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