  error_retries;
	long          ibf_timeout;
	long          obf_timeout;
	unsigned long  error0_timeout;
};

static unsigned int init_kcs_data(struct si_sm_data *kcs,
				  struct si_sm_io *io)
{
	kcs->state = KCS_IDLE;
	kcs->io = io;
	kcs->write_pos = 0;
	kcs->write_count = 0;
	kcs->orig_write_count = 0;
	kcs->read_pos = 0;
	kcs->error_retries = 0;
	kcs->truncated = 0;
	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
	kcs->obf_timeout = OBF_RETRY_TIMEOUT;

	/* Reserve 2 I/O bytes. */
	return 2;
}

static inline unsigned char read_status(struct si_sm_data *kcs)
{
	return kcs->io->inputb(kcs->io, 1);
}

static inline unsigned char read_data(struct si_sm_data *kcs)
{
	return kcs->io->inputb(kcs->io, 0);
}

static inline void write_cmd(struct si_sm_data *kcs, unsigned char data)
{
	kcs->io->outputb(kcs->io, 1, data);
}

static inline void write_data(struct si_sm_data *kcs, unsigned char data)
{
	kcs->io->outputb(kcs->io, 0, data);
}

/* Control codes. */
#define KCS_GET_STATUS_ABORT	0x60
#define KCS_WRITE_START		0x61
#define KCS_WRITE_END		0x62
#define KCS_READ_BYTE		0x68

/* Status bits. */
#define GET_STATUS_STATE(status) (((status) >> 6) & 0x03)
#define KCS_IDLE_STATE	0
#define KCS_READ_STATE	1
#define KCS_WRITE_STATE	2
#define KCS_ERROR_STATE	3
#define GET_STATUS_ATN(status) ((status) & 0x04)
#define GET_STATUS_IBF(status) ((status) & 0x02)
#define GET_STATUS_OBF(status) ((status) & 0x01)


static inline void write_next_byte(struct si_sm_data *kcs)
{
	write_data(kcs, kcs->write_data[kcs->write_pos]);
	(kcs->write_pos)++;
	(kcs->write_count)--;
}

static inline void start_error_recovery(struct si_sm_data *kcs, char *reason)
{
	(kcs->error_retries)++;
	if (kcs->error_retries > MAX_ERROR_RETRIES) {
		if (kcs_debug & KCS_DEBUG_ENABLE)
			printk(KERN_DEBUG "ipmi_kcs_sm: kcs hosed: %s\n",
			       reason);
		kcs->state = KCS_HOSED;
	} else {
		kcs->error0_timeout = jiffies + ERROR0_OBF_WAIT_JIFFIES;
		kcs->state = KCS_ERROR0;
	}
}

static inline void read_next_byte(struct si_sm_data *kcs)
{
	if (kcs->read_pos >= MAX_KCS_READ_SIZE) {
		/* Throw the data away and mark it truncated. */
		read_data(kcs);
		kcs->truncated = 1;
	} else {
		kcs->read_data[kcs->read_pos] = read_data(kcs);
		(kcs->read_pos)++;
	}
	write_data(kcs, KCS_READ_BYTE);
}

static inline int check_ibf(struct si_sm_data *kcs, unsigned char status,
			    long time)
{
	if (GET_STATUS_IBF(status)) {
		kcs->ibf_timeout -= time;
		if (kcs->ibf_timeout < 0) {
			start_error_recovery(kcs, "IBF not ready in time");
			kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
			return 1;
		}
		return 0;
	}
	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
	return 1;
}

static inline int check_obf(struct si_sm_data *kcs, unsigned char status,
			    long time)
{
	if (!GET_STATUS_OBF(status)) {
		kcs->obf_timeout -= time;
		if (kcs->obf_timeout < 0) {
		    start_error_recovery(kcs, "OBF not ready in time");
		    return 1;
		}
		return 0;
	}
	kcs->obf_timeout = OBF_RETRY_TIMEOUT;
	return 1;
}

static void clear_obf(struct si_sm_data *kcs, unsigned char status)
{
	if (GET_STATUS_OBF(status))
		read_data(kcs);
}

static void restart_kcs_transaction(struct si_sm_data *kcs)
{
	kcs->write_count = kcs->orig_write_count;
	kcs->write_pos = 0;
	kcs->read_pos = 0;
	kcs->state = KCS_WAIT_WRITE_START;
	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
	kcs->obf_timeout = OBF_RETRY_TIMEOUT;
	write_cmd(kcs, KCS_WRITE_START);
}

static int start_kcs_transaction(struct si_sm_data *kcs, unsigned char *data,
				 unsigned int size)
{
	unsigned int i;

	if (size < 2)
		return IPMI_REQ_LEN_INVALID_ERR;
	if (size > MAX_KCS_WRITE_SIZE)
		return IPMI_REQ_LEN_EXCEEDED_ERR;

	if ((kcs->state != KCS_IDLE) && (kcs->state != KCS_HOSED))
		return IPMI_NOT_IN_MY_STATE_ERR;

	if (kcs_debug & KCS_DEBUG_MSG) {
		printk(KERN_DEBUG "start_kcs_transaction -");
		for (i = 0; i < size; i++)
			printk(" %02x", (unsigned char) (data [i]));
		printk("\n");
	}
	kcs->error_retries = 0;
	memcpy(kcs->write_data, data, size);
	kcs->write_count = size;
	kcs->orig_write_count = size;
	kcs->write_pos = 0;
	kcs->read_pos = 0;
	kcs->state = KCS_START_OP;
	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
	kcs->obf_timeout = OBF_RETRY_TIMEOUT;
	return 0;
}

static int get_kcs_result(struct si_sm_data *kcs, unsigned char *data,
			  unsigned int length)
{
	if (length < kcs->read_pos) {
		kcs->read_pos = length;
		kcs->truncated = 1;
	}

	memcpy(data, kcs->read_data, kcs->read_pos);

	if ((length >= 3) && (kcs->read_pos < 3)) {
		/* Guarantee that we return at least 3 bytes, with an
		   error in the third byte if it is too short. */
		data[2] = IPMI_ERR_UNSPECIFIED;
		kcs->read_pos = 3;
	}
	if (kcs->truncated) {
		/*
		 * Report a truncated error.  We might overwrite
		 * another error, but that's too bad, the user needs
		 * to know it was truncated.
		 */
		data[2] = IPMI_ERR_MSG_TRUNCATED;
		kcs->truncated = 0;
	}

	return kcs->read_pos;
}

/*
 * This implements the state machine defined in the IPMI manual, see
 * that for details on how this works.  Divide that flowchart into
 * sections delimited by "Wait for IBF" and this will become clear.
 */
static enum si_sm_result kcs_event(struct si_sm_data *kcs, long time)
{
	unsigned char status;
	unsigned char state;

	status = read_status(kcs);

	if (kcs_debug & KCS_DEBUG_STATES)
		printk(KERN_DEBUG "KCS: State = %d, %x\n", kcs->state, status);

	/* All states wait for ibf, so just do it here. */
	if (!check_ibf(kcs, status, time))
		return SI_SM_CALL_WITH_DELAY;

	/* Just about everything looks at the KCS state, so grab that, too. */
	state = GET_STATUS_STATE(status);

	switch (kcs->state) {
	case KCS_IDLE:
		/* If there's and interrupt source, turn it off. */
		clear_obf(kcs, status);

		if (GET_STATUS_ATN(status))
			return SI_SM_ATTN;
		else
			return SI_SM_IDLE;

	case KCS_START_OP:
		if (state != KCS_IDLE_STATE) {
			start_error_recovery(kcs,
					     "State machine not idle at start");
			break;
		}

		clear_obf(kcs, status);
		write_cmd(kcs, KCS_WRITE_START);
		kcs->state = KCS_WAIT_WRITE_START;
		break;

	case KCS_WAIT_WRITE_START:
		if (state != KCS_WRITE_STATE) {
			start_error_recovery(
				kcs,
				"Not in write state at write start");
			break;
		}
		read_data(kcs);
		if (kcs->write_count == 1) {
			write_cmd(kcs, KCS_WRITE_END);
			kcs->state = KCS_WAIT_WRITE_END;
		} else {
			write_next_byte(kcs);
			kcs->state = KCS_WAIT_WRITE;
		}
		break;

	case KCS_WAIT_WRITE:
		if (state != KCS_WRITE_STATE) {
			start_error_recovery(kcs,
					     "Not in write state for write");
			break;
		}
		clear_obf(kcs, status);
		if (kcs->write_count == 1) {
			write_cmd(kcs, KCS_WRITE_END);
			kcs->state = KCS_WAIT_WRITE_END;
		} else {
			write_next_byte(kcs);
		}
		break;

	case KCS_WAIT_WRITE_END:
		if (state != KCS_WRITE_STATE) {
			start_error_recovery(kcs,
					     "Not in write state"
					     " for write end");
			break;
		}
		clear_obf(kcs, status);
		write_next_byte(kcs);
		kcs->state = KCS_WAIT_READ;
		break;

	case KCS_WAIT_READ:
		if ((state != KCS_READ_STATE) && (state != KCS_IDLE_STATE)) {
			start_error_recovery(
				kcs,
				"Not in read or idle in read state");
			break;
		}

		if (state == KCS_READ_STATE) {
			if (!check_obf(kcs, status, time))
				return SI_SM_CALL_WITH_DELAY;
			read_next_byte(kcs);
		} else {
			/*
			 * We don't implement this exactly like the state
			 * machine in the spec.  Some broken hardware
			 * does not write the final dummy byte to the
			 * read register.  Thus obf will never go high
			 * here.  We just go straight to idle, and we
			 * handle clearing out obf in idle state if it
			 * happens to come in.
			 */
			clear_obf(kcs, status);
			kcs->orig_write_count = 0;
			kcs->state = KCS_IDLE;
			return SI_SM_TRANSACTION_COMPLETE;
		}
		break;

	case KCS_ERROR0:
		clear_obf(kcs, status);
		status = read_status(kcs);
		if (GET_STATUS_OBF(status))
			/* controller isn't responding */
			if (time_before(jiffies, kcs->error0_timeout))
				return SI_SM_CALL_WITH_TICK_DELAY;
		write_cmd(kcs, KCS_GET_STATUS_ABORT);
		kcs->state = KCS_ERROR1;
		break;

	case KCS_ERROR1:
		clear_obf(kcs, status);
		write_data(kcs, 0);
		kcs->state = KCS_ERROR2;
		break;

	case KCS_ERROR2:
		if (state != KCS_READ_STATE) {
			start_error_recovery(kcs,
					     "Not in read state for error2");
			break;
		}
		if (!check_obf(kcs, status, time))
			return SI_SM_CALL_WITH_DELAY;

		clear_obf(kcs, status);
		write_data(kcs, KCS_READ_BYTE);
		kcs->state = KCS_ERROR3;
		break;

	case KCS_ERROR3:
		if (state != KCS_IDLE_STATE) {
			start_error_recovery(kcs,
					     "Not in idle state for error3");
			break;
		}

		if (!check_obf(kcs, status, time))
			return SI_SM_CALL_WITH_DELAY;

		clear_obf(kcs, status);
		if (kcs->orig_write_count) {
			restart_kcs_transaction(kcs);
		} else {
			kcs->state = KCS_IDLE;
			return SI_SM_TRANSACTION_COMPLETE;
		}
		break;

	case KCS_HOSED:
		break;
	}

	if (kcs->state == KCS_HOSED) {
		init_kcs_data(kcs, kcs->io);
		return SI_SM_HOSED;
	}

	return SI_SM_CALL_WITHOUT_DELAY;
}

static int kcs_size(void)
{
	return sizeof(struct si_sm_data);
}

static int kcs_detect(struct si_sm_data *kcs)
{
	/*
	 * It's impossible for the KCS status register to be all 1's,
	 * (assuming a properly functioning, self-initialized BMC)
	 * but that's what you get from reading a bogus address, so we
	 * test that first.
	 */
	if (read_status(kcs) == 0xff)
		return 1;

	return 0;
}

static void kcs_cleanup(struct si_sm_data *kcs)
{
}

struct si_sm_handlers kcs_smi_handlers = {
	.init_data         = init_kcs_data,
	.start_transaction = start_kcs_transaction,
	.get_result        = get_kcs_result,
	.event             = kcs_event,
	.detect            = kcs_detect,
	.cleanup           = kcs_cleanup,
	.size              = kcs_size,
};