/*
 * linux/arch/unicore32/kernel/process.c
 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 * Copyright (C) 2001-2010 GUAN Xue-tao
 *
 * 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/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 <linux/random.h>
#include <linux/gpio.h>
#include <linux/stacktrace.h>

#include <asm/cacheflush.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/stacktrace.h>

#include "setup.h"

static const char * const processor_modes[] = {
        "UK00", "UK01", "UK02", "UK03", "UK04", "UK05", "UK06", "UK07",
        "UK08", "UK09", "UK0A", "UK0B", "UK0C", "UK0D", "UK0E", "UK0F",
        "USER", "REAL", "INTR", "PRIV", "UK14", "UK15", "UK16", "ABRT",
        "UK18", "UK19", "UK1A", "EXTN", "UK1C", "UK1D", "UK1E", "SUSR"
};

/*
 * 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.
 */
void cpu_idle(void)
{
        /* endless idle loop with no priority at all */
        while (1) {
                tick_nohz_stop_sched_tick(1);
                while (!need_resched()) {
                        local_irq_disable();
                        stop_critical_timings();
                        cpu_do_idle();
                        local_irq_enable();
                        start_critical_timings();
                }
                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)
{
        gpio_set_value(GPO_SOFT_OFF, 0);
}

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

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

void machine_restart(char *cmd)
{
        /* Disable interrupts first */
        local_irq_disable();

        /*
         * 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(reboot_mode);

        /* Clean and invalidate caches */
        flush_cache_all();

        /* Turn off caching */
        cpu_proc_fin();

        /* Push out any further dirty data, and ensure cache is empty */
        flush_cache_all();

        /*
         * Now handle reboot code.
         */
        if (reboot_mode == 's') {
                /* Jump into ROM at address 0xffff0000 */
                cpu_reset(VECTORS_BASE);
        } else {
                writel(0x00002001, PM_PLLSYSCFG); /* cpu clk = 250M */
                writel(0x00100800, PM_PLLDDRCFG); /* ddr clk =  44M */
                writel(0x00002001, PM_PLLVGACFG); /* vga clk = 250M */

                /* Use on-chip reset capability */
                /* following instructions must be in one icache line */
                __asm__ __volatile__(
                        "       .align 5\n\t"
                        "       stw     %1, [%0]\n\t"
                        "201:   ldw     r0, [%0]\n\t"
                        "       cmpsub.a        r0, #0\n\t"
                        "       bne     201b\n\t"
                        "       stw     %3, [%2]\n\t"
                        "       nop; nop; nop\n\t"
                        /* prefetch 3 instructions at most */
                        :
                        : "r" (PM_PMCR),
                          "r" (PM_PMCR_CFBSYS | PM_PMCR_CFBDDR
                                | PM_PMCR_CFBVGA),
                          "r" (RESETC_SWRR),
                          "r" (RESETC_SWRR_SRB)
                        : "r0", "memory");
        }

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

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

        printk(KERN_DEFAULT "CPU: %d    %s  (%s %.*s)\n",
                raw_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->UCreg_lr);
        printk(KERN_DEFAULT "pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n"
               "sp : %08lx  ip : %08lx  fp : %08lx\n",
                regs->UCreg_pc, regs->UCreg_lr, regs->UCreg_asr,
                regs->UCreg_sp, regs->UCreg_ip, regs->UCreg_fp);
        printk(KERN_DEFAULT "r26: %08lx  r25: %08lx  r24: %08lx\n",
                regs->UCreg_26, regs->UCreg_25,
                regs->UCreg_24);
        printk(KERN_DEFAULT "r23: %08lx  r22: %08lx  r21: %08lx  r20: %08lx\n",
                regs->UCreg_23, regs->UCreg_22,
                regs->UCreg_21, regs->UCreg_20);
        printk(KERN_DEFAULT "r19: %08lx  r18: %08lx  r17: %08lx  r16: %08lx\n",
                regs->UCreg_19, regs->UCreg_18,
                regs->UCreg_17, regs->UCreg_16);
        printk(KERN_DEFAULT "r15: %08lx  r14: %08lx  r13: %08lx  r12: %08lx\n",
                regs->UCreg_15, regs->UCreg_14,
                regs->UCreg_13, regs->UCreg_12);
        printk(KERN_DEFAULT "r11: %08lx  r10: %08lx  r9 : %08lx  r8 : %08lx\n",
                regs->UCreg_11, regs->UCreg_10,
                regs->UCreg_09, regs->UCreg_08);
        printk(KERN_DEFAULT "r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
                regs->UCreg_07, regs->UCreg_06,
                regs->UCreg_05, regs->UCreg_04);
        printk(KERN_DEFAULT "r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
                regs->UCreg_03, regs->UCreg_02,
                regs->UCreg_01, regs->UCreg_00);

        flags = regs->UCreg_asr;
        buf[0] = flags & PSR_S_BIT ? 'S' : 's';
        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(KERN_DEFAULT "Flags: %s  INTR o%s  REAL o%s  Mode %s  Segment %s\n",
                buf, interrupts_enabled(regs) ? "n" : "ff",
                fast_interrupts_enabled(regs) ? "n" : "ff",
                processor_modes[processor_mode(regs)],
                segment_eq(get_fs(), get_ds()) ? "kernel" : "user");
        {
                unsigned int ctrl;

                buf[0] = '\0';
                {
                        unsigned int transbase;
                        asm("movc %0, p0.c2, #0\n"
                            : "=r" (transbase));
                        snprintf(buf, sizeof(buf), "  Table: %08x", transbase);
                }
                asm("movc %0, p0.c1, #0\n" : "=r" (ctrl));

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

void show_regs(struct pt_regs *regs)
{
        printk(KERN_DEFAULT "\n");
        printk(KERN_DEFAULT "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)
{
}

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));
#ifdef CONFIG_UNICORE_FPU_F64
        memset(&thread->fpstate, 0, sizeof(struct fp_state));
#endif
}

void release_thread(struct task_struct *dead_task)
{
}

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->UCreg_00 = 0;
        childregs->UCreg_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)
                childregs->UCreg_16 = regs->UCreg_03;

        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, elf_fpregset_t *fp)
{
        struct thread_info *thread = current_thread_info();
        int used_math = thread->used_cp[1] | thread->used_cp[2];

#ifdef CONFIG_UNICORE_FPU_F64
        if (used_math)
                memcpy(fp, &thread->fpstate, sizeof(*fp));
#endif
        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.
 */
asm(".pushsection .text\n"
"       .align\n"
"       .type   kernel_thread_helper, #function\n"
"kernel_thread_helper:\n"
"       mov.a   asr, r7\n"
"       mov     r0, r4\n"
"       mov     lr, r6\n"
"       mov     pc, r5\n"
"       .size   kernel_thread_helper, . - kernel_thread_helper\n"
"       .popsection");

/*
 * 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.UCreg_04 = (unsigned long)arg;
        regs.UCreg_05 = (unsigned long)fn;
        regs.UCreg_06 = (unsigned long)do_exit;
        regs.UCreg_07 = PRIV_MODE;
        regs.UCreg_pc = (unsigned long)kernel_thread_helper;
        regs.UCreg_asr = regs.UCreg_07 | PSR_I_BIT;

        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;
}

unsigned long arch_randomize_brk(struct mm_struct *mm)
{
        unsigned long range_end = mm->brk + 0x02000000;
        return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
}

/*
 * The vectors page is always readable from user space for the
 * atomic helpers and the signal restart code.  Let's declare a mapping
 * for it so it is visible through ptrace and /proc/<pid>/mem.
 */

int vectors_user_mapping(void)
{
        struct mm_struct *mm = current->mm;
        return install_special_mapping(mm, 0xffff0000, PAGE_SIZE,
                                       VM_READ | VM_EXEC |
                                       VM_MAYREAD | VM_MAYEXEC |
                                       VM_ALWAYSDUMP | VM_RESERVED,
                                       NULL);
}

const char *arch_vma_name(struct vm_area_struct *vma)
{
        return (vma->vm_start == 0xffff0000) ? "[vectors]" : NULL;
}