/*
 * Blackfin architecture-dependent process handling
 *
 * Copyright 2004-2009 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later
 */

#include <linux/module.h>
#include <linux/unistd.h>
#include <linux/user.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/tick.h>
#include <linux/fs.h>
#include <linux/err.h>

#include <asm/blackfin.h>
#include <asm/fixed_code.h>
#include <asm/mem_map.h>

asmlinkage void ret_from_fork(void);

/* Points to the SDRAM backup memory for the stack that is currently in
 * L1 scratchpad memory.
 */
void *current_l1_stack_save;

/* The number of tasks currently using a L1 stack area.  The SRAM is
 * allocated/deallocated whenever this changes from/to zero.
 */
int nr_l1stack_tasks;

/* Start and length of the area in L1 scratchpad memory which we've allocated
 * for process stacks.
 */
void *l1_stack_base;
unsigned long l1_stack_len;

/*
 * Powermanagement idle function, if any..
 */
void (*pm_idle)(void) = NULL;
EXPORT_SYMBOL(pm_idle);

void (*pm_power_off)(void) = NULL;
EXPORT_SYMBOL(pm_power_off);

/*
 * The idle loop on BFIN
 */
#ifdef CONFIG_IDLE_L1
static void default_idle(void)__attribute__((l1_text));
void cpu_idle(void)__attribute__((l1_text));
#endif

/*
 * 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)
{
#ifdef CONFIG_IPIPE
        ipipe_suspend_domain();
#endif
        hard_local_irq_disable();
        if (!need_resched())
                idle_with_irq_disabled();

        hard_local_irq_enable();
}

/*
 * The idle thread.  We try to conserve power, while trying to keep
 * overall latency low.  The architecture specific idle is passed
 * a value to indicate the level of "idleness" of the system.
 */
void cpu_idle(void)
{
        /* endless idle loop with no priority at all */
        while (1) {
                void (*idle)(void) = pm_idle;

#ifdef CONFIG_HOTPLUG_CPU
                if (cpu_is_offline(smp_processor_id()))
                        cpu_die();
#endif
                if (!idle)
                        idle = default_idle;
                tick_nohz_stop_sched_tick(1);
                while (!need_resched())
                        idle();
                tick_nohz_restart_sched_tick();
                preempt_enable_no_resched();
                schedule();
                preempt_disable();
        }
}

/*
 * This gets run with P1 containing the
 * function to call, and R1 containing
 * the "args".  Note P0 is clobbered on the way here.
 */
void kernel_thread_helper(void);
__asm__(".section .text\n"
        ".align 4\n"
        "_kernel_thread_helper:\n\t"
        "\tsp += -12;\n\t"
        "\tr0 = r1;\n\t" "\tcall (p1);\n\t" "\tcall _do_exit;\n" ".previous");

/*
 * 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.r1 = (unsigned long)arg;
        regs.p1 = (unsigned long)fn;
        regs.pc = (unsigned long)kernel_thread_helper;
        regs.orig_p0 = -1;
        /* Set bit 2 to tell ret_from_fork we should be returning to kernel
           mode.  */
        regs.ipend = 0x8002;
        __asm__ __volatile__("%0 = syscfg;":"=da"(regs.syscfg):);
        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL,
                       NULL);
}
EXPORT_SYMBOL(kernel_thread);

/*
 * Do necessary setup to start up a newly executed thread.
 *
 * pass the data segment into user programs if it exists,
 * it can't hurt anything as far as I can tell
 */
void start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
{
        set_fs(USER_DS);
        regs->pc = new_ip;
        if (current->mm)
                regs->p5 = current->mm->start_data;
#ifndef CONFIG_SMP
        task_thread_info(current)->l1_task_info.stack_start =
                (void *)current->mm->context.stack_start;
        task_thread_info(current)->l1_task_info.lowest_sp = (void *)new_sp;
        memcpy(L1_SCRATCH_TASK_INFO, &task_thread_info(current)->l1_task_info,
               sizeof(*L1_SCRATCH_TASK_INFO));
#endif
        wrusp(new_sp);
}
EXPORT_SYMBOL_GPL(start_thread);

void flush_thread(void)
{
}

asmlinkage int bfin_vfork(struct pt_regs *regs)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0, NULL,
                       NULL);
}

asmlinkage int bfin_clone(struct pt_regs *regs)
{
        unsigned long clone_flags;
        unsigned long newsp;

#ifdef __ARCH_SYNC_CORE_DCACHE
        if (current->rt.nr_cpus_allowed == num_possible_cpus()) {
                current->cpus_allowed = cpumask_of_cpu(smp_processor_id());
                current->rt.nr_cpus_allowed = 1;
        }
#endif

        /* syscall2 puts clone_flags in r0 and usp in r1 */
        clone_flags = regs->r0;
        newsp = regs->r1;
        if (!newsp)
                newsp = rdusp();
        else
                newsp -= 12;
        return do_fork(clone_flags, newsp, regs, 0, NULL, NULL);
}

int
copy_thread(unsigned long clone_flags,
            unsigned long usp, unsigned long topstk,
            struct task_struct *p, struct pt_regs *regs)
{
        struct pt_regs *childregs;

        childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;
        *childregs = *regs;
        childregs->r0 = 0;

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

        return 0;
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(const char __user *name,
                          const char __user *const __user *argv,
                          const char __user *const __user *envp)
{
        int error;
        char *filename;
        struct pt_regs *regs = (struct pt_regs *)((&name) + 6);

        filename = getname(name);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                return error;
        error = do_execve(filename, argv, envp, regs);
        putname(filename);
        return error;
}

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

        stack_page = (unsigned long)p;
        fp = p->thread.usp;
        do {
                if (fp < stack_page + sizeof(struct thread_info) ||
                    fp >= 8184 + stack_page)
                        return 0;
                pc = ((unsigned long *)fp)[1];
                if (!in_sched_functions(pc))
                        return pc;
                fp = *(unsigned long *)fp;
        }
        while (count++ < 16);
        return 0;
}

void finish_atomic_sections (struct pt_regs *regs)
{
        int __user *up0 = (int __user *)regs->p0;

        switch (regs->pc) {
        default:
                /* not in middle of an atomic step, so resume like normal */
                return;

        case ATOMIC_XCHG32 + 2:
                put_user(regs->r1, up0);
                break;

        case ATOMIC_CAS32 + 2:
        case ATOMIC_CAS32 + 4:
                if (regs->r0 == regs->r1)
        case ATOMIC_CAS32 + 6:
                        put_user(regs->r2, up0);
                break;

        case ATOMIC_ADD32 + 2:
                regs->r0 = regs->r1 + regs->r0;
                /* fall through */
        case ATOMIC_ADD32 + 4:
                put_user(regs->r0, up0);
                break;

        case ATOMIC_SUB32 + 2:
                regs->r0 = regs->r1 - regs->r0;
                /* fall through */
        case ATOMIC_SUB32 + 4:
                put_user(regs->r0, up0);
                break;

        case ATOMIC_IOR32 + 2:
                regs->r0 = regs->r1 | regs->r0;
                /* fall through */
        case ATOMIC_IOR32 + 4:
                put_user(regs->r0, up0);
                break;

        case ATOMIC_AND32 + 2:
                regs->r0 = regs->r1 & regs->r0;
                /* fall through */
        case ATOMIC_AND32 + 4:
                put_user(regs->r0, up0);
                break;

        case ATOMIC_XOR32 + 2:
                regs->r0 = regs->r1 ^ regs->r0;
                /* fall through */
        case ATOMIC_XOR32 + 4:
                put_user(regs->r0, up0);
                break;
        }

        /*
         * We've finished the atomic section, and the only thing left for
         * userspace is to do a RTS, so we might as well handle that too
         * since we need to update the PC anyways.
         */
        regs->pc = regs->rets;
}

static inline
int in_mem(unsigned long addr, unsigned long size,
           unsigned long start, unsigned long end)
{
        return addr >= start && addr + size <= end;
}
static inline
int in_mem_const_off(unsigned long addr, unsigned long size, unsigned long off,
                     unsigned long const_addr, unsigned long const_size)
{
        return const_size &&
               in_mem(addr, size, const_addr + off, const_addr + const_size);
}
static inline
int in_mem_const(unsigned long addr, unsigned long size,
                 unsigned long const_addr, unsigned long const_size)
{
        return in_mem_const_off(addr, size, 0, const_addr, const_size);
}
#define ASYNC_ENABLED(bnum, bctlnum) \
({ \
        (bfin_read_EBIU_AMGCTL() & 0xe) < ((bnum + 1) << 1) ? 0 : \
        bfin_read_EBIU_AMBCTL##bctlnum() & B##bnum##RDYEN ? 0 : \
        1; \
})
/*
 * We can't read EBIU banks that aren't enabled or we end up hanging
 * on the access to the async space.  Make sure we validate accesses
 * that cross async banks too.
 *      0 - found, but unusable
 *      1 - found & usable
 *      2 - not found
 */
static
int in_async(unsigned long addr, unsigned long size)
{
        if (addr >= ASYNC_BANK0_BASE && addr < ASYNC_BANK0_BASE + ASYNC_BANK0_SIZE) {
                if (!ASYNC_ENABLED(0, 0))
                        return 0;
                if (addr + size <= ASYNC_BANK0_BASE + ASYNC_BANK0_SIZE)
                        return 1;
                size -= ASYNC_BANK0_BASE + ASYNC_BANK0_SIZE - addr;
                addr = ASYNC_BANK0_BASE + ASYNC_BANK0_SIZE;
        }
        if (addr >= ASYNC_BANK1_BASE && addr < ASYNC_BANK1_BASE + ASYNC_BANK1_SIZE) {
                if (!ASYNC_ENABLED(1, 0))
                        return 0;
                if (addr + size <= ASYNC_BANK1_BASE + ASYNC_BANK1_SIZE)
                        return 1;
                size -= ASYNC_BANK1_BASE + ASYNC_BANK1_SIZE - addr;
                addr = ASYNC_BANK1_BASE + ASYNC_BANK1_SIZE;
        }
        if (addr >= ASYNC_BANK2_BASE && addr < ASYNC_BANK2_BASE + ASYNC_BANK2_SIZE) {
                if (!ASYNC_ENABLED(2, 1))
                        return 0;
                if (addr + size <= ASYNC_BANK2_BASE + ASYNC_BANK2_SIZE)
                        return 1;
                size -= ASYNC_BANK2_BASE + ASYNC_BANK2_SIZE - addr;
                addr = ASYNC_BANK2_BASE + ASYNC_BANK2_SIZE;
        }
        if (addr >= ASYNC_BANK3_BASE && addr < ASYNC_BANK3_BASE + ASYNC_BANK3_SIZE) {
                if (ASYNC_ENABLED(3, 1))
                        return 0;
                if (addr + size <= ASYNC_BANK3_BASE + ASYNC_BANK3_SIZE)
                        return 1;
                return 0;
        }

        /* not within async bounds */
        return 2;
}

int bfin_mem_access_type(unsigned long addr, unsigned long size)
{
        int cpu = raw_smp_processor_id();

        /* Check that things do not wrap around */
        if (addr > ULONG_MAX - size)
                return -EFAULT;

        if (in_mem(addr, size, FIXED_CODE_START, physical_mem_end))
                return BFIN_MEM_ACCESS_CORE;

        if (in_mem_const(addr, size, L1_CODE_START, L1_CODE_LENGTH))
                return cpu == 0 ? BFIN_MEM_ACCESS_ITEST : BFIN_MEM_ACCESS_IDMA;
        if (in_mem_const(addr, size, L1_SCRATCH_START, L1_SCRATCH_LENGTH))
                return cpu == 0 ? BFIN_MEM_ACCESS_CORE_ONLY : -EFAULT;
        if (in_mem_const(addr, size, L1_DATA_A_START, L1_DATA_A_LENGTH))
                return cpu == 0 ? BFIN_MEM_ACCESS_CORE : BFIN_MEM_ACCESS_IDMA;
        if (in_mem_const(addr, size, L1_DATA_B_START, L1_DATA_B_LENGTH))
                return cpu == 0 ? BFIN_MEM_ACCESS_CORE : BFIN_MEM_ACCESS_IDMA;
#ifdef COREB_L1_CODE_START
        if (in_mem_const(addr, size, COREB_L1_CODE_START, COREB_L1_CODE_LENGTH))
                return cpu == 1 ? BFIN_MEM_ACCESS_ITEST : BFIN_MEM_ACCESS_IDMA;
        if (in_mem_const(addr, size, COREB_L1_SCRATCH_START, L1_SCRATCH_LENGTH))
                return cpu == 1 ? BFIN_MEM_ACCESS_CORE_ONLY : -EFAULT;
        if (in_mem_const(addr, size, COREB_L1_DATA_A_START, COREB_L1_DATA_A_LENGTH))
                return cpu == 1 ? BFIN_MEM_ACCESS_CORE : BFIN_MEM_ACCESS_IDMA;
        if (in_mem_const(addr, size, COREB_L1_DATA_B_START, COREB_L1_DATA_B_LENGTH))
                return cpu == 1 ? BFIN_MEM_ACCESS_CORE : BFIN_MEM_ACCESS_IDMA;
#endif
        if (in_mem_const(addr, size, L2_START, L2_LENGTH))
                return BFIN_MEM_ACCESS_CORE;

        if (addr >= SYSMMR_BASE)
                return BFIN_MEM_ACCESS_CORE_ONLY;

        switch (in_async(addr, size)) {
        case 0: return -EFAULT;
        case 1: return BFIN_MEM_ACCESS_CORE;
        case 2: /* fall through */;
        }

        if (in_mem_const(addr, size, BOOT_ROM_START, BOOT_ROM_LENGTH))
                return BFIN_MEM_ACCESS_CORE;
        if (in_mem_const(addr, size, L1_ROM_START, L1_ROM_LENGTH))
                return BFIN_MEM_ACCESS_DMA;

        return -EFAULT;
}

#if defined(CONFIG_ACCESS_CHECK)
#ifdef CONFIG_ACCESS_OK_L1
__attribute__((l1_text))
#endif
/* Return 1 if access to memory range is OK, 0 otherwise */
int _access_ok(unsigned long addr, unsigned long size)
{
        int aret;

        if (size == 0)
                return 1;
        /* Check that things do not wrap around */
        if (addr > ULONG_MAX - size)
                return 0;
        if (segment_eq(get_fs(), KERNEL_DS))
                return 1;
#ifdef CONFIG_MTD_UCLINUX
        if (1)
#else
        if (0)
#endif
        {
                if (in_mem(addr, size, memory_start, memory_end))
                        return 1;
                if (in_mem(addr, size, memory_mtd_end, physical_mem_end))
                        return 1;
# ifndef CONFIG_ROMFS_ON_MTD
                if (0)
# endif
                        /* For XIP, allow user space to use pointers within the ROMFS.  */
                        if (in_mem(addr, size, memory_mtd_start, memory_mtd_end))
                                return 1;
        } else {
                if (in_mem(addr, size, memory_start, physical_mem_end))
                        return 1;
        }

        if (in_mem(addr, size, (unsigned long)__init_begin, (unsigned long)__init_end))
                return 1;

        if (in_mem_const(addr, size, L1_CODE_START, L1_CODE_LENGTH))
                return 1;
        if (in_mem_const_off(addr, size, _etext_l1 - _stext_l1, L1_CODE_START, L1_CODE_LENGTH))
                return 1;
        if (in_mem_const_off(addr, size, _ebss_l1 - _sdata_l1, L1_DATA_A_START, L1_DATA_A_LENGTH))
                return 1;
        if (in_mem_const_off(addr, size, _ebss_b_l1 - _sdata_b_l1, L1_DATA_B_START, L1_DATA_B_LENGTH))
                return 1;
#ifdef COREB_L1_CODE_START
        if (in_mem_const(addr, size, COREB_L1_CODE_START, COREB_L1_CODE_LENGTH))
                return 1;
        if (in_mem_const(addr, size, COREB_L1_SCRATCH_START, L1_SCRATCH_LENGTH))
                return 1;
        if (in_mem_const(addr, size, COREB_L1_DATA_A_START, COREB_L1_DATA_A_LENGTH))
                return 1;
        if (in_mem_const(addr, size, COREB_L1_DATA_B_START, COREB_L1_DATA_B_LENGTH))
                return 1;
#endif

#ifndef CONFIG_EXCEPTION_L1_SCRATCH
        if (in_mem_const(addr, size, (unsigned long)l1_stack_base, l1_stack_len))
                return 1;
#endif

        aret = in_async(addr, size);
        if (aret < 2)
                return aret;

        if (in_mem_const_off(addr, size, _ebss_l2 - _stext_l2, L2_START, L2_LENGTH))
                return 1;

        if (in_mem_const(addr, size, BOOT_ROM_START, BOOT_ROM_LENGTH))
                return 1;
        if (in_mem_const(addr, size, L1_ROM_START, L1_ROM_LENGTH))
                return 1;

        return 0;
}
EXPORT_SYMBOL(_access_ok);
#endif /* CONFIG_ACCESS_CHECK */