Merge branch 'acpi-debug'

* acpi-debug:
  ACPI / debugger: Fix a redundant mutex unlock issue in acpi_aml_open()
  ACPI / debugger: copy_to_user doesn't return errors
  ACPI / debugger: remove some unneeded conditions
  ACPI / debugger: Fix an issue a flag is modified without locking
  ACPI / debugger: Add module support for ACPI debugger
  tools/power/acpi: Add userspace AML interface support
  ACPI / debugger: Add IO interface to access debugger functionalities
  ACPICA: Debugger: Fix runtime stub issues of ACPI_DEBUGGER_EXEC using different stub mechanism
  ACPICA: Debugger: Convert some mechanisms to OSPM specific
  ACPICA: Debugger: Remove unnecessary status check

15 files changed, 1187 insertions, 202 deletions

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
@@ -401,17 +401,6 @@
 #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, th