Reset to 3.12.19

3 files changed, 2 insertions, 1281 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index e9b20e8..8dacd4c 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -63,7 +63,6 @@ config ATMEL_PWM
 config ATMEL_TCLIB
 	bool "Atmel AT32/AT91 Timer/Counter Library"
 	depends on (AVR32 || ARCH_AT91)
-	default y if PREEMPT_RT_FULL
 	help
 	  Select this if you want a library to allocate the Timer/Counter
 	  blocks found on many Atmel processors.  This facilitates using
@@ -79,7 +78,8 @@ config ATMEL_TCB_CLKSRC
 	  are combined to make a single 32-bit timer.
 
 	  When GENERIC_CLOCKEVENTS is defined, the third timer channel
-	  may be used as a clock event device supporting oneshot mode.
+	  may be used as a clock event device supporting oneshot mode
+	  (delays of up to two seconds) based on the 32 KiHz clock.
 
 config ATMEL_TCB_CLKSRC_BLOCK
 	int
@@ -93,15 +93,6 @@ config ATMEL_TCB_CLKSRC_BLOCK
 	  TC can be used for other purposes, such as PWM generation and
 	  interval timing.
 
-config ATMEL_TCB_CLKSRC_USE_SLOW_CLOCK
-	bool "TC Block use 32 KiHz clock"
-	depends on ATMEL_TCB_CLKSRC
-	default y if !PREEMPT_RT_FULL
-	help
-	  Select this to use 32 KiHz base clock rate as TC block clock
-	  source for clock events.
-
-
 config DUMMY_IRQ
 	tristate "Dummy IRQ handler"
 	default n
@@ -131,35 +122,6 @@ config IBM_ASM
 	  for information on the specific driver level and support statement
 	  for your IBM server.
 
-config HWLAT_DETECTOR
-	tristate "Testing module to detect hardware-induced latencies"
-	depends on DEBUG_FS
-	depends on RING_BUFFER
-	default m
-	---help---
-	  A simple hardware latency detector. Use this module to detect
-	  large latencies introduced by the behavior of the underlying
-	  system firmware external to Linux. We do this using periodic
-	  use of stop_machine to grab all available CPUs and measure
-	  for unexplainable gaps in the CPU timestamp counter(s). By
-	  default, the module is not enabled until the "enable" file
-	  within the "hwlat_detector" debugfs directory is toggled.
-
-	  This module is often used to detect SMI (System Management
-	  Interrupts) on x86 systems, though is not x86 specific. To
-	  this end, we default to using a sample window of 1 second,
-	  during which we will sample for 0.5 seconds. If an SMI or
-	  similar event occurs during that time, it is recorded
-	  into an 8K samples global ring buffer until retreived.
-
-	  WARNING: This software should never be enabled (it can be built
-	  but should not be turned on after it is loaded) in a production
-	  environment where high latencies are a concern since the
-	  sampling mechanism actually introduces latencies for
-	  regular tasks while the CPU(s) are being held.
-
-	  If unsure, say N
-
 config PHANTOM
 	tristate "Sensable PHANToM (PCI)"
 	depends on PCI
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 6bb08da40..c235d5b 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -53,4 +53,3 @@ obj-$(CONFIG_INTEL_MEI)		+= mei/
 obj-$(CONFIG_VMWARE_VMCI)	+= vmw_vmci/
 obj-$(CONFIG_LATTICE_ECP3_CONFIG)	+= lattice-ecp3-config.o
 obj-$(CONFIG_SRAM)		+= sram.o
-obj-$(CONFIG_HWLAT_DETECTOR)	+= hwlat_detector.o
diff --git a/drivers/misc/hwlat_detector.c b/drivers/misc/hwlat_detector.c
deleted file mode 100644
index 2429c43..0000000
--- a/drivers/misc/hwlat_detector.c
+++ /dev/null
@@ -1,1240 +0,0 @@
-/*
- * hwlat_detector.c - A simple Hardware Latency detector.
- *
- * Use this module to detect large system latencies induced by the behavior of
- * certain underlying system hardware or firmware, independent of Linux itself.
- * The code was developed originally to detect the presence of SMIs on Intel
- * and AMD systems, although there is no dependency upon x86 herein.
- *
- * The classical example usage of this module is in detecting the presence of
- * SMIs or System Management Interrupts on Intel and AMD systems. An SMI is a
- * somewhat special form of hardware interrupt spawned from earlier CPU debug
- * modes in which the (BIOS/EFI/etc.) firmware arranges for the South Bridge
- * LPC (or other device) to generate a special interrupt under certain
- * circumstances, for example, upon expiration of a special SMI timer device,
- * due to certain external thermal readings, on certain I/O address accesses,
- * and other situations. An SMI hits a special CPU pin, triggers a special
- * SMI mode (complete with special memory map), and the OS is unaware.
- *
- * Although certain hardware-inducing latencies are necessary (for example,
- * a modern system often requires an SMI handler for correct thermal control
- * and remote management) they can wreak havoc upon any OS-level performance
- * guarantees toward low-latency, especially when the OS is not even made
- * aware of the presence of these interrupts. For this reason, we need a
- * somewhat brute force mechanism to detect these interrupts. In this case,
- * we do it by hogging all of the CPU(s) for configurable timer intervals,
- * sampling the built-in CPU timer, looking for discontiguous readings.
- *
- * WARNING: This implementation necessarily introduces latencies. Therefore,
- *          you should NEVER use this module in a production environment
- *          requiring any kind of low-latency performance guarantee(s).
- *
- * Copyright (C) 2008-2009 Jon Masters, Red Hat, Inc. <jcm@redhat.com>
- *
- * Includes useful feedback from Clark Williams <clark@redhat.com>
- *
- * This file is licensed under the terms of the GNU General Public
- * License version 2. This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
- */
-
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/ring_buffer.h>
-#include <linux/time.h>
-#include <linux/hrtimer.h>
-#include <linux/kthread.h>
-#include <linux/debugfs.h>
-#include <linux/seq_file.h>
-#include <linux/uaccess.h>
-#include <linux/version.h>
-#include <linux/delay.h>
-#include <linux/slab.h>
-#include <linux/trace_clock.h>
-
-#define BUF_SIZE_DEFAULT	262144UL		/* 8K*(sizeof(entry)) */
-#define BUF_FLAGS		(RB_FL_OVERWRITE)	/* no block on full */
-#define U64STR_SIZE		22			/* 20 digits max */
-
-#define VERSION			"1.0.0"
-#define BANNER			"hwlat_detector: "
-#define DRVNAME			"hwlat_detector"
-#define DEFAULT_SAMPLE_WINDOW	1000000			/* 1s */
-#define DEFAULT_SAMPLE_WIDTH	500000			/* 0.5s */
-#define DEFAULT_LAT_THRESHOLD	10			/* 10us */
-
-/* Module metadata */
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Jon Masters <jcm@redhat.com>");
-MODULE_DESCRIPTION("A simple hardware latency detector");
-MODULE_VERSION(VERSION);
-
-/* Module parameters */
-
-static int debug;
-static int enabled;
-static int threshold;
-
-module_param(debug, int, 0);			/* enable debug */
-module_param(enabled, int, 0);			/* enable detector */
-module_param(threshold, int, 0);		/* latency threshold */
-
-/* Buffering and sampling */
-
-static struct ring_buffer *ring_buffer;		/* sample buffer */
-static DEFINE_MUTEX(ring_buffer_mutex);		/* lock changes */
-static unsigned long buf_size = BUF_SIZE_DEFAULT;
-static struct task_struct *kthread;		/* sampling thread */
-
-/* DebugFS filesystem entries */
-
-static struct dentry *debug_dir;		/* debugfs directory */
-static struct dentry *debug_max;		/* maximum TSC delta */
-static struct dentry *debug_count;		/* total detect count */
-static struct dentry *debug_sample_width;	/* sample width us */
-static struct dentry *debug_sample_window;	/* sample window us */
-static struct dentry *debug_sample;		/* raw samples us */
-static struct dentry *debug_threshold;		/* threshold us */
-static struct dentry *debug_enable;		/* enable/disable */
-
-/* Individual samples and global state */
-
-struct sample;					/* latency sample */
-struct data;					/* Global state */
-
-/* Sampling functions */
-static int __buffer_add_sample(struct sample *sample);
-static struct sample *buffer_get_sample(struct sample *sample);
-
-/* Threading and state */
-static int kthread_fn(void *unused);
-static int start_kthread(void);
-static int stop_kthread(void);
-static void __reset_stats(void);
-static int init_stats(void);
-
-/* Debugfs interface */
-static ssize_t simple_data_read(struct file *filp, char __user *ubuf,
-				size_t cnt, loff_t *ppos, const u64 *entry);
-static ssize_t simple_data_write(struct file *filp, const char __user *ubuf,
-				 size_t cnt, loff_t *ppos, u64 *entry);
-static int debug_sample_fopen(struct inode *inode, struct file *filp);
-static ssize_t debug_sample_fread(struct file *filp, char __user *ubuf,
-				  size_t cnt, loff_t *ppos);
-static int debug_sample_release(struct inode *inode, struct file *filp);
-static int debug_enable_fopen(struct inode *inode, struct file *filp);
-static ssize_t debug_enable_fread(struct file *filp, char __user *ubuf,
-				  size_t cnt, loff_t *ppos);
-static ssize_t debug_enable_fwrite(struct file *file,
-				   const char __user *user_buffer,
-				   size_t user_size, loff_t *offset);
-
-/* Initialization functions */
-static int init_debugfs(void);
-static void free_debugfs(void);
-static int detector_init(void);
-static void detector_exit(void);
-
-/* Individual latency samples are stored here when detected and packed into
- * the ring_buffer circular buffer, where they are overwritten when
- * more than buf_size/sizeof(sample) samples are received. */
-struct sample {
-	u64		seqnum;		/* unique sequence */
-	u64		duration;	/* ktime delta */
-	u64		outer_duration;	/* ktime delta (outer loop) */
-	struct timespec	timestamp;	/* wall time */
-	unsigned long   lost;
-};
-
-/* keep the global state somewhere. */
-static struct data {
-
-	struct mutex lock;		/* protect changes */
-
-	u64	count;			/* total since reset */
-	u64	max_sample;		/* max hardware latency */
-	u64	threshold;		/* sample threshold level */
-
-	u64	sample_window;		/* total sampling window (on+off) */
-	u64	sample_width;		/* active sampling portion of window */
-
-	atomic_t sample_open;		/* whether the sample file is open */
-
-	wait_queue_head_t wq;		/* waitqeue for new sample values */
-
-} data;
-
-/**
- * __buffer_add_sample - add a new latency sample recording to the ring buffer
- * @sample: The new latency sample value
- *
- * This receives a new latency sample and records it in a global ring buffer.
- * No additional locking is used in this case.
- */
-static int __buffer_add_sample(struct sample *sample)
-{
-	return ring_buffer_write(ring_buffer,
-				 sizeof(struct sample), sample);
-}
-
-/**
- * buffer_get_sample - remove a hardware latency sample from the ring buffer
- * @sample: Pre-allocated storage for the sample
- *
- * This retrieves a hardware latency sample from the global circular buffer
- */
-static struct sample *buffer_get_sample(struct sample *sample)
-{
-	struct ring_buffer_event *e = NULL;
-	struct sample *s = NULL;
-	unsigned int cpu = 0;
-
-	if (!sample)
-		return NULL;
-
-	mutex_lock(&ring_buffer_mutex);
-	for_each_online_cpu(cpu) {
-		e = ring_buffer_consume(ring_buffer, cpu, NULL, &sample->lost);
-		if (e)
-			break;
-	}
-
-	if (e) {
-		s = ring_buffer_event_data(e);
-		memcpy(sample, s, sizeof(struct sample));
-	} else
-		sample = NULL;
-	mutex_unlock(&ring_buffer_mutex);
-
-	return sample;
-}
-
-#ifndef CONFIG_TRACING
-#define time_type	ktime_t
-#define time_get()	ktime_get()
-#define time_to_us(x)	ktime_to_us(x)
-#define time_sub(a, b)	ktime_sub(a, b)
-#define init_time(a, b)	(a).tv64 = b
-#define time_u64(a)	((a).tv64)
-#else
-#define time_type	u64
-#define time_get()	trace_clock_local()
-#define time_to_us(x)	div_u64(x, 1000)
-#define time_sub(a, b)	((a) - (b))
-#define init_time(a, b)	(a = b)
-#define time_u64(a)	a
-#endif
-/**
- * get_sample - sample the CPU TSC and look for likely hardware latencies
- *
- * Used to repeatedly capture the CPU TSC (or similar), looking for potential
- * hardware-induced latency. Called with interrupts disabled and with
- * data.lock held.
- */
-static int get_sample(void)
-{
-	time_type start, t1, t2, last_t2;
-	s64 diff, total = 0;
-	u64 sample = 0;
-	u64 outer_sample = 0;
-	int ret = -1;
-
-	init_time(last_t2, 0);
-	start = time_get(); /* start timestamp */
-
-	do {
-
-		t1 = time_get();	/* we'll look for a discontinuity */
-		t2 = time_get();
-
-		if (time_u64(last_t2)) {
-			/* Check the delta from outer loop (t2 to next t1) */
-			diff = time_to_us(time_sub(t1, last_t2));
-			/* This shouldn't happen */
-			if (diff < 0) {
-				pr_err(BANNER "time running backwards\n");
-				goto out;
-			}
-			if (diff > outer_sample)
-				outer_sample = diff;
-		}
-		last_t2 = t2;
-
-		total = time_to_us(time_sub(t2, start)); /* sample width */
-
-		/* This checks the inner loop (t1 to t2) */
-		diff = time_to_us(time_sub(t2, t1));     /* current diff */
-
-		/* This shouldn't happen */
-		if (diff < 0) {
-			pr_err(BANNER "time running backwards\n");
-			goto out;
-		}
-
-		if (diff > sample)
-			sample = diff; /* only want highest value */
-
-	} while (total <= data.sample_width);
-
-	ret = 0;
-
-	/* If we exceed the threshold value, we have found a hardware latency */
-	if (sample > data.threshold || outer_sample > data.threshold) {
-		struct sample s;
-
-		ret = 1;
-
-		data.count++;
-		s.seqnum = data.count;
-		s.duration = sample;
-		s.outer_duration = outer_sample;
-		s.timestamp = CURRENT_TIME;
-		__buffer_add_sample(&s);
-
-		/* Keep a running maximum ever recorded hardware latency */
-		if (sample > data.max_sample)
-			data.max_sample = sample;
-	}
-
-out:
-	return ret;
-}
-
-/*
- * kthread_fn - The CPU time sampling/hardware latency detection kernel thread
- * @unused: A required part of the kthread API.
- *
- * Used to periodically sample the CPU TSC via a call to get_sample. We
- * disable interrupts, which does (intentionally) introduce latency since we
- * need to ensure nothing else might be running (and thus pre-empting).
- * Obviously this should never be used in production environments.
- *
- * Currently this runs on which ever CPU it was scheduled on, but most
- * real-worald hardware latency situations occur across several CPUs,
- * but we might later generalize this if we find there are any actualy
- * systems with alternate SMI delivery or other hardware latencies.
- */
-static int kthread_fn(void *unused)
-{
-	int ret;
-	u64 interval;
-
-	while (!kthread_should_stop()) {
-
-		mutex_lock(&data.lock);
-
-		local_irq_disable();
-		ret = get_sample();
-		local_irq_enable();
-
-		if (ret > 0)
-			wake_up(&data.wq); /* wake up reader(s) */
-
-		interval = data.sample_window - data.sample_width;
-		do_div(interval, USEC_PER_MSEC); /* modifies interval value */
-
-		mutex_unlock(&data.lock);
-
-		if (msleep_interruptible(interval))
-			break;
-	}
-
-	return 0;
-}
-
-/**
- * start_kthread - Kick off the hardware latency sampling/detector kthread
- *
- * This starts a kernel thread that will sit and sample the CPU timestamp
- * counter (TSC or similar) and look for potential hardware latencies.
- */
-static int start_kthread(void)
-{
-	kthread = kthread_run(kthread_fn, NULL,
-					DRVNAME);
-	if (IS_ERR(kthread)) {
-		pr_err(BANNER "could not start sampling thread\n");
-		enabled = 0;
-		return -ENOMEM;
-	}
-
-	return 0;
-}
-
-/**
- * stop_kthread - Inform the hardware latency samping/detector kthread to stop
- *
- * This kicks the running hardware latency sampling/detector kernel thread and
- * tells it to stop sampling now. Use this on unload and at system shutdown.
- */
-static int stop_kthread(void)
-{
-	int ret;
-
-	ret = kthread_stop(kthread);
-
-	return ret;
-}
-
-/**
- * __reset_stats - Reset statistics for the hardware latency detector
- *
- * We use data to store various statistics and global state. We call this
- * function in order to reset those when "enable" is toggled on or off, and
- * also at initialization. Should be called with data.lock held.
- */
-static void __reset_stats(void)
-{
-	data.count = 0;
-	data.max_sample = 0;
-	ring_buffer_reset(ring_buffer); /* flush out old sample entries */
-}
-
-/**
- * init_stats - Setup global state statistics for the hardware latency detector
- *
- * We use data to store various statistics and global state. We also use
- * a global ring buffer (ring_buffer) to keep raw samples of detected hardware
- * induced system latencies. This function initializes these structures and
- * allocates the global ring buffer also.
- */
-static int init_stats(void)
-{
-	int ret = -ENOMEM;
-
-	mutex_init(&data.lock);
-	init_waitqueue_head(&data.wq);
-	atomic_set(&data.sample_open, 0);
-
-	ring_buffer = ring_buffer_alloc(buf_size, BUF_FLAGS);
-
-	if (WARN(!ring_buffer, KERN_ERR BANNER
-			       "failed to allocate ring buffer!\n"))
-		goto out;
-
-	__reset_stats();
-	data.threshold = threshold ?: DEFAULT_LAT_THRESHOLD; /* threshold us */
-	data.sample_window = DEFAULT_SAMPLE_WINDOW; /* window us */
-	data.sample_width = DEFAULT_SAMPLE_WIDTH;   /* width us */
-
-	ret = 0;
-
-out:
-	return ret;
-
-}
-
-/*
- * simple_data_read - Wrapper read function for global state debugfs entries
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The userspace provided buffer to read value into
- * @cnt: The maximum number of bytes to read
- * @ppos: The current "file" position
- * @entry: The entry to read from
- *
- * This function provides a generic read implementation for the global state
- * "data" structure debugfs filesystem entries. It would be nice to use
- * simple_attr_read directly, but we need to make sure that the data.lock
- * is held during the actual read.
- */
-static ssize_t simple_data_read(struct file *filp, char __user *ubuf,
-				size_t cnt, loff_t *ppos, const u64 *entry)
-{
-	char buf[U64STR_SIZE];
-	u64 val = 0;
-	int len = 0;
-
-	memset(buf, 0, sizeof(buf));
-
-	if (!entry)
-		return -EFAULT;
-
-	mutex_lock(&data.lock);
-	val = *entry;
-	mutex_unlock(&data.lock);
-
-	len = snprintf(buf, sizeof(buf), "%llu\n", (unsigned long long)val);
-
-	return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
-
-}
-
-/*
- * simple_data_write - Wrapper write function for global state debugfs entries
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The userspace provided buffer to write value from
- * @cnt: The maximum number of bytes to write
- * @ppos: The current "file" position
- * @entry: The entry to write to
- *
- * This function provides a generic write implementation for the global state
- * "data" structure debugfs filesystem entries. It would be nice to use
- * simple_attr_write directly, but we need to make sure that the data.lock
- * is held during the actual write.
- */
-static ssize_t simple_data_write(struct file *filp, const char __user *ubuf,
-				 size_t cnt, loff_t *ppos, u64 *entry)
-{
-	char buf[U64STR_SIZE];
-	int csize = min(cnt, sizeof(buf));
-	u64 val = 0;
-	int err = 0;
-
-	memset(buf, '\0', sizeof(buf));
-	if (copy_from_user(buf, ubuf, csize))
-		return -EFAULT;
-
-	buf[U64STR_SIZE-1] = '\0';			/* just in case */
-	err = kstrtoull(buf, 10, &val);
-	if (err)
-		return -EINVAL;
-
-	mutex_lock(&data.lock);
-	*entry = val;
-	mutex_unlock(&data.lock);
-
-	return csize;
-}
-
-/**
- * debug_count_fopen - Open function for "count" debugfs entry
- * @inode: The in-kernel inode representation of the debugfs "file"
- * @filp: The active open file structure for the debugfs "file"
- *
- * This function provides an open implementation for the "count" debugfs
- * interface to the hardware latency detector.
- */
-static int debug_count_fopen(struct inode *inode, struct file *filp)
-{
-	return 0;
-}
-
-/**
- * debug_count_fread - Read function for "count" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The userspace provided buffer to read value into
- * @cnt: The maximum number of bytes to read
- * @ppos: The current "file" position
- *
- * This function provides a read implementation for the "count" debugfs
- * interface to the hardware latency detector. Can be used to read the
- * number of latency readings exceeding the configured threshold since
- * the detector was last reset (e.g. by writing a zero into "count").
- */
-static ssize_t debug_count_fread(struct file *filp, char __user *ubuf,
-				     size_t cnt, loff_t *ppos)
-{
-	return simple_data_read(filp, ubuf, cnt, ppos, &data.count);
-}
-
-/**
- * debug_count_fwrite - Write function for "count" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The user buffer that contains the value to write
- * @cnt: The maximum number of bytes to write to "file"
- * @ppos: The current position in the debugfs "file"
- *
- * This function provides a write implementation for the "count" debugfs
- * interface to the hardware latency detector. Can be used to write a
- * desired value, especially to zero the total count.
- */
-static ssize_t  debug_count_fwrite(struct file *filp,
-				       const char __user *ubuf,
-				       size_t cnt,
-				       loff_t *ppos)
-{
-	return simple_data_write(filp, ubuf, cnt, ppos, &data.count);
-}
-
-/**
- * debug_enable_fopen - Dummy open function for "enable" debugfs interface
- * @inode: The in-kernel inode representation of the debugfs "file"
- * @filp: The active open file structure for the debugfs "file"
- *
- * This function provides an open implementation for the "enable" debugfs
- * interface to the hardware latency detector.
- */
-static int debug_enable_fopen(struct inode *inode, struct file *filp)
-{
-	return 0;
-}
-
-/**
- * debug_enable_fread - Read function for "enable" debugfs interface
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The userspace provided buffer to read value into
- * @cnt: The maximum number of bytes to read
- * @ppos: The current "file" position
- *
- * This function provides a read implementation for the "enable" debugfs
- * interface to the hardware latency detector. Can be used to determine
- * whether the detector is currently enabled ("0\n" or "1\n" returned).
- */
-static ssize_t debug_enable_fread(struct file *filp, char __user *ubuf,
-				      size_t cnt, loff_t *ppos)
-{
-	char buf[4];
-
-	if ((cnt < sizeof(buf)) || (*ppos))
-		return 0;
-
-	buf[0] = enabled ? '1' : '0';
-	buf[1] = '\n';
-	buf[2] = '\0';
-	if (copy_to_user(ubuf, buf, strlen(buf)))
-		return -EFAULT;
-	return *ppos = strlen(buf);
-}
-
-/**
- * debug_enable_fwrite - Write function for "enable" debugfs interface
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The user buffer that contains the value to write
- * @cnt: The maximum number of bytes to write to "file"
- * @ppos: The current position in the debugfs "file"
- *
- * This function provides a write implementation for the "enable" debugfs
- * interface to the hardware latency detector. Can be used to enable or
- * disable the detector, which will have the side-effect of possibly
- * also resetting the global stats and kicking off the measuring
- * kthread (on an enable) or the converse (upon a disable).
- */
-static ssize_t  debug_enable_fwrite(struct file *filp,
-					const char __user *ubuf,
-					size_t cnt,
-					loff_t *ppos)
-{
-	char buf[4];
-	int csize = min(cnt, sizeof(buf));
-	long val = 0;
-	int err = 0;
-
-	memset(buf, '\0', sizeof(buf));
-	if (copy_from_user(buf, ubuf, csize))
-		return -EFAULT;
-
-	buf[sizeof(buf)-1] = '\0';			/* just in case */
-	err = kstrtoul(buf, 10, &val);
-	if (0 != err)
-		return -EINVAL;
-
-	if (val) {
-		if (enabled)
-			goto unlock;
-		enabled = 1;
-		__reset_stats();
-		if (start_kthread())
-			return -EFAULT;
-	} else {
-		if (!enabled)
-			goto unlock;
-		enabled = 0;
-		err = stop_kthread();
-		if (err) {
-			pr_err(BANNER "cannot stop kthread\n");
-			return -EFAULT;
-		}
-		wake_up(&data.wq);		/* reader(s) should return */
-	}
-unlock:
-	return csize;
-}
-
-/**
- * debug_max_fopen - Open function for "max" debugfs entry
- * @inode: The in-kernel inode representation of the debugfs "file"
- * @filp: The active open file structure for the debugfs "file"
- *
- * This function provides an open implementation for the "max" debugfs
- * interface to the hardware latency detector.
- */
-static int debug_max_fopen(struct inode *inode, struct file *filp)
-{
-	return 0;
-}
-
-/**
- * debug_max_fread - Read function for "max" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The userspace provided buffer to read value into
- * @cnt: The maximum number of bytes to read
- * @ppos: The current "file" position
- *
- * This function provides a read implementation for the "max" debugfs
- * interface to the hardware latency detector. Can be used to determine
- * the maximum latency value observed since it was last reset.
- */
-static ssize_t debug_max_fread(struct file *filp, char __user *ubuf,
-				   size_t cnt, loff_t *ppos)
-{
-	return simple_data_read(filp, ubuf, cnt, ppos, &data.max_sample);
-}
-
-/**
- * debug_max_fwrite - Write function for "max" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The user buffer that contains the value to write
- * @cnt: The maximum number of bytes to write to "file"
- * @ppos: The current position in the debugfs "file"
- *
- * This function provides a write implementation for the "max" debugfs
- * interface to the hardware latency detector. Can be used to reset the
- * maximum or set it to some other desired value - if, then, subsequent
- * measurements exceed this value, the maximum will be updated.
- */
-static ssize_t  debug_max_fwrite(struct file *filp,
-				     const char __user *ubuf,
-				     size_t cnt,
-				     loff_t *ppos)
-{
-	return simple_data_write(filp, ubuf, cnt, ppos, &data.max_sample);
-}
-
-
-/**
- * debug_sample_fopen - An open function for "sample" debugfs interface
- * @inode: The in-kernel inode representation of this debugfs "file"
- * @filp: The active open file structure for the debugfs "file"
- *
- * This function handles opening the "sample" file within the hardware
- * latency detector debugfs directory interface. This file is used to read
- * raw samples from the global ring_buffer and allows the user to see a
- * running latency history. Can be opened blocking or non-blocking,
- * affecting whether it behaves as a buffer read pipe, or does not.
- * Implements simple locking to prevent multiple simultaneous use.
- */
-static int debug_sample_fopen(struct inode *inode, struct file *filp)
-{
-	if (!atomic_add_unless(&data.sample_open, 1, 1))
-		return -EBUSY;
-	else
-		return 0;
-}
-
-/**
- * debug_sample_fread - A read function for "sample" debugfs interface
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The user buffer that will contain the samples read
- * @cnt: The maximum bytes to read from the debugfs "file"
- * @ppos: The current position in the debugfs "file"
- *
- * This function handles reading from the "sample" file within the hardware
- * latency detector debugfs directory interface. This file is used to read
- * raw samples from the global ring_buffer and allows the user to see a
- * running latency history. By default this will block pending a new
- * value written into the sample buffer, unless there are already a
- * number of value(s) waiting in the buffer, or the sample file was
- * previously opened in a non-blocking mode of operation.
- */
-static ssize_t debug_sample_fread(struct file *filp, char __user *ubuf,
-					size_t cnt, loff_t *ppos)
-{
-	int len = 0;
-	char buf[64];
-	struct sample *sample = NULL;
-
-	if (!enabled)
-		return 0;
-
-	sample = kzalloc(sizeof(struct sample), GFP_KERNEL);
-	if (!sample)
-		return -ENOMEM;
-
-	while (!buffer_get_sample(sample)) {
-
-		DEFINE_WAIT(wait);
-
-		if (filp->f_flags & O_NONBLOCK) {
-			len = -EAGAIN;
-			goto out;
-		}
-
-		prepare_to_wait(&data.wq, &wait, TASK_INTERRUPTIBLE);
-		schedule();
-		finish_wait(&data.wq, &wait);
-
-		if (signal_pending(current)) {
-			len = -EINTR;
-			goto out;
-		}
-
-		if (!enabled) {			/* enable was toggled */
-			len = 0;
-			goto out;
-		}
-	}
-
-	len = snprintf(buf, sizeof(buf), "%010lu.%010lu\t%llu\t%llu\n",
-		       sample->timestamp.tv_sec,
-		       sample->timestamp.tv_nsec,
-		       sample->duration,
-		       sample->outer_duration);
-
-
-	/* handling partial reads is more trouble than it's worth */
-	if (len > cnt)
-		goto out;
-
-	if (copy_to_user(ubuf, buf, len))
-		len = -EFAULT;
-
-out:
-	kfree(sample);
-	return len;
-}
-
-/**
- * debug_sample_release - Release function for "sample" debugfs interface
- * @inode: The in-kernel inode represenation of the debugfs "file"
- * @filp: The active open file structure for the debugfs "file"
- *
- * This function completes the close of the debugfs interface "sample" file.
- * Frees the sample_open "lock" so that other users may open the interface.
- */
-static int debug_sample_release(struct inode *inode, struct file *filp)
-{
-	atomic_dec(&data.sample_open);
-
-	return 0;
-}
-
-/**
- * debug_threshold_fopen - Open function for "threshold" debugfs entry
- * @inode: The in-kernel inode representation of the debugfs "file"
- * @filp: The active open file structure for the debugfs "file"
- *
- * This function provides an open implementation for the "threshold" debugfs
- * interface to the hardware latency detector.
- */
-static int debug_threshold_fopen(struct inode *inode, struct file *filp)
-{
-	return 0;
-}
-
-/**
- * debug_threshold_fread - Read function for "threshold" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The userspace provided buffer to read value into
- * @cnt: The maximum number of bytes to read
- * @ppos: The current "file" position
- *
- * This function provides a read implementation for the "threshold" debugfs
- * interface to the hardware latency detector. It can be used to determine
- * the current threshold level at which a latency will be recorded in the
- * global ring buffer, typically on the order of 10us.
- */
-static ssize_t debug_threshold_fread(struct file *filp, char __user *ubuf,
-					 size_t cnt, loff_t *ppos)
-{
-	return simple_data_read(filp, ubuf, cnt, ppos, &data.threshold);
-}
-
-/**
- * debug_threshold_fwrite - Write function for "threshold" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The user buffer that contains the value to write
- * @cnt: The maximum number of bytes to write to "file"
- * @ppos: The current position in the debugfs "file"
- *
- * This function provides a write implementation for the "threshold" debugfs
- * interface to the hardware latency detector. It can be used to configure
- * the threshold level at which any subsequently detected latencies will
- * be recorded into the global ring buffer.
- */
-static ssize_t  debug_threshold_fwrite(struct file *filp,
-					const char __user *ubuf,
-					size_t cnt,
-					loff_t *ppos)
-{
-	int ret;
-
-	ret = simple_data_write(filp, ubuf, cnt, ppos, &data.threshold);
-
-	if (enabled)
-		wake_up_process(kthread);
-
-	return ret;
-}
-
-/**
- * debug_width_fopen - Open function for "width" debugfs entry
- * @inode: The in-kernel inode representation of the debugfs "file"
- * @filp: The active open file structure for the debugfs "file"
- *
- * This function provides an open implementation for the "width" debugfs
- * interface to the hardware latency detector.
- */
-static int debug_width_fopen(struct inode *inode, struct file *filp)
-{
-	return 0;
-}
-
-/**
- * debug_width_fread - Read function for "width" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The userspace provided buffer to read value into
- * @cnt: The maximum number of bytes to read
- * @ppos: The current "file" position
- *
- * This function provides a read implementation for the "width" debugfs
- * interface to the hardware latency detector. It can be used to determine
- * for how many us of the total window us we will actively sample for any
- * hardware-induced latecy periods. Obviously, it is not possible to
- * sample constantly and have the system respond to a sample reader, or,
- * worse, without having the system appear to have gone out to lunch.
- */
-static ssize_t debug_width_fread(struct file *filp, char __user *ubuf,
-				     size_t cnt, loff_t *ppos)
-{
-	return simple_data_read(filp, ubuf, cnt, ppos, &data.sample_width);
-}
-
-/**
- * debug_width_fwrite - Write function for "width" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The user buffer that contains the value to write
- * @cnt: The maximum number of bytes to write to "file"
- * @ppos: The current position in the debugfs "file"
- *
- * This function provides a write implementation for the "width" debugfs
- * interface to the hardware latency detector. It can be used to configure
- * for how many us of the total window us we will actively sample for any
- * hardware-induced latency periods. Obviously, it is not possible to
- * sample constantly and have the system respond to a sample reader, or,
- * worse, without having the system appear to have gone out to lunch. It
- * is enforced that width is less that the total window size.
- */
-static ssize_t  debug_width_fwrite(struct file *filp,
-				       const char __user *ubuf,
-				       size_t cnt,
-				       loff_t *ppos)
-{
-	char buf[U64STR_SIZE];
-	int csize = min(cnt, sizeof(buf));
-	u64 val = 0;
-	int err = 0;
-
-	memset(buf, '\0', sizeof(buf));
-	if (copy_from_user(buf, ubuf, csize))
-		return -EFAULT;
-
-	buf[U64STR_SIZE-1] = '\0';			/* just in case */
-	err = kstrtoull(buf, 10, &val);
-	if (0 != err)
-		return -EINVAL;
-
-	mutex_lock(&data.lock);
-	if (val < data.sample_window)
-		data.sample_width = val;
-	else {
-		mutex_unlock(&data.lock);
-		return -EINVAL;
-	}
-	mutex_unlock(&data.lock);
-
-	if (enabled)
-		wake_up_process(kthread);
-
-	return csize;
-}
-
-/**
- * debug_window_fopen - Open function for "window" debugfs entry
- * @inode: The in-kernel inode representation of the debugfs "file"
- * @filp: The active open file structure for the debugfs "file"
- *
- * This function provides an open implementation for the "window" debugfs
- * interface to the hardware latency detector. The window is the total time
- * in us that will be considered one sample period. Conceptually, windows
- * occur back-to-back and contain a sample width period during which
- * actual sampling occurs.
- */
-static int debug_window_fopen(struct inode *inode, struct file *filp)
-{
-	return 0;
-}
-
-/**
- * debug_window_fread - Read function for "window" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The userspace provided buffer to read value into
- * @cnt: The maximum number of bytes to read
- * @ppos: The current "file" position
- *
- * This function provides a read implementation for the "window" debugfs
- * interface to the hardware latency detector. The window is the total time
- * in us that will be considered one sample period. Conceptually, windows
- * occur back-to-back and contain a sample width period during which
- * actual sampling occurs. Can be used to read the total window size.
- */
-static ssize_t debug_window_fread(struct file *filp, char __user *ubuf,
-				      size_t cnt, loff_t *ppos)
-{
-	return simple_data_read(filp, ubuf, cnt, ppos, &data.sample_window);
-}
-
-/**
- * debug_window_fwrite - Write function for "window" debugfs entry
- * @filp: The active open file structure for the debugfs "file"
- * @ubuf: The user buffer that contains the value to write
- * @cnt: The maximum number of bytes to write to "file"
- * @ppos: The current position in the debugfs "file"
- *
- * This function provides a write implementation for the "window" debufds
- * interface to the hardware latency detetector. The window is the total time
- * in us that will be considered one sample period. Conceptually, windows
- * occur back-to-back and contain a sample width period during which
- * actual sampling occurs. Can be used to write a new total window size. It
- * is enfoced that any value written must be greater than the sample width
- * size, or an error results.
- */
-static ssize_t  debug_window_fwrite(struct file *filp,
-					const char __user *ubuf,
-					size_t cnt,
-					loff_t *ppos)
-{
-	char buf[U64STR_SIZE];
-	int csize = min(cnt, sizeof(buf));
-	u64 val = 0;
-	int err = 0;
-
-	memset(buf, '\0', sizeof(buf));
-	if (copy_from_user(buf, ubuf, csize))
-		return -EFAULT;
-
-	buf[U64STR_SIZE-1] = '\0';			/* just in case */
-	err = kstrtoull(buf, 10, &val);
-	if (0 != err)
-		return -EINVAL;
-
-	mutex_lock(&data.lock);
-	if (data.sample_width < val)
-		data.sample_window = val;
-	else {
-		mutex_unlock(&data.lock);
-		return -EINVAL;
-	}
-	mutex_unlock(&data.lock);
-
-	return csize;
-}
-
-/*
- * Function pointers for the "count" debugfs file operations
- */
-static const struct file_operations count_fops = {
-	.open		= debug_count_fopen,
-	.read		= debug_count_fread,
-	.write		= debug_count_fwrite,
-	.owner		= THIS_MODULE,
-};
-
-/*
- * Function pointers for the "enable" debugfs file operations
- */
-static const struct file_operations enable_fops = {
-	.open		= debug_enable_fopen,
-	.read		= debug_enable_fread,
-	.write		= debug_enable_fwrite,
-	.owner		= THIS_MODULE,
-};
-
-/*
- * Function pointers for the "max" debugfs file operations
- */
-static const struct file_operations max_fops = {
-	.open		= debug_max_fopen,
-	.read		= debug_max_fread,
-	.write		= debug_max_fwrite,
-	.owner		= THIS_MODULE,
-};
-
-/*
- * Function pointers for the "sample" debugfs file operations
- */
-static const struct file_operations sample_fops = {
-	.open		= debug_sample_fopen,
-	.read		= debug_sample_fread,
-	.release	= debug_sample_release,
-	.owner		= THIS_MODULE,
-};
-
-/*
- * Function pointers for the "threshold" debugfs file operations
- */
-static const struct file_operations threshold_fops = {
-	.open		= debug_threshold_fopen,
-	.read		= debug_threshold_fread,
-	.write		= debug_threshold_fwrite,
-	.owner		= THIS_MODULE,
-};
-
-/*
- * Function pointers for the "width" debugfs file operations
- */
-static const struct file_operations width_fops = {
-	.open		= debug_width_fopen,
-	.read		= debug_width_fread,
-	.write		= debug_width_fwrite,
-	.owner		= THIS_MODULE,
-};
-
-/*
- * Function pointers for the "window" debugfs file operations
- */
-static const struct file_operations window_fops = {
-	.open		= debug_window_fopen,
-	.read		= debug_window_fread,
-	.write		= debug_window_fwrite,
-	.owner		= THIS_MODULE,
-};
-
-/**
- * init_debugfs - A function to initialize the debugfs interface files
- *
- * This function creates entries in debugfs for "hwlat_detector", including
- * files to read values from the detector, current samples, and the
- * maximum sample that has been captured since the hardware latency
- * dectector was started.
- */
-static int init_debugfs(void)
-{
-	int ret = -ENOMEM;
-
-	debug_dir = debugfs_create_dir(DRVNAME, NULL);
-	if (!debug_dir)
-		goto err_debug_dir;
-
-	debug_sample = debugfs_create_file("sample", 0444,
-					       debug_dir, NULL,
-					       &sample_fops);
-	if (!debug_sample)
-		goto err_sample;
-
-	debug_count = debugfs_create_file("count", 0444,
-					      debug_dir, NULL,
-					      &count_fops);
-	if (!debug_count)
-		goto err_count;
-
-	debug_max = debugfs_create_file("max", 0444,
-					    debug_dir, NULL,
-					    &max_fops);
-	if (!debug_max)
-		goto err_max;
-
-	debug_sample_window = debugfs_create_file("window", 0644,
-						      debug_dir, NULL,
-						      &window_fops);
-	if (!debug_sample_window)
-		goto err_window;
-
-	debug_sample_width = debugfs_create_file("width", 0644,
-						     debug_dir, NULL,
-						     &width_fops);
-	if (!debug_sample_width)
-		goto err_width;
-
-	debug_threshold = debugfs_create_file("threshold", 0644,
-						  debug_dir, NULL,
-						  &threshold_fops);
-	if (!debug_threshold)
-		goto err_threshold;
-
-	debug_enable = debugfs_create_file("enable", 0644,
-					       debug_dir, &enabled,
-					       &enable_fops);
-	if (!debug_enable)
-		goto err_enable;
-
-	else {
-		ret = 0;
-		goto out;
-	}
-
-err_enable:
-	debugfs_remove(debug_threshold);
-err_threshold:
-	debugfs_remove(debug_sample_width);
-err_width:
-	debugfs_remove(debug_sample_window);
-err_window:
-	debugfs_remove(debug_max);
-err_max:
-	debugfs_remove(debug_count);
-err_count:
-	debugfs_remove(debug_sample);
-err_sample:
-	debugfs_remove(debug_dir);
-err_debug_dir:
-out:
-	return ret;
-}
-
-/**
- * free_debugfs - A function to cleanup the debugfs file interface
- */
-static void free_debugfs(void)
-{
-	/* could also use a debugfs_remove_recursive */
-	debugfs_remove(debug_enable);
-	debugfs_remove(debug_threshold);
-	debugfs_remove(debug_sample_width);
-	debugfs_remove(debug_sample_window);
-	debugfs_remove(debug_max);
-	debugfs_remove(debug_count);
-	debugfs_remove(debug_sample);
-	debugfs_remove(debug_dir);
-}
-
-/**
- * detector_init - Standard module initialization code
- */
-static int detector_init(void)
-{
-	int ret = -ENOMEM;
-
-	pr_info(BANNER "version %s\n", VERSION);
-
-	ret = init_stats();
-	if (0 != ret)
-		goto out;
-
-	ret = init_debugfs();
-	if (0 != ret)
-		goto err_stats;
-
-	if (enabled)
-		ret = start_kthread();
-
-	goto out;
-
-err_stats:
-	ring_buffer_free(ring_buffer);
-out:
-	return ret;
-
-}
-
-/**
- * detector_exit - Standard module cleanup code
- */
-static void detector_exit(void)
-{
-	int err;
-
-	if (enabled) {
-		enabled = 0;
-		err = stop_kthread();
-		if (err)
-			pr_err(BANNER "cannot stop kthread\n");
-	}
-
-	free_debugfs();
-	ring_buffer_free(ring_buffer);	/* free up the ring buffer */
-
-}
-
-module_init(detector_init);
-module_exit(detector_exit);