/*
 * 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 - 2008  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#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/ftrace.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>
#include <asm/fpu.h>
#include <asm/syscalls.h>
#include <asm/watchdog.h>

int ubc_usercnt = 0;

#ifdef CONFIG_32BIT
static void watchdog_trigger_immediate(void)
{
        sh_wdt_write_cnt(0xFF);
        sh_wdt_write_csr(0xC2);
}

void machine_restart(char * __unused)
{
        local_irq_disable();

        /* Use watchdog timer to trigger reset */
        watchdog_trigger_immediate();

        while (1)
                cpu_sleep();
}
#else
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));
}
#endif

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: \t\t%s\n", task_pid_nr(current), current->comm);
        printk("CPU : %d        \t\t%s  (%s %.*s)\n\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("PR is at %s\n", regs->pr);

        printk("PC  : %08lx SP  : %08lx SR  : %08lx ",
               regs->pc, regs->regs[15], regs->sr);
#ifdef CONFIG_MMU
        printk("TEA : %08x\n", ctrl_inl(MMU_TEA));
#else
        printk("\n");
#endif

        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);
        show_code(regs);
}

/*
 * Create a kernel thread
 */
ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
{
        do_exit(fn(arg));
}

/* 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;
        int pid;

        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 = SR_MD;
#if defined(CONFIG_SH_FPU)
        regs.sr |= SR_FD;
#endif

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

        return pid;
}
EXPORT_SYMBOL(kernel_thread);

/*
 * 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)
                fpvalid = !fpregs_get(tsk, NULL, 0,
                                      sizeof(struct user_fpu_struct),
                                      fpu, NULL);
#endif

        return fpvalid;
}
EXPORT_SYMBOL(dump_fpu);

/*
 * This gets called before we allocate a new thread and copy
 * the current task into it.
 */
void prepare_to_copy(struct task_struct *tsk)
{
        unlazy_fpu(tsk, task_pt_regs(tsk));
}

asmlinkage void ret_from_fork(void);

int copy_thread(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_DSP)
        struct task_struct *tsk = current;
#endif

#if defined(CONFIG_SH_DSP)
        if (is_dsp_enabled(tsk)) {
                /* We can use the __save_dsp or just copy the struct:
                 * __save_dsp(p);
                 * p->thread.dsp_status.status |= SR_DSP
                 */
                p->thread.dsp_status = tsk->thread.dsp_status;
        }
#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;
                ti->status &= ~TS_USEDFPU;
                p->fpu_counter = 0;
        }

        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 ||
            current_cpu_data.type == CPU_SH7203){
                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.
 *
 */
__notrace_funcgraph struct task_struct *
__switch_to(struct task_struct *prev, struct task_struct *next)
{
        struct thread_struct *next_t = &next->thread;

        unlazy_fpu(prev, task_pt_regs(prev));

        /* we're going to use this soon, after a few expensive things */
        if (next->fpu_counter > 5)
                prefetch(&next_t->fpu.hard);

#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
        }

        /*
         * If the task has used fpu the last 5 timeslices, just do a full
         * restore of the math state immediately to avoid the trap; the
         * chances of needing FPU soon are obviously high now
         */
        if (next->fpu_counter > 5)
                fpu_state_restore(task_pt_regs(next));

        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);
        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);
        ctrl_outl(0, UBC_BRCR);
#endif
        current->thread.ubc_pc = 0;
        ubc_usercnt -= 1;

        force_sig(SIGTRAP, current);
}