/*
 * Copyright (C) 2005,2006,2007,2008,2009,2010,2011 Imagination Technologies
 *
 * This file contains the architecture-dependent parts of process handling.
 *
 */

#include <linux/errno.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/reboot.h>
#include <linux/elfcore.h>
#include <linux/fs.h>
#include <linux/tick.h>
#include <linux/slab.h>
#include <linux/mman.h>
#include <linux/pm.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <linux/smp.h>
#include <asm/core_reg.h>
#include <asm/user_gateway.h>
#include <asm/tcm.h>
#include <asm/traps.h>
#include <asm/switch_to.h>

/*
 * Wait for the next interrupt and enable local interrupts
 */
void arch_cpu_idle(void)
{
	int tmp;

	/*
	 * Quickly jump straight into the interrupt entry point without actually
	 * triggering an interrupt. When TXSTATI gets read the processor will
	 * block until an interrupt is triggered.
	 */
	asm volatile (/* Switch into ISTAT mode */
		      "RTH\n\t"
		      /* Enable local interrupts */
		      "MOV	TXMASKI, %1\n\t"
		      /*
		       * We can't directly "SWAP PC, PCX", so we swap via a
		       * temporary. Essentially we do:
		       *  PCX_new = 1f (the place to continue execution)
		       *  PC = PCX_old
		       */
		      "ADD	%0, CPC0, #(1f-.)\n\t"
		      "SWAP	PCX, %0\n\t"
		      "MOV	PC, %0\n"
		      /* Continue execution here with interrupts enabled */
		      "1:"
		      : "=a" (tmp)
		      : "r" (get_trigger_mask()));
}

#ifdef CONFIG_HOTPLUG_CPU
void arch_cpu_idle_dead(void)
{
	cpu_die();
}
#endif

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

void (*soc_restart)(char *cmd);
void (*soc_halt)(void);

void machine_restart(char *cmd)
{
	if (soc_restart)
		soc_restart(cmd);
	hard_processor_halt(HALT_OK);
}

void machine_halt(void)
{
	if (soc_halt)
		soc_halt();
	smp_send_stop();
	hard_processor_halt(HALT_OK);
}

void machine_power_off(void)
{
	if (pm_power_off)
		pm_power_off();
	smp_send_stop();
	hard_processor_halt(HALT_OK);
}

#define FLAG_Z 0x8
#define FLAG_N 0x4
#define FLAG_O 0x2
#define FLAG_C 0x1

void show_regs(struct pt_regs *regs)
{
	int i;
	const char *AX0_names[] = {"A0StP", "A0FrP"};
	const char *AX1_names[] = {"A1GbP", "A1LbP"};

	const char *DX0_names[] = {
		"D0Re0",
		"D0Ar6",
		"D0Ar4",
		"D0Ar2",
		"D0FrT",
		"D0.5 ",
		"D0.6 ",
		"D0.7 "
	};

	const char *DX1_names[] = {
		"D1Re0",
		"D1Ar5",
		"D1Ar3",
		"D1Ar1",
		"D1RtP",
		"D1.5 ",
		"D1.6 ",
		"D1.7 "
	};

	show_regs_print_info(KERN_INFO);

	pr_info(" pt_regs @ %p\n", regs);
	pr_info(" SaveMask = 0x%04hx\n", regs->ctx.SaveMask);
	pr_info(" Flags = 0x%04hx (%c%c%c%c)\n", regs->ctx.Flags,
		regs->ctx.Flags & FLAG_Z ? 'Z' : 'z',
		regs->ctx.Flags & FLAG_N ? 'N' : 'n',
		regs->ctx.Flags & FLAG_O ? 'O' : 'o',
		regs->ctx.Flags & FLAG_C ? 'C' : 'c');
	pr_info(" TXRPT = 0x%08x\n", regs->ctx.CurrRPT);
	pr_info(" PC = 0x%08x\n", regs->ctx.CurrPC);

	/* AX regs */
	for (i = 0; i < 2; i++) {
		pr_info(" %s = 0x%08x    ",
			AX0_names[i],
			regs->ctx.AX[i].U0);
		printk(" %s = 0x%08x\n",
			AX1_names[i],
			regs->ctx.AX[i].U1);
	}

	if (regs->ctx.SaveMask & TBICTX_XEXT_BIT)
		pr_warn(" Extended state present - AX2.[01] will be WRONG\n");

	/* Special place with AXx.2 */
	pr_info(" A0.2  = 0x%08x    ",
		regs->ctx.Ext.AX2.U0);
	printk(" A1.2  = 0x%08x\n",
		regs->ctx.Ext.AX2.U1);

	/* 'extended' AX regs (nominally, just AXx.3) */
	for (i = 0; i < (TBICTX_AX_REGS - 3); i++) {
		pr_info(" A0.%d  = 0x%08x    ", i + 3, regs->ctx.AX3[i].U0);
		printk(" A1.%d  = 0x%08x\n", i + 3, regs->ctx.AX3[i].U1);
	}

	for (i = 0; i < 8; i++) {
		pr_info(" %s = 0x%08x    ", DX0_names[i], regs->ctx.DX[i].U0);
		printk(" %s = 0x%08x\n", DX1_names[i], regs->ctx.DX[i].U1);
	}

	show_trace(NULL, (unsigned long *)regs->ctx.AX[0].U0, regs);
}

/*
 * Copy architecture-specific thread state
 */
int copy_thread(unsigned long clone_flags, unsigned long usp,
		unsigned long kthread_arg, struct task_struct *tsk)
{
	struct pt_regs *childregs = task_pt_regs(tsk);
	void *kernel_context = ((void *) childregs +
				sizeof(struct pt_regs));
	unsigned long global_base;

	BUG_ON(((unsigned long)childregs) & 0x7);
	BUG_ON(((unsigned long)kernel_context) & 0x7);

	memset(&tsk->thread.kernel_context, 0,
			sizeof(tsk->thread.kernel_context));

	tsk->thread.kernel_context = __TBISwitchInit(kernel_context,
						     ret_from_fork,
						     0, 0);

	if (unlikely(tsk->flags & PF_KTHREAD)) {
		/*
		 * Make sure we don't leak any kernel data to child's regs
		 * if kernel thread becomes a userspace thread in the future
		 */
		memset(childregs, 0 , sizeof(struct pt_regs));

		global_base = __core_reg_get(A1GbP);
		childregs->ctx.AX[0].U1 = (unsigned long) global_base;
		childregs->ctx.AX[0].U0 = (unsigned long) kernel_context;
		/* Set D1Ar1=kthread_arg and D1RtP=usp (fn) */
		childregs->ctx.DX[4].U1 = usp;
		childregs->ctx.DX[3].U1 = kthread_arg;
		tsk->thread.int_depth = 2;
		return 0;
	}

	/*
	 * Get a pointer to where the new child's register block should have
	 * been pushed.
	 * The Meta's stack grows upwards, and the context is the the first
	 * thing to be pushed by TBX (phew)
	 */
	*childregs = *current_pt_regs();
	/* Set the correct stack for the clone mode */
	if (usp)
		childregs->ctx.AX[0].U0 = ALIGN(usp, 8);
	tsk->thread.int_depth = 1;

	/* set return value for child process */
	childregs->ctx.DX[0].U0 = 0;

	/* The TLS pointer is passed as an argument to sys_clone. */
	if (clone_flags & CLONE_SETTLS)
		tsk->thread.tls_ptr =
				(__force void __user *)childregs->ctx.DX[1].U1;

#ifdef CONFIG_METAG_FPU
	if (tsk->thread.fpu_context) {
		struct meta_fpu_context *ctx;

		ctx = kmemdup(tsk->thread.fpu_context,
			      sizeof(struct meta_fpu_context), GFP_ATOMIC);
		tsk->thread.fpu_context = ctx;
	}
#endif

#ifdef CONFIG_METAG_DSP
	if (tsk->thread.dsp_context) {
		struct meta_ext_context *ctx;
		int i;

		ctx = kmemdup(tsk->thread.dsp_context,
			      sizeof(struct meta_ext_context), GFP_ATOMIC);
		for (i = 0; i < 2; i++)
			ctx->ram[i] = kmemdup(ctx->ram[i], ctx->ram_sz[i],
					      GFP_ATOMIC);
		tsk->thread.dsp_context = ctx;
	}
#endif

	return 0;
}

#ifdef CONFIG_METAG_FPU
static void alloc_fpu_context(struct thread_struct *thread)
{
	thread->fpu_context = kzalloc(sizeof(struct meta_fpu_context),
				      GFP_ATOMIC);
}

static void clear_fpu(struct thread_struct *thread)
{
	thread->user_flags &= ~TBICTX_FPAC_BIT;
	kfree(thread->fpu_context);
	thread->fpu_context = NULL;
}
#else
static void clear_fpu(struct thread_struct *thread)
{
}
#endif

#ifdef CONFIG_METAG_DSP
static void clear_dsp(struct thread_struct *thread)
{
	if (thread->dsp_context) {
		kfree(thread->dsp_context->ram[0]);
		kfree(thread->dsp_context->ram[1]);

		kfree(thread->dsp_context);

		thread->dsp_context = NULL;
	}

	__core_reg_set(D0.8, 0);
}
#else
static void clear_dsp(struct thread_struct *thread)
{
}
#endif

struct task_struct *__sched __switch_to(struct task_struct *prev,
					struct task_struct *next)
{
	TBIRES to, from;

	to.Switch.pCtx = next->thread.kernel_context;
	to.Switch.pPara = prev;

#ifdef CONFIG_METAG_FPU
	if (prev->thread.user_flags & TBICTX_FPAC_BIT) {
		struct pt_regs *regs = task_pt_regs(prev);
		TBIRES state;

		state.Sig.SaveMask = prev->thread.user_flags;
		state.Sig.pCtx = &regs->ctx;

		if (!prev->thread.fpu_context)
			alloc_fpu_context(&prev->thread);
		if (prev->thread.fpu_context)
			__TBICtxFPUSave(state, prev->thread.fpu_context);
	}
	/*
	 * Force a restore of the FPU context next time this process is
	 * scheduled.
	 */
	if (prev->thread.fpu_context)
		prev->thread.fpu_context->needs_restore = true;
#endif


	from = __TBISwitch(to, &prev->thread.kernel_context);

	/* Restore TLS pointer for this process. */
	set_gateway_tls(current->thread.tls_ptr);

	return (struct task_struct *) from.Switch.pPara;
}

void flush_thread(void)
{
	clear_fpu(&current->thread);
	clear_dsp(&current->thread);
}

/*
 * Free current thread data structures etc.
 */
void exit_thread(struct task_struct *tsk)
{
	clear_fpu(&tsk->thread);
	clear_dsp(&tsk->thread);
}

/* TODO: figure out how to unwind the kernel stack here to figure out
 * where we went to sleep. */
unsigned long get_wchan(struct task_struct *p)
{
	return 0;
}

int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
{
	/* Returning 0 indicates that the FPU state was not stored (as it was
	 * not in use) */
	return 0;
}

#ifdef CONFIG_METAG_USER_TCM

#define ELF_MIN_ALIGN	PAGE_SIZE

#define ELF_PAGESTART(_v) ((_v) & ~(unsigned long)(ELF_MIN_ALIGN-1))
#define ELF_PAGEOFFSET(_v) ((_v) & (ELF_MIN_ALIGN-1))
#define ELF_PAGEALIGN(_v) (((_v) + ELF_MIN_ALIGN - 1) & ~(ELF_MIN_ALIGN - 1))

#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)

unsigned long __metag_elf_map(struct file *filep, unsigned long addr,
			      struct elf_phdr *eppnt, int prot, int type,
			      unsigned long total_size)
{
	unsigned long map_addr, size;
	unsigned long page_off = ELF_PAGEOFFSET(eppnt->p_vaddr);
	unsigned long raw_size = eppnt->p_filesz + page_off;
	unsigned long off = eppnt->p_offset - page_off;
	unsigned int tcm_tag;
	addr = ELF_PAGESTART(addr);
	size = ELF_PAGEALIGN(raw_size);

	/* mmap() will return -EINVAL if given a zero size, but a
	 * segment with zero filesize is perfectly valid */
	if (!size)
		return addr;

	tcm_tag = tcm_lookup_tag(addr);

	if (tcm_tag != TCM_INVALID_TAG)
		type &= ~MAP_FIXED;

	/*
	* total_size is the size of the ELF (interpreter) image.
	* The _first_ mmap needs to know the full size, otherwise
	* randomization might put this image into an overlapping
	* position with the ELF binary image. (since size < total_size)
	* So we first map the 'big' image - and unmap the remainder at
	* the end. (which unmap is needed for ELF images with holes.)
	*/
	if (total_size) {
		total_size = ELF_PAGEALIGN(total_size);
		map_addr = vm_mmap(filep, addr, total_size, prot, type, off);
		if (!BAD_ADDR(map_addr))
			vm_munmap(map_addr+size, total_size-size);
	} else
		map_addr = vm_mmap(filep, addr, size, prot, type, off);

	if (!BAD_ADDR(map_addr) && tcm_tag != TCM_INVALID_TAG) {
		struct tcm_allocation *tcm;
		unsigned long tcm_addr;

		tcm = kmalloc(sizeof(*tcm), GFP_KERNEL);
		if (!tcm)
			return -ENOMEM;

		tcm_addr = tcm_alloc(tcm_tag, raw_size);
		if (tcm_addr != addr) {
			kfree(tcm);
			return -ENOMEM;
		}

		tcm->tag = tcm_tag;
		tcm->addr = tcm_addr;
		tcm->size = raw_size;

		list_add(&tcm->list, &current->mm->context.tcm);

		eppnt->p_vaddr = map_addr;
		if (copy_from_user((void *) addr, (void __user *) map_addr,
				   raw_size))
			return -EFAULT;
	}

	return map_addr;
}
#endif