arch/mips/sibyte/sb1250/bcm1250_tbprof.c - maze/linux - Git at Google

 /*
  * Copyright (C) 2001, 2002, 2003 Broadcom Corporation
  *
  * 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 program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  */

 #define SBPROF_TB_DEBUG 0

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/fs.h>
 #include <linux/errno.h>
 #include <linux/reboot.h>
 #include <linux/smp_lock.h>
 #include <linux/wait.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/sibyte/sb1250.h>
 #include <asm/sibyte/sb1250_regs.h>
 #include <asm/sibyte/sb1250_scd.h>
 #include <asm/sibyte/sb1250_int.h>
 #include <asm/sibyte/trace_prof.h>

 #define DEVNAME "bcm1250_tbprof"

 static struct sbprof_tb sbp;

 #define TB_FULL (sbp.next_tb_sample == MAX_TB_SAMPLES)

 /************************************************************************
  * Support for ZBbus sampling using the trace buffer
  *
  * We use the SCD performance counter interrupt, caused by a Zclk counter
  * overflow, to trigger the start of tracing.
  *
  * We set the trace buffer to sample everything and freeze on
  * overflow.
  *
  * We map the interrupt for trace_buffer_freeze to handle it on CPU 0.
  *
  ************************************************************************/

 static u_int64_t tb_period;

 static void arm_tb(void)
 {
         u_int64_t scdperfcnt;
 	u_int64_t next = (1ULL << 40) - tb_period;
 	u_int64_t tb_options = M_SCD_TRACE_CFG_FREEZE_FULL;
 	/* Generate an SCD_PERFCNT interrupt in TB_PERIOD Zclks to
 	   trigger start of trace.  XXX vary sampling period */
 	__raw_writeq(0, IOADDR(A_SCD_PERF_CNT_1));
 	scdperfcnt = __raw_readq(IOADDR(A_SCD_PERF_CNT_CFG));
 	/* Unfortunately, in Pass 2 we must clear all counters to knock down
 	   a previous interrupt request.  This means that bus profiling
 	   requires ALL of the SCD perf counters. */
 	__raw_writeq((scdperfcnt & ~M_SPC_CFG_SRC1) |
 						// keep counters 0,2,3 as is
 		     M_SPC_CFG_ENABLE |		// enable counting
 		     M_SPC_CFG_CLEAR |		// clear all counters
 		     V_SPC_CFG_SRC1(1),		// counter 1 counts cycles
 		     IOADDR(A_SCD_PERF_CNT_CFG));
 	__raw_writeq(next, IOADDR(A_SCD_PERF_CNT_1));
 	/* Reset the trace buffer */
 	__raw_writeq(M_SCD_TRACE_CFG_RESET, IOADDR(A_SCD_TRACE_CFG));
 #if 0 && defined(M_SCD_TRACE_CFG_FORCECNT)
 	/* XXXKW may want to expose control to the data-collector */
 	tb_options |= M_SCD_TRACE_CFG_FORCECNT;
 #endif
 	__raw_writeq(tb_options, IOADDR(A_SCD_TRACE_CFG));
 	sbp.tb_armed = 1;
 }

 static irqreturn_t sbprof_tb_intr(int irq, void *dev_id)
 {
 	int i;
 	DBG(printk(DEVNAME ": tb_intr\n"));
 	if (sbp.next_tb_sample < MAX_TB_SAMPLES) {
 		/* XXX should use XKPHYS to make writes bypass L2 */
 		u_int64_t *p = sbp.sbprof_tbbuf[sbp.next_tb_sample++];
 		/* Read out trace */
 		__raw_writeq(M_SCD_TRACE_CFG_START_READ,
 			     IOADDR(A_SCD_TRACE_CFG));
 		__asm__ __volatile__ ("sync" : : : "memory");
 		/* Loop runs backwards because bundles are read out in reverse order */
 		for (i = 256 * 6; i > 0; i -= 6) {
 			// Subscripts decrease to put bundle in the order
 			//   t0 lo, t0 hi, t1 lo, t1 hi, t2 lo, t2 hi
 			p[i - 1] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
 								// read t2 hi
 			p[i - 2] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
 								// read t2 lo
 			p[i - 3] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
 								// read t1 hi
 			p[i - 4] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
 								// read t1 lo
 			p[i - 5] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
 								// read t0 hi
 			p[i - 6] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
 								// read t0 lo
 		}
 		if (!sbp.tb_enable) {
 			DBG(printk(DEVNAME ": tb_intr shutdown\n"));
 			__raw_writeq(M_SCD_TRACE_CFG_RESET,
 				     IOADDR(A_SCD_TRACE_CFG));
 			sbp.tb_armed = 0;
 			wake_up(&sbp.tb_sync);
 		} else {
 			arm_tb();	// knock down current interrupt and get another one later
 		}
 	} else {
 		/* No more trace buffer samples */
 		DBG(printk(DEVNAME ": tb_intr full\n"));
 		__raw_writeq(M_SCD_TRACE_CFG_RESET, IOADDR(A_SCD_TRACE_CFG));
 		sbp.tb_armed = 0;
 		if (!sbp.tb_enable) {
 			wake_up(&sbp.tb_sync);
 		}
 		wake_up(&sbp.tb_read);
 	}
 	return IRQ_HANDLED;
 }

 static irqreturn_t sbprof_pc_intr(int irq, void *dev_id)
 {
 	printk(DEVNAME ": unexpected pc_intr");
 	return IRQ_NONE;
 }

 int sbprof_zbprof_start(struct file *filp)
 {
 	u_int64_t scdperfcnt;

 	if (sbp.tb_enable)
 		return -EBUSY;

 	DBG(printk(DEVNAME ": starting\n"));

 	sbp.tb_enable = 1;
 	sbp.next_tb_sample = 0;
 	filp->f_pos = 0;

 	if (request_irq
 	    (K_INT_TRACE_FREEZE, sbprof_tb_intr, 0, DEVNAME " trace freeze", &sbp)) {
 		return -EBUSY;
 	}
 	/* Make sure there isn't a perf-cnt interrupt waiting */
 	scdperfcnt = __raw_readq(IOADDR(A_SCD_PERF_CNT_CFG));
 	/* Disable and clear counters, override SRC_1 */
 	__raw_writeq((scdperfcnt & ~(M_SPC_CFG_SRC1 | M_SPC_CFG_ENABLE)) |
 		     M_SPC_CFG_ENABLE | M_SPC_CFG_CLEAR | V_SPC_CFG_SRC1(1),
 		     IOADDR(A_SCD_PERF_CNT_CFG));

 	/* We grab this interrupt to prevent others from trying to use
            it, even though we don't want to service the interrupts
            (they only feed into the trace-on-interrupt mechanism) */
 	if (request_irq
 	    (K_INT_PERF_CNT, sbprof_pc_intr, 0, DEVNAME " scd perfcnt", &sbp)) {
 		free_irq(K_INT_TRACE_FREEZE, &sbp);
 		return -EBUSY;
 	}

 	/* I need the core to mask these, but the interrupt mapper to
 	   pass them through.  I am exploiting my knowledge that
 	   cp0_status masks out IP[5]. krw */
 	__raw_writeq(K_INT_MAP_I3,
 		     IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_MAP_BASE) +
 			    (K_INT_PERF_CNT << 3)));

 	/* Initialize address traps */
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_0));
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_1));
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_2));
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_3));

 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_0));
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_1));
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_2));
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_3));

 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_0));
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_1));
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_2));
 	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_3));

 	/* Initialize Trace Event 0-7 */
 	//				when interrupt
 	__raw_writeq(M_SCD_TREVT_INTERRUPT, IOADDR(A_SCD_TRACE_EVENT_0));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_1));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_2));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_3));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_4));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_5));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_6));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_7));

 	/* Initialize Trace Sequence 0-7 */
 	//				     Start on event 0 (interrupt)
 	__raw_writeq(V_SCD_TRSEQ_FUNC_START | 0x0fff,
 		     IOADDR(A_SCD_TRACE_SEQUENCE_0));
 	//			  dsamp when d used | asamp when a used
 	__raw_writeq(M_SCD_TRSEQ_ASAMPLE | M_SCD_TRSEQ_DSAMPLE |
 		     K_SCD_TRSEQ_TRIGGER_ALL,
 		     IOADDR(A_SCD_TRACE_SEQUENCE_1));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_2));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_3));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_4));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_5));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_6));
 	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_7));

 	/* Now indicate the PERF_CNT interrupt as a trace-relevant interrupt */
 	__raw_writeq(1ULL << K_INT_PERF_CNT,
 		     IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_TRACE)));

 	arm_tb();

 	DBG(printk(DEVNAME ": done starting\n"));

 	return 0;
 }

 int sbprof_zbprof_stop(void)
 {
 	DEFINE_WAIT(wait);
 	DBG(printk(DEVNAME ": stopping\n"));

 	if (sbp.tb_enable) {
 		sbp.tb_enable = 0;
 		/* XXXKW there is a window here where the intr handler
 		   may run, see the disable, and do the wake_up before
 		   this sleep happens. */
 		if (sbp.tb_armed) {
 			DBG(printk(DEVNAME ": wait for disarm\n"));
 			prepare_to_wait(&sbp.tb_sync, &wait, TASK_INTERRUPTIBLE);
 			schedule();
 			finish_wait(&sbp.tb_sync, &wait);
 			DBG(printk(DEVNAME ": disarm complete\n"));
 		}
 		free_irq(K_INT_TRACE_FREEZE, &sbp);
 		free_irq(K_INT_PERF_CNT, &sbp);
 	}

 	DBG(printk(DEVNAME ": done stopping\n"));

 	return 0;
 }

 static int sbprof_tb_open(struct inode *inode, struct file *filp)
 {
 	int minor;

 	minor = iminor(inode);
 	if (minor != 0) {
 		return -ENODEV;
 	}
 	if (sbp.open) {
 		return -EBUSY;
 	}

 	memset(&sbp, 0, sizeof(struct sbprof_tb));
 	sbp.sbprof_tbbuf = vmalloc(MAX_TBSAMPLE_BYTES);
 	if (!sbp.sbprof_tbbuf) {
 		return -ENOMEM;
 	}
 	memset(sbp.sbprof_tbbuf, 0, MAX_TBSAMPLE_BYTES);
 	init_waitqueue_head(&sbp.tb_sync);
 	init_waitqueue_head(&sbp.tb_read);
 	sbp.open = 1;

 	return 0;
 }

 static int sbprof_tb_release(struct inode *inode, struct file *filp)
 {
 	int minor;

 	minor = iminor(inode);
 	if (minor != 0 || !sbp.open) {
 		return -ENODEV;
 	}

 	if (sbp.tb_armed || sbp.tb_enable) {
 		sbprof_zbprof_stop();
 	}

 	vfree(sbp.sbprof_tbbuf);
 	sbp.open = 0;

 	return 0;
 }

 static ssize_t sbprof_tb_read(struct file *filp, char *buf,
 			      size_t size, loff_t *offp)
 {
 	int cur_sample, sample_off, cur_count, sample_left;
 	char *src;
 	int   count   =	 0;
 	char *dest    =	 buf;
 	long  cur_off = *offp;

 	count = 0;
 	cur_sample = cur_off / TB_SAMPLE_SIZE;
 	sample_off = cur_off % TB_SAMPLE_SIZE;
 	sample_left = TB_SAMPLE_SIZE - sample_off;
 	while (size && (cur_sample < sbp.next_tb_sample)) {
 		cur_count = size < sample_left ? size : sample_left;
 		src = (char *)(((long)sbp.sbprof_tbbuf[cur_sample])+sample_off);
 		copy_to_user(dest, src, cur_count);
 		DBG(printk(DEVNAME ": read from sample %d, %d bytes\n",
 			   cur_sample, cur_count));
 		size -= cur_count;
 		sample_left -= cur_count;
 		if (!sample_left) {
 			cur_sample++;
 			sample_off = 0;
 			sample_left = TB_SAMPLE_SIZE;
 		} else {
 			sample_off += cur_count;
 		}
 		cur_off += cur_count;
 		dest += cur_count;
 		count += cur_count;
 	}
 	*offp = cur_off;

 	return count;
 }

 static long sbprof_tb_ioctl(struct file *filp,
 			    unsigned int command,
 			    unsigned long arg)
 {
 	int error = 0;

 	lock_kernel();
 	switch (command) {
 	case SBPROF_ZBSTART:
 		error = sbprof_zbprof_start(filp);
 		break;
 	case SBPROF_ZBSTOP:
 		error = sbprof_zbprof_stop();
 		break;
 	case SBPROF_ZBWAITFULL:
 		DEFINE_WAIT(wait);
 		prepare_to_wait(&sbp.tb_read, &wait, TASK_INTERRUPTIBLE);
 		schedule();
 		finish_wait(&sbp.tb_read, &wait);
 		/* XXXKW check if interrupted? */
 		return put_user(TB_FULL, (int *) arg);
 	default:
 		error = -EINVAL;
 		break;
 	}
 	unlock_kernel();

 	return error;
 }

 static struct file_operations sbprof_tb_fops = {
 	.owner		= THIS_MODULE,
 	.open		= sbprof_tb_open,
 	.release	= sbprof_tb_release,
 	.read		= sbprof_tb_read,
 	.unlocked_ioctl	= sbprof_tb_ioctl,
 	.compat_ioctl	= sbprof_tb_ioctl,
 	.mmap		= NULL,
 };

 static int __init sbprof_tb_init(void)
 {
 	if (register_chrdev(SBPROF_TB_MAJOR, DEVNAME, &sbprof_tb_fops)) {
 		printk(KERN_WARNING DEVNAME ": initialization failed (dev %d)\n",
 		       SBPROF_TB_MAJOR);
 		return -EIO;
 	}
 	sbp.open = 0;
 	tb_period = zbbus_mhz * 10000LL;
 	printk(KERN_INFO DEVNAME ": initialized - tb_period = %lld\n", tb_period);
 	return 0;
 }

 static void __exit sbprof_tb_cleanup(void)
 {
 	unregister_chrdev(SBPROF_TB_MAJOR, DEVNAME);
 }

 module_init(sbprof_tb_init);
 module_exit(sbprof_tb_cleanup);
	/*
	* Copyright (C) 2001, 2002, 2003 Broadcom Corporation
	*
	* 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 program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	*/

	#define SBPROF_TB_DEBUG 0

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/types.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/slab.h>
	#include <linux/vmalloc.h>
	#include <linux/fs.h>
	#include <linux/errno.h>
	#include <linux/reboot.h>
	#include <linux/smp_lock.h>
	#include <linux/wait.h>
	#include <asm/uaccess.h>
	#include <asm/io.h>
	#include <asm/sibyte/sb1250.h>
	#include <asm/sibyte/sb1250_regs.h>
	#include <asm/sibyte/sb1250_scd.h>
	#include <asm/sibyte/sb1250_int.h>
	#include <asm/sibyte/trace_prof.h>

	#define DEVNAME "bcm1250_tbprof"

	static struct sbprof_tb sbp;

	#define TB_FULL (sbp.next_tb_sample == MAX_TB_SAMPLES)

	/************************************************************************
	* Support for ZBbus sampling using the trace buffer
	*
	* We use the SCD performance counter interrupt, caused by a Zclk counter
	* overflow, to trigger the start of tracing.
	*
	* We set the trace buffer to sample everything and freeze on
	* overflow.
	*
	* We map the interrupt for trace_buffer_freeze to handle it on CPU 0.
	*
	************************************************************************/

	static u_int64_t tb_period;

	static void arm_tb(void)
	{
	u_int64_t scdperfcnt;
	u_int64_t next = (1ULL << 40) - tb_period;
	u_int64_t tb_options = M_SCD_TRACE_CFG_FREEZE_FULL;
	/* Generate an SCD_PERFCNT interrupt in TB_PERIOD Zclks to
	trigger start of trace. XXX vary sampling period */
	__raw_writeq(0, IOADDR(A_SCD_PERF_CNT_1));
	scdperfcnt = __raw_readq(IOADDR(A_SCD_PERF_CNT_CFG));
	/* Unfortunately, in Pass 2 we must clear all counters to knock down
	a previous interrupt request. This means that bus profiling
	requires ALL of the SCD perf counters. */
	__raw_writeq((scdperfcnt & ~M_SPC_CFG_SRC1) \|
	// keep counters 0,2,3 as is
	M_SPC_CFG_ENABLE \| // enable counting
	M_SPC_CFG_CLEAR \| // clear all counters
	V_SPC_CFG_SRC1(1), // counter 1 counts cycles
	IOADDR(A_SCD_PERF_CNT_CFG));
	__raw_writeq(next, IOADDR(A_SCD_PERF_CNT_1));
	/* Reset the trace buffer */
	__raw_writeq(M_SCD_TRACE_CFG_RESET, IOADDR(A_SCD_TRACE_CFG));
	#if 0 && defined(M_SCD_TRACE_CFG_FORCECNT)
	/* XXXKW may want to expose control to the data-collector */
	tb_options \|= M_SCD_TRACE_CFG_FORCECNT;
	#endif
	__raw_writeq(tb_options, IOADDR(A_SCD_TRACE_CFG));
	sbp.tb_armed = 1;
	}

	static irqreturn_t sbprof_tb_intr(int irq, void *dev_id)
	{
	int i;
	DBG(printk(DEVNAME ": tb_intr\n"));
	if (sbp.next_tb_sample < MAX_TB_SAMPLES) {
	/* XXX should use XKPHYS to make writes bypass L2 */
	u_int64_t *p = sbp.sbprof_tbbuf[sbp.next_tb_sample++];
	/* Read out trace */
	__raw_writeq(M_SCD_TRACE_CFG_START_READ,
	IOADDR(A_SCD_TRACE_CFG));
	__asm__ __volatile__ ("sync" : : : "memory");
	/* Loop runs backwards because bundles are read out in reverse order */
	for (i = 256 * 6; i > 0; i -= 6) {
	// Subscripts decrease to put bundle in the order
	// t0 lo, t0 hi, t1 lo, t1 hi, t2 lo, t2 hi
	p[i - 1] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
	// read t2 hi
	p[i - 2] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
	// read t2 lo
	p[i - 3] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
	// read t1 hi
	p[i - 4] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
	// read t1 lo
	p[i - 5] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
	// read t0 hi
	p[i - 6] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
	// read t0 lo
	}
	if (!sbp.tb_enable) {
	DBG(printk(DEVNAME ": tb_intr shutdown\n"));
	__raw_writeq(M_SCD_TRACE_CFG_RESET,
	IOADDR(A_SCD_TRACE_CFG));
	sbp.tb_armed = 0;
	wake_up(&sbp.tb_sync);
	} else {
	arm_tb(); // knock down current interrupt and get another one later
	}
	} else {
	/* No more trace buffer samples */
	DBG(printk(DEVNAME ": tb_intr full\n"));
	__raw_writeq(M_SCD_TRACE_CFG_RESET, IOADDR(A_SCD_TRACE_CFG));
	sbp.tb_armed = 0;
	if (!sbp.tb_enable) {
	wake_up(&sbp.tb_sync);
	}
	wake_up(&sbp.tb_read);
	}
	return IRQ_HANDLED;
	}

	static irqreturn_t sbprof_pc_intr(int irq, void *dev_id)
	{
	printk(DEVNAME ": unexpected pc_intr");
	return IRQ_NONE;
	}

	int sbprof_zbprof_start(struct file *filp)
	{
	u_int64_t scdperfcnt;

	if (sbp.tb_enable)
	return -EBUSY;

	DBG(printk(DEVNAME ": starting\n"));

	sbp.tb_enable = 1;
	sbp.next_tb_sample = 0;
	filp->f_pos = 0;

	if (request_irq
	(K_INT_TRACE_FREEZE, sbprof_tb_intr, 0, DEVNAME " trace freeze", &sbp)) {
	return -EBUSY;
	}
	/* Make sure there isn't a perf-cnt interrupt waiting */
	scdperfcnt = __raw_readq(IOADDR(A_SCD_PERF_CNT_CFG));
	/* Disable and clear counters, override SRC_1 */
	__raw_writeq((scdperfcnt & ~(M_SPC_CFG_SRC1 \| M_SPC_CFG_ENABLE)) \|
	M_SPC_CFG_ENABLE \| M_SPC_CFG_CLEAR \| V_SPC_CFG_SRC1(1),
	IOADDR(A_SCD_PERF_CNT_CFG));

	/* We grab this interrupt to prevent others from trying to use
	it, even though we don't want to service the interrupts
	(they only feed into the trace-on-interrupt mechanism) */
	if (request_irq
	(K_INT_PERF_CNT, sbprof_pc_intr, 0, DEVNAME " scd perfcnt", &sbp)) {
	free_irq(K_INT_TRACE_FREEZE, &sbp);
	return -EBUSY;
	}

	/* I need the core to mask these, but the interrupt mapper to
	pass them through. I am exploiting my knowledge that
	cp0_status masks out IP[5]. krw */
	__raw_writeq(K_INT_MAP_I3,
	IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_MAP_BASE) +
	(K_INT_PERF_CNT << 3)));

	/* Initialize address traps */
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_0));
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_1));
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_2));
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_3));

	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_0));
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_1));
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_2));
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_3));

	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_0));
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_1));
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_2));
	__raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_3));

	/* Initialize Trace Event 0-7 */
	// when interrupt
	__raw_writeq(M_SCD_TREVT_INTERRUPT, IOADDR(A_SCD_TRACE_EVENT_0));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_1));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_2));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_3));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_4));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_5));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_6));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_7));

	/* Initialize Trace Sequence 0-7 */
	// Start on event 0 (interrupt)
	__raw_writeq(V_SCD_TRSEQ_FUNC_START \| 0x0fff,
	IOADDR(A_SCD_TRACE_SEQUENCE_0));
	// dsamp when d used \| asamp when a used
	__raw_writeq(M_SCD_TRSEQ_ASAMPLE \| M_SCD_TRSEQ_DSAMPLE \|
	K_SCD_TRSEQ_TRIGGER_ALL,
	IOADDR(A_SCD_TRACE_SEQUENCE_1));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_2));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_3));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_4));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_5));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_6));
	__raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_7));

	/* Now indicate the PERF_CNT interrupt as a trace-relevant interrupt */
	__raw_writeq(1ULL << K_INT_PERF_CNT,
	IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_TRACE)));

	arm_tb();

	DBG(printk(DEVNAME ": done starting\n"));

	return 0;
	}

	int sbprof_zbprof_stop(void)
	{
	DEFINE_WAIT(wait);
	DBG(printk(DEVNAME ": stopping\n"));

	if (sbp.tb_enable) {
	sbp.tb_enable = 0;
	/* XXXKW there is a window here where the intr handler
	may run, see the disable, and do the wake_up before
	this sleep happens. */
	if (sbp.tb_armed) {
	DBG(printk(DEVNAME ": wait for disarm\n"));
	prepare_to_wait(&sbp.tb_sync, &wait, TASK_INTERRUPTIBLE);
	schedule();
	finish_wait(&sbp.tb_sync, &wait);
	DBG(printk(DEVNAME ": disarm complete\n"));
	}
	free_irq(K_INT_TRACE_FREEZE, &sbp);
	free_irq(K_INT_PERF_CNT, &sbp);
	}

	DBG(printk(DEVNAME ": done stopping\n"));

	return 0;
	}

	static int sbprof_tb_open(struct inode inode, struct file filp)
	{
	int minor;

	minor = iminor(inode);
	if (minor != 0) {
	return -ENODEV;
	}
	if (sbp.open) {
	return -EBUSY;
	}

	memset(&sbp, 0, sizeof(struct sbprof_tb));
	sbp.sbprof_tbbuf = vmalloc(MAX_TBSAMPLE_BYTES);
	if (!sbp.sbprof_tbbuf) {
	return -ENOMEM;
	}
	memset(sbp.sbprof_tbbuf, 0, MAX_TBSAMPLE_BYTES);
	init_waitqueue_head(&sbp.tb_sync);
	init_waitqueue_head(&sbp.tb_read);
	sbp.open = 1;

	return 0;
	}

	static int sbprof_tb_release(struct inode inode, struct file filp)
	{
	int minor;

	minor = iminor(inode);
	if (minor != 0 \|\| !sbp.open) {
	return -ENODEV;
	}

	if (sbp.tb_armed \|\| sbp.tb_enable) {
	sbprof_zbprof_stop();
	}

	vfree(sbp.sbprof_tbbuf);
	sbp.open = 0;

	return 0;
	}

	static ssize_t sbprof_tb_read(struct file filp, char buf,
	size_t size, loff_t *offp)
	{
	int cur_sample, sample_off, cur_count, sample_left;
	char *src;
	int count = 0;
	char *dest = buf;
	long cur_off = *offp;

	count = 0;
	cur_sample = cur_off / TB_SAMPLE_SIZE;
	sample_off = cur_off % TB_SAMPLE_SIZE;
	sample_left = TB_SAMPLE_SIZE - sample_off;
	while (size && (cur_sample < sbp.next_tb_sample)) {
	cur_count = size < sample_left ? size : sample_left;
	src = (char *)(((long)sbp.sbprof_tbbuf[cur_sample])+sample_off);
	copy_to_user(dest, src, cur_count);
	DBG(printk(DEVNAME ": read from sample %d, %d bytes\n",
	cur_sample, cur_count));
	size -= cur_count;
	sample_left -= cur_count;
	if (!sample_left) {
	cur_sample++;
	sample_off = 0;
	sample_left = TB_SAMPLE_SIZE;
	} else {
	sample_off += cur_count;
	}
	cur_off += cur_count;
	dest += cur_count;
	count += cur_count;
	}
	*offp = cur_off;

	return count;
	}

	static long sbprof_tb_ioctl(struct file *filp,
	unsigned int command,
	unsigned long arg)
	{
	int error = 0;

	lock_kernel();
	switch (command) {
	case SBPROF_ZBSTART:
	error = sbprof_zbprof_start(filp);
	break;
	case SBPROF_ZBSTOP:
	error = sbprof_zbprof_stop();
	break;
	case SBPROF_ZBWAITFULL:
	DEFINE_WAIT(wait);
	prepare_to_wait(&sbp.tb_read, &wait, TASK_INTERRUPTIBLE);
	schedule();
	finish_wait(&sbp.tb_read, &wait);
	/* XXXKW check if interrupted? */
	return put_user(TB_FULL, (int *) arg);
	default:
	error = -EINVAL;
	break;
	}
	unlock_kernel();

	return error;
	}

	static struct file_operations sbprof_tb_fops = {
	.owner = THIS_MODULE,
	.open = sbprof_tb_open,
	.release = sbprof_tb_release,
	.read = sbprof_tb_read,
	.unlocked_ioctl = sbprof_tb_ioctl,
	.compat_ioctl = sbprof_tb_ioctl,
	.mmap = NULL,
	};

	static int __init sbprof_tb_init(void)
	{
	if (register_chrdev(SBPROF_TB_MAJOR, DEVNAME, &sbprof_tb_fops)) {
	printk(KERN_WARNING DEVNAME ": initialization failed (dev %d)\n",
	SBPROF_TB_MAJOR);
	return -EIO;
	}
	sbp.open = 0;
	tb_period = zbbus_mhz * 10000LL;
	printk(KERN_INFO DEVNAME ": initialized - tb_period = %lld\n", tb_period);
	return 0;
	}

	static void __exit sbprof_tb_cleanup(void)
	{
	unregister_chrdev(SBPROF_TB_MAJOR, DEVNAME);
	}

	module_init(sbprof_tb_init);
	module_exit(sbprof_tb_cleanup);