/*
 *  linux/arch/arm/vfp/vfpmodule.c
 *
 *  Copyright (C) 2004 ARM Limited.
 *  Written by Deep Blue Solutions Limited.
 *
 * 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 <linux/types.h>
#include <linux/cpu.h>
#include <linux/cpu_pm.h>
#include <linux/hardirq.h>
#include <linux/kernel.h>
#include <linux/notifier.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/uaccess.h>
#include <linux/user.h>

#include <asm/cp15.h>
#include <asm/cputype.h>
#include <asm/system_info.h>
#include <asm/thread_notify.h>
#include <asm/vfp.h>

#include "vfpinstr.h"
#include "vfp.h"

/*
 * Our undef handlers (in entry.S)
 */
void vfp_testing_entry(void);
void vfp_support_entry(void);
void vfp_null_entry(void);

void (*vfp_vector)(void) = vfp_null_entry;

/*
 * Dual-use variable.
 * Used in startup: set to non-zero if VFP checks fail
 * After startup, holds VFP architecture
 */
unsigned int VFP_arch;

/*
 * The pointer to the vfpstate structure of the thread which currently
 * owns the context held in the VFP hardware, or NULL if the hardware
 * context is invalid.
 *
 * For UP, this is sufficient to tell which thread owns the VFP context.
 * However, for SMP, we also need to check the CPU number stored in the
 * saved state too to catch migrations.
 */
union vfp_state *vfp_current_hw_state[NR_CPUS];

/*
 * Is 'thread's most up to date state stored in this CPUs hardware?
 * Must be called from non-preemptible context.
 */
static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread)
{
#ifdef CONFIG_SMP
	if (thread->vfpstate.hard.cpu != cpu)
		return false;
#endif
	return vfp_current_hw_state[cpu] == &thread->vfpstate;
}

/*
 * Force a reload of the VFP context from the thread structure.  We do
 * this by ensuring that access to the VFP hardware is disabled, and
 * clear vfp_current_hw_state.  Must be called from non-preemptible context.
 */
static void vfp_force_reload(unsigned int cpu, struct thread_info *thread)
{
	if (vfp_state_in_hw(cpu, thread)) {
		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
		vfp_current_hw_state[cpu] = NULL;
	}
#ifdef CONFIG_SMP
	thread->vfpstate.hard.cpu = NR_CPUS;
#endif
}

/*
 * Per-thread VFP initialization.
 */
static void vfp_thread_flush(struct thread_info *thread)
{
	union vfp_state *vfp = &thread->vfpstate;
	unsigned int cpu;

	/*
	 * Disable VFP to ensure we initialize it first.  We must ensure
	 * that the modification of vfp_current_hw_state[] and hardware
	 * disable are done for the same CPU and without preemption.
	 *
	 * Do this first to ensure that preemption won't overwrite our
	 * state saving should access to the VFP be enabled at this point.
	 */
	cpu = get_cpu();
	if (vfp_current_hw_state[cpu] == vfp)
		vfp_current_hw_state[cpu] = NULL;
	fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
	put_cpu();

	memset(vfp, 0, sizeof(union vfp_state));

	vfp->hard.fpexc = FPEXC_EN;
	vfp->hard.fpscr = FPSCR_ROUND_NEAREST;
#ifdef CONFIG_SMP
	vfp->hard.cpu = NR_CPUS;
#endif
}

static void vfp_thread_exit(struct thread_info *thread)
{
	/* release case: Per-thread VFP cleanup. */
	union vfp_state *vfp = &thread->vfpstate;
	unsigned int cpu = get_cpu();

	if (vfp_current_hw_state[cpu] == vfp)
		vfp_current_hw_state[cpu] = NULL;
	put_cpu();
}

static void vfp_thread_copy(struct thread_info *thread)
{
	struct thread_info *parent = current_thread_info();

	vfp_sync_hwstate(parent);
	thread->vfpstate = parent->vfpstate;
#ifdef CONFIG_SMP
	thread->vfpstate.hard.cpu = NR_CPUS;
#endif
}

/*
 * When this function is called with the following 'cmd's, the following
 * is true while this function is being run:
 *  THREAD_NOFTIFY_SWTICH:
 *   - the previously running thread will not be scheduled onto another CPU.
 *   - the next thread to be run (v) will not be running on another CPU.
 *   - thread->cpu is the local CPU number
 *   - not preemptible as we're called in the middle of a thread switch
 *  THREAD_NOTIFY_FLUSH:
 *   - the thread (v) will be running on the local CPU, so
 *	v === current_thread_info()
 *   - thread->cpu is the local CPU number at the time it is accessed,
 *	but may change at any time.
 *   - we could be preempted if tree preempt rcu is enabled, so
 *	it is unsafe to use thread->cpu.
 *  THREAD_NOTIFY_EXIT
 *   - the thread (v) will be running on the local CPU, so
 *	v === current_thread_info()
 *   - thread->cpu is the local CPU number at the time it is accessed,
 *	but may change at any time.
 *   - we could be preempted if tree preempt rcu is enabled, so
 *	it is unsafe to use thread->cpu.
 */
static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
{
	struct thread_info *thread = v;
	u32 fpexc;
#ifdef CONFIG_SMP
	unsigned int cpu;
#endif

	switch (cmd) {
	case THREAD_NOTIFY_SWITCH:
		fpexc = fmrx(FPEXC);

#ifdef CONFIG_SMP
		cpu = thread->cpu;

		/*
		 * On SMP, if VFP is enabled, save the old state in
		 * case the thread migrates to a different CPU. The
		 * restoring is done lazily.
		 */
		if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu])
			vfp_save_state(vfp_current_hw_state[cpu], fpexc);
#endif

		/*
		 * Always disable VFP so we can lazily save/restore the
		 * old state.
		 */
		fmxr(FPEXC, fpexc & ~FPEXC_EN);
		break;

	case THREAD_NOTIFY_FLUSH:
		vfp_thread_flush(thread);
		break;

	case THREAD_NOTIFY_EXIT:
		vfp_thread_exit(thread);
		break;

	case THREAD_NOTIFY_COPY:
		vfp_thread_copy(thread);
		break;
	}

	return NOTIFY_DONE;
}

static struct notifier_block vfp_notifier_block = {
	.notifier_call	= vfp_notifier,
};

/*
 * Raise a SIGFPE for the current process.
 * sicode describes the signal being raised.
 */
static void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs)
{
	siginfo_t info;

	memset(&info, 0, sizeof(info));

	info.si_signo = SIGFPE;
	info.si_code = sicode;
	info.si_addr = (void __user *)(instruction_pointer(regs) - 4);

	/*
	 * This is the same as NWFPE, because it's not clear what
	 * this is used for
	 */
	current->thread.error_code = 0;
	current->thread.trap_no = 6;

	send_sig_info(SIGFPE, &info, current);
}

static void vfp_panic(char *reason, u32 inst)
{
	int i;

	pr_err("VFP: Error: %s\n", reason);
	pr_err("VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n",
		fmrx(FPEXC), fmrx(FPSCR), inst);
	for (i = 0; i < 32; i += 2)
		pr_err("VFP: s%2u: 0x%08x s%2u: 0x%08x\n",
		       i, vfp_get_float(i), i+1, vfp_get_float(i+1));
}

/*
 * Process bitmask of exception conditions.
 */
static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs)
{
	int si_code = 0;

	pr_debug("VFP: raising exceptions %08x\n", exceptions);

	if (exceptions == VFP_EXCEPTION_ERROR) {
		vfp_panic("unhandled bounce", inst);
		vfp_raise_sigfpe(0, regs);
		return;
	}

	/*
	 * If any of the status flags are set, update the FPSCR.
	 * Comparison instructions always return at least one of
	 * these flags set.
	 */
	if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V))
		fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V);

	fpscr |= exceptions;

	fmxr(FPSCR, fpscr);

#define RAISE(stat,en,sig)				\
	if (exceptions & stat && fpscr & en)		\
		si_code = sig;

	/*
	 * These are arranged in priority order, least to highest.
	 */
	RAISE(FPSCR_DZC, FPSCR_DZE, FPE_FLTDIV);
	RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES);
	RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND);
	RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF);
	RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV);

	if (si_code)
		vfp_raise_sigfpe(si_code, regs);
}

/*
 * Emulate a VFP instruction.
 */
static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
{
	u32 exceptions = VFP_EXCEPTION_ERROR;

	pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr);

	if (INST_CPRTDO(inst)) {
		if (!INST_CPRT(inst)) {
			/*
			 * CPDO
			 */
			if (vfp_single(inst)) {
				exceptions = vfp_single_cpdo(inst, fpscr);
			} else {
				exceptions = vfp_double_cpdo(inst, fpscr);
			}
		} else {
			/*
			 * A CPRT instruction can not appear in FPINST2, nor
			 * can it cause an exception.  Therefore, we do not