diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 5eef4cb4f70e..82b96ee8624c 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -58,14 +58,25 @@ config ACPI_CCA_REQUIRED
 	bool
 
 config ACPI_DEBUGGER
-	bool "AML debugger interface (EXPERIMENTAL)"
+	bool "AML debugger interface"
 	select ACPI_DEBUG
 	help
-	  Enable in-kernel debugging of AML facilities: statistics, internal
-	  object dump, single step control method execution.
+	  Enable in-kernel debugging of AML facilities: statistics,
+	  internal object dump, single step control method execution.
 	  This is still under development, currently enabling this only
 	  results in the compilation of the ACPICA debugger files.
 
+if ACPI_DEBUGGER
+
+config ACPI_DEBUGGER_USER
+	tristate "Userspace debugger accessiblity"
+	depends on DEBUG_FS
+	help
+	  Export /sys/kernel/debug/acpi/acpidbg for userspace utilities
+	  to access the debugger functionalities.
+
+endif
+
 config ACPI_SLEEP
 	bool
 	depends on SUSPEND || HIBERNATION
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 675eaf337178..c6f236f1b510 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -79,6 +79,7 @@ obj-$(CONFIG_ACPI_EC_DEBUGFS)	+= ec_sys.o
 obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o
 obj-$(CONFIG_ACPI_BGRT)		+= bgrt.o
 obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc_acpi.o
+obj-$(CONFIG_ACPI_DEBUGGER_USER) += acpi_dbg.o
 
 # processor has its own "processor." module_param namespace
 processor-y			:= processor_driver.o
diff --git a/drivers/acpi/acpi_dbg.c b/drivers/acpi/acpi_dbg.c
new file mode 100644
index 000000000000..15e4604efba7
--- /dev/null
+++ b/drivers/acpi/acpi_dbg.c
@@ -0,0 +1,804 @@
+/*
+ * ACPI AML interfacing support
+ *
+ * Copyright (C) 2015, Intel Corporation
+ * Authors: Lv Zheng <lv.zheng@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/* #define DEBUG */
+#define pr_fmt(fmt) "ACPI : AML: " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/wait.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+#include <linux/kthread.h>
+#include <linux/proc_fs.h>
+#include <linux/debugfs.h>
+#include <linux/circ_buf.h>
+#include <linux/acpi.h>
+#include "internal.h"
+
+#define ACPI_AML_BUF_ALIGN	(sizeof (acpi_size))
+#define ACPI_AML_BUF_SIZE	PAGE_SIZE
+
+#define circ_count(circ) \
+	(CIRC_CNT((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))
+#define circ_count_to_end(circ) \
+	(CIRC_CNT_TO_END((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))
+#define circ_space(circ) \
+	(CIRC_SPACE((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))
+#define circ_space_to_end(circ) \
+	(CIRC_SPACE_TO_END((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))
+
+#define ACPI_AML_OPENED		0x0001
+#define ACPI_AML_CLOSED		0x0002
+#define ACPI_AML_IN_USER	0x0004 /* user space is writing cmd */
+#define ACPI_AML_IN_KERN	0x0008 /* kernel space is reading cmd */
+#define ACPI_AML_OUT_USER	0x0010 /* user space is reading log */
+#define ACPI_AML_OUT_KERN	0x0020 /* kernel space is writing log */
+#define ACPI_AML_USER		(ACPI_AML_IN_USER | ACPI_AML_OUT_USER)
+#define ACPI_AML_KERN		(ACPI_AML_IN_KERN | ACPI_AML_OUT_KERN)
+#define ACPI_AML_BUSY		(ACPI_AML_USER | ACPI_AML_KERN)
+#define ACPI_AML_OPEN		(ACPI_AML_OPENED | ACPI_AML_CLOSED)
+
+struct acpi_aml_io {
+	wait_queue_head_t wait;
+	unsigned long flags;
+	unsigned long users;
+	struct mutex lock;
+	struct task_struct *thread;
+	char out_buf[ACPI_AML_BUF_SIZE] __aligned(ACPI_AML_BUF_ALIGN);
+	struct circ_buf out_crc;
+	char in_buf[ACPI_AML_BUF_SIZE] __aligned(ACPI_AML_BUF_ALIGN);
+	struct circ_buf in_crc;
+	acpi_osd_exec_callback function;
+	void *context;
+	unsigned long usages;
+};
+
+static struct acpi_aml_io acpi_aml_io;
+static bool acpi_aml_initialized;
+static struct file *acpi_aml_active_reader;
+static struct dentry *acpi_aml_dentry;
+
+static inline bool __acpi_aml_running(void)
+{
+	return acpi_aml_io.thread ? true : false;
+}
+
+static inline bool __acpi_aml_access_ok(unsigned long flag)
+{
+	/*
+	 * The debugger interface is in opened state (OPENED && !CLOSED),
+	 * then it is allowed to access the debugger buffers from either
+	 * user space or the kernel space.
+	 * In addition, for the kernel space, only the debugger thread
+	 * (thread ID matched) is allowed to access.
+	 */
+	if (!(acpi_aml_io.flags & ACPI_AML_OPENED) ||
+	    (acpi_aml_io.flags & ACPI_AML_CLOSED) ||
+	    !__acpi_aml_running())
+		return false;
+	if ((flag & ACPI_AML_KERN) &&
+	    current != acpi_aml_io.thread)
+		return false;
+	return true;
+}
+
+static inline bool __acpi_aml_readable(struct circ_buf *circ, unsigned long flag)
+{
+	/*
+	 * Another read is not in progress and there is data in buffer
+	 * available for read.
+	 */
+	if (!(acpi_aml_io.flags & flag) && circ_count(circ))
+		return true;
+	return false;
+}
+
+static inline bool __acpi_aml_writable(struct circ_buf *circ, unsigned long flag)
+{
+	/*
+	 * Another write is not in progress and there is buffer space
+	 * available for write.
+	 */
+	if (!(acpi_aml_io.flags & flag) && circ_space(circ))
+		return true;
+	return false;
+}
+
+static inline bool __acpi_aml_busy(void)
+{
+	if (acpi_aml_io.flags & ACPI_AML_BUSY)
+		return true;
+	return false;
+}
+
+static inline bool __acpi_aml_opened(void)
+{
+	if (acpi_aml_io.flags & ACPI_AML_OPEN)
+		return true;
+	return false;
+}
+
+static inline bool __acpi_aml_used(void)
+{
+	return acpi_aml_io.usages ? true : false;
+}
+
+static inline bool acpi_aml_running(void)
+{
+	bool ret;
+
+	mutex_lock(&acpi_aml_io.lock);
+	ret = __acpi_aml_running();
+	mutex_unlock(&acpi_aml_io.lock);
+	return ret;
+}
+
+static bool acpi_aml_busy(void)
+{
+	bool ret;
+
+	mutex_lock(&acpi_aml_io.lock);
+	ret = __acpi_aml_busy();
+	mutex_unlock(&acpi_aml_io.lock);
+	return ret;
+}
+
+static bool acpi_aml_used(void)
+{
+	bool ret;
+
+	/*
+	 * The usage count is prepared to avoid race conditions between the
+	 * starts and the stops of the debugger thread.
+	 */
+	mutex_lock(&acpi_aml_io.lock);
+	ret = __acpi_aml_used();
+	mutex_unlock(&acpi_aml_io.lock);
+	return ret;
+}
+
+static bool acpi_aml_kern_readable(void)
+{
+	bool ret;
+
+	mutex_lock(&acpi_aml_io.lock);
+	ret = !__acpi_aml_access_ok(ACPI_AML_IN_KERN) ||
+	      __acpi_aml_readable(&acpi_aml_io.in_crc, ACPI_AML_IN_KERN);
+	mutex_unlock(&acpi_aml_io.lock);
+	return ret;
+}
+
+static bool acpi_aml_kern_writable(void)
+{
+	bool ret;
+
+	mutex_lock(&acpi_aml_io.lock);
+	ret = !__acpi_aml_access_ok(ACPI_AML_OUT_KERN) ||
+	      __acpi_aml_writable(&acpi_aml_io.out_crc, ACPI_AML_OUT_KERN);
+	mutex_unlock(&acpi_aml_io.lock);
+	return ret;
+}
+
+static bool acpi_aml_user_readable(void)
+{
+	bool ret;
+
+	mutex_lock(&acpi_aml_io.lock);
+	ret = !__acpi_aml_access_ok(ACPI_AML_OUT_USER) ||
+	      __acpi_aml_readable(&acpi_aml_io.out_crc, ACPI_AML_OUT_USER);
+	mutex_unlock(&acpi_aml_io.lock);
+	return ret;
+}
+
+static bool acpi_aml_user_writable(void)
+{
+	bool ret;
+
+	mutex_lock(&acpi_aml_io.lock);
+	ret = !__acpi_aml_access_ok(ACPI_AML_IN_USER) ||
+	      __acpi_aml_writable(&acpi_aml_io.in_crc, ACPI_AML_IN_USER);
+	mutex_unlock(&acpi_aml_io.lock);
+	return ret;
+}
+
+static int acpi_aml_lock_write(struct circ_buf *circ, unsigned long flag)
+{
+	int ret = 0;
+
+	mutex_lock(&acpi_aml_io.lock);
+	if (!__acpi_aml_access_ok(flag)) {
+		ret = -EFAULT;
+		goto out;
+	}
+	if (!__acpi_aml_writable(circ, flag)) {
+		ret = -EAGAIN;
+		goto out;
+	}
+	acpi_aml_io.flags |= flag;
+out:
+	mutex_unlock(&acpi_aml_io.lock);
+	return ret;
+}
+
+static int acpi_aml_lock_read(struct circ_buf *circ, unsigned long flag)
+{
+	int ret = 0;
+
+	mutex_lock(&acpi_aml_io.lock);
+	if (!__acpi_aml_access_ok(flag)) {
+		ret = -EFAULT;
+		goto out;
+	}
+	if (!__acpi_aml_readable(circ, flag)) {
+		ret = -EAGAIN;
+		goto out;
+	}
+	acpi_aml_io.flags |= flag;
+out:
+	mutex_unlock(&acpi_aml_io.lock);
+	return ret;
+}
+
+static void acpi_aml_unlock_fifo(unsigned long flag, bool wakeup)
+{
+	mutex_lock(&acpi_aml_io.lock);
+	acpi_aml_io.flags &= ~flag;
+	if (wakeup)
+		wake_up_interruptible(&acpi_aml_io.wait);
+	mutex_unlock(&acpi_aml_io.lock);
+}
+
+static int acpi_aml_write_kern(const char *buf, int len)
+{
+	int ret;
+	struct circ_buf *crc = &acpi_aml_io.out_crc;
+	int n;
+	char *p;
+
+	ret = acpi_aml_lock_write(crc, ACPI_AML_OUT_KERN);
+	if (IS_ERR_VALUE(ret))
+		return ret;
+	/* sync tail before inserting logs */
+	smp_mb();
+	p = &crc->buf[crc->head];
+	n = min(len, circ_space_to_end(crc));
+	memcpy(p, buf, n);
+	/* sync head after inserting logs */
+	smp_wmb();
+	crc->head = (crc->head + n) & (ACPI_AML_BUF_SIZE - 1);
+	acpi_aml_unlock_fifo(ACPI_AML_OUT_KERN, true);
+	return n;
+}
+
+static int acpi_aml_readb_kern(void)
+{
+	int ret;
+	struct circ_buf *crc = &acpi_aml_io.in_crc;
+	char *p;
+
+	ret = acpi_aml_lock_read(crc, ACPI_AML_IN_KERN);
+	if (IS_ERR_VALUE(ret))
+		return ret;
+	/* sync head before removing cmds */
+	smp_rmb();
+	p = &crc->buf[crc->tail];
+	ret = (int)*p;
+	/* sync tail before inserting cmds */
+	smp_mb();
+	crc->tail = (crc->tail + 1) & (ACPI_AML_BUF_SIZE - 1);
+	acpi_aml_unlock_fifo(ACPI_AML_IN_KERN, true);
+	return ret;
+}
+
+/*
+ * acpi_aml_write_log() - Capture debugger output
+ * @msg: the debugger output
+ *
+ * This function should be used to implement acpi_os_printf() to filter out
+ * the debugger output and store the output into the debugger interface
+ * buffer. Return the size of stored logs or errno.
+ */
+static ssize_t acpi_aml_write_log(const char *msg)
+{
+	int ret = 0;
+	int count = 0, size = 0;
+
+	if (!acpi_aml_initialized)
+		return -ENODEV;
+	if (msg)
+		count = strlen(msg);
+	while (count > 0) {
+again:
+		ret = acpi_aml_write_kern(msg + size, count);
+		if (ret == -EAGAIN) {
+			ret = wait_event_interruptible(acpi_aml_io.wait,
+				acpi_aml_kern_writable());
+			/*
+			 * We need to retry when the condition
+			 * becomes true.
+			 */
+			if (ret == 0)
+				goto again;
+			break;
+		}
+		if (IS_ERR_VALUE(ret))
+			break;
+		size += ret;
+		count -= ret;
+	}
+	return size > 0 ? size : ret;
+}
+
+/*
+ * acpi_aml_read_cmd() - Capture debugger input
+ * @msg: the debugger input
+ * @size: the size of the debugger input
+ *
+ * This function should be used to implement acpi_os_get_line() to capture
+ * the debugger input commands and store the input commands into the
+ * debugger interface buffer. Return the size of stored commands or errno.
+ */
+static ssize_t acpi_aml_read_cmd(char *msg, size_t count)
+{
+	int ret = 0;
+	int size = 0;
+
+	/*
+	 * This is ensured by the running fact of the debugger thread
+	 * unless a bug is introduced.
+	 */
+	BUG_ON(!acpi_aml_initialized);
+	while (count > 0) {
+again:
+		/*
+		 * Check each input byte to find the end of the command.
+		 */
+		ret = acpi_aml_readb_kern();
+		if (ret == -EAGAIN) {
+			ret = wait_event_interruptible(acpi_aml_io.wait,
+				acpi_aml_kern_readable());
+			/*
+			 * We need to retry when the condition becomes
+			 * true.
+			 */
+			if (ret == 0)
+				goto again;
+		}
+		if (IS_ERR_VALUE(ret))
+			break;
+		*(msg + size) = (char)ret;
+		size++;
+		count--;
+		if (ret == '\n') {
+			/*
+			 * acpi_os_get_line() requires a zero terminated command
+			 * string.
+			 */
+			*(msg + size - 1) = '\0';
+			break;
+		}
+	}
+	return size > 0 ? size : ret;
+}
+
+static int acpi_aml_thread(void *unsed)
+{
+	acpi_osd_exec_callback function = NULL;
+	void *context;
+
+	mutex_lock(&acpi_aml_io.lock);
+	if (acpi_aml_io.function) {
+		acpi_aml_io.usages++;
+		function = acpi_aml_io.function;
+		context = acpi_aml_io.context;
+	}
+	mutex_unlock(&acpi_aml_io.lock);
+
+	if (function)
+		function(context);
+
+	mutex_lock(&acpi_aml_io.lock);
+	acpi_aml_io.usages--;
+	if (!__acpi_aml_used()) {
+		acpi_aml_io.thread = NULL;
+		wake_up(&acpi_aml_io.wait);
+	}
+	mutex_unlock(&acpi_aml_io.lock);
+
+	return 0;
+}
+
+/*
+ * acpi_aml_create_thread() - Create AML debugger thread
+ * @function: the debugger thread callback
+ * @context: the context to be passed to the debugger thread
+ *
+ * This function should be used to implement acpi_os_execute() which is
+ * used by the ACPICA debugger to create the debugger thread.
+ */
+static int acpi_aml_create_thread(acpi_osd_exec_callback function, void *context)
+{
+	struct task_struct *t;
+
+	mutex_lock(&acpi_aml_io.lock);
+	acpi_aml_io.function = function;
+	acpi_aml_io.context = context;
+	mutex_unlock(&acpi_aml_io.lock);
+
+	t = kthread_create(acpi_aml_thread, NULL, "aml");
+	if (IS_ERR(t)) {
+		pr_err("Failed to create AML debugger thread.\n");
+		return PTR_ERR(t);
+	}
+
+	mutex_lock(&acpi_aml_io.lock);
+	acpi_aml_io.thread = t;
+	acpi_set_debugger_thread_id((acpi_thread_id)(unsigned long)t);
+	wake_up_process(t);
+	mutex_unlock(&acpi_aml_io.lock);
+	return 0;
+}
+
+static int acpi_aml_wait_command_ready(bool single_step,
+				       char *buffer, size_t length)
+{
+	acpi_status status;
+
+	if (single_step)
+		acpi_os_printf("\n%1c ", ACPI_DEBUGGER_EXECUTE_PROMPT);
+	else
+		acpi_os_printf("\n%1c ", ACPI_DEBUGGER_COMMAND_PROMPT);
+
+	status = acpi_os_get_line(buffer, length, NULL);
+	if (ACPI_FAILURE(status))
+		return -EINVAL;
+	return 0;
+}
+
+static int acpi_aml_notify_command_complete(void)
+{
+	return 0;
+}
+
+static int acpi_aml_open(struct inode *inode, struct file *file)
+{
+	int ret = 0;
+	acpi_status status;
+
+	mutex_lock(&acpi_aml_io.lock);
+	/*
+	 * The debugger interface is being closed, no new user is allowed
+	 * during this period.
+	 */
+	if (acpi_aml_io.flags & ACPI_AML_CLOSED) {
+		ret = -EBUSY;
+		goto err_lock;
+	}
+	if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
+		/*
+		 * Only one reader is allowed to initiate the debugger
+		 * thread.
+		 */
+		if (acpi_aml_active_reader) {
+			ret = -EBUSY;
+			goto err_lock;
+		} else {
+			pr_debug("Opening debugger reader.\n");
+			acpi_aml_active_reader = file;
+		}
+	} else {
+		/*
+		 * No writer is allowed unless the debugger thread is
+		 * ready.
+		 */
+		if (!(acpi_aml_io.flags & ACPI_AML_OPENED)) {
+			ret = -ENODEV;
+			goto err_lock;
+		}
+	}
+	if (acpi_aml_active_reader == file) {
+		pr_debug("Opening debugger interface.\n");
+		mutex_unlock(&acpi_aml_io.lock);
+
+		pr_debug("Initializing debugger thread.\n");
+		status = acpi_initialize_debugger();
+		if (ACPI_FAILURE(status)) {
+			pr_err("Failed to initialize debugger.\n");
+			ret = -EINVAL;
+			goto err_exit;
+		}
+		pr_debug("Debugger thread initialized.\n");
+
+		mutex_lock(&acpi_aml_io.lock);
+		acpi_aml_io.flags |= ACPI_AML_OPENED;
+		acpi_aml_io.out_crc.head = acpi_aml_io.out_crc.tail = 0;
+		acpi_aml_io.in_crc.head = acpi_aml_io.in_crc.tail = 0;
+		pr_debug("Debugger interface opened.\n");
+	}
+	acpi_aml_io.users++;
+err_lock:
+	if (IS_ERR_VALUE(ret)) {
+		if (acpi_aml_active_reader == file)
+			acpi_aml_active_reader = NULL;
+	}
+	mutex_unlock(&acpi_aml_io.lock);
+err_exit:
+	return ret;
+}
+
+static int acpi_aml_release(struct inode *inode, struct file *file)
+{
+	mutex_lock(&acpi_aml_io.lock);
+	acpi_aml_io.users--;
+	if (file == acpi_aml_active_reader) {
+		pr_debug("Closing debugger reader.\n");
+		acpi_aml_active_reader = NULL;
+
+		pr_debug("Closing debugger interface.\n");
+		acpi_aml_io.flags |= ACPI_AML_CLOSED;
+
+		/*
+		 * Wake up all user space/kernel space blocked
+		 * readers/writers.
+		 */
+		wake_up_interruptible(&acpi_aml_io.wait);
+		mutex_unlock(&acpi_aml_io.lock);
+		/*
+		 * Wait all user space/kernel space readers/writers to
+		 * stop so that ACPICA command loop of the debugger thread
+		 * should fail all its command line reads after this point.
+		 */
+		wait_event(acpi_aml_io.wait, !acpi_aml_busy());
+
+		/*
+		 * Then we try to terminate the debugger thread if it is
+		 * not terminated.
+		 */
+		pr_debug("Terminating debugger thread.\n");
+		acpi_terminate_debugger();
+		wait_event(acpi_aml_io.wait, !acpi_aml_used());
+		pr_debug("Debugger thread terminated.\n");
+
+		mutex_lock(&acpi_aml_io.lock);
+		acpi_aml_io.flags &= ~ACPI_AML_OPENED;
+	}
+	if (acpi_aml_io.users == 0) {
+		pr_debug("Debugger interface closed.\n");
+		acpi_aml_io.flags &= ~ACPI_AML_CLOSED;
+	}
+	mutex_unlock(&acpi_aml_io.lock);
+	return 0;
+}
+
+static int acpi_aml_read_user(char __user *buf, int len)
+{
+	int ret;
+	struct circ_buf *crc = &acpi_aml_io.out_crc;
+	int n;
+	char *p;
+
+	ret = acpi_aml_lock_read(crc, ACPI_AML_OUT_USER);
+	if (IS_ERR_VALUE(ret))
+		return ret;
+	/* sync head before removing logs */
+	smp_rmb();
+	p = &crc->buf[crc->tail];
+	n = min(len, circ_count_to_end(crc));
+	if (copy_to_user(buf, p, n)) {
+		ret = -EFAULT;
+		goto out;
+	}
+	/* sync tail after removing logs */
+	smp_mb();
+	crc->tail = (crc->tail + n) & (ACPI_AML_BUF_SIZE - 1);
+	ret = n;
+out:
+	acpi_aml_unlock_fifo(ACPI_AML_OUT_USER, !IS_ERR_VALUE(ret));
+	return ret;
+}
+
+static ssize_t acpi_aml_read(struct file *file, char __user *buf,
+			     size_t count, loff_t *ppos)
+{
+	int ret = 0;
+	int size = 0;
+
+	if (!count)
+		return 0;
+	if (!access_ok(VERIFY_WRITE, buf, count))
+		return -EFAULT;
+
+	while (count > 0) {
+again:
+		ret = acpi_aml_read_user(buf + size, count);
+		if (ret == -EAGAIN) {
+			if (file->f_flags & O_NONBLOCK)
+				break;
+			else {
+				ret = wait_event_interruptible(acpi_aml_io.wait,
+					acpi_aml_user_readable());
+				/*
+				 * We need to retry when the condition
+				 * becomes true.
+				 */
+				if (ret == 0)
+					goto again;
+			}
+		}
+		if (IS_ERR_VALUE(ret)) {
+			if (!acpi_aml_running())
+				ret = 0;
+			break;
+		}
+		if (ret) {
+			size += ret;
+			count -= ret;
+			*ppos += ret;
+			break;
+		}
+	}
+	return size > 0 ? size : ret;
+}
+
+static int acpi_aml_write_user(const char __user *buf, int len)
+{
+	int ret;
+	struct circ_buf *crc = &acpi_aml_io.in_crc;
+	int n;
+	char *p;
+
+	ret = acpi_aml_lock_write(crc, ACPI_AML_IN_USER);
+	if (IS_ERR_VALUE(ret))
+		return ret;
+	/* sync tail before inserting cmds */
+	smp_mb();
+	p = &crc->buf[crc->head];
+	n = min(len, circ_space_to_end(crc));
+	if (copy_from_user(p, buf, n)) {
+		ret = -EFAULT;
+		goto out;
+	}
+	/* sync head after inserting cmds */
+	smp_wmb();
+	crc->head = (crc->head + n) & (ACPI_AML_BUF_SIZE - 1);
+	ret = n;
+out:
+	acpi_aml_unlock_fifo(ACPI_AML_IN_USER, !IS_ERR_VALUE(ret));
+	return n;
+}
+
+static ssize_t acpi_aml_write(struct file *file, const char __user *buf,
+			      size_t count, loff_t *ppos)
+{
+	int ret = 0;
+	int size = 0;
+
+	if (!count)
+		return 0;
+	if (!access_ok(VERIFY_READ, buf, count))
+		return -EFAULT;
+
+	while (count > 0) {
+again:
+		ret = acpi_aml_write_user(buf + size, count);
+		if (ret == -EAGAIN) {
+			if (file->f_flags & O_NONBLOCK)
+				break;
+			else {
+				ret = wait_event_interruptible(acpi_aml_io.wait,
+					acpi_aml_user_writable());
+				/*
+				 * We need to retry when the condition
+				 * becomes true.
+				 */
+				if (ret == 0)
+					goto again;
+			}
+		}
+		if (IS_ERR_VALUE(ret)) {
+			if (!acpi_aml_running())
+				ret = 0;
+			break;
+		}
+		if (ret) {
+			size += ret;
+			count -= ret;
+			*ppos += ret;
+		}
+	}
+	return size > 0 ? size : ret;
+}
+
+static unsigned int acpi_aml_poll(struct file *file, poll_table *wait)
+{
+	int masks = 0;
+
+	poll_wait(file, &acpi_aml_io.wait, wait);
+	if (acpi_aml_user_readable())
+		masks |= POLLIN | POLLRDNORM;
+	if (acpi_aml_user_writable())
+		masks |= POLLOUT | POLLWRNORM;
+
+	return masks;
+}
+
+static const struct file_operations acpi_aml_operations = {
+	.read		= acpi_aml_read,
+	.write		= acpi_aml_write,
+	.poll		= acpi_aml_poll,
+	.open		= acpi_aml_open,
+	.release	= acpi_aml_release,
+	.llseek		= generic_file_llseek,
+};
+
+static const struct acpi_debugger_ops acpi_aml_debugger = {
+	.create_thread		 = acpi_aml_create_thread,
+	.read_cmd		 = acpi_aml_read_cmd,
+	.write_log		 = acpi_aml_write_log,
+	.wait_command_ready	 = acpi_aml_wait_command_ready,
+	.notify_command_complete = acpi_aml_notify_command_complete,
+};
+
+int __init acpi_aml_init(void)
+{
+	int ret = 0;
+
+	if (!acpi_debugfs_dir) {
+		ret = -ENOENT;
+		goto err_exit;
+	}
+
+	/* Initialize AML IO interface */
+	mutex_init(&acpi_aml_io.lock);
+	init_waitqueue_head(&acpi_aml_io.wait);
+	acpi_aml_io.out_crc.buf = acpi_aml_io.out_buf;
+	acpi_aml_io.in_crc.buf = acpi_aml_io.in_buf;
+	acpi_aml_dentry = debugfs_create_file("acpidbg",
+					      S_IFREG | S_IRUGO | S_IWUSR,
+					      acpi_debugfs_dir, NULL,
+					      &acpi_aml_operations);
+	if (acpi_aml_dentry == NULL) {
+		ret = -ENODEV;
+		goto err_exit;
+	}
+	ret = acpi_register_debugger(THIS_MODULE, &acpi_aml_debugger);
+	if (ret)
+		goto err_fs;
+	acpi_aml_initialized = true;
+
+err_fs:
+	if (ret) {
+		debugfs_remove(acpi_aml_dentry);
+		acpi_aml_dentry = NULL;
+	}
+err_exit:
+	return ret;
+}
+
+void __exit acpi_aml_exit(void)
+{
+	if (acpi_aml_initialized) {
+		acpi_unregister_debugger(&acpi_aml_debugger);
+		if (acpi_aml_dentry) {
+			debugfs_remove(acpi_aml_dentry);
+			acpi_aml_dentry = NULL;
+		}
+		acpi_aml_initialized = false;
+	}
+}
+
+module_init(acpi_aml_init);
+module_exit(acpi_aml_exit);
+
+MODULE_AUTHOR("Lv Zheng");
+MODULE_DESCRIPTION("ACPI debugger userspace IO driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/acpi/acpica/acdebug.h b/drivers/acpi/acpica/acdebug.h
index c928ba494c40..dcaa15d5fe27 100644
--- a/drivers/acpi/acpica/acdebug.h
+++ b/drivers/acpi/acpica/acdebug.h
@@ -80,9 +80,15 @@ struct acpi_db_execute_walk {
 /*
  * dbxface - external debugger interfaces
  */
-acpi_status
-acpi_db_single_step(struct acpi_walk_state *walk_state,
-		    union acpi_parse_object *op, u32 op_type);
+ACPI_DBR_DEPENDENT_RETURN_OK(acpi_status
+			     acpi_db_single_step(struct acpi_walk_state
+						 *walk_state,
+						 union acpi_parse_object *op,
+						 u32 op_type))
+ ACPI_DBR_DEPENDENT_RETURN_VOID(void
+				acpi_db_signal_break_point(struct
+							   acpi_walk_state
+							   *walk_state))
 
 /*
  * dbcmds - debug commands and output routines
@@ -182,11 +188,15 @@ void acpi_db_display_method_info(union acpi_parse_object *op);
 
 void acpi_db_decode_and_display_object(char *target, char *output_type);
 
-void
-acpi_db_display_result_object(union acpi_operand_object *obj_desc,
-			      struct acpi_walk_state *walk_state);
+ACPI_DBR_DEPENDENT_RETURN_VOID(void
+			       acpi_db_display_result_object(union
+							     acpi_operand_object
+							     *obj_desc,
+							     struct
+							     acpi_walk_state
+							     *walk_state))
 
-acpi_status acpi_db_display_all_methods(char *display_count_arg);
+ acpi_status acpi_db_display_all_methods(char *display_count_arg);
 
 void acpi_db_display_arguments(void);
 
@@ -198,9 +208,13 @@ void acpi_db_display_calling_tree(void);
 
 void acpi_db_display_object_type(char *object_arg);
 
-void
-acpi_db_display_argument_object(union acpi_operand_object *obj_desc,
-				struct acpi_walk_state *walk_state);
+ACPI_DBR_DEPENDENT_RETURN_VOID(void
+			       acpi_db_display_argument_object(union
+							       acpi_operand_object
+							       *obj_desc,
+							       struct
+							       acpi_walk_state
+							       *walk_state))
 
 /*
  * dbexec - debugger control method execution
@@ -257,7 +271,7 @@ acpi_db_command_dispatch(char *input_buffer,
 
 void ACPI_SYSTEM_XFACE acpi_db_execute_thread(void *context);
 
-acpi_status acpi_db_user_commands(char prompt, union acpi_parse_object *op);
+acpi_status acpi_db_user_commands(void);
 
 char *acpi_db_get_next_token(char *string,
 			     char **next, acpi_object_type * return_type);
diff --git a/drivers/acpi/acpica/acglobal.h b/drivers/acpi/acpica/acglobal.h
index faa97604d878..3977134f2619 100644
--- a/drivers/acpi/acpica/acglobal.h
+++ b/drivers/acpi/acpica/acglobal.h
@@ -326,7 +326,6 @@ ACPI_GLOBAL(struct acpi_external_file *, acpi_gbl_external_file_list);
 #ifdef ACPI_DEBUGGER
 
 ACPI_INIT_GLOBAL(u8, acpi_gbl_abort_method, FALSE);
-ACPI_INIT_GLOBAL(u8, acpi_gbl_method_executing, FALSE);
 ACPI_INIT_GLOBAL(acpi_thread_id, acpi_gbl_db_thread_id, ACPI_INVALID_THREAD_ID);
 
 ACPI_GLOBAL(u8, acpi_gbl_db_opt_no_ini_methods);
@@ -345,7 +344,6 @@ ACPI_GLOBAL(acpi_object_type, acpi_gbl_db_arg_types[ACPI_DEBUGGER_MAX_ARGS]);
 
 /* These buffers should all be the same size */
 
-ACPI_GLOBAL(char, acpi_gbl_db_line_buf[ACPI_DB_LINE_BUFFER_SIZE]);
 ACPI_GLOBAL(char, acpi_gbl_db_parsed_buf[ACPI_DB_LINE_BUFFER_SIZE]);
 ACPI_GLOBAL(char, acpi_gbl_db_scope_buf[ACPI_DB_LINE_BUFFER_SIZE]);
 ACPI_GLOBAL(char, acpi_gbl_db_debug_filename[ACPI_DB_LINE_BUFFER_SIZE]);
@@ -360,9 +358,6 @@ ACPI_GLOBAL(u16, acpi_gbl_node_type_count_misc);
 ACPI_GLOBAL(u32, acpi_gbl_num_nodes);
 ACPI_GLOBAL(u32, acpi_gbl_num_objects);
 
-ACPI_GLOBAL(acpi_mutex, acpi_gbl_db_command_ready);
-ACPI_GLOBAL(acpi_mutex, acpi_gbl_db_command_complete);
-
 #endif				/* ACPI_DEBUGGER */
 
 /*****************************************************************************
diff --git a/drivers/acpi/acpica/acmacros.h b/drivers/acpi/acpica/acmacros.h
index e85366ceb15a..bad5bca03acc 100644
--- a/drivers/acpi/acpica/acmacros.h
+++ b/drivers/acpi/acpica/acmacros.h
@@ -400,17 +400,6 @@
 #define ACPI_HW_OPTIONAL_FUNCTION(addr)     NULL
 #endif
 
-/*
- * Some code only gets executed when the debugger is built in.
- * Note that this is entirely independent of whether the
- * DEBUG_PRINT stuff (set by ACPI_DEBUG_OUTPUT) is on, or not.
- */
-#ifdef ACPI_DEBUGGER
-#define ACPI_DEBUGGER_EXEC(a)           a
-#else
-#define ACPI_DEBUGGER_EXEC(a)
-#endif
-
 /*
  * Macros used for ACPICA utilities only
  */
diff --git a/drivers/acpi/acpica/dbdisply.c b/drivers/acpi/acpica/dbdisply.c
index 672977ec7c7d..c42ce8aa9dfe 100644
--- a/drivers/acpi/acpica/dbdisply.c
+++ b/drivers/acpi/acpica/dbdisply.c
@@ -679,6 +679,12 @@ acpi_db_display_result_object(union acpi_operand_object *obj_desc,
 			      struct acpi_walk_state *walk_state)
 {
 
+#ifndef ACPI_APPLICATION
+	if (acpi_gbl_db_thread_id != acpi_os_get_thread_id()) {
+		return;
+	}
+#endif
+
 	/* Only display if single stepping */
 
 	if (!acpi_gbl_cm_single_step) {
@@ -708,6 +714,12 @@ acpi_db_display_argument_object(union acpi_operand_object *obj_desc,
 				struct acpi_walk_state *walk_state)
 {
 
+#ifndef ACPI_APPLICATION
+	if (acpi_gbl_db_thread_id != acpi_os_get_thread_id()) {
+		return;
+	}
+#endif
+
 	if (!acpi_gbl_cm_single_step) {
 		return;
 	}
diff --git a/drivers/acpi/acpica/dbinput.c b/drivers/acpi/acpica/dbinput.c
index 0480254437f1..2bf8e6b90d5b 100644
--- a/drivers/acpi/acpica/dbinput.c
+++ b/drivers/acpi/acpica/dbinput.c
@@ -53,8 +53,6 @@ static u32 acpi_db_get_line(char *input_buffer);
 
 static u32 acpi_db_match_command(char *user_command);
 
-static void acpi_db_single_thread(void);
-
 static void acpi_db_display_command_info(char *command, u8 display_all);
 
 static void acpi_db_display_help(char *command);
@@ -1149,55 +1147,16 @@ acpi_db_command_dispatch(char *input_buffer,
 
 void ACPI_SYSTEM_XFACE acpi_db_execute_thread(void *context)
 {
-	acpi_status status = AE_OK;
-	acpi_status Mstatus;
 
-	while (status != AE_CTRL_TERMINATE && !acpi_gbl_db_terminate_loop) {
-		acpi_gbl_method_executing = FALSE;
-		acpi_gbl_step_to_next_call = FALSE;
-
-		Mstatus = acpi_os_acquire_mutex(acpi_gbl_db_command_ready,
-						ACPI_WAIT_FOREVER);
-		if (ACPI_FAILURE(Mstatus)) {
-			return;
-		}
-
-		status =
-		    acpi_db_command_dispatch(acpi_gbl_db_line_buf, NULL, NULL);
-
-		acpi_os_release_mutex(acpi_gbl_db_command_complete);
-	}
+	(void)acpi_db_user_commands();
 	acpi_gbl_db_threads_terminated = TRUE;
 }
 
-/*******************************************************************************
- *
- * FUNCTION:    acpi_db_single_thread
- *
- * PARAMETERS:  None
- *
- * RETURN:      None
- *
- * DESCRIPTION: Debugger execute thread. Waits for a command line, then
- *              simply dispatches it.
- *
- ******************************************************************************/
-
-static void acpi_db_single_thread(void)
-{
-
-	acpi_gbl_method_executing = FALSE;
-	acpi_gbl_step_to_next_call = FALSE;
-
-	(void)acpi_db_command_dispatch(acpi_gbl_db_line_buf, NULL, NULL);
-}
-
 /*******************************************************************************
  *
  * FUNCTION:    acpi_db_user_commands
  *
- * PARAMETERS:  prompt              - User prompt (depends on mode)
- *              op                  - Current executing parse op
+ * PARAMETERS:  None
  *
  * RETURN:      None
  *
@@ -1206,7 +1165,7 @@ static void acpi_db_single_thread(void)
  *
  ******************************************************************************/
 
-acpi_status acpi_db_user_commands(char prompt, union acpi_parse_object *op)
+acpi_status acpi_db_user_commands(void)
 {
 	acpi_status status = AE_OK;
 
@@ -1216,52 +1175,31 @@ acpi_status acpi_db_user_commands(char prompt, union acpi_parse_object *op)
 
 	while (!acpi_gbl_db_terminate_loop) {
 
-		/* Force output to console until a command is entered */
+		/* Wait the readiness of the command */
 
-		acpi_db_set_output_destination(ACPI_DB_CONSOLE_OUTPUT);
-
-		/* Different prompt if method is executing */
-
-		if (!acpi_gbl_method_executing) {
-			acpi_os_printf("%1c ", ACPI_DEBUGGER_COMMAND_PROMPT);
-		} else {
-			acpi_os_printf("%1c ", ACPI_DEBUGGER_EXECUTE_PROMPT);
-		}
-
-		/* Get the user input line */
-
-		status = acpi_os_get_line(acpi_gbl_db_line_buf,
-					  ACPI_DB_LINE_BUFFER_SIZE, NULL);
+		status = acpi_os_wait_command_ready();
 		if (ACPI_FAILURE(status)) {
-			ACPI_EXCEPTION((AE_INFO, status,
-					"While parsing command line"));
-			return (status);
+			break;
 		}
 
-		/* Check for single or multithreaded debug */
+		/* Just call to the command line interpreter */
 
-		if (acpi_gbl_debugger_configuration & DEBUGGER_MULTI_THREADED) {
-			/*
-			 * Signal the debug thread that we have a command to execute,
-			 * and wait for the command to complete.
-			 */
-			acpi_os_release_mutex(acpi_gbl_db_command_ready);
-			if (ACPI_FAILURE(status)) {
-				return (status);
-			}
+		acpi_gbl_method_executing = FALSE;
+		acpi_gbl_step_to_next_call = FALSE;
 
-			status =
-			    acpi_os_acquire_mutex(acpi_gbl_db_command_complete,
-						  ACPI_WAIT_FOREVER);
-			if (ACPI_FAILURE(status)) {
-				return (status);
-			}
-		} else {
-			/* Just call to the command line interpreter */
+		(void)acpi_db_command_dispatch(acpi_gbl_db_line_buf, NULL,
+					       NULL);
 
-			acpi_db_single_thread();
+		/* Notify the completion of the command */
+
+		status = acpi_os_notify_command_complete();
+		if (ACPI_FAILURE(status)) {
+			break;
 		}
 	}
 
+	if (ACPI_FAILURE(status) && status != AE_CTRL_TERMINATE) {
+		ACPI_EXCEPTION((AE_INFO, status, "While parsing command line"));
+	}
 	return (status);
 }
diff --git a/drivers/acpi/acpica/dbxface.c b/drivers/acpi/acpica/dbxface.c
index 342298a6e10f..d7ff58e8c233 100644
--- a/drivers/acpi/acpica/dbxface.c
+++ b/drivers/acpi/acpica/dbxface.c
@@ -85,46 +85,21 @@ acpi_db_start_command(struct acpi_walk_state *walk_state,
 
 	acpi_gbl_method_executing = TRUE;
 	status = AE_CTRL_TRUE;
+
 	while (status == AE_CTRL_TRUE) {
-		if (acpi_gbl_debugger_configuration == DEBUGGER_MULTI_THREADED) {
 
-			/* Handshake with the front-end that gets user command lines */
+		/* Notify the completion of the command */
 
-			acpi_os_release_mutex(acpi_gbl_db_command_complete);
+		status = acpi_os_notify_command_complete();
+		if (ACPI_FAILURE(status)) {
+			goto error_exit;
+		}
 
-			status =
-			    acpi_os_acquire_mutex(acpi_gbl_db_command_ready,
-						  ACPI_WAIT_FOREVER);
-			if (ACPI_FAILURE(status)) {
-				return (status);
-			}
-		} else {
-			/* Single threaded, we must get a command line ourselves */
+		/* Wait the readiness of the command */
 
-			/* Force output to console until a command is entered */
-
-			acpi_db_set_output_destination(ACPI_DB_CONSOLE_OUTPUT);
-
-			/* Different prompt if method is executing */
-
-			if (!acpi_gbl_method_executing) {
-				acpi_os_printf("%1c ",
-					       ACPI_DEBUGGER_COMMAND_PROMPT);
-			} else {
-				acpi_os_printf("%1c ",
-					       ACPI_DEBUGGER_EXECUTE_PROMPT);
-			}
-
-			/* Get the user input line */
-
-			status = acpi_os_get_line(acpi_gbl_db_line_buf,
-						  ACPI_DB_LINE_BUFFER_SIZE,
-						  NULL);
-			if (ACPI_FAILURE(status)) {
-				ACPI_EXCEPTION((AE_INFO, status,
-						"While parsing command line"));
-				return (status);
-			}
+		status = acpi_os_wait_command_ready();
+		if (ACPI_FAILURE(status)) {
+			goto error_exit;
 		}
 
 		status =
@@ -134,9 +109,44 @@ acpi_db_start_command(struct acpi_walk_state *walk_state,
 
 	/* acpi_ut_acquire_mutex (ACPI_MTX_NAMESPACE); */
 
+error_exit:
+	if (ACPI_FAILURE(status) && status != AE_CTRL_TERMINATE) {
+		ACPI_EXCEPTION((AE_INFO, status,
+				"While parsing/handling command line"));
+	}
 	return (status);
 }
 
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_signal_break_point
+ *
+ * PARAMETERS:  walk_state      - Current walk
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Called for AML_BREAK_POINT_OP
+ *
+ ******************************************************************************/
+
+void acpi_db_signal_break_point(struct acpi_walk_state *walk_state)
+{
+
+#ifndef ACPI_APPLICATION
+	if (acpi_gbl_db_thread_id != acpi_os_get_thread_id()) {
+		return;
+	}
+#endif
+
+	/*
+	 * Set the single-step flag. This will cause the debugger (if present)
+	 * to break to the console within the AML debugger at the start of the
+	 * next AML instruction.
+	 */
+	acpi_gbl_cm_single_step = TRUE;
+	acpi_os_printf("**break** Executed AML BreakPoint opcode\n");
+}
+
 /*******************************************************************************
  *
  * FUNCTION:    acpi_db_single_step
@@ -420,15 +430,7 @@ acpi_status acpi_initialize_debugger(void)
 
 		/* These were created with one unit, grab it */
 
-		status = acpi_os_acquire_mutex(acpi_gbl_db_command_complete,
-					       ACPI_WAIT_FOREVER);
-		if (ACPI_FAILURE(status)) {
-			acpi_os_printf("Could not get debugger mutex\n");
-			return_ACPI_STATUS(status);
-		}
-
-		status = acpi_os_acquire_mutex(acpi_gbl_db_command_ready,
-					       ACPI_WAIT_FOREVER);
+		status = acpi_os_initialize_command_signals();
 		if (ACPI_FAILURE(status)) {
 			acpi_os_printf("Could not get debugger mutex\n");
 			return_ACPI_STATUS(status);
@@ -473,13 +475,14 @@ void acpi_terminate_debugger(void)
 	acpi_gbl_db_terminate_loop = TRUE;
 
 	if (acpi_gbl_debugger_configuration & DEBUGGER_MULTI_THREADED) {
-		acpi_os_release_mutex(acpi_gbl_db_command_ready);
 
 		/* Wait the AML Debugger threads */
 
 		while (!acpi_gbl_db_threads_terminated) {
 			acpi_os_sleep(100);
 		}
+
+		acpi_os_terminate_command_signals();
 	}
 
 	if (acpi_gbl_db_buffer) {
diff --git a/drivers/acpi/acpica/dscontrol.c b/drivers/acpi/acpica/dscontrol.c
index 435fc16e2f83..06a6f7f3af52 100644
--- a/drivers/acpi/acpica/dscontrol.c
+++ b/drivers/acpi/acpica/dscontrol.c
@@ -47,6 +47,7 @@
 #include "amlcode.h"
 #include "acdispat.h"
 #include "acinterp.h"
+#include "acdebug.h"
 
 #define _COMPONENT          ACPI_DISPATCHER
 ACPI_MODULE_NAME("dscontrol")
@@ -348,14 +349,7 @@ acpi_ds_exec_end_control_op(struct acpi_walk_state * walk_state,
 
 	case AML_BREAK_POINT_OP:
 
-		/*
-		 * Set the single-step flag. This will cause the debugger (if present)
-		 * to break to the console within the AML debugger at the start of the
-		 * next AML instruction.
-		 */
-		ACPI_DEBUGGER_EXEC(acpi_gbl_cm_single_step = TRUE);
-		ACPI_DEBUGGER_EXEC(acpi_os_printf
-				   ("**break** Executed AML BreakPoint opcode\n"));
+		acpi_db_signal_break_point(walk_state);
 
 		/* Call to the OSL in case OS wants a piece of the action */
 
diff --git a/drivers/acpi/acpica/dsutils.c b/drivers/acpi/acpica/dsutils.c
index ebc577baeaf9..e4293a8794ea 100644
--- a/drivers/acpi/acpica/dsutils.c
+++ b/drivers/acpi/acpica/dsutils.c
@@ -605,8 +605,8 @@ acpi_ds_create_operand(struct acpi_walk_state *walk_state,
 		if (ACPI_FAILURE(status)) {
 			return_ACPI_STATUS(status);
 		}
-		ACPI_DEBUGGER_EXEC(acpi_db_display_argument_object
-				   (obj_desc, walk_state));
+
+		acpi_db_display_argument_object(obj_desc, walk_state);
 	} else {
 		/* Check for null name case */
 
@@ -638,10 +638,11 @@ acpi_ds_create_operand(struct acpi_walk_state *walk_state,
 			ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
 					  "Argument previously created, already stacked\n"));
 
-			ACPI_DEBUGGER_EXEC(acpi_db_display_argument_object
-					   (walk_state->
-					    operands[walk_state->num_operands -
-						     1], walk_state));
+			acpi_db_display_argument_object(walk_state->
+							operands[walk_state->
+								 num_operands -
+								 1],
+							walk_state);
 
 			/*
 			 * Use value that was already previously returned
@@ -685,8 +686,7 @@ acpi_ds_create_operand(struct acpi_walk_state *walk_state,
 			return_ACPI_STATUS(status);
 		}
 
-		ACPI_DEBUGGER_EXEC(acpi_db_display_argument_object
-				   (obj_desc, walk_state));
+		acpi_db_display_argument_object(obj_desc, walk_state);
 	}
 
 	return_ACPI_STATUS(AE_OK);
diff --git a/drivers/acpi/acpica/dswexec.c b/drivers/acpi/acpica/dswexec.c
index df54d46225cd..9cc5761ef483 100644
--- a/drivers/acpi/acpica/dswexec.c
+++ b/drivers/acpi/acpica/dswexec.c
@@ -178,8 +178,7 @@ cleanup:
 
 	/* Break to debugger to display result */
 
-	ACPI_DEBUGGER_EXEC(acpi_db_display_result_object
-			   (local_obj_desc, walk_state));
+	acpi_db_display_result_object(local_obj_desc, walk_state);
 
 	/*
 	 * Delete the predicate result object (we know that
@@ -386,11 +385,10 @@ acpi_status acpi_ds_exec_end_op(struct acpi_walk_state *walk_state)
 
 	/* Call debugger for single step support (DEBUG build only) */
 
-	ACPI_DEBUGGER_EXEC(status =
-			   acpi_db_single_step(walk_state, op, op_class));
-	ACPI_DEBUGGER_EXEC(if (ACPI_FAILURE(status)) {
-			   return_ACPI_STATUS(status);}
-	) ;
+	status = acpi_db_single_step(walk_state, op, op_class);
+	if (ACPI_FAILURE(status)) {
+		return_ACPI_STATUS(status);
+	}
 
 	/* Decode the Opcode Class */
 
@@ -728,8 +726,8 @@ cleanup:
 
 		/* Break to debugger to display result */
 
-		ACPI_DEBUGGER_EXEC(acpi_db_display_result_object
-				   (walk_state->result_obj, walk_state));
+		acpi_db_display_result_object(walk_state->result_obj,
+					      walk_state);
 
 		/*
 		 * Delete the result op if and only if:
diff --git a/drivers/acpi/acpica/utmutex.c b/drivers/acpi/acpica/utmutex.c
index ce406e39b669..ea0c207ff572 100644
--- a/drivers/acpi/acpica/utmutex.c
+++ b/drivers/acpi/acpica/utmutex.c
@@ -111,17 +111,6 @@ acpi_status acpi_ut_mutex_initialize(void)
 	if (ACPI_FAILURE(status)) {
 		return_ACPI_STATUS(status);
 	}
-#ifdef ACPI_DEBUGGER
-
-	/* Debugger Support */
-
-	status = acpi_os_create_mutex(&acpi_gbl_db_command_ready);
-	if (ACPI_FAILURE(status)) {
-		return_ACPI_STATUS(status);
-	}
-
-	status = acpi_os_create_mutex(&acpi_gbl_db_command_complete);
-#endif
 
 	return_ACPI_STATUS(status);
 }
@@ -162,12 +151,6 @@ void acpi_ut_mutex_terminate(void)
 	/* Delete the reader/writer lock */
 
 	acpi_ut_delete_rw_lock(&acpi_gbl_namespace_rw_lock);
-
-#ifdef ACPI_DEBUGGER
-	acpi_os_delete_mutex(acpi_gbl_db_command_ready);
-	acpi_os_delete_mutex(acpi_gbl_db_command_complete);
-#endif
-
 	return_VOID;
 }
 
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index a212cefae524..1a40111e1c86 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -1094,6 +1094,7 @@ static int __init acpi_init(void)
 	acpi_debugfs_init();
 	acpi_sleep_proc_init();
 	acpi_wakeup_device_init();
+	acpi_debugger_init();
 	return 0;
 }
 
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 32d684af0ec7..bb66093b7799 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -220,6 +220,7 @@ void acpi_os_printf(const char *fmt, ...)
 	acpi_os_vprintf(fmt, args);
 	va_end(args);
 }
+EXPORT_SYMBOL(acpi_os_printf);
 
 void acpi_os_vprintf(const char *fmt, va_list args)
 {
@@ -234,7 +235,8 @@ void acpi_os_vprintf(const char *fmt, va_list args)
 		printk(KERN_CONT "%s", buffer);
 	}
 #else
-	printk(KERN_CONT "%s", buffer);
+	if (acpi_debugger_write_log(buffer) < 0)
+		printk(KERN_CONT "%s", buffer);
 #endif
 }
 
@@ -1101,6 +1103,200 @@ static void acpi_os_execute_deferred(struct work_struct *work)
 	kfree(dpc);
 }
 
+#ifdef CONFIG_ACPI_DEBUGGER
+static struct acpi_debugger acpi_debugger;
+static bool acpi_debugger_initialized;
+
+int acpi_register_debugger(struct module *owner,
+			   const struct acpi_debugger_ops *ops)
+{
+	int ret = 0;
+
+	mutex_lock(&acpi_debugger.lock);
+	if (acpi_debugger.ops) {
+		ret = -EBUSY;
+		goto err_lock;
+	}
+
+	acpi_debugger.owner = owner;
+	acpi_debugger.ops = ops;
+
+err_lock:
+	mutex_unlock(&acpi_debugger.lock);
+	return ret;
+}
+EXPORT_SYMBOL(acpi_register_debugger);
+
+void acpi_unregister_debugger(const struct acpi_debugger_ops *ops)
+{
+	mutex_lock(&acpi_debugger.lock);
+	if (ops == acpi_debugger.ops) {
+		acpi_debugger.ops = NULL;
+		acpi_debugger.owner = NULL;
+	}
+	mutex_unlock(&acpi_debugger.lock);
+}
+EXPORT_SYMBOL(acpi_unregister_debugger);
+
+int acpi_debugger_create_thread(acpi_osd_exec_callback function, void *context)
+{
+	int ret;
+	int (*func)(acpi_osd_exec_callback, void *);
+	struct module *owner;
+
+	if (!acpi_debugger_initialized)
+		return -ENODEV;
+	mutex_lock(&acpi_debugger.lock);
+	if (!acpi_debugger.ops) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	if (!try_module_get(acpi_debugger.owner)) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	func = acpi_debugger.ops->create_thread;
+	owner = acpi_debugger.owner;
+	mutex_unlock(&acpi_debugger.lock);
+
+	ret = func(function, context);
+
+	mutex_lock(&acpi_debugger.lock);
+	module_put(owner);
+err_lock:
+	mutex_unlock(&acpi_debugger.lock);
+	return ret;
+}
+
+ssize_t acpi_debugger_write_log(const char *msg)
+{
+	ssize_t ret;
+	ssize_t (*func)(const char *);
+	struct module *owner;
+
+	if (!acpi_debugger_initialized)
+		return -ENODEV;
+	mutex_lock(&acpi_debugger.lock);
+	if (!acpi_debugger.ops) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	if (!try_module_get(acpi_debugger.owner)) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	func = acpi_debugger.ops->write_log;
+	owner = acpi_debugger.owner;
+	mutex_unlock(&acpi_debugger.lock);
+
+	ret = func(msg);
+
+	mutex_lock(&acpi_debugger.lock);
+	module_put(owner);
+err_lock:
+	mutex_unlock(&acpi_debugger.lock);
+	return ret;
+}
+
+ssize_t acpi_debugger_read_cmd(char *buffer, size_t buffer_length)
+{
+	ssize_t ret;
+	ssize_t (*func)(char *, size_t);
+	struct module *owner;
+
+	if (!acpi_debugger_initialized)
+		return -ENODEV;
+	mutex_lock(&acpi_debugger.lock);
+	if (!acpi_debugger.ops) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	if (!try_module_get(acpi_debugger.owner)) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	func = acpi_debugger.ops->read_cmd;
+	owner = acpi_debugger.owner;
+	mutex_unlock(&acpi_debugger.lock);
+
+	ret = func(buffer, buffer_length);
+
+	mutex_lock(&acpi_debugger.lock);
+	module_put(owner);
+err_lock:
+	mutex_unlock(&acpi_debugger.lock);
+	return ret;
+}
+
+int acpi_debugger_wait_command_ready(void)
+{
+	int ret;
+	int (*func)(bool, char *, size_t);
+	struct module *owner;
+
+	if (!acpi_debugger_initialized)
+		return -ENODEV;
+	mutex_lock(&acpi_debugger.lock);
+	if (!acpi_debugger.ops) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	if (!try_module_get(acpi_debugger.owner)) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	func = acpi_debugger.ops->wait_command_ready;
+	owner = acpi_debugger.owner;
+	mutex_unlock(&acpi_debugger.lock);
+
+	ret = func(acpi_gbl_method_executing,
+		   acpi_gbl_db_line_buf, ACPI_DB_LINE_BUFFER_SIZE);
+
+	mutex_lock(&acpi_debugger.lock);
+	module_put(owner);
+err_lock:
+	mutex_unlock(&acpi_debugger.lock);
+	return ret;
+}
+
+int acpi_debugger_notify_command_complete(void)
+{
+	int ret;
+	int (*func)(void);
+	struct module *owner;
+
+	if (!acpi_debugger_initialized)
+		return -ENODEV;
+	mutex_lock(&acpi_debugger.lock);
+	if (!acpi_debugger.ops) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	if (!try_module_get(acpi_debugger.owner)) {
+		ret = -ENODEV;
+		goto err_lock;
+	}
+	func = acpi_debugger.ops->notify_command_complete;
+	owner = acpi_debugger.owner;
+	mutex_unlock(&acpi_debugger.lock);
+
+	ret = func();
+
+	mutex_lock(&acpi_debugger.lock);
+	module_put(owner);
+err_lock:
+	mutex_unlock(&acpi_debugger.lock);
+	return ret;
+}
+
+int __init acpi_debugger_init(void)
+{
+	mutex_init(&acpi_debugger.lock);
+	acpi_debugger_initialized = true;
+	return 0;
+}
+#endif
+
 /*******************************************************************************
  *
  * FUNCTION:    acpi_os_execute
@@ -1127,6 +1323,15 @@ acpi_status acpi_os_execute(acpi_execute_type type,
 			  "Scheduling function [%p(%p)] for deferred execution.\n",
 			  function, context));
 
+	if (type == OSL_DEBUGGER_MAIN_THREAD) {
+		ret = acpi_debugger_create_thread(function, context);
+		if (ret) {
+			pr_err("Call to kthread_create() failed.\n");
+			status = AE_ERROR;
+		}
+		goto out_thread;
+	}
+
 	/*
 	 * Allocate/initialize DPC structure.  Note that this memory will be
 	 * freed by the callee.  The kernel handles the work_struct list  in a
@@ -1151,11 +1356,17 @@ acpi_status acpi_os_execute(acpi_execute_type type,
 	if (type == OSL_NOTIFY_HANDLER) {
 		queue = kacpi_notify_wq;
 		INIT_WORK(&dpc->work, acpi_os_execute_deferred);
-	} else {
+	} else if (type == OSL_GPE_HANDLER) {
 		queue = kacpid_wq;
 		INIT_WORK(&dpc->work, acpi_os_execute_deferred);
+	} else {
+		pr_err("Unsupported os_execute type %d.\n", type);
+		status = AE_ERROR;
 	}
 
+	if (ACPI_FAILURE(status))
+		goto err_workqueue;
+
 	/*
 	 * On some machines, a software-initiated SMI causes corruption unless
 	 * the SMI runs on CPU 0.  An SMI can be initiated by any AML, but
@@ -1164,13 +1375,15 @@ acpi_status acpi_os_execute(acpi_execute_type type,
 	 * queueing on CPU 0.
 	 */
 	ret = queue_work_on(0, queue, &dpc->work);
-
 	if (!ret) {
 		printk(KERN_ERR PREFIX
 			  "Call to queue_work() failed.\n");
 		status = AE_ERROR;
-		kfree(dpc);
 	}
+err_workqueue:
+	if (ACPI_FAILURE(status))
+		kfree(dpc);
+out_thread:
 	return status;
 }
 EXPORT_SYMBOL(acpi_os_execute);
@@ -1358,10 +1571,39 @@ acpi_status acpi_os_get_line(char *buffer, u32 buffer_length, u32 *bytes_read)
 		chars = strlen(buffer) - 1;
 		buffer[chars] = '\0';
 	}
+#else
+	int ret;
+
+	ret = acpi_debugger_read_cmd(buffer, buffer_length);
+	if (ret < 0)
+		return AE_ERROR;
+	if (bytes_read)
+		*bytes_read = ret;
 #endif
 
 	return AE_OK;
 }
+EXPORT_SYMBOL(acpi_os_get_line);
+
+acpi_status acpi_os_wait_command_ready(void)
+{
+	int ret;
+
+	ret = acpi_debugger_wait_command_ready();
+	if (ret < 0)
+		return AE_ERROR;
+	return AE_OK;
+}
+
+acpi_status acpi_os_notify_command_complete(void)
+{
+	int ret;
+
+	ret = acpi_debugger_notify_command_complete();
+	if (ret < 0)
+		return AE_ERROR;
+	return AE_OK;
+}
 
 acpi_status acpi_os_signal(u32 function, void *info)
 {
diff --git a/include/acpi/acpiosxf.h b/include/acpi/acpiosxf.h
index fbc2baf2b9dc..0d824a28522d 100644
--- a/include/acpi/acpiosxf.h
+++ b/include/acpi/acpiosxf.h
@@ -349,12 +349,28 @@ void acpi_os_redirect_output(void *destination);
 #endif
 
 /*
- * Debug input
+ * Debug IO
  */
 #ifndef ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_get_line
 acpi_status acpi_os_get_line(char *buffer, u32 buffer_length, u32 *bytes_read);
 #endif
 
+#ifndef ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_initialize_command_signals
+acpi_status acpi_os_initialize_command_signals(void);
+#endif
+
+#ifndef ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_terminate_command_signals
+void acpi_os_terminate_command_signals(void);
+#endif
+
+#ifndef ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_wait_command_ready
+acpi_status acpi_os_wait_command_ready(void);
+#endif
+
+#ifndef ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_notify_command_complete
+acpi_status acpi_os_notify_command_complete(void);
+#endif
+
 /*
  * Obtain ACPI table(s)
  */
diff --git a/include/acpi/acpixf.h b/include/acpi/acpixf.h
index 3aaaa8630735..5dfab9c2142e 100644
--- a/include/acpi/acpixf.h
+++ b/include/acpi/acpixf.h
@@ -263,6 +263,15 @@ ACPI_INIT_GLOBAL(u32, acpi_gbl_trace_dbg_layer, ACPI_TRACE_LAYER_DEFAULT);
 ACPI_INIT_GLOBAL(u32, acpi_dbg_level, ACPI_DEBUG_DEFAULT);
 ACPI_INIT_GLOBAL(u32, acpi_dbg_layer, 0);
 
+/*
+ * Debugger command handshake globals. Host OSes need to access these
+ * variables to implement their own command handshake mechanism.
+ */
+#ifdef ACPI_DEBUGGER
+ACPI_INIT_GLOBAL(u8, acpi_gbl_method_executing, FALSE);
+ACPI_GLOBAL(char, acpi_gbl_db_line_buf[ACPI_DB_LINE_BUFFER_SIZE]);
+#endif
+
 /*
  * Other miscellaneous globals
  */
@@ -366,6 +375,29 @@ ACPI_GLOBAL(u8, acpi_gbl_system_awake_and_running);
 
 #endif				/* ACPI_APPLICATION */
 
+/*
+ * Debugger prototypes
+ *
+ * All interfaces used by debugger will be configured
+ * out of the ACPICA build unless the ACPI_DEBUGGER
+ * flag is defined.
+ */
+#ifdef ACPI_DEBUGGER
+#define ACPI_DBR_DEPENDENT_RETURN_OK(prototype) \
+	ACPI_EXTERNAL_RETURN_OK(prototype)
+
+#define ACPI_DBR_DEPENDENT_RETURN_VOID(prototype) \
+	ACPI_EXTERNAL_RETURN_VOID(prototype)
+
+#else
+#define ACPI_DBR_DEPENDENT_RETURN_OK(prototype) \
+	static ACPI_INLINE prototype {return(AE_OK);}
+
+#define ACPI_DBR_DEPENDENT_RETURN_VOID(prototype) \
+	static ACPI_INLINE prototype {return;}
+
+#endif				/* ACPI_DEBUGGER */
+
 /*****************************************************************************
  *
  * ACPICA public interface prototypes
@@ -929,6 +961,8 @@ ACPI_EXTERNAL_RETURN_STATUS(acpi_status
 					       void **data,
 					       void (*callback)(void *)))
 
+void acpi_run_debugger(char *batch_buffer);
+
 void acpi_set_debugger_thread_id(acpi_thread_id thread_id);
 
 #endif				/* __ACXFACE_H__ */
diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h
index 323e5daece54..e21857d2ec05 100644
--- a/include/acpi/platform/aclinux.h
+++ b/include/acpi/platform/aclinux.h
@@ -150,6 +150,8 @@
  */
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_readable
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_writable
+#define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_initialize_command_signals
+#define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_terminate_command_signals
 
 /*
  * OSL interfaces used by utilities
diff --git a/include/acpi/platform/aclinuxex.h b/include/acpi/platform/aclinuxex.h
index fd6d70fe1219..ceea026b2c0b 100644
--- a/include/acpi/platform/aclinuxex.h
+++ b/include/acpi/platform/aclinuxex.h
@@ -129,6 +129,15 @@ static inline u8 acpi_os_readable(void *pointer, acpi_size length)
 	return TRUE;
 }
 
+static inline acpi_status acpi_os_initialize_command_signals(void)
+{
+	return AE_OK;
+}
+
+static inline void acpi_os_terminate_command_signals(void)
+{
+}
+
 /*
  * OSL interfaces added by Linux
  */
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 1991aea2ec4c..a03a05474527 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -37,6 +37,8 @@
 #include <linux/list.h>
 #include <linux/mod_devicetable.h>
 #include <linux/dynamic_debug.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
 
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
@@ -119,6 +121,75 @@ typedef int (*acpi_tbl_table_handler)(struct acpi_table_header *table);
 typedef int (*acpi_tbl_entry_handler)(struct acpi_subtable_header *header,
 				      const unsigned long end);
 
+/* Debugger support */
+
+struct acpi_debugger_ops {
+	int (*create_thread)(acpi_osd_exec_callback function, void *context);
+	ssize_t (*write_log)(const char *msg);
+	ssize_t (*read_cmd)(char *buffer, size_t length);
+	int (*wait_command_ready)(bool single_step, char *buffer, size_t length);
+	int (*notify_command_complete)(void);
+};
+
+struct acpi_debugger {
+	const struct acpi_debugger_ops *ops;
+	struct module *owner;
+	struct mutex lock;
+};
+
+#ifdef CONFIG_ACPI_DEBUGGER
+int __init acpi_debugger_init(void);
+int acpi_register_debugger(struct module *owner,
+			   const struct acpi_debugger_ops *ops);
+void acpi_unregister_debugger(const struct acpi_debugger_ops *ops);
+int acpi_debugger_create_thread(acpi_osd_exec_callback function, void *context);
+ssize_t acpi_debugger_write_log(const char *msg);
+ssize_t acpi_debugger_read_cmd(char *buffer, size_t buffer_length);
+int acpi_debugger_wait_command_ready(void);
+int acpi_debugger_notify_command_complete(void);
+#else
+static inline int acpi_debugger_init(void)
+{
+	return -ENODEV;
+}
+
+static inline int acpi_register_debugger(struct module *owner,
+					 const struct acpi_debugger_ops *ops)
+{
+	return -ENODEV;
+}
+
+static inline void acpi_unregister_debugger(const struct acpi_debugger_ops *ops)
+{
+}
+
+static inline int acpi_debugger_create_thread(acpi_osd_exec_callback function,
+					      void *context)
+{
+	return -ENODEV;
+}
+
+static inline int acpi_debugger_write_log(const char *msg)
+{
+	return -ENODEV;
+}
+
+static inline int acpi_debugger_read_cmd(char *buffer, u32 buffer_length)
+{
+	return -ENODEV;
+}
+
+static inline int acpi_debugger_wait_command_ready(void)
+{
+	return -ENODEV;
+}
+
+static inline int acpi_debugger_notify_command_complete(void)
+{
+	return -ENODEV;
+}
+#endif
+
 #ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
 void acpi_initrd_override(void *data, size_t size);
 #else
diff --git a/tools/power/acpi/Makefile b/tools/power/acpi/Makefile
index e882c8320135..a8bf9081512b 100644
--- a/tools/power/acpi/Makefile
+++ b/tools/power/acpi/Makefile
@@ -10,18 +10,18 @@
 
 include ../../scripts/Makefile.include
 
-all: acpidump ec
-clean: acpidump_clean ec_clean
-install: acpidump_install ec_install
-uninstall: acpidump_uninstall ec_uninstall
+all: acpidbg acpidump ec
+clean: acpidbg_clean acpidump_clean ec_clean
+install: acpidbg_install acpidump_install ec_install
+uninstall: acpidbg_uninstall acpidump_uninstall ec_uninstall
 
-acpidump ec: FORCE
+acpidbg acpidump ec: FORCE
 	$(call descend,tools/$@,all)
-acpidump_clean ec_clean:
+acpidbg_clean acpidump_clean ec_clean:
 	$(call descend,tools/$(@:_clean=),clean)
-acpidump_install ec_install:
+acpidbg_install acpidump_install ec_install:
 	$(call descend,tools/$(@:_install=),install)
-acpidump_uninstall ec_uninstall:
+acpidbg_uninstall acpidump_uninstall ec_uninstall:
 	$(call descend,tools/$(@:_uninstall=),uninstall)
 
 .PHONY: FORCE
diff --git a/tools/power/acpi/tools/acpidbg/Makefile b/tools/power/acpi/tools/acpidbg/Makefile
new file mode 100644
index 000000000000..352df4b41ae9
--- /dev/null
+++ b/tools/power/acpi/tools/acpidbg/Makefile
@@ -0,0 +1,27 @@
+# tools/power/acpi/tools/acpidbg/Makefile - ACPI tool Makefile
+#
+# Copyright (c) 2015, Intel Corporation
+#   Author: Lv Zheng <lv.zheng@intel.com>
+#
+# 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; version 2
+# of the License.
+
+include ../../Makefile.config
+
+TOOL = acpidbg
+vpath %.c \
+	../../../../../drivers/acpi/acpica\
+	../../common\
+	../../os_specific/service_layers\
+	.
+CFLAGS += -DACPI_APPLICATION -DACPI_SINGLE_THREAD -DACPI_DEBUGGER\
+	-I.\
+	-I../../../../../drivers/acpi/acpica\
+	-I../../../../../include
+LDFLAGS += -lpthread
+TOOL_OBJS = \
+	acpidbg.o
+
+include ../../Makefile.rules
diff --git a/tools/power/acpi/tools/acpidbg/acpidbg.c b/tools/power/acpi/tools/acpidbg/acpidbg.c
new file mode 100644
index 000000000000..d070fccdba6d
--- /dev/null
+++ b/tools/power/acpi/tools/acpidbg/acpidbg.c
@@ -0,0 +1,438 @@
+/*
+ * ACPI AML interfacing userspace utility
+ *
+ * Copyright (C) 2015, Intel Corporation
+ * Authors: Lv Zheng <lv.zheng@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <acpi/acpi.h>
+
+/* Headers not included by include/acpi/platform/aclinux.h */
+#include <stdbool.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <linux/circ_buf.h>
+
+#define ACPI_AML_FILE		"/sys/kernel/debug/acpi/acpidbg"
+#define ACPI_AML_SEC_TICK	1
+#define ACPI_AML_USEC_PEEK	200
+#define ACPI_AML_BUF_SIZE	4096
+
+#define ACPI_AML_BATCH_WRITE_CMD	0x00 /* Write command to kernel */
+#define ACPI_AML_BATCH_READ_LOG		0x01 /* Read log from kernel */
+#define ACPI_AML_BATCH_WRITE_LOG	0x02 /* Write log to console */
+
+#define ACPI_AML_LOG_START		0x00
+#define ACPI_AML_PROMPT_START		0x01
+#define ACPI_AML_PROMPT_STOP		0x02
+#define ACPI_AML_LOG_STOP		0x03
+#define ACPI_AML_PROMPT_ROLL		0x04
+
+#define ACPI_AML_INTERACTIVE	0x00
+#define ACPI_AML_BATCH		0x01
+
+#define circ_count(circ) \
+	(CIRC_CNT((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))
+#define circ_count_to_end(circ) \
+	(CIRC_CNT_TO_END((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))
+#define circ_space(circ) \
+	(CIRC_SPACE((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))
+#define circ_space_to_end(circ) \
+	(CIRC_SPACE_TO_END((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))
+
+#define acpi_aml_cmd_count()	circ_count(&acpi_aml_cmd_crc)
+#define acpi_aml_log_count()	circ_count(&acpi_aml_log_crc)
+#define acpi_aml_cmd_space()	circ_space(&acpi_aml_cmd_crc)
+#define acpi_aml_log_space()	circ_space(&acpi_aml_log_crc)
+
+#define ACPI_AML_DO(_fd, _op, _buf, _ret)				\
+	do {								\
+		_ret = acpi_aml_##_op(_fd, &acpi_aml_##_buf##_crc);	\
+		if (_ret == 0) {					\
+			fprintf(stderr,					\
+				"%s %s pipe closed.\n", #_buf, #_op);	\
+			return;						\
+		}							\
+	} while (0)
+#define ACPI_AML_BATCH_DO(_fd, _op, _buf, _ret)				\
+	do {								\
+		_ret = acpi_aml_##_op##_batch_##_buf(_fd,		\
+			 &acpi_aml_##_buf##_crc);			\
+		if (_ret == 0)						\
+			return;						\
+	} while (0)
+
+
+static char acpi_aml_cmd_buf[ACPI_AML_BUF_SIZE];
+static char acpi_aml_log_buf[ACPI_AML_BUF_SIZE];
+static struct circ_buf acpi_aml_cmd_crc = {
+	.buf = acpi_aml_cmd_buf,
+	.head = 0,
+	.tail = 0,
+};
+static struct circ_buf acpi_aml_log_crc = {
+	.buf = acpi_aml_log_buf,
+	.head = 0,
+	.tail = 0,
+};
+static const char *acpi_aml_file_path = ACPI_AML_FILE;
+static unsigned long acpi_aml_mode = ACPI_AML_INTERACTIVE;
+static bool acpi_aml_exit;
+
+static bool acpi_aml_batch_drain;
+static unsigned long acpi_aml_batch_state;
+static char acpi_aml_batch_prompt;
+static char acpi_aml_batch_roll;
+static unsigned long acpi_aml_log_state;
+static char *acpi_aml_batch_cmd = NULL;
+static char *acpi_aml_batch_pos = NULL;
+
+static int acpi_aml_set_fl(int fd, int flags)
+{
+	int ret;
+
+	ret = fcntl(fd, F_GETFL, 0);
+	if (ret < 0) {
+		perror("fcntl(F_GETFL)");
+		return ret;
+	}
+	flags |= ret;
+	ret = fcntl(fd, F_SETFL, flags);
+	if (ret < 0) {
+		perror("fcntl(F_SETFL)");
+		return ret;
+	}
+	return ret;
+}
+
+static int acpi_aml_set_fd(int fd, int maxfd, fd_set *set)
+{
+	if (fd > maxfd)
+		maxfd = fd;
+	FD_SET(fd, set);
+	return maxfd;
+}
+
+static int acpi_aml_read(int fd, struct circ_buf *crc)
+{
+	char *p;
+	int len;
+
+	p = &crc->buf[crc->head];
+	len = circ_space_to_end(crc);
+	len = read(fd, p, len);
+	if (len < 0)
+		perror("read");
+	else if (len > 0)
+		crc->head = (crc->head + len) & (ACPI_AML_BUF_SIZE - 1);
+	return len;
+}
+
+static int acpi_aml_read_batch_cmd(int unused, struct circ_buf *crc)
+{
+	char *p;
+	int len;
+	int remained = strlen(acpi_aml_batch_pos);
+
+	p = &crc->buf[crc->head];
+	len = circ_space_to_end(crc);
+	if (len > remained) {
+		memcpy(p, acpi_aml_batch_pos, remained);
+		acpi_aml_batch_pos += remained;
+		len = remained;
+	} else {
+		memcpy(p, acpi_aml_batch_pos, len);
+		acpi_aml_batch_pos += len;
+	}
+	if (len > 0)
+		crc->head = (crc->head + len) & (ACPI_AML_BUF_SIZE - 1);
+	return len;
+}
+
+static int acpi_aml_read_batch_log(int fd, struct circ_buf *crc)
+{
+	char *p;
+	int len;
+	int ret = 0;
+
+	p = &crc->buf[crc->head];
+	len = circ_space_to_end(crc);
+	while (ret < len && acpi_aml_log_state != ACPI_AML_LOG_STOP) {
+		if (acpi_aml_log_state == ACPI_AML_PROMPT_ROLL) {
+			*p = acpi_aml_batch_roll;
+			len = 1;
+			crc->head = (crc->head + 1) & (ACPI_AML_BUF_SIZE - 1);
+			ret += 1;
+			acpi_aml_log_state = ACPI_AML_LOG_START;
+		} else {
+			len = read(fd, p, 1);
+			if (len <= 0) {
+				if (len < 0)
+					perror("read");
+				ret = len;
+				break;
+			}
+		}
+		switch (acpi_aml_log_state) {
+		case ACPI_AML_LOG_START:
+			if (*p == '\n')
+				acpi_aml_log_state = ACPI_AML_PROMPT_START;
+			crc->head = (crc->head + 1) & (ACPI_AML_BUF_SIZE - 1);
+			ret += 1;
+			break;
+		case ACPI_AML_PROMPT_START:
+			if (*p == ACPI_DEBUGGER_COMMAND_PROMPT ||
+			    *p == ACPI_DEBUGGER_EXECUTE_PROMPT) {
+				acpi_aml_batch_prompt = *p;
+				acpi_aml_log_state = ACPI_AML_PROMPT_STOP;
+			} else {
+				if (*p != '\n')
+					acpi_aml_log_state = ACPI_AML_LOG_START;
+				crc->head = (crc->head + 1) & (ACPI_AML_BUF_SIZE - 1);
+				ret += 1;
+			}
+			break;
+		case ACPI_AML_PROMPT_STOP:
+			if (*p == ' ') {
+				acpi_aml_log_state = ACPI_AML_LOG_STOP;
+				acpi_aml_exit = true;
+			} else {
+				/* Roll back */
+				acpi_aml_log_state = ACPI_AML_PROMPT_ROLL;
+				acpi_aml_batch_roll = *p;
+				*p = acpi_aml_batch_prompt;
+				crc->head = (crc->head + 1) & (ACPI_AML_BUF_SIZE - 1);
+				ret += 1;
+			}
+			break;
+		default:
+			assert(0);
+			break;
+		}
+	}
+	return ret;
+}
+
+static int acpi_aml_write(int fd, struct circ_buf *crc)
+{
+	char *p;
+	int len;
+
+	p = &crc->buf[crc->tail];
+	len = circ_count_to_end(crc);
+	len = write(fd, p, len);
+	if (len < 0)
+		perror("write");
+	else if (len > 0)
+		crc->tail = (crc->tail + len) & (ACPI_AML_BUF_SIZE - 1);
+	return len;
+}
+
+static int acpi_aml_write_batch_log(int fd, struct circ_buf *crc)
+{
+	char *p;
+	int len;
+
+	p = &crc->buf[crc->tail];
+	len = circ_count_to_end(crc);
+	if (!acpi_aml_batch_drain) {
+		len = write(fd, p, len);
+		if (len < 0)
+			perror("write");
+	}
+	if (len > 0)
+		crc->tail = (crc->tail + len) & (ACPI_AML_BUF_SIZE - 1);
+	return len;
+}
+
+static int acpi_aml_write_batch_cmd(int fd, struct circ_buf *crc)
+{
+	int len;
+
+	len = acpi_aml_write(fd, crc);
+	if (circ_count_to_end(crc) == 0)
+		acpi_aml_batch_state = ACPI_AML_BATCH_READ_LOG;
+	return len;
+}
+
+static void acpi_aml_loop(int fd)
+{
+	fd_set rfds;
+	fd_set wfds;
+	struct timeval tv;
+	int ret;
+	int maxfd = 0;
+
+	if (acpi_aml_mode == ACPI_AML_BATCH) {
+		acpi_aml_log_state = ACPI_AML_LOG_START;
+		acpi_aml_batch_pos = acpi_aml_batch_cmd;
+		if (acpi_aml_batch_drain)
+			acpi_aml_batch_state = ACPI_AML_BATCH_READ_LOG;
+		else
+			acpi_aml_batch_state = ACPI_AML_BATCH_WRITE_CMD;
+	}
+	acpi_aml_exit = false;
+	while (!acpi_aml_exit) {
+		tv.tv_sec = ACPI_AML_SEC_TICK;
+		tv.tv_usec = 0;
+		FD_ZERO(&rfds);
+		FD_ZERO(&wfds);
+
+		if (acpi_aml_cmd_space()) {
+			if (acpi_aml_mode == ACPI_AML_INTERACTIVE)
+				maxfd = acpi_aml_set_fd(STDIN_FILENO, maxfd, &rfds);
+			else if (strlen(acpi_aml_batch_pos) &&
+				 acpi_aml_batch_state == ACPI_AML_BATCH_WRITE_CMD)
+				ACPI_AML_BATCH_DO(STDIN_FILENO, read, cmd, ret);
+		}
+		if (acpi_aml_cmd_count() &&
+		    (acpi_aml_mode == ACPI_AML_INTERACTIVE ||
+		     acpi_aml_batch_state == ACPI_AML_BATCH_WRITE_CMD))
+			maxfd = acpi_aml_set_fd(fd, maxfd, &wfds);
+		if (acpi_aml_log_space() &&
+		    (acpi_aml_mode == ACPI_AML_INTERACTIVE ||
+		     acpi_aml_batch_state == ACPI_AML_BATCH_READ_LOG))
+			maxfd = acpi_aml_set_fd(fd, maxfd, &rfds);
+		if (acpi_aml_log_count())
+			maxfd = acpi_aml_set_fd(STDOUT_FILENO, maxfd, &wfds);
+
+		ret = select(maxfd+1, &rfds, &wfds, NULL, &tv);
+		if (ret < 0) {
+			perror("select");
+			break;
+		}
+		if (ret > 0) {
+			if (FD_ISSET(STDIN_FILENO, &rfds))
+				ACPI_AML_DO(STDIN_FILENO, read, cmd, ret);
+			if (FD_ISSET(fd, &wfds)) {
+				if (acpi_aml_mode == ACPI_AML_BATCH)
+					ACPI_AML_BATCH_DO(fd, write, cmd, ret);
+				else
+					ACPI_AML_DO(fd, write, cmd, ret);
+			}
+			if (FD_ISSET(fd, &rfds)) {
+				if (acpi_aml_mode == ACPI_AML_BATCH)
+					ACPI_AML_BATCH_DO(fd, read, log, ret);
+				else
+					ACPI_AML_DO(fd, read, log, ret);
+			}
+			if (FD_ISSET(STDOUT_FILENO, &wfds)) {
+				if (acpi_aml_mode == ACPI_AML_BATCH)
+					ACPI_AML_BATCH_DO(STDOUT_FILENO, write, log, ret);
+				else
+					ACPI_AML_DO(STDOUT_FILENO, write, log, ret);
+			}
+		}
+	}
+}
+
+static bool acpi_aml_readable(int fd)
+{
+	fd_set rfds;
+	struct timeval tv;
+	int ret;
+	int maxfd = 0;
+
+	tv.tv_sec = 0;
+	tv.tv_usec = ACPI_AML_USEC_PEEK;
+	FD_ZERO(&rfds);
+	maxfd = acpi_aml_set_fd(fd, maxfd, &rfds);
+	ret = select(maxfd+1, &rfds, NULL, NULL, &tv);
+	if (ret < 0)
+		perror("select");
+	if (ret > 0 && FD_ISSET(fd, &rfds))
+		return true;
+	return false;
+}
+
+/*
+ * This is a userspace IO flush implementation, replying on the prompt
+ * characters and can be turned into a flush() call after kernel implements
+ * .flush() filesystem operation.
+ */
+static void acpi_aml_flush(int fd)
+{
+	while (acpi_aml_readable(fd)) {
+		acpi_aml_batch_drain = true;
+		acpi_aml_loop(fd);
+		acpi_aml_batch_drain = false;
+	}
+}
+
+void usage(FILE *file, char *progname)
+{
+	fprintf(file, "usage: %s [-b cmd] [-f file] [-h]\n", progname);
+	fprintf(file, "\nOptions:\n");
+	fprintf(file, "  -b     Specify command to be executed in batch mode\n");
+	fprintf(file, "  -f     Specify interface file other than");
+	fprintf(file, "         /sys/kernel/debug/acpi/acpidbg\n");
+	fprintf(file, "  -h     Print this help message\n");
+}
+
+int main(int argc, char **argv)
+{
+	int fd = 0;
+	int ch;
+	int len;
+	int ret = EXIT_SUCCESS;
+
+	while ((ch = getopt(argc, argv, "b:f:h")) != -1) {
+		switch (ch) {
+		case 'b':
+			if (acpi_aml_batch_cmd) {
+				fprintf(stderr, "Already specify %s\n",
+					acpi_aml_batch_cmd);
+				ret = EXIT_FAILURE;
+				goto exit;
+			}
+			len = strlen(optarg);
+			acpi_aml_batch_cmd = calloc(len + 2, 1);
+			if (!acpi_aml_batch_cmd) {
+				perror("calloc");
+				ret = EXIT_FAILURE;
+				goto exit;
+			}
+			memcpy(acpi_aml_batch_cmd, optarg, len);
+			acpi_aml_batch_cmd[len] = '\n';
+			acpi_aml_mode = ACPI_AML_BATCH;
+			break;
+		case 'f':
+			acpi_aml_file_path = optarg;
+			break;
+		case 'h':
+			usage(stdout, argv[0]);
+			goto exit;
+			break;
+		case '?':
+		default:
+			usage(stderr, argv[0]);
+			ret = EXIT_FAILURE;
+			goto exit;
+			break;
+		}
+	}
+
+	fd = open(acpi_aml_file_path, O_RDWR | O_NONBLOCK);
+	if (fd < 0) {
+		perror("open");
+		ret = EXIT_FAILURE;
+		goto exit;
+	}
+	acpi_aml_set_fl(STDIN_FILENO, O_NONBLOCK);
+	acpi_aml_set_fl(STDOUT_FILENO, O_NONBLOCK);
+
+	if (acpi_aml_mode == ACPI_AML_BATCH)
+		acpi_aml_flush(fd);
+	acpi_aml_loop(fd);
+
+exit:
+	if (fd < 0)
+		close(fd);
+	if (acpi_aml_batch_cmd)
+		free(acpi_aml_batch_cmd);
+	return ret;
+}