xref: /linux/arch/mips/sibyte/common/sb_tbprof.c (revision 60e13231561b3a4c5269bfa1ef6c0569ad6f28ec)
1 /*
2  * This program is free software; you can redistribute it and/or
3  * modify it under the terms of the GNU General Public License
4  * as published by the Free Software Foundation; either version 2
5  * of the License, or (at your option) any later version.
6  *
7  * This program is distributed in the hope that it will be useful,
8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10  * GNU General Public License for more details.
11  *
12  * You should have received a copy of the GNU General Public License
13  * along with this program; if not, write to the Free Software
14  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
15  *
16  * Copyright (C) 2001, 2002, 2003 Broadcom Corporation
17  * Copyright (C) 2007 Ralf Baechle <ralf@linux-mips.org>
18  * Copyright (C) 2007 MIPS Technologies, Inc.
19  *    written by Ralf Baechle <ralf@linux-mips.org>
20  */
21 
22 #undef DEBUG
23 
24 #include <linux/device.h>
25 #include <linux/module.h>
26 #include <linux/kernel.h>
27 #include <linux/types.h>
28 #include <linux/init.h>
29 #include <linux/interrupt.h>
30 #include <linux/vmalloc.h>
31 #include <linux/fs.h>
32 #include <linux/errno.h>
33 #include <linux/wait.h>
34 #include <asm/io.h>
35 #include <asm/sibyte/sb1250.h>
36 
37 #if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
38 #include <asm/sibyte/bcm1480_regs.h>
39 #include <asm/sibyte/bcm1480_scd.h>
40 #include <asm/sibyte/bcm1480_int.h>
41 #elif defined(CONFIG_SIBYTE_SB1250) || defined(CONFIG_SIBYTE_BCM112X)
42 #include <asm/sibyte/sb1250_regs.h>
43 #include <asm/sibyte/sb1250_scd.h>
44 #include <asm/sibyte/sb1250_int.h>
45 #else
46 #error invalid SiByte UART configuration
47 #endif
48 
49 #if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
50 #undef K_INT_TRACE_FREEZE
51 #define K_INT_TRACE_FREEZE K_BCM1480_INT_TRACE_FREEZE
52 #undef K_INT_PERF_CNT
53 #define K_INT_PERF_CNT K_BCM1480_INT_PERF_CNT
54 #endif
55 
56 #include <asm/system.h>
57 #include <asm/uaccess.h>
58 
59 #define SBPROF_TB_MAJOR 240
60 
61 typedef u64 tb_sample_t[6*256];
62 
63 enum open_status {
64 	SB_CLOSED,
65 	SB_OPENING,
66 	SB_OPEN
67 };
68 
69 struct sbprof_tb {
70 	wait_queue_head_t	tb_sync;
71 	wait_queue_head_t	tb_read;
72 	struct mutex		lock;
73 	enum open_status	open;
74 	tb_sample_t		*sbprof_tbbuf;
75 	int			next_tb_sample;
76 
77 	volatile int		tb_enable;
78 	volatile int		tb_armed;
79 
80 };
81 
82 static struct sbprof_tb sbp;
83 
84 #define MAX_SAMPLE_BYTES (24*1024*1024)
85 #define MAX_TBSAMPLE_BYTES (12*1024*1024)
86 
87 #define MAX_SAMPLES (MAX_SAMPLE_BYTES/sizeof(u_int32_t))
88 #define TB_SAMPLE_SIZE (sizeof(tb_sample_t))
89 #define MAX_TB_SAMPLES (MAX_TBSAMPLE_BYTES/TB_SAMPLE_SIZE)
90 
91 /* ioctls */
92 #define SBPROF_ZBSTART		_IOW('s', 0, int)
93 #define SBPROF_ZBSTOP		_IOW('s', 1, int)
94 #define SBPROF_ZBWAITFULL	_IOW('s', 2, int)
95 
96 /*
97  * Routines for using 40-bit SCD cycle counter
98  *
99  * Client responsible for either handling interrupts or making sure
100  * the cycles counter never saturates, e.g., by doing
101  * zclk_timer_init(0) at least every 2^40 - 1 ZCLKs.
102  */
103 
104 /*
105  * Configures SCD counter 0 to count ZCLKs starting from val;
106  * Configures SCD counters1,2,3 to count nothing.
107  * Must not be called while gathering ZBbus profiles.
108  */
109 
110 #define zclk_timer_init(val) \
111   __asm__ __volatile__ (".set push;" \
112 			".set mips64;" \
113 			"la   $8, 0xb00204c0;" /* SCD perf_cnt_cfg */ \
114 			"sd   %0, 0x10($8);"   /* write val to counter0 */ \
115 			"sd   %1, 0($8);"      /* config counter0 for zclks*/ \
116 			".set pop" \
117 			: /* no outputs */ \
118 						     /* enable, counter0 */ \
119 			: /* inputs */ "r"(val), "r" ((1ULL << 33) | 1ULL) \
120 			: /* modifies */ "$8" )
121 
122 
123 /* Reads SCD counter 0 and puts result in value
124    unsigned long long val; */
125 #define zclk_get(val) \
126   __asm__ __volatile__ (".set push;" \
127 			".set mips64;" \
128 			"la   $8, 0xb00204c0;" /* SCD perf_cnt_cfg */ \
129 			"ld   %0, 0x10($8);"   /* write val to counter0 */ \
130 			".set pop" \
131 			: /* outputs */ "=r"(val) \
132 			: /* inputs */ \
133 			: /* modifies */ "$8" )
134 
135 #define DEVNAME "sb_tbprof"
136 
137 #define TB_FULL (sbp.next_tb_sample == MAX_TB_SAMPLES)
138 
139 /*
140  * Support for ZBbus sampling using the trace buffer
141  *
142  * We use the SCD performance counter interrupt, caused by a Zclk counter
143  * overflow, to trigger the start of tracing.
144  *
145  * We set the trace buffer to sample everything and freeze on
146  * overflow.
147  *
148  * We map the interrupt for trace_buffer_freeze to handle it on CPU 0.
149  *
150  */
151 
152 static u64 tb_period;
153 
154 static void arm_tb(void)
155 {
156         u64 scdperfcnt;
157 	u64 next = (1ULL << 40) - tb_period;
158 	u64 tb_options = M_SCD_TRACE_CFG_FREEZE_FULL;
159 
160 	/*
161 	 * Generate an SCD_PERFCNT interrupt in TB_PERIOD Zclks to
162 	 * trigger start of trace.  XXX vary sampling period
163 	 */
164 	__raw_writeq(0, IOADDR(A_SCD_PERF_CNT_1));
165 	scdperfcnt = __raw_readq(IOADDR(A_SCD_PERF_CNT_CFG));
166 
167 	/*
168 	 * Unfortunately, in Pass 2 we must clear all counters to knock down
169 	 * a previous interrupt request.  This means that bus profiling
170 	 * requires ALL of the SCD perf counters.
171 	 */
172 #if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
173 	__raw_writeq((scdperfcnt & ~M_SPC_CFG_SRC1) |
174 						/* keep counters 0,2,3,4,5,6,7 as is */
175 		     V_SPC_CFG_SRC1(1),		/* counter 1 counts cycles */
176 		     IOADDR(A_BCM1480_SCD_PERF_CNT_CFG0));
177 	__raw_writeq(
178 		     M_SPC_CFG_ENABLE |		/* enable counting */
179 		     M_SPC_CFG_CLEAR |		/* clear all counters */
180 		     V_SPC_CFG_SRC1(1),		/* counter 1 counts cycles */
181 		     IOADDR(A_BCM1480_SCD_PERF_CNT_CFG1));
182 #else
183 	__raw_writeq((scdperfcnt & ~M_SPC_CFG_SRC1) |
184 						/* keep counters 0,2,3 as is */
185 		     M_SPC_CFG_ENABLE |		/* enable counting */
186 		     M_SPC_CFG_CLEAR |		/* clear all counters */
187 		     V_SPC_CFG_SRC1(1),		/* counter 1 counts cycles */
188 		     IOADDR(A_SCD_PERF_CNT_CFG));
189 #endif
190 	__raw_writeq(next, IOADDR(A_SCD_PERF_CNT_1));
191 	/* Reset the trace buffer */
192 	__raw_writeq(M_SCD_TRACE_CFG_RESET, IOADDR(A_SCD_TRACE_CFG));
193 #if 0 && defined(M_SCD_TRACE_CFG_FORCECNT)
194 	/* XXXKW may want to expose control to the data-collector */
195 	tb_options |= M_SCD_TRACE_CFG_FORCECNT;
196 #endif
197 	__raw_writeq(tb_options, IOADDR(A_SCD_TRACE_CFG));
198 	sbp.tb_armed = 1;
199 }
200 
201 static irqreturn_t sbprof_tb_intr(int irq, void *dev_id)
202 {
203 	int i;
204 
205 	pr_debug(DEVNAME ": tb_intr\n");
206 
207 	if (sbp.next_tb_sample < MAX_TB_SAMPLES) {
208 		/* XXX should use XKPHYS to make writes bypass L2 */
209 		u64 *p = sbp.sbprof_tbbuf[sbp.next_tb_sample++];
210 		/* Read out trace */
211 		__raw_writeq(M_SCD_TRACE_CFG_START_READ,
212 			     IOADDR(A_SCD_TRACE_CFG));
213 		__asm__ __volatile__ ("sync" : : : "memory");
214 		/* Loop runs backwards because bundles are read out in reverse order */
215 		for (i = 256 * 6; i > 0; i -= 6) {
216 			/* Subscripts decrease to put bundle in the order */
217 			/*   t0 lo, t0 hi, t1 lo, t1 hi, t2 lo, t2 hi */
218 			p[i - 1] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
219 			/* read t2 hi */
220 			p[i - 2] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
221 			/* read t2 lo */
222 			p[i - 3] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
223 			/* read t1 hi */
224 			p[i - 4] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
225 			/* read t1 lo */
226 			p[i - 5] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
227 			/* read t0 hi */
228 			p[i - 6] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
229 			/* read t0 lo */
230 		}
231 		if (!sbp.tb_enable) {
232 			pr_debug(DEVNAME ": tb_intr shutdown\n");
233 			__raw_writeq(M_SCD_TRACE_CFG_RESET,
234 				     IOADDR(A_SCD_TRACE_CFG));
235 			sbp.tb_armed = 0;
236 			wake_up_interruptible(&sbp.tb_sync);
237 		} else {
238 			/* knock down current interrupt and get another one later */
239 			arm_tb();
240 		}
241 	} else {
242 		/* No more trace buffer samples */
243 		pr_debug(DEVNAME ": tb_intr full\n");
244 		__raw_writeq(M_SCD_TRACE_CFG_RESET, IOADDR(A_SCD_TRACE_CFG));
245 		sbp.tb_armed = 0;
246 		if (!sbp.tb_enable)
247 			wake_up_interruptible(&sbp.tb_sync);
248 		wake_up_interruptible(&sbp.tb_read);
249 	}
250 	return IRQ_HANDLED;
251 }
252 
253 static irqreturn_t sbprof_pc_intr(int irq, void *dev_id)
254 {
255 	printk(DEVNAME ": unexpected pc_intr");
256 	return IRQ_NONE;
257 }
258 
259 /*
260  * Requires: Already called zclk_timer_init with a value that won't
261  *           saturate 40 bits.  No subsequent use of SCD performance counters
262  *           or trace buffer.
263  */
264 
265 static int sbprof_zbprof_start(struct file *filp)
266 {
267 	u64 scdperfcnt;
268 	int err;
269 
270 	if (xchg(&sbp.tb_enable, 1))
271 		return -EBUSY;
272 
273 	pr_debug(DEVNAME ": starting\n");
274 
275 	sbp.next_tb_sample = 0;
276 	filp->f_pos = 0;
277 
278 	err = request_irq(K_INT_TRACE_FREEZE, sbprof_tb_intr, 0,
279 			  DEVNAME " trace freeze", &sbp);
280 	if (err)
281 		return -EBUSY;
282 
283 	/* Make sure there isn't a perf-cnt interrupt waiting */
284 	scdperfcnt = __raw_readq(IOADDR(A_SCD_PERF_CNT_CFG));
285 	/* Disable and clear counters, override SRC_1 */
286 	__raw_writeq((scdperfcnt & ~(M_SPC_CFG_SRC1 | M_SPC_CFG_ENABLE)) |
287 		     M_SPC_CFG_ENABLE | M_SPC_CFG_CLEAR | V_SPC_CFG_SRC1(1),
288 		     IOADDR(A_SCD_PERF_CNT_CFG));
289 
290 	/*
291 	 * We grab this interrupt to prevent others from trying to use
292          * it, even though we don't want to service the interrupts
293          * (they only feed into the trace-on-interrupt mechanism)
294 	 */
295 	if (request_irq(K_INT_PERF_CNT, sbprof_pc_intr, 0, DEVNAME " scd perfcnt", &sbp)) {
296 		free_irq(K_INT_TRACE_FREEZE, &sbp);
297 		return -EBUSY;
298 	}
299 
300 	/*
301 	 * I need the core to mask these, but the interrupt mapper to
302 	 *  pass them through.  I am exploiting my knowledge that
303 	 *  cp0_status masks out IP[5]. krw
304 	 */
305 #if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
306 	__raw_writeq(K_BCM1480_INT_MAP_I3,
307 		     IOADDR(A_BCM1480_IMR_REGISTER(0, R_BCM1480_IMR_INTERRUPT_MAP_BASE_L) +
308 			    ((K_BCM1480_INT_PERF_CNT & 0x3f) << 3)));
309 #else
310 	__raw_writeq(K_INT_MAP_I3,
311 		     IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_MAP_BASE) +
312 			    (K_INT_PERF_CNT << 3)));
313 #endif
314 
315 	/* Initialize address traps */
316 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_0));
317 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_1));
318 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_2));
319 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_3));
320 
321 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_0));
322 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_1));
323 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_2));
324 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_3));
325 
326 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_0));
327 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_1));
328 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_2));
329 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_3));
330 
331 	/* Initialize Trace Event 0-7 */
332 	/*				when interrupt  */
333 	__raw_writeq(M_SCD_TREVT_INTERRUPT, IOADDR(A_SCD_TRACE_EVENT_0));
334 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_1));
335 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_2));
336 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_3));
337 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_4));
338 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_5));
339 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_6));
340 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_7));
341 
342 	/* Initialize Trace Sequence 0-7 */
343 	/*				     Start on event 0 (interrupt) */
344 	__raw_writeq(V_SCD_TRSEQ_FUNC_START | 0x0fff,
345 		     IOADDR(A_SCD_TRACE_SEQUENCE_0));
346 	/*			  dsamp when d used | asamp when a used */
347 	__raw_writeq(M_SCD_TRSEQ_ASAMPLE | M_SCD_TRSEQ_DSAMPLE |
348 		     K_SCD_TRSEQ_TRIGGER_ALL,
349 		     IOADDR(A_SCD_TRACE_SEQUENCE_1));
350 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_2));
351 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_3));
352 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_4));
353 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_5));
354 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_6));
355 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_7));
356 
357 	/* Now indicate the PERF_CNT interrupt as a trace-relevant interrupt */
358 #if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
359 	__raw_writeq(1ULL << (K_BCM1480_INT_PERF_CNT & 0x3f),
360 		     IOADDR(A_BCM1480_IMR_REGISTER(0, R_BCM1480_IMR_INTERRUPT_TRACE_L)));
361 #else
362 	__raw_writeq(1ULL << K_INT_PERF_CNT,
363 		     IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_TRACE)));
364 #endif
365 	arm_tb();
366 
367 	pr_debug(DEVNAME ": done starting\n");
368 
369 	return 0;
370 }
371 
372 static int sbprof_zbprof_stop(void)
373 {
374 	int err = 0;
375 
376 	pr_debug(DEVNAME ": stopping\n");
377 
378 	if (sbp.tb_enable) {
379 		/*
380 		 * XXXKW there is a window here where the intr handler may run,
381 		 * see the disable, and do the wake_up before this sleep
382 		 * happens.
383 		 */
384 		pr_debug(DEVNAME ": wait for disarm\n");
385 		err = wait_event_interruptible(sbp.tb_sync, !sbp.tb_armed);
386 		pr_debug(DEVNAME ": disarm complete, stat %d\n", err);
387 
388 		if (err)
389 			return err;
390 
391 		sbp.tb_enable = 0;
392 		free_irq(K_INT_TRACE_FREEZE, &sbp);
393 		free_irq(K_INT_PERF_CNT, &sbp);
394 	}
395 
396 	pr_debug(DEVNAME ": done stopping\n");
397 
398 	return err;
399 }
400 
401 static int sbprof_tb_open(struct inode *inode, struct file *filp)
402 {
403 	int minor;
404 
405 	minor = iminor(inode);
406 	if (minor != 0)
407 		return -ENODEV;
408 
409 	if (xchg(&sbp.open, SB_OPENING) != SB_CLOSED)
410 		return -EBUSY;
411 
412 	memset(&sbp, 0, sizeof(struct sbprof_tb));
413 	sbp.sbprof_tbbuf = vzalloc(MAX_TBSAMPLE_BYTES);
414 	if (!sbp.sbprof_tbbuf) {
415 		sbp.open = SB_CLOSED;
416 		wmb();
417 		return -ENOMEM;
418 	}
419 
420 	init_waitqueue_head(&sbp.tb_sync);
421 	init_waitqueue_head(&sbp.tb_read);
422 	mutex_init(&sbp.lock);
423 
424 	sbp.open = SB_OPEN;
425 	wmb();
426 
427 	return 0;
428 }
429 
430 static int sbprof_tb_release(struct inode *inode, struct file *filp)
431 {
432 	int minor;
433 
434 	minor = iminor(inode);
435 	if (minor != 0 || sbp.open != SB_CLOSED)
436 		return -ENODEV;
437 
438 	mutex_lock(&sbp.lock);
439 
440 	if (sbp.tb_armed || sbp.tb_enable)
441 		sbprof_zbprof_stop();
442 
443 	vfree(sbp.sbprof_tbbuf);
444 	sbp.open = SB_CLOSED;
445 	wmb();
446 
447 	mutex_unlock(&sbp.lock);
448 
449 	return 0;
450 }
451 
452 static ssize_t sbprof_tb_read(struct file *filp, char *buf,
453 			      size_t size, loff_t *offp)
454 {
455 	int cur_sample, sample_off, cur_count, sample_left;
456 	char *src;
457 	int   count   =	 0;
458 	char *dest    =	 buf;
459 	long  cur_off = *offp;
460 
461 	if (!access_ok(VERIFY_WRITE, buf, size))
462 		return -EFAULT;
463 
464 	mutex_lock(&sbp.lock);
465 
466 	count = 0;
467 	cur_sample = cur_off / TB_SAMPLE_SIZE;
468 	sample_off = cur_off % TB_SAMPLE_SIZE;
469 	sample_left = TB_SAMPLE_SIZE - sample_off;
470 
471 	while (size && (cur_sample < sbp.next_tb_sample)) {
472 		int err;
473 
474 		cur_count = size < sample_left ? size : sample_left;
475 		src = (char *)(((long)sbp.sbprof_tbbuf[cur_sample])+sample_off);
476 		err = __copy_to_user(dest, src, cur_count);
477 		if (err) {
478 			*offp = cur_off + cur_count - err;
479 			mutex_unlock(&sbp.lock);
480 			return err;
481 		}
482 		pr_debug(DEVNAME ": read from sample %d, %d bytes\n",
483 		         cur_sample, cur_count);
484 		size -= cur_count;
485 		sample_left -= cur_count;
486 		if (!sample_left) {
487 			cur_sample++;
488 			sample_off = 0;
489 			sample_left = TB_SAMPLE_SIZE;
490 		} else {
491 			sample_off += cur_count;
492 		}
493 		cur_off += cur_count;
494 		dest += cur_count;
495 		count += cur_count;
496 	}
497 	*offp = cur_off;
498 	mutex_unlock(&sbp.lock);
499 
500 	return count;
501 }
502 
503 static long sbprof_tb_ioctl(struct file *filp,
504 			    unsigned int command,
505 			    unsigned long arg)
506 {
507 	int err = 0;
508 
509 	switch (command) {
510 	case SBPROF_ZBSTART:
511 		mutex_lock(&sbp.lock);
512 		err = sbprof_zbprof_start(filp);
513 		mutex_unlock(&sbp.lock);
514 		break;
515 
516 	case SBPROF_ZBSTOP:
517 		mutex_lock(&sbp.lock);
518 		err = sbprof_zbprof_stop();
519 		mutex_unlock(&sbp.lock);
520 		break;
521 
522 	case SBPROF_ZBWAITFULL: {
523 		err = wait_event_interruptible(sbp.tb_read, TB_FULL);
524 		if (err)
525 			break;
526 
527 		err = put_user(TB_FULL, (int *) arg);
528 		break;
529 	}
530 
531 	default:
532 		err = -EINVAL;
533 		break;
534 	}
535 
536 	return err;
537 }
538 
539 static const struct file_operations sbprof_tb_fops = {
540 	.owner		= THIS_MODULE,
541 	.open		= sbprof_tb_open,
542 	.release	= sbprof_tb_release,
543 	.read		= sbprof_tb_read,
544 	.unlocked_ioctl	= sbprof_tb_ioctl,
545 	.compat_ioctl	= sbprof_tb_ioctl,
546 	.mmap		= NULL,
547 	.llseek		= default_llseek,
548 };
549 
550 static struct class *tb_class;
551 static struct device *tb_dev;
552 
553 static int __init sbprof_tb_init(void)
554 {
555 	struct device *dev;
556 	struct class *tbc;
557 	int err;
558 
559 	if (register_chrdev(SBPROF_TB_MAJOR, DEVNAME, &sbprof_tb_fops)) {
560 		printk(KERN_WARNING DEVNAME ": initialization failed (dev %d)\n",
561 		       SBPROF_TB_MAJOR);
562 		return -EIO;
563 	}
564 
565 	tbc = class_create(THIS_MODULE, "sb_tracebuffer");
566 	if (IS_ERR(tbc)) {
567 		err = PTR_ERR(tbc);
568 		goto out_chrdev;
569 	}
570 
571 	tb_class = tbc;
572 
573 	dev = device_create(tbc, NULL, MKDEV(SBPROF_TB_MAJOR, 0), NULL, "tb");
574 	if (IS_ERR(dev)) {
575 		err = PTR_ERR(dev);
576 		goto out_class;
577 	}
578 	tb_dev = dev;
579 
580 	sbp.open = SB_CLOSED;
581 	wmb();
582 	tb_period = zbbus_mhz * 10000LL;
583 	pr_info(DEVNAME ": initialized - tb_period = %lld\n",
584 		(long long) tb_period);
585 	return 0;
586 
587 out_class:
588 	class_destroy(tb_class);
589 out_chrdev:
590 	unregister_chrdev(SBPROF_TB_MAJOR, DEVNAME);
591 
592 	return err;
593 }
594 
595 static void __exit sbprof_tb_cleanup(void)
596 {
597 	device_destroy(tb_class, MKDEV(SBPROF_TB_MAJOR, 0));
598 	unregister_chrdev(SBPROF_TB_MAJOR, DEVNAME);
599 	class_destroy(tb_class);
600 }
601 
602 module_init(sbprof_tb_init);
603 module_exit(sbprof_tb_cleanup);
604 
605 MODULE_ALIAS_CHARDEV_MAJOR(SBPROF_TB_MAJOR);
606 MODULE_AUTHOR("Ralf Baechle <ralf@linux-mips.org>");
607 MODULE_LICENSE("GPL");
608