ARM: Add generic fiq serial debugger

Change-Id: Ibb536c88f0dbaf4766d0599296907e35e42cbfd6
Signed-off-by: Iliyan Malchev <malchev@google.com>
Signed-off-by: Arve Hjønnevåg <arve@android.com>

4 files changed, 758 insertions, 0 deletions

diff --git a/arch/arm/common/Kconfig b/arch/arm/common/Kconfig
index 897b3fbe6e33..8ee3288a4b0a 100644
--- a/arch/arm/common/Kconfig
+++ b/arch/arm/common/Kconfig
@@ -43,3 +43,34 @@ config SHARP_SCOOP
 config FIQ_GLUE
 	bool
 	select FIQ
+
+config FIQ_DEBUGGER
+	bool "FIQ Mode Serial Debugger"
+	select FIQ
+	select FIQ_GLUE
+	select KERNEL_DEBUGGER_CORE
+	default n
+	help
+	  The FIQ serial debugger can accept commands even when the
+	  kernel is unresponsive due to being stuck with interrupts
+	  disabled.  Depends on the kernel debugger core in drivers/misc.
+
+
+config FIQ_DEBUGGER_NO_SLEEP
+	bool "Keep serial debugger active"
+	depends on FIQ_DEBUGGER
+	default n
+	help
+	  Enables the serial debugger at boot. Passing
+	  fiq_debugger.no_sleep on the kernel commandline will
+	  override this config option.
+
+config FIQ_DEBUGGER_WAKEUP_IRQ_ALWAYS_ON
+	bool "Don't disable wakeup IRQ when debugger is active"
+	depends on FIQ_DEBUGGER
+	default n
+	help
+	  Don't disable the wakeup irq when enabling the uart clock.  This will
+	  cause extra interrupts, but it makes the serial debugger usable with
+	  on some MSM radio builds that ignore the uart clock request in power
+	  collapse.
diff --git a/arch/arm/common/Makefile b/arch/arm/common/Makefile
index 0ca99bbe9d84..3ab5d765fedd 100644
--- a/arch/arm/common/Makefile
+++ b/arch/arm/common/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_ARCH_IXP23XX)	+= uengine.o
 obj-$(CONFIG_PCI_HOST_ITE8152)  += it8152.o
 obj-$(CONFIG_ARM_TIMER_SP804)	+= timer-sp.o
 obj-$(CONFIG_FIQ_GLUE)		+= fiq_glue.o fiq_glue_setup.o
+obj-$(CONFIG_FIQ_DEBUGGER)	+= fiq_debugger.o
diff --git a/arch/arm/common/fiq_debugger.c b/arch/arm/common/fiq_debugger.c
new file mode 100644
index 000000000000..c4679a16f340
--- /dev/null
+++ b/arch/arm/common/fiq_debugger.c
@@ -0,0 +1,680 @@
+/*
+ * arch/arm/common/fiq_debugger.c
+ *
+ * Serial Debugger Interface accessed through an FIQ interrupt.
+ *
+ * Copyright (C) 2008 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <stdarg.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+#include <linux/kernel_debugger.h>
+#include <linux/kernel_stat.h>
+#include <linux/irq.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+#include <linux/wakelock.h>
+
+#include <asm/fiq_debugger.h>
+#include <asm/fiq_glue.h>
+#include <asm/stacktrace.h>
+
+#include <mach/system.h>
+
+#include <linux/uaccess.h>
+
+#define DEBUG_MAX 64
+
+struct fiq_debugger_state {
+	struct fiq_glue_handler handler;
+
+	int fiq;
+	int signal_irq;
+	int wakeup_irq;
+	bool wakeup_irq_no_set_wake;
+	struct clk *clk;
+	struct fiq_debugger_pdata *pdata;
+	struct platform_device *pdev;
+
+	char debug_cmd[DEBUG_MAX];
+	int debug_busy;
+	int debug_abort;
+
+	char debug_buf[DEBUG_MAX];
+	int debug_count;
+
+	bool no_sleep;
+	bool debug_enable;
+	bool ignore_next_wakeup_irq;
+	struct timer_list sleep_timer;
+	bool uart_clk_enabled;
+	struct wake_lock debugger_wake_lock;
+
+	unsigned int last_irqs[NR_IRQS];
+};
+
+#ifdef CONFIG_FIQ_DEBUGGER_NO_SLEEP
+static bool initial_no_sleep = true;
+#else
+static bool initial_no_sleep;
+#endif
+static bool initial_debug_enable;
+
+module_param_named(no_sleep, initial_no_sleep, bool, 0644);
+module_param_named(debug_enable, initial_debug_enable, bool, 0644);
+
+#ifdef CONFIG_FIQ_DEBUGGER_WAKEUP_IRQ_ALWAYS_ON
+static inline void enable_wakeup_irq(struct fiq_debugger_state *state) {}
+static inline void disable_wakeup_irq(struct fiq_debugger_state *state) {}
+#else
+static inline void enable_wakeup_irq(struct fiq_debugger_state *state)
+{
+	if (state->wakeup_irq < 0)
+		return;
+	enable_irq(state->wakeup_irq);
+	if (!state->wakeup_irq_no_set_wake)
+		enable_irq_wake(state->wakeup_irq);
+}
+static inline void disable_wakeup_irq(struct fiq_debugger_state *state)
+{
+	if (state->wakeup_irq < 0)
+		return;
+	disable_irq_nosync(state->wakeup_irq);
+	if (!state->wakeup_irq_no_set_wake)
+		disable_irq_wake(state->wakeup_irq);
+}
+#endif
+
+static void debug_force_irq(struct fiq_debugger_state *state)
+{
+	unsigned int irq = state->signal_irq;
+	if (state->pdata->force_irq)
+		state->pdata->force_irq(state->pdev, irq);
+	else {
+		struct irq_chip *chip = get_irq_chip(irq);
+		if (chip && chip->retrigger)
+			chip->retrigger(irq);
+	}
+}
+
+static void debug_uart_flush(struct fiq_debugger_state *state)
+{
+	if (state->pdata->uart_flush)
+		state->pdata->uart_flush(state->pdev);
+}
+
+static void debug_puts(struct fiq_debugger_state *state, char *s)
+{
+	unsigned c;
+	while ((c = *s++)) {
+		if (c == '\n')
+			state->pdata->uart_putc(state->pdev, '\r');
+		state->pdata->uart_putc(state->pdev, c);
+	}
+}
+
+static void debug_prompt(struct fiq_debugger_state *state)
+{
+	debug_puts(state, "debug> ");
+}
+
+int log_buf_copy(char *dest, int idx, int len);
+static void dump_kernel_log(struct fiq_debugger_state *state)
+{
+	char buf[1024];
+	int idx = 0;
+	int ret;
+	int saved_oip;
+
+	/* setting oops_in_progress prevents log_buf_copy()
+	 * from trying to take a spinlock which will make it
+	 * very unhappy in some cases...
+	 */
+	saved_oip = oops_in_progress;
+	oops_in_progress = 1;
+	for (;;) {
+		ret = log_buf_copy(buf, idx, 1023);
+		if (ret <= 0)
+			break;
+		buf[ret] = 0;
+		debug_puts(state, buf);
+		idx += ret;
+	}
+	oops_in_progress = saved_oip;
+}
+
+static char *mode_name(unsigned cpsr)
+{
+	switch (cpsr & MODE_MASK) {
+	case USR_MODE: return "USR";
+	case FIQ_MODE: return "FIQ";
+	case IRQ_MODE: return "IRQ";
+	case SVC_MODE: return "SVC";
+	case ABT_MODE: return "ABT";
+	case UND_MODE: return "UND";
+	case SYSTEM_MODE: return "SYS";
+	default: return "???";
+	}
+}
+
+static int debug_printf(void *cookie, const char *fmt, ...)
+{
+	struct fiq_debugger_state *state = cookie;
+	char buf[256];
+	va_list ap;
+
+	va_start(ap, fmt);
+	vsnprintf(buf, sizeof(buf), fmt, ap);
+	va_end(ap);
+
+	debug_puts(state, buf);
+	return state->debug_abort;
+}
+
+/* Safe outside fiq context */
+static int debug_printf_nfiq(void *cookie, const char *fmt, ...)
+{
+	struct fiq_debugger_state *state = cookie;
+	char buf[256];
+	va_list ap;
+	unsigned long irq_flags;
+
+	va_start(ap, fmt);
+	vsnprintf(buf, 128, fmt, ap);
+	va_end(ap);
+
+	local_irq_save(irq_flags);
+	debug_puts(state, buf);
+	debug_uart_flush(state);
+	local_irq_restore(irq_flags);
+	return state->debug_abort;
+}
+
+static void dump_regs(struct fiq_debugger_state *state, unsigned *regs)
+{
+	debug_printf(state, " r0 %08x  r1 %08x  r2 %08x  r3 %08x\n",
+			regs[0], regs[1], regs[2], regs[3]);
+	debug_printf(state, " r4 %08x  r5 %08x  r6 %08x  r7 %08x\n",
+			regs[4], regs[5], regs[6], regs[7]);
+	debug_printf(state, " r8 %08x  r9 %08x r10 %08x r11 %08x  mode %s\n",
+			regs[8], regs[9], regs[10], regs[11],
+			mode_name(regs[16]));
+	if ((regs[16] & MODE_MASK) == USR_MODE)
+		debug_printf(state, " ip %08x  sp %08x  lr %08x  pc %08x  "
+				"cpsr %08x\n", regs[12], regs[13], regs[14],
+				regs[15], regs[16]);
+	else
+		debug_printf(state, " ip %08x  sp %08x  lr %08x  pc %08x  "
+				"cpsr %08x  spsr %08x\n", regs[12], regs[13],
+				regs[14], regs[15], regs[16], regs[17]);
+}
+
+struct mode_regs {
+	unsigned long sp_svc;
+	unsigned long lr_svc;
+	unsigned long spsr_svc;
+
+	unsigned long sp_abt;
+	unsigned long lr_abt;
+	unsigned long spsr_abt;
+
+	unsigned long sp_und;
+	unsigned long lr_und;
+	unsigned long spsr_und;
+
+	unsigned long sp_irq;
+	unsigned long lr_irq;
+	unsigned long spsr_irq;
+
+	unsigned long r8_fiq;
+	unsigned long r9_fiq;
+	unsigned long r10_fiq;
+	unsigned long r11_fiq;
+	unsigned long r12_fiq;
+	unsigned long sp_fiq;
+	unsigned long lr_fiq;
+	unsigned long spsr_fiq;
+};
+
+void __naked get_mode_regs(struct mode_regs *regs)
+{
+	asm volatile (
+	"mrs	r1, cpsr\n"
+	"msr	cpsr_c, #0xd3 @(SVC_MODE | PSR_I_BIT | PSR_F_BIT)\n"
+	"stmia	r0!, {r13 - r14}\n"
+	"mrs	r2, spsr\n"
+	"msr	cpsr_c, #0xd7 @(ABT_MODE | PSR_I_BIT | PSR_F_BIT)\n"
+	"stmia	r0!, {r2, r13 - r14}\n"
+	"mrs	r2, spsr\n"
+	"msr	cpsr_c, #0xdb @(UND_MODE | PSR_I_BIT | PSR_F_BIT)\n"
+	"stmia	r0!, {r2, r13 - r14}\n"
+	"mrs	r2, spsr\n"
+	"msr	cpsr_c, #0xd2 @(IRQ_MODE | PSR_I_BIT | PSR_F_BIT)\n"
+	"stmia	r0!, {r2, r13 - r14}\n"
+	"mrs	r2, spsr\n"
+	"msr	cpsr_c, #0xd1 @(FIQ_MODE | PSR_I_BIT | PSR_F_BIT)\n"
+	"stmia	r0!, {r2, r8 - r14}\n"
+	"mrs	r2, spsr\n"
+	"stmia	r0!, {r2}\n"
+	"msr	cpsr_c, r1\n"
+	"bx	lr\n");
+}
+
+
+static void dump_allregs(struct fiq_debugger_state *state, unsigned *regs)
+{
+	struct mode_regs mode_regs;
+	dump_regs(state, regs);
+	get_mode_regs(&mode_regs);
+	debug_printf(state, " svc: sp %08x  lr %08x  spsr %08x\n",
+			mode_regs.sp_svc, mode_regs.lr_svc, mode_regs.spsr_svc);
+	debug_printf(state, " abt: sp %08x  lr %08x  spsr %08x\n",
+			mode_regs.sp_abt, mode_regs.lr_abt, mode_regs.spsr_abt);
+	debug_printf(state, " und: sp %08x  lr %08x  spsr %08x\n",
+			mode_regs.sp_und, mode_regs.lr_und, mode_regs.spsr_und);
+	debug_printf(state, " irq: sp %08x  lr %08x  spsr %08x\n",
+			mode_regs.sp_irq, mode_regs.lr_irq, mode_regs.spsr_irq);
+	debug_printf(state, " fiq: r8 %08x  r9 %08x  r10 %08x  r11 %08x  "
+			"r12 %08x\n",
+			mode_regs.r8_fiq, mode_regs.r9_fiq, mode_regs.r10_fiq,
+			mode_regs.r11_fiq, mode_regs.r12_fiq);
+	debug_printf(state, " fiq: sp %08x  lr %08x  spsr %08x\n",
+			mode_regs.sp_fiq, mode_regs.lr_fiq, mode_regs.spsr_fiq);
+}
+
+static void dump_irqs(struct fiq_debugger_state *state)
+{
+	int n;
+	debug_printf(state, "irqnr       total  since-last   status  name\n");
+	for (n = 0; n < NR_IRQS; n++) {
+		struct irqaction *act = irq_desc[n].action;
+		if (!act && !kstat_irqs(n))
+			continue;
+		debug_printf(state, "%5d: %10u %11u %8x  %s\n", n,
+			kstat_irqs(n),
+			kstat_irqs(n) - state->last_irqs[n],
+			irq_desc[n].status,
+			(act && act->name) ? act->name : "???");
+		state->last_irqs[n] = kstat_irqs(n);
+	}
+}
+
+struct stacktrace_state {
+	struct fiq_debugger_state *state;
+	unsigned int depth;
+};
+
+static int report_trace(struct stackframe *frame, void *d)
+{
+	struct stacktrace_state *sts = d;
+
+	if (sts->depth) {
+		debug_printf(sts->state,
+			"  pc: %p (%pF), lr %p (%pF), sp %p, fp %p\n",
+			frame->pc, frame->pc, frame->lr, frame->lr,
+			frame->sp, frame->fp);
+		sts->depth--;
+		return 0;
+	}
+	debug_printf(sts->state, "  ...\n");
+
+	return sts->depth == 0;
+}
+
+struct frame_tail {
+	struct frame_tail *fp;
+	unsigned long sp;
+	unsigned long lr;
+} __attribute__((packed));
+
+static struct frame_tail *user_backtrace(struct fiq_debugger_state *state,
+					struct frame_tail *tail)
+{
+	struct frame_tail buftail[2];
+
+	/* Also check accessibility of one struct frame_tail beyond */
+	if (!access_ok(VERIFY_READ, tail, sizeof(buftail))) {
+		debug_printf(state, "  invalid frame pointer %p\n", tail);
+		return NULL;
+	}
+	if (__copy_from_user_inatomic(buftail, tail, sizeof(buftail))) {
+		debug_printf(state,
+			"  failed to copy frame pointer %p\n", tail);
+		return NULL;
+	}
+
+	debug_printf(state, "  %p\n", buftail[0].lr);
+
+	/* frame pointers should strictly progress back up the stack
+	 * (towards higher addresses) */
+	if (tail >= buftail[0].fp)
+		return NULL;
+
+	return buftail[0].fp-1;
+}
+
+void dump_stacktrace(struct fiq_debugger_state *state,
+		struct pt_regs * const regs, unsigned int depth, void *ssp)
+{
+	struct frame_tail *tail;
+	struct thread_info *real_thread_info = (struct thread_info *)
+				((unsigned long)ssp & ~(THREAD_SIZE - 1));
+	struct stacktrace_state sts;
+
+	sts.depth = depth;
+	sts.state = state;
+	*current_thread_info() = *real_thread_info;
+
+	if (!current)
+		debug_printf(state, "current NULL\n");
+	else
+		debug_printf(state, "pid: %d  comm: %s\n",
+			current->pid, current->comm);
+	dump_regs(state, (unsigned *)regs);
+
+	if (!user_mode(regs)) {
+		struct stackframe frame;
+		frame.fp = regs->ARM_fp;
+		frame.sp = regs->ARM_sp;
+		frame.lr = regs->ARM_lr;
+		frame.pc = regs->ARM_pc;
+		debug_printf(state,
+			"  pc: %p (%pF), lr %p (%pF), sp %p, fp %p\n",
+			regs->ARM_pc, regs->ARM_pc, regs->ARM_lr, regs->ARM_lr,
+			regs->ARM_sp, regs->ARM_fp);
+		walk_stackframe(&frame, report_trace, &sts);
+		return;
+	}
+
+	tail = ((struct frame_tail *) regs->ARM_fp) - 1;
+	while (depth-- && tail && !((unsigned long) tail & 3))
+		tail = user_backtrace(state, tail);
+}
+
+static void debug_exec(struct fiq_debugger_state *state,
+			const char *cmd, unsigned *regs, void *svc_sp)
+{
+	if (!strcmp(cmd, "pc")) {
+		debug_printf(state, " pc %08x cpsr %08x mode %s\n",
+			regs[15], regs[16], mode_name(regs[16]));
+	} else if (!strcmp(cmd, "regs")) {
+		dump_regs(state, regs);
+	} else if (!strcmp(cmd, "allregs")) {
+		dump_allregs(state, regs);
+	} else if (!strcmp(cmd, "bt")) {
+		dump_stacktrace(state, (struct pt_regs *)regs, 100, svc_sp);
+	} else if (!strcmp(cmd, "reboot")) {
+		arch_reset(0, 0);
+	} else if (!strcmp(cmd, "irqs")) {
+		dump_irqs(state);
+	} else if (!strcmp(cmd, "kmsg")) {
+		dump_kernel_log(state);
+	} else if (!strcmp(cmd, "version")) {
+		debug_printf(state, "%s\n", linux_banner);
+	} else if (!strcmp(cmd, "sleep")) {
+		state->no_sleep = false;
+	} else if (!strcmp(cmd, "nosleep")) {
+		state->no_sleep = true;
+	} else {
+		if (state->debug_busy) {
+			debug_printf(state,
+				"command processor busy. trying to abort.\n");
+			state->debug_abort = -1;
+		} else {
+			strcpy(state->debug_cmd, cmd);
+			state->debug_busy = 1;
+		}
+
+		debug_force_irq(state);
+
+		return;
+	}
+	debug_prompt(state);
+}
+
+static void sleep_timer_expired(unsigned long data)
+{
+	struct fiq_debugger_state *state = (struct fiq_debugger_state *)data;
+
+	if (state->uart_clk_enabled && !state->no_sleep) {
+		if (state->debug_enable) {
+			state->debug_enable = false;
+			debug_printf_nfiq(state, "suspending fiq debugger\n");
+		}
+		state->ignore_next_wakeup_irq = true;
+		if (state->clk)
+			clk_disable(state->clk);
+		state->uart_clk_enabled = false;
+		enable_wakeup_irq(state);
+	}
+	wake_unlock(&state->debugger_wake_lock);
+}
+
+static irqreturn_t wakeup_irq_handler(int irq, void *dev)
+{
+	struct fiq_debugger_state *state = dev;
+
+	if (!state->no_sleep)
+		debug_puts(state, "WAKEUP\n");
+	if (state->ignore_next_wakeup_irq)
+		state->ignore_next_wakeup_irq = false;
+	else if (!state->uart_clk_enabled) {
+		wake_lock(&state->debugger_wake_lock);
+		if (state->clk)
+			clk_enable(state->clk);
+		state->uart_clk_enabled = true;
+		disable_wakeup_irq(state);
+		mod_timer(&state->sleep_timer, jiffies + HZ / 2);
+	}
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t debug_irq(int irq, void *dev)
+{
+	struct fiq_debugger_state *state = dev;
+	if (state->pdata->force_irq_ack)
+		state->pdata->force_irq_ack(state->pdev, state->signal_irq);
+
+	if (!state->no_sleep) {
+		wake_lock(&state->debugger_wake_lock);
+		mod_timer(&state->sleep_timer, jiffies + HZ * 5);
+	}
+	if (state->debug_busy) {
+		struct kdbg_ctxt ctxt;
+
+		ctxt.printf = debug_printf_nfiq;
+		ctxt.cookie = state;
+		kernel_debugger(&ctxt, state->debug_cmd);
+		debug_prompt(state);
+
+		state->debug_busy = 0;
+	}
+	return IRQ_HANDLED;
+}
+
+static int debug_getc(struct fiq_debugger_state *state)
+{
+	return state->pdata->uart_getc(state->pdev);
+}
+
+static void debug_fiq(struct fiq_glue_handler *h, void *regs, void *svc_sp)
+{
+	struct fiq_debugger_state *state =
+		container_of(h, struct fiq_debugger_state, handler);
+	int c;
+	static int last_c;
+	int count = 0;
+
+	while ((c = debug_getc(state)) != FIQ_DEBUGGER_NO_CHAR) {
+		count++;
+		if (!state->debug_enable) {
+			if ((c == 13) || (c == 10)) {
+				state->debug_enable = true;
+				state->debug_count = 0;
+				debug_prompt(state);
+			}
+		} else if ((c >= ' ') && (c < 127)) {
+			if (state->debug_count < (DEBUG_MAX - 1)) {
+				state->debug_buf[state->debug_count++] = c;
+				state->pdata->uart_putc(state->pdev, c);
+			}
+		} else if ((c == 8) || (c == 127)) {
+			if (state->debug_count > 0) {
+				state->debug_count--;
+				state->pdata->uart_putc(state->pdev, 8);
+				state->pdata->uart_putc(state->pdev, ' ');
+				state->pdata->uart_putc(state->pdev, 8);
+			}
+		} else if ((c == 13) || (c == 10)) {
+			if (c == '\r' || (c == '\n' && last_c != '\r')) {
+				state->pdata->uart_putc(state->pdev, '\r');
+				state->pdata->uart_putc(state->pdev, '\n');
+			}
+			if (state->debug_count) {
+				state->debug_buf[state->debug_count] = 0;
+				state->debug_count = 0;
+				debug_exec(state, state->debug_buf,
+					regs, svc_sp);
+			} else {
+				debug_prompt(state);
+			}
+		}
+		last_c = c;
+	}
+	debug_uart_flush(state);
+	if (state->pdata->fiq_ack)
+		state->pdata->fiq_ack(state->pdev, state->fiq);
+
+	/* poke sleep timer if necessary */
+	if (state->debug_enable && !state->no_sleep)
+		debug_force_irq(state);
+}
+
+static void debug_resume(struct fiq_glue_handler *h)
+{
+	struct fiq_debugger_state *state =
+		container_of(h, struct fiq_debugger_state, handler);
+	if (state->pdata->uart_resume)
+		state->pdata->uart_resume(state->pdev);
+}
+
+static int fiq_debugger_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct fiq_debugger_pdata *pdata = dev_get_platdata(&pdev->dev);
+	struct fiq_debugger_state *state;
+
+	if (!pdata->uart_getc || !pdata->uart_putc || !pdata->fiq_enable)
+		return -EINVAL;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	state->handler.fiq = debug_fiq;
+	state->handler.resume = debug_resume;
+	setup_timer(&state->sleep_timer, sleep_timer_expired,
+		    (unsigned long)state);
+	state->pdata = pdata;
+	state->pdev = pdev;
+	state->no_sleep = initial_no_sleep;
+	state->debug_enable = initial_debug_enable;
+
+	state->fiq = platform_get_irq_byname(pdev, "fiq");
+	state->signal_irq = platform_get_irq_byname(pdev, "signal");
+	state->wakeup_irq = platform_get_irq_byname(pdev, "wakeup");
+
+	if (state->wakeup_irq < 0)
+		state->no_sleep = true;
+	state->ignore_next_wakeup_irq = !state->no_sleep;
+
+	wake_lock_init(&state->debugger_wake_lock,
+			WAKE_LOCK_SUSPEND, "serial-debug");
+
+	state->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(state->clk))
+		state->clk = NULL;
+
+	if (state->clk)
+		clk_enable(state->clk);
+
+	if (pdata->uart_init) {
+		ret = pdata->uart_init(pdev);
+		if (ret)
+			goto err_uart_init;
+	}
+
+	debug_printf_nfiq(state, "<hit enter %sto activate fiq debugger>\n",
+				state->no_sleep ? "" : "twice ");
+
+	ret = fiq_glue_register_handler(&state->handler);
+	if (ret) {
+		pr_err("serial_debugger: could not install fiq handler\n");
+		goto err_register_fiq;
+	}
+
+	pdata->fiq_enable(pdev, state->fiq, 1);
+
+	if (state->clk)
+		clk_disable(state->clk);
+
+	ret = request_irq(state->signal_irq, debug_irq,
+			  IRQF_TRIGGER_RISING, "debug", state);
+	if (ret)
+		pr_err("serial_debugger: could not install signal_irq");
+
+	if (state->wakeup_irq >= 0) {
+		ret = request_irq(state->wakeup_irq, wakeup_irq_handler,
+				  IRQF_TRIGGER_FALLING | IRQF_DISABLED,
+				  "debug-wakeup", state);
+		if (ret) {
+			pr_err("serial_debugger: "
+				"could not install wakeup irq\n");
+			state->wakeup_irq = -1;
+		} else {
+			ret = enable_irq_wake(state->wakeup_irq);
+			if (ret) {
+				pr_err("serial_debugger: "
+					"could not enable wakeup\n");
+				state->wakeup_irq_no_set_wake = true;
+			}
+		}
+	}
+	if (state->no_sleep)
+		wakeup_irq_handler(state->wakeup_irq, state);
+
+	return 0;
+
+err_register_fiq:
+	if (pdata->uart_free)
+		pdata->uart_free(pdev);
+err_uart_init:
+	kfree(state);
+	if (state->clk)
+		clk_put(state->clk);
+	return ret;
+}
+
+static struct platform_driver fiq_debugger_driver = {
+	.probe = fiq_debugger_probe,
+	.driver.name = "fiq_debugger",
+};
+
+static int __init fiq_debugger_init(void)
+{
+	return platform_driver_register(&fiq_debugger_driver);
+}
+
+postcore_initcall(fiq_debugger_init);
diff --git a/arch/arm/include/asm/fiq_debugger.h b/arch/arm/include/asm/fiq_debugger.h
new file mode 100644
index 000000000000..e711b57b22f1
--- /dev/null
+++ b/arch/arm/include/asm/fiq_debugger.h
@@ -0,0 +1,46 @@
+/*
+ * arch/arm/include/asm/fiq_debugger.h
+ *
+ * Copyright (C) 2010 Google, Inc.
+ * Author: Colin Cross <ccross@android.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _ARCH_ARM_MACH_TEGRA_FIQ_DEBUGGER_H_
+#define _ARCH_ARM_MACH_TEGRA_FIQ_DEBUGGER_H_
+
+#include <linux/serial_core.h>
+
+#define FIQ_DEBUGGER_NO_CHAR NO_POLL_CHAR
+#define FIQ_DEBUGGER_BREAK 0x00ff0100
+
+#define FIQ_DEBUGGER_FIQ_IRQ_NAME	"fiq"
+#define FIQ_DEBUGGER_SIGNAL_IRQ_NAME	"signal"
+#define FIQ_DEBUGGER_WAKEUP_IRQ_NAME	"wakeup"
+
+struct fiq_debugger_pdata {
+	int (*uart_init)(struct platform_device *pdev);
+	void (*uart_free)(struct platform_device *pdev);
+	int (*uart_resume)(struct platform_device *pdev);
+	int (*uart_getc)(struct platform_device *pdev);
+	void (*uart_putc)(struct platform_device *pdev, unsigned int c);
+	void (*uart_flush)(struct platform_device *pdev);
+
+	void (*fiq_enable)(struct platform_device *pdev, unsigned int fiq,
+								bool enable);
+	void (*fiq_ack)(struct platform_device *pdev, unsigned int fiq);
+
+	void (*force_irq)(struct platform_device *pdev, unsigned int irq);
+	void (*force_irq_ack)(struct platform_device *pdev, unsigned int irq);
+};
+
+#endif