/*
 * arch/sh/kernel/process.c
 *
 * This file handles the architecture-dependent parts of process handling..
 *
 *  Copyright (C) 1995  Linus Torvalds
 *
 *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
 *                   Copyright (C) 2006 Lineo Solutions Inc. support SH4A UBC
 *                   Copyright (C) 2002 - 2007  Paul Mundt
 */
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/elfcore.h>
#include <linux/pm.h>
#include <linux/kallsyms.h>
#include <linux/kexec.h>
#include <linux/kdebug.h>
#include <linux/tick.h>
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/preempt.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/ubc.h>

static int hlt_counter;
int ubc_usercnt = 0;

void (*pm_idle)(void);
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

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;
}
__setup("nohlt", nohlt_setup);

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

void default_idle(void)
{
        if (!hlt_counter) {
                clear_thread_flag(TIF_POLLING_NRFLAG);
                smp_mb__after_clear_bit();
                set_bl_bit();
                while (!need_resched())
                        cpu_sleep();
                clear_bl_bit();
                set_thread_flag(TIF_POLLING_NRFLAG);
        } else
                while (!need_resched())
                        cpu_relax();
}

void cpu_idle(void)
{
        set_thread_flag(TIF_POLLING_NRFLAG);

        /* endless idle loop with no priority at all */
        while (1) {
                void (*idle)(void) = pm_idle;

                if (!idle)
                        idle = default_idle;

                tick_nohz_stop_sched_tick();
                while (!need_resched())
                        idle();
                tick_nohz_restart_sched_tick();

                preempt_enable_no_resched();
                schedule();
                preempt_disable();
                check_pgt_cache();
        }
}

void machine_restart(char * __unused)
{
        /* SR.BL=1 and invoke address error to let CPU reset (manual reset) */
        asm volatile("ldc %0, sr\n\t"
                     "mov.l @%1, %0" : : "r" (0x10000000), "r" (0x80000001));
}

void machine_halt(void)
{
        local_irq_disable();

        while (1)
                cpu_sleep();
}

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

void show_regs(struct pt_regs * regs)
{
        printk("\n");
        printk("Pid : %d, Comm: %20s\n", task_pid_nr(current), current->comm);
        print_symbol("PC is at %s\n", instruction_pointer(regs));
        printk("PC  : %08lx SP  : %08lx SR  : %08lx ",
               regs->pc, regs->regs[15], regs->sr);
#ifdef CONFIG_MMU
        printk("TEA : %08x    ", ctrl_inl(MMU_TEA));
#else
        printk("                  ");
#endif
        printk("%s\n", print_tainted());

        printk("R0  : %08lx R1  : %08lx R2  : %08lx R3  : %08lx\n",
               regs->regs[0],regs->regs[1],
               regs->regs[2],regs->regs[3]);
        printk("R4  : %08lx R5  : %08lx R6  : %08lx R7  : %08lx\n",
               regs->regs[4],regs->regs[5],
               regs->regs[6],regs->regs[7]);
        printk("R8  : %08lx R9  : %08lx R10 : %08lx R11 : %08lx\n",
               regs->regs[8],regs->regs[9],
               regs->regs[10],regs->regs[11]);
        printk("R12 : %08lx R13 : %08lx R14 : %08lx\n",
               regs->regs[12],regs->regs[13],
               regs->regs[14]);
        printk("MACH: %08lx MACL: %08lx GBR : %08lx PR  : %08lx\n",
               regs->mach, regs->macl, regs->gbr, regs->pr);

        show_trace(NULL, (unsigned long *)regs->regs[15], regs);
}

/*
 * Create a kernel thread
 */

/*
 * This is the mechanism for creating a new kernel thread.
 *
 */
extern void kernel_thread_helper(void);
__asm__(".align 5\n"
        "kernel_thread_helper:\n\t"
        "jsr    @r5\n\t"
        " nop\n\t"
        "mov.l  1f, r1\n\t"
        "jsr    @r1\n\t"
        " mov   r0, r4\n\t"
        ".align 2\n\t"
        "1:.long do_exit");

/* Don't use this in BL=1(cli).  Or else, CPU resets! */
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
        struct pt_regs regs;

        memset(&regs, 0, sizeof(regs));
        regs.regs[4] = (unsigned long)arg;
        regs.regs[5] = (unsigned long)fn;

        regs.pc = (unsigned long)kernel_thread_helper;
        regs.sr = (1 << 30);

        /* Ok, create the new process.. */
        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
                       &regs, 0, NULL, NULL);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
        if (current->thread.ubc_pc) {
                current->thread.ubc_pc = 0;
                ubc_usercnt -= 1;
        }
}

void flush_thread(void)
{
#if defined(CONFIG_SH_FPU)
        struct task_struct *tsk = current;
        /* Forget lazy FPU state */
        clear_fpu(tsk, task_pt_regs(tsk));
        clear_used_math();
#endif
}

void release_thread(struct task_struct *dead_task)
{
        /* do nothing */
}

/* Fill in the fpu structure for a core dump.. */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
{
        int fpvalid = 0;

#if defined(CONFIG_SH_FPU)
        struct task_struct *tsk = current;

        fpvalid = !!tsk_used_math(tsk);
        if (fpvalid) {
                unlazy_fpu(tsk, regs);
                memcpy(fpu, &tsk->thread.fpu.hard, sizeof(*fpu));
        }
#endif

        return fpvalid;
}

/*
 * Capture the user space registers if the task is not running (in user space)
 */
int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
{
        struct pt_regs ptregs;

        ptregs = *task_pt_regs(tsk);
        elf_core_copy_regs(regs, &ptregs);

        return 1;
}

int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpu)
{
        int fpvalid = 0;

#if defined(CONFIG_SH_FPU)
        fpvalid = !!tsk_used_math(tsk);
        if (fpvalid) {
                unlazy_fpu(tsk, task_pt_regs(tsk));
                memcpy(fpu, &tsk->thread.fpu.hard, sizeof(*fpu));
        }
#endif

        return fpvalid;
}

asmlinkage void ret_from_fork(void);

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
                unsigned long unused,
                struct task_struct *p, struct pt_regs *regs)
{
        struct thread_info *ti = task_thread_info(p);
        struct pt_regs *childregs;
#if defined(CONFIG_SH_FPU)
        struct task_struct *tsk = current;

        unlazy_fpu(tsk, regs);
        p->thread.fpu = tsk->thread.fpu;
        copy_to_stopped_child_used_math(p);
#endif

        childregs = task_pt_regs(p);
        *childregs = *regs;

        if (user_mode(regs)) {
                childregs->regs[15] = usp;
                ti->addr_limit = USER_DS;
        } else {
                childregs->regs[15] = (unsigned long)childregs;
                ti->addr_limit = KERNEL_DS;
        }

        if (clone_flags & CLONE_SETTLS)
                childregs->gbr = childregs->regs[0];

        childregs->regs[0] = 0; /* Set return value for child */

        p->thread.sp = (unsigned long) childregs;
        p->thread.pc = (unsigned long) ret_from_fork;

        p->thread.ubc_pc = 0;

        return 0;
}

/* Tracing by user break controller.  */
static void ubc_set_tracing(int asid, unsigned long pc)
{
#if defined(CONFIG_CPU_SH4A)
        unsigned long val;

        val = (UBC_CBR_ID_INST | UBC_CBR_RW_READ | UBC_CBR_CE);
        val |= (UBC_CBR_AIE | UBC_CBR_AIV_SET(asid));

        ctrl_outl(val, UBC_CBR0);
        ctrl_outl(pc,  UBC_CAR0);
        ctrl_outl(0x0, UBC_CAMR0);
        ctrl_outl(0x0, UBC_CBCR);

        val = (UBC_CRR_RES | UBC_CRR_PCB | UBC_CRR_BIE);
        ctrl_outl(val, UBC_CRR0);

        /* Read UBC register that we wrote last, for checking update */
        val = ctrl_inl(UBC_CRR0);

#else   /* CONFIG_CPU_SH4A */
        ctrl_outl(pc, UBC_BARA);

#ifdef CONFIG_MMU
        ctrl_outb(asid, UBC_BASRA);
#endif

        ctrl_outl(0, UBC_BAMRA);

        if (current_cpu_data.type == CPU_SH7729 ||
            current_cpu_data.type == CPU_SH7710 ||
            current_cpu_data.type == CPU_SH7712) {
                ctrl_outw(BBR_INST | BBR_READ | BBR_CPU, UBC_BBRA);
                ctrl_outl(BRCR_PCBA | BRCR_PCTE, UBC_BRCR);
        } else {
                ctrl_outw(BBR_INST | BBR_READ, UBC_BBRA);
                ctrl_outw(BRCR_PCBA, UBC_BRCR);
        }
#endif  /* CONFIG_CPU_SH4A */
}

/*
 *      switch_to(x,y) should switch tasks from x to y.
 *
 */
struct task_struct *__switch_to(struct task_struct *prev,
                                struct task_struct *next)
{
#if defined(CONFIG_SH_FPU)
        unlazy_fpu(prev, task_pt_regs(prev));
#endif

#if defined(CONFIG_GUSA) && defined(CONFIG_PREEMPT)
        {
                struct pt_regs *regs;

                preempt_disable();
                regs = task_pt_regs(prev);
                if (user_mode(regs) && regs->regs[15] >= 0xc0000000) {
                        int offset = (int)regs->regs[15];

                        /* Reset stack pointer: clear critical region mark */
                        regs->regs[15] = regs->regs[1];
                        if (regs->pc < regs->regs[0])
                                /* Go to rewind point */
                                regs->pc = regs->regs[0] + offset;
                }
                preempt_enable_no_resched();
        }
#endif

#ifdef CONFIG_MMU
        /*
         * Restore the kernel mode register
         *      k7 (r7_bank1)
         */
        asm volatile("ldc       %0, r7_bank"
                     : /* no output */
                     : "r" (task_thread_info(next)));
#endif

        /* If no tasks are using the UBC, we're done */
        if (ubc_usercnt == 0)
                /* If no tasks are using the UBC, we're done */;
        else if (next->thread.ubc_pc && next->mm) {
                int asid = 0;
#ifdef CONFIG_MMU
                asid |= cpu_asid(smp_processor_id(), next->mm);
#endif
                ubc_set_tracing(asid, next->thread.ubc_pc);
        } else {
#if defined(CONFIG_CPU_SH4A)
                ctrl_outl(UBC_CBR_INIT, UBC_CBR0);
                ctrl_outl(UBC_CRR_INIT, UBC_CRR0);
#else
                ctrl_outw(0, UBC_BBRA);
                ctrl_outw(0, UBC_BBRB);
#endif
        }

        return prev;
}

asmlinkage int sys_fork(unsigned long r4, unsigned long r5,
                        unsigned long r6, unsigned long r7,
                        struct pt_regs __regs)
{
#ifdef CONFIG_MMU
        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
        return do_fork(SIGCHLD, regs->regs[15], regs, 0, NULL, NULL);
#else
        /* fork almost works, enough to trick you into looking elsewhere :-( */
        return -EINVAL;
#endif
}

asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
                         unsigned long parent_tidptr,
                         unsigned long child_tidptr,
                         struct pt_regs __regs)
{
        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
        if (!newsp)
                newsp = regs->regs[15];
        return do_fork(clone_flags, newsp, regs, 0,
                        (int __user *)parent_tidptr,
                        (int __user *)child_tidptr);
}

/*
 * This is trivial, and on the face of it looks like it
 * could equally well be done in user mode.
 *
 * Not so, for quite unobvious reasons - register pressure.
 * In user mode vfork() cannot have a stack frame, and if
 * done by calling the "clone()" system call directly, you
 * do not have enough call-clobbered registers to hold all
 * the information you need.
 */
asmlinkage int sys_vfork(unsigned long r4, unsigned long r5,
                         unsigned long r6, unsigned long r7,
                         struct pt_regs __regs)
{
        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->regs[15], regs,
                       0, NULL, NULL);
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(char __user *ufilename, char __user * __user *uargv,
                          char __user * __user *uenvp, unsigned long r7,
                          struct pt_regs __regs)
{
        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
        int error;
        char *filename;

        filename = getname(ufilename);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;

        error = do_execve(filename, uargv, uenvp, regs);
        if (error == 0) {
                task_lock(current);
                current->ptrace &= ~PT_DTRACE;
                task_unlock(current);
        }
        putname(filename);
out:
        return error;
}

unsigned long get_wchan(struct task_struct *p)
{
        unsigned long pc;

        if (!p || p == current || p->state == TASK_RUNNING)
                return 0;

        /*
         * The same comment as on the Alpha applies here, too ...
         */
        pc = thread_saved_pc(p);

#ifdef CONFIG_FRAME_POINTER
        if (in_sched_functions(pc)) {
                unsigned long schedule_frame = (unsigned long)p->thread.sp;
                return ((unsigned long *)schedule_frame)[21];
        }
#endif

        return pc;
}

asmlinkage void break_point_trap(void)
{
        /* Clear tracing.  */
#if defined(CONFIG_CPU_SH4A)
        ctrl_outl(UBC_CBR_INIT, UBC_CBR0);
        ctrl_outl(UBC_CRR_INIT, UBC_CRR0);
#else
        ctrl_outw(0, UBC_BBRA);
        ctrl_outw(0, UBC_BBRB);
#endif
        current->thread.ubc_pc = 0;
        ubc_usercnt -= 1;

        force_sig(SIGTRAP, current);
}

/*
 * Generic trap handler.
 */
asmlinkage void debug_trap_handler(unsigned long r4, unsigned long r5,
                                   unsigned long r6, unsigned long r7,
                                   struct pt_regs __regs)
{
        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);

        /* Rewind */
        regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));

        if (notify_die(DIE_TRAP, "debug trap", regs, 0, regs->tra & 0xff,
                       SIGTRAP) == NOTIFY_STOP)
                return;

        force_sig(SIGTRAP, current);
}

/*
 * Special handler for BUG() traps.
 */
asmlinkage void bug_trap_handler(unsigned long r4, unsigned long r5,
                                 unsigned long r6, unsigned long r7,
                                 struct pt_regs __regs)
{
        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);

        /* Rewind */
        regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));

        if (notify_die(DIE_TRAP, "bug trap", regs, 0, TRAPA_BUG_OPCODE & 0xff,
                       SIGTRAP) == NOTIFY_STOP)
                return;

#ifdef CONFIG_BUG
        if (__kernel_text_address(instruction_pointer(regs))) {
                u16 insn = *(u16 *)instruction_pointer(regs);
                if (insn == TRAPA_BUG_OPCODE)
                        handle_BUG(regs);
        }
#endif

        force_sig(SIGTRAP, current);
}