/*
 *  linux/arch/arm/kernel/process.c
 *
 *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
 *  Original Copyright (C) 1995  Linus Torvalds
 *
 * 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 <stdarg.h>

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/elfcore.h>
#include <linux/pm.h>
#include <linux/tick.h>
#include <linux/utsname.h>
#include <linux/uaccess.h>

#include <asm/leds.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/thread_notify.h>
#include <asm/stacktrace.h>
#include <asm/mach/time.h>

static const char *processor_modes[] = {
  "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
  "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
  "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "UK6_32" , "ABT_32" ,
  "UK8_32" , "UK9_32" , "UK10_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
};

static const char *isa_modes[] = {
  "ARM" , "Thumb" , "Jazelle", "ThumbEE"
};

extern void setup_mm_for_reboot(char mode);

static volatile int hlt_counter;

#include <mach/system.h>

void disable_hlt(void)
{
        hlt_counter++;
}

EXPORT_SYMBOL(disable_hlt);

void enable_hlt(void)
{
        hlt_counter--;
}

EXPORT_SYMBOL(enable_hlt);

static int __init nohlt_setup(char *__unused)
{
        hlt_counter = 1;
        return 1;
}

static int __init hlt_setup(char *__unused)
{
        hlt_counter = 0;
        return 1;
}

__setup("nohlt", nohlt_setup);
__setup("hlt", hlt_setup);

void arm_machine_restart(char mode, const char *cmd)
{
        /*
         * Clean and disable cache, and turn off interrupts
         */
        cpu_proc_fin();

        /*
         * Tell the mm system that we are going to reboot -
         * we may need it to insert some 1:1 mappings so that
         * soft boot works.
         */
        setup_mm_for_reboot(mode);

        /*
         * Now call the architecture specific reboot code.
         */
        arch_reset(mode, cmd);

        /*
         * Whoops - the architecture was unable to reboot.
         * Tell the user!
         */
        mdelay(1000);
        printk("Reboot failed -- System halted\n");
        while (1);
}

/*
 * Function pointers to optional machine specific functions
 */
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

void (*arm_pm_restart)(char str, const char *cmd) = arm_machine_restart;
EXPORT_SYMBOL_GPL(arm_pm_restart);


/*
 * This is our default idle handler.  We need to disable
 * interrupts here to ensure we don't miss a wakeup call.
 */
static void default_idle(void)
{
        if (!need_resched())
                arch_idle();
        local_irq_enable();
}

void (*pm_idle)(void) = default_idle;
EXPORT_SYMBOL(pm_idle);

/*
 * The idle thread, has rather strange semantics for calling pm_idle,
 * but this is what x86 does and we need to do the same, so that
 * things like cpuidle get called in the same way.  The only difference
 * is that we always respect 'hlt_counter' to prevent low power idle.
 */
void cpu_idle(void)
{
        local_fiq_enable();

        /* endless idle loop with no priority at all */
        while (1) {
                tick_nohz_stop_sched_tick(1);
                leds_event(led_idle_start);
                while (!need_resched()) {
#ifdef CONFIG_HOTPLUG_CPU
                        if (cpu_is_offline(smp_processor_id()))
                                cpu_die();
#endif

                        local_irq_disable();
                        if (hlt_counter) {
                                local_irq_enable();
                                cpu_relax();
                        } else {
                                stop_critical_timings();
                                pm_idle();
                                start_critical_timings();
                                /*
                                 * This will eventually be removed - pm_idle
                                 * functions should always return with IRQs
                                 * enabled.
                                 */
                                WARN_ON(irqs_disabled());
                                local_irq_enable();
                        }
                }
                leds_event(led_idle_end);
                tick_nohz_restart_sched_tick();
                preempt_enable_no_resched();
                schedule();
                preempt_disable();
        }
}

static char reboot_mode = 'h';

int __init reboot_setup(char *str)
{
        reboot_mode = str[0];
        return 1;
}

__setup("reboot=", reboot_setup);

void machine_halt(void)
{
}


void machine_power_off(void)
{
        if (pm_power_off)
                pm_power_off();
}

void machine_restart(char *cmd)
{
        arm_pm_restart(reboot_mode, cmd);
}

void __show_regs(struct pt_regs *regs)
{
        unsigned long flags;
        char buf[64];

        printk("CPU: %d    %s  (%s %.*s)\n",
                smp_processor_id(), print_tainted(), init_utsname()->release,
                (int)strcspn(init_utsname()->version, " "),
                init_utsname()->version);
        print_symbol("PC is at %s\n", instruction_pointer(regs));
        print_symbol("LR is at %s\n", regs->ARM_lr);
        printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n"
               "sp : %08lx  ip : %08lx  fp : %08lx\n",
                regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr,
                regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
        printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
                regs->ARM_r10, regs->ARM_r9,
                regs->ARM_r8);
        printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
                regs->ARM_r7, regs->ARM_r6,
                regs->ARM_r5, regs->ARM_r4);
        printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
                regs->ARM_r3, regs->ARM_r2,
                regs->ARM_r1, regs->ARM_r0);

        flags = regs->ARM_cpsr;
        buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
        buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
        buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
        buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
        buf[4] = '\0';

        printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
                buf, interrupts_enabled(regs) ? "n" : "ff",
                fast_interrupts_enabled(regs) ? "n" : "ff",
                processor_modes[processor_mode(regs)],
                isa_modes[isa_mode(regs)],
                get_fs() == get_ds() ? "kernel" : "user");
#ifdef CONFIG_CPU_CP15
        {
                unsigned int ctrl;

                buf[0] = '\0';
#ifdef CONFIG_CPU_CP15_MMU
                {
                        unsigned int transbase, dac;
                        asm("mrc p15, 0, %0, c2, c0\n\t"
                            "mrc p15, 0, %1, c3, c0\n"
                            : "=r" (transbase), "=r" (dac));
                        snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
                                transbase, dac);
                }
#endif
                asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));

                printk("Control: %08x%s\n", ctrl, buf);
        }
#endif
}

void show_regs(struct pt_regs * regs)
{
        printk("\n");
        printk("Pid: %d, comm: %20s\n", task_pid_nr(current), current->comm);
        __show_regs(regs);
        __backtrace();
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
}

ATOMIC_NOTIFIER_HEAD(thread_notify_head);

EXPORT_SYMBOL_GPL(thread_notify_head);

void flush_thread(void)
{
        struct thread_info *thread = current_thread_info();
        struct task_struct *tsk = current;

        memset(thread->used_cp, 0, sizeof(thread->used_cp));
        memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
        memset(&thread->fpstate, 0, sizeof(union fp_state));

        thread_notify(THREAD_NOTIFY_FLUSH, thread);
}

void release_thread(struct task_struct *dead_task)
{
        struct thread_info *thread = task_thread_info(dead_task);

        thread_notify(THREAD_NOTIFY_RELEASE, thread);
}

asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");

int
copy_thread(unsigned long clone_flags, unsigned long stack_start,
            unsigned long stk_sz, struct task_struct *p, struct pt_regs *regs)
{
        struct thread_info *thread = task_thread_info(p);
        struct pt_regs *childregs = task_pt_regs(p);

        *childregs = *regs;
        childregs->ARM_r0 = 0;
        childregs->ARM_sp = stack_start;

        memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
        thread->cpu_context.sp = (unsigned long)childregs;
        thread->cpu_context.pc = (unsigned long)ret_from_fork;

        if (clone_flags & CLONE_SETTLS)
                thread->tp_value = regs->ARM_r3;

        return 0;
}

/*
 * Fill in the task's elfregs structure for a core dump.
 */
int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs)
{
        elf_core_copy_regs(elfregs, task_pt_regs(t));
        return 1;
}

/*
 * fill in the fpe structure for a core dump...
 */
int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
{
        struct thread_info *thread = current_thread_info();
        int used_math = thread->used_cp[1] | thread->used_cp[2];

        if (used_math)
                memcpy(fp, &thread->fpstate.soft, sizeof (*fp));

        return used_math != 0;
}
EXPORT_SYMBOL(dump_fpu);

/*
 * Shuffle the argument into the correct register before calling the
 * thread function.  r1 is the thread argument, r2 is the pointer to
 * the thread function, and r3 points to the exit function.
 */
extern void kernel_thread_helper(void);
asm(    ".section .text\n"
"       .align\n"
"       .type   kernel_thread_helper, #function\n"
"kernel_thread_helper:\n"
"       mov     r0, r1\n"
"       mov     lr, r3\n"
"       mov     pc, r2\n"
"       .size   kernel_thread_helper, . - kernel_thread_helper\n"
"       .previous");

#ifdef CONFIG_ARM_UNWIND
extern void kernel_thread_exit(long code);
asm(    ".section .text\n"
"       .align\n"
"       .type   kernel_thread_exit, #function\n"
"kernel_thread_exit:\n"
"       .fnstart\n"
"       .cantunwind\n"
"       bl      do_exit\n"
"       nop\n"
"       .fnend\n"
"       .size   kernel_thread_exit, . - kernel_thread_exit\n"
"       .previous");
#else
#define kernel_thread_exit      do_exit
#endif

/*
 * Create a kernel thread.
 */
pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
        struct pt_regs regs;

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

        regs.ARM_r1 = (unsigned long)arg;
        regs.ARM_r2 = (unsigned long)fn;
        regs.ARM_r3 = (unsigned long)kernel_thread_exit;
        regs.ARM_pc = (unsigned long)kernel_thread_helper;
        regs.ARM_cpsr = SVC_MODE | PSR_ENDSTATE | PSR_ISETSTATE;

        return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
}
EXPORT_SYMBOL(kernel_thread);

unsigned long get_wchan(struct task_struct *p)
{
        struct stackframe frame;
        int count = 0;
        if (!p || p == current || p->state == TASK_RUNNING)
                return 0;

        frame.fp = thread_saved_fp(p);
        frame.sp = thread_saved_sp(p);
        frame.lr = 0;                   /* recovered from the stack */
        frame.pc = thread_saved_pc(p);
        do {
                int ret = unwind_frame(&frame);
                if (ret < 0)
                        return 0;
                if (!in_sched_functions(frame.pc))
                        return frame.pc;
        } while (count ++ < 16);
        return 0;
}