ARM: Add fiq_glue

Change-Id: I27d2554e07d9de204e0a06696d38db51608d9f6b
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: Colin Cross <ccross@android.com>

5 files changed, 246 insertions, 0 deletions

diff --git a/arch/arm/common/Kconfig b/arch/arm/common/Kconfig
index 9353184d730..ce01364a96e 100644
--- a/arch/arm/common/Kconfig
+++ b/arch/arm/common/Kconfig
@@ -17,3 +17,7 @@ config SHARP_PARAM
 
 config SHARP_SCOOP
 	bool
+
+config FIQ_GLUE
+	bool
+	select FIQ
diff --git a/arch/arm/common/Makefile b/arch/arm/common/Makefile
index dc8dd0de5c0..a3fc75842dc 100644
--- a/arch/arm/common/Makefile
+++ b/arch/arm/common/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_SHARP_PARAM)	+= sharpsl_param.o
 obj-$(CONFIG_SHARP_SCOOP)	+= scoop.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
diff --git a/arch/arm/common/fiq_glue.S b/arch/arm/common/fiq_glue.S
new file mode 100644
index 00000000000..9e3455a09f8
--- /dev/null
+++ b/arch/arm/common/fiq_glue.S
@@ -0,0 +1,111 @@
+/*
+ * 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 <linux/linkage.h>
+#include <asm/assembler.h>
+
+		.text
+
+		.global fiq_glue_end
+
+		/* fiq stack: r0-r15,cpsr,spsr of interrupted mode */
+
+ENTRY(fiq_glue)
+		/* store pc, cpsr from previous mode */
+		mrs	r12, spsr
+		sub	r11, lr, #4
+		subs	r10, #1
+		bne	nested_fiq
+
+		stmfd	sp!, {r11-r12, lr}
+
+		/* store r8-r14 from previous mode */
+		sub	sp, sp, #(7 * 4)
+		stmia	sp, {r8-r14}^
+		nop
+
+		/* store r0-r7 from previous mode */
+		stmfd	sp!, {r0-r7}
+
+		/* setup func(data,regs) arguments */
+		mov	r0, r9
+		mov	r1, sp
+		mov	r3, r8
+
+		mov	r7, sp
+
+		/* Get sp and lr from non-user modes */
+		and	r4, r12, #MODE_MASK
+		cmp	r4, #USR_MODE
+		beq	fiq_from_usr_mode
+
+		mov	r7, sp
+		orr	r4, r4, #(PSR_I_BIT | PSR_F_BIT)
+		msr	cpsr_c, r4
+		str	sp, [r7, #(4 * 13)]
+		str	lr, [r7, #(4 * 14)]
+		mrs	r5, spsr
+		str	r5, [r7, #(4 * 17)]
+
+		cmp	r4, #(SVC_MODE | PSR_I_BIT | PSR_F_BIT)
+		/* use fiq stack if we reenter this mode */
+		subne	sp, r7, #(4 * 3)
+
+fiq_from_usr_mode:
+		msr	cpsr_c, #(SVC_MODE | PSR_I_BIT | PSR_F_BIT)
+		mov	r2, sp
+		sub	sp, r7, #12
+		stmfd	sp!, {r2, ip, lr}
+		/* call func(data,regs) */
+		blx	r3
+		ldmfd	sp, {r2, ip, lr}
+		mov	sp, r2
+
+		/* restore/discard saved state */
+		cmp	r4, #USR_MODE
+		beq	fiq_from_usr_mode_exit
+
+		msr	cpsr_c, r4
+		ldr	sp, [r7, #(4 * 13)]
+		ldr	lr, [r7, #(4 * 14)]
+		msr	spsr_cxsf, r5
+
+fiq_from_usr_mode_exit:
+		msr	cpsr_c, #(FIQ_MODE | PSR_I_BIT | PSR_F_BIT)
+
+		ldmfd	sp!, {r0-r7}
+		add	sp, sp, #(7 * 4)
+		ldmfd	sp!, {r11-r12, lr}
+exit_fiq:
+		msr	spsr_cxsf, r12
+		add	r10, #1
+		movs	pc, r11
+
+nested_fiq:
+		orr	r12, r12, #(PSR_F_BIT)
+		b	exit_fiq
+
+fiq_glue_end:
+
+ENTRY(fiq_glue_setup) /* func, data, sp */
+		mrs		r3, cpsr
+		msr		cpsr_c, #(FIQ_MODE | PSR_I_BIT | PSR_F_BIT)
+		movs		r8, r0
+		mov		r9, r1
+		mov		sp, r2
+		moveq		r10, #0
+		movne		r10, #1
+		msr		cpsr_c, r3
+		bx		lr
+
diff --git a/arch/arm/common/fiq_glue_setup.c b/arch/arm/common/fiq_glue_setup.c
new file mode 100644
index 00000000000..4044c7db95c
--- /dev/null
+++ b/arch/arm/common/fiq_glue_setup.c
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2010 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 <linux/kernel.h>
+#include <linux/percpu.h>
+#include <linux/slab.h>
+#include <asm/fiq.h>
+#include <asm/fiq_glue.h>
+
+extern unsigned char fiq_glue, fiq_glue_end;
+extern void fiq_glue_setup(void *func, void *data, void *sp);
+
+static struct fiq_handler fiq_debbuger_fiq_handler = {
+	.name = "fiq_glue",
+};
+DEFINE_PER_CPU(void *, fiq_stack);
+static struct fiq_glue_handler *current_handler;
+static DEFINE_MUTEX(fiq_glue_lock);
+
+static void fiq_glue_setup_helper(void *info)
+{
+	struct fiq_glue_handler *handler = info;
+	fiq_glue_setup(handler->fiq, handler,
+		__get_cpu_var(fiq_stack) + THREAD_START_SP);
+}
+
+int fiq_glue_register_handler(struct fiq_glue_handler *handler)
+{
+	int ret;
+	int cpu;
+
+	if (!handler || !handler->fiq)
+		return -EINVAL;
+
+	mutex_lock(&fiq_glue_lock);
+	if (fiq_stack) {
+		ret = -EBUSY;
+		goto err_busy;
+	}
+
+	for_each_possible_cpu(cpu) {
+		void *stack;
+		stack = (void *)__get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
+		if (WARN_ON(!stack)) {
+			ret = -ENOMEM;
+			goto err_alloc_fiq_stack;
+		}
+		per_cpu(fiq_stack, cpu) = stack;
+	}
+
+	ret = claim_fiq(&fiq_debbuger_fiq_handler);
+	if (WARN_ON(ret))
+		goto err_claim_fiq;
+
+	current_handler = handler;
+	on_each_cpu(fiq_glue_setup_helper, handler, true);
+	set_fiq_handler(&fiq_glue, &fiq_glue_end - &fiq_glue);
+
+	mutex_unlock(&fiq_glue_lock);
+	return 0;
+
+err_claim_fiq:
+err_alloc_fiq_stack:
+	for_each_possible_cpu(cpu) {
+		__free_pages(per_cpu(fiq_stack, cpu), THREAD_SIZE_ORDER);
+		per_cpu(fiq_stack, cpu) = NULL;
+	}
+err_busy:
+	mutex_unlock(&fiq_glue_lock);
+	return ret;
+}
+
+/**
+ * fiq_glue_resume - Restore fiqs after suspend or low power idle states
+ *
+ * This must be called before calling local_fiq_enable after returning from a
+ * power state where the fiq mode registers were lost. If a driver provided
+ * a resume hook when it registered the handler it will be called.
+ */
+
+void fiq_glue_resume(void)
+{
+	if (!current_handler)
+		return;
+	fiq_glue_setup(current_handler->fiq, current_handler,
+		__get_cpu_var(fiq_stack) + THREAD_START_SP);
+	if (current_handler->resume)
+		current_handler->resume(current_handler);
+}
+
diff --git a/arch/arm/include/asm/fiq_glue.h b/arch/arm/include/asm/fiq_glue.h
new file mode 100644
index 00000000000..d54c29db97a
--- /dev/null
+++ b/arch/arm/include/asm/fiq_glue.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2010 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.
+ */
+
+#ifndef __ASM_FIQ_GLUE_H
+#define __ASM_FIQ_GLUE_H
+
+struct fiq_glue_handler {
+	void (*fiq)(struct fiq_glue_handler *h, void *regs, void *svc_sp);
+	void (*resume)(struct fiq_glue_handler *h);
+};
+
+int fiq_glue_register_handler(struct fiq_glue_handler *handler);
+
+#ifdef CONFIG_FIQ_GLUE
+void fiq_glue_resume(void);
+#else
+static inline void fiq_glue_resume(void) {}
+#endif
+
+#endif