/*
 *  linux/arch/alpha/kernel/process.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 */

/*
 * This file handles the architecture-dependent parts of process handling.
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/malloc.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/utsname.h>
#include <linux/time.h>
#include <linux/major.h>
#include <linux/stat.h>
#include <linux/mman.h>
#include <linux/elfcore.h>
#include <linux/reboot.h>
#include <linux/console.h>

#ifdef CONFIG_RTC
#include <linux/mc146818rtc.h>
#endif

#include <asm/reg.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/hwrpb.h>
#include <asm/fpu.h>

#include "proto.h"
#include "bios32.h"

/*
 * Initial task structure. Make this a per-architecture thing,
 * because different architectures tend to have different
 * alignment requirements and potentially different initial
 * setup.
 */

unsigned long init_user_stack[1024] = { STACK_MAGIC, };
static struct vm_area_struct init_mmap = INIT_MMAP;
static struct fs_struct init_fs = INIT_FS;
static struct file * init_fd_array[NR_OPEN] = { NULL, };
static struct files_struct init_files = INIT_FILES;
static struct signal_struct init_signals = INIT_SIGNALS;
struct mm_struct init_mm = INIT_MM(init_mm);

union task_union init_task_union __attribute__((section("init_task")))
	 = { task: INIT_TASK(init_task_union.task) };

/*
 * No need to acquire the kernel lock, we're entirely local..
 */
asmlinkage int
sys_sethae(unsigned long hae, unsigned long a1, unsigned long a2,
	   unsigned long a3, unsigned long a4, unsigned long a5,
	   struct pt_regs regs)
{
	(&regs)->hae = hae;
	return 0;
}

#ifdef __SMP__
void
cpu_idle(void *unused)
{
	/* An endless idle loop with no priority at all.  */
	current->priority = 0;
	current->counter = -100;

	while (1) {
		/* FIXME -- EV6 and LCA45 know how to power down
		   the CPU.  */

		/* Although we are an idle CPU, we do not want to 
		   get into the scheduler unnecessarily.  */
		if (current->need_resched) {
			schedule();
			check_pgt_cache();
		}
	}
}
#endif

asmlinkage int
sys_idle(void)
{
	if (current->pid != 0)
		return -EPERM;

	/* An endless idle loop with no priority at all.  */
	current->priority = 0;
	current->counter = -100;
	init_idle();

	while (1) {
		/* FIXME -- EV6 and LCA45 know how to power down
		   the CPU.  */

		schedule();
		check_pgt_cache();
	}
}

void
generic_kill_arch (int mode, char *restart_cmd)
{
	/* The following currently only has any effect on SRM.  We should
	   fix MILO to understand it.  Should be pretty easy.  Also we can
	   support RESTART2 via the ipc_buffer machinations pictured below,
	   which SRM ignores.  */

	if (alpha_using_srm) {
		struct percpu_struct *cpup;
		unsigned long flags;
	
		cpup = (struct percpu_struct *)
		  ((unsigned long)hwrpb + hwrpb->processor_offset);

		flags = cpup->flags;

		/* Clear reason to "default"; clear "bootstrap in progress". */
		flags &= ~0x00ff0001UL;

		if (mode == LINUX_REBOOT_CMD_RESTART) {
			if (!restart_cmd) {
				flags |= 0x00020000UL; /* "cold bootstrap" */
				cpup->ipc_buffer[0] = 0;
			} else {
				flags |=  0x00030000UL; /* "warm bootstrap" */
				strncpy((char *)cpup->ipc_buffer, restart_cmd,
					sizeof(cpup->ipc_buffer));
			}
		} else {
			flags |=  0x00040000UL; /* "remain halted" */
		}
			
		cpup->flags = flags;					       
		mb();						

		reset_for_srm();
		set_hae(srm_hae);

#ifdef CONFIG_DUMMY_CONSOLE
		/* This has the effect of reseting the VGA video origin.  */
		take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
#endif
	}

#ifdef CONFIG_RTC
	/* Reset rtc to defaults.  */
	{
		unsigned char control;

		cli();

		/* Reset periodic interrupt frequency.  */
		CMOS_WRITE(0x26, RTC_FREQ_SELECT);

		/* Turn on periodic interrupts.  */
		control = CMOS_READ(RTC_CONTROL);
		control |= RTC_PIE;
		CMOS_WRITE(control, RTC_CONTROL);	
		CMOS_READ(RTC_INTR_FLAGS);

		sti();
	}
#endif

	if (!alpha_using_srm && mode != LINUX_REBOOT_CMD_RESTART) {
		/* Unfortunately, since MILO doesn't currently understand
		   the hwrpb bits above, we can't reliably halt the 
		   processor and keep it halted.  So just loop.  */
		return;
	}

	if (alpha_using_srm)
		srm_paging_stop();

	halt();
}

void
machine_restart(char *restart_cmd)
{
	alpha_mv.kill_arch(LINUX_REBOOT_CMD_RESTART, restart_cmd);
}

void
machine_halt(void)
{
	alpha_mv.kill_arch(LINUX_REBOOT_CMD_HALT, NULL);
}

void machine_power_off(void)
{
	alpha_mv.kill_arch(LINUX_REBOOT_CMD_POWER_OFF, NULL);
}

void show_regs(struct pt_regs * regs)
{
	printk("\nps: %04lx pc: [<%016lx>]\n", regs->ps, regs->pc);
	printk("rp: [<%016lx>] sp: %p\n", regs->r26, regs+1);
	printk(" r0: %016lx  r1: %016lx  r2: %016lx  r3: %016lx\n",
	       regs->r0, regs->r1, regs->r2, regs->r3);
	printk(" r4: %016lx  r5: %016lx  r6: %016lx  r7: %016lx\n",
	       regs->r4, regs->r5, regs->r6, regs->r7);
	printk(" r8: %016lx r16: %016lx r17: %016lx r18: %016lx\n",
	       regs->r8, regs->r16, regs->r17, regs->r18);
	printk("r19: %016lx r20: %016lx r21: %016lx r22: %016lx\n",
	       regs->r19, regs->r20, regs->r21, regs->r22);
	printk("r23: %016lx r24: %016lx r25: %016lx r26: %016lx\n",
	       regs->r23, regs->r24, regs->r25, regs->r26);
	printk("r27: %016lx r28: %016lx r29: %016lx hae: %016lx\n",
	       regs->r27, regs->r28, regs->gp, regs->hae);
}

/*
 * Re-start a thread when doing execve()
 */
void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
{
	set_fs(USER_DS);
	regs->pc = pc;
	regs->ps = 8;
	wrusp(sp);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
}

void flush_thread(void)
{
	/* Arrange for each exec'ed process to start off with a clean slate
	   with respect to the FPU.  This is all exceptions disabled.  Note
           that EV6 defines UNFD valid only with UNDZ, which we don't want
	   for IEEE conformance -- so that disabled bit remains in software.  */

	current->tss.flags &= ~IEEE_SW_MASK;
	wrfpcr(FPCR_DYN_NORMAL | FPCR_INVD | FPCR_DZED | FPCR_OVFD | FPCR_INED);
}

void release_thread(struct task_struct *dead_task)
{
}

/*
 * "alpha_clone()".. By the time we get here, the
 * non-volatile registers have also been saved on the
 * stack. We do some ugly pointer stuff here.. (see
 * also copy_thread)
 *
 * Notice that "fork()" is implemented in terms of clone,
 * with parameters (SIGCHLD, 0).
 */
int alpha_clone(unsigned long clone_flags, unsigned long usp,
		struct switch_stack * swstack)
{
	if (!usp)
		usp = rdusp();
	return do_fork(clone_flags, usp, (struct pt_regs *) (swstack+1));
}

int alpha_vfork(struct switch_stack * swstack)
{
	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(),
			(struct pt_regs *) (swstack+1));
}

/*
 * Copy an alpha thread..
 *
 * Note the "stack_offset" stuff: when returning to kernel mode, we need
 * to have some extra stack-space for the kernel stack that still exists
 * after the "ret_from_sys_call". When returning to user mode, we only
 * want the space needed by the syscall stack frame (ie "struct pt_regs").
 * Use the passed "regs" pointer to determine how much space we need
 * for a kernel fork().
 */

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
	struct task_struct * p, struct pt_regs * regs)
{
	extern void ret_from_sys_call(void);
	extern void ret_from_smp_fork(void);

	struct pt_regs * childregs;
	struct switch_stack * childstack, *stack;
	unsigned long stack_offset;

	stack_offset = PAGE_SIZE - sizeof(struct pt_regs);
	if (!(regs->ps & 8))
		stack_offset = (PAGE_SIZE-1) & (unsigned long) regs;
	childregs = (struct pt_regs *) (stack_offset + PAGE_SIZE + (long)p);
		
	*childregs = *regs;
	childregs->r0 = 0;
	childregs->r19 = 0;
	childregs->r20 = 1;	/* OSF/1 has some strange fork() semantics.  */
	regs->r20 = 0;
	stack = ((struct switch_stack *) regs) - 1;
	childstack = ((struct switch_stack *) childregs) - 1;
	*childstack = *stack;
#ifdef __SMP__
	childstack->r26 = (unsigned long) ret_from_smp_fork;
#else
	childstack->r26 = (unsigned long) ret_from_sys_call;
#endif
	p->tss.usp = usp;
	p->tss.ksp = (unsigned long) childstack;
	p->tss.pal_flags = 1;	/* set FEN, clear everything else */
	p->tss.flags = current->tss.flags;
	p->tss.mm_context = p->tss.asn = 0;

	return 0;
}

/*
 * fill in the user structure for a core dump..
 */
void dump_thread(struct pt_regs * pt, struct user * dump)
{
	/* switch stack follows right below pt_regs: */
	struct switch_stack * sw = ((struct switch_stack *) pt) - 1;

	dump->magic = CMAGIC;
	dump->start_code  = current->mm->start_code;
	dump->start_data  = current->mm->start_data;
	dump->start_stack = rdusp() & ~(PAGE_SIZE - 1);
	dump->u_tsize = ((current->mm->end_code - dump->start_code)
			 >> PAGE_SHIFT);
	dump->u_dsize = ((current->mm->brk + PAGE_SIZE-1 - dump->start_data)
			 >> PAGE_SHIFT);
	dump->u_ssize = (current->mm->start_stack - dump->start_stack
			 + PAGE_SIZE-1) >> PAGE_SHIFT;

	/*
	 * We store the registers in an order/format that is
	 * compatible with DEC Unix/OSF/1 as this makes life easier
	 * for gdb.
	 */
	dump->regs[EF_V0]  = pt->r0;
	dump->regs[EF_T0]  = pt->r1;
	dump->regs[EF_T1]  = pt->r2;
	dump->regs[EF_T2]  = pt->r3;
	dump->regs[EF_T3]  = pt->r4;
	dump->regs[EF_T4]  = pt->r5;
	dump->regs[EF_T5]  = pt->r6;
	dump->regs[EF_T6]  = pt->r7;
	dump->regs[EF_T7]  = pt->r8;
	dump->regs[EF_S0]  = sw->r9;
	dump->regs[EF_S1]  = sw->r10;
	dump->regs[EF_S2]  = sw->r11;
	dump->regs[EF_S3]  = sw->r12;
	dump->regs[EF_S4]  = sw->r13;
	dump->regs[EF_S5]  = sw->r14;
	dump->regs[EF_S6]  = sw->r15;
	dump->regs[EF_A3]  = pt->r19;
	dump->regs[EF_A4]  = pt->r20;
	dump->regs[EF_A5]  = pt->r21;
	dump->regs[EF_T8]  = pt->r22;
	dump->regs[EF_T9]  = pt->r23;
	dump->regs[EF_T10] = pt->r24;
	dump->regs[EF_T11] = pt->r25;
	dump->regs[EF_RA]  = pt->r26;
	dump->regs[EF_T12] = pt->r27;
	dump->regs[EF_AT]  = pt->r28;
	dump->regs[EF_SP]  = rdusp();
	dump->regs[EF_PS]  = pt->ps;
	dump->regs[EF_PC]  = pt->pc;
	dump->regs[EF_GP]  = pt->gp;
	dump->regs[EF_A0]  = pt->r16;
	dump->regs[EF_A1]  = pt->r17;
	dump->regs[EF_A2]  = pt->r18;
	memcpy((char *)dump->regs + EF_SIZE, sw->fp, 32 * 8);
}

int dump_fpu (struct pt_regs * regs, elf_fpregset_t *r)
{
	/* switch stack follows right below pt_regs: */
	struct switch_stack * sw = ((struct switch_stack *) regs) - 1;
	memcpy(r, sw->fp, 32 * 8);
	return 1;
}

/*
 * sys_execve() executes a new program.
 *
 * This works due to the alpha calling sequence: the first 6 args
 * are gotten from registers, while the rest is on the stack, so
 * we get a0-a5 for free, and then magically find "struct pt_regs"
 * on the stack for us..
 *
 * Don't do this at home.
 */
asmlinkage int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
	unsigned long a3, unsigned long a4, unsigned long a5,
	struct pt_regs regs)
{
	int error;
	char * filename;

	lock_kernel();
	filename = getname((char *) a0);
	error = PTR_ERR(filename);
	if (IS_ERR(filename))
		goto out;
	error = do_execve(filename, (char **) a1, (char **) a2, &regs);
	putname(filename);
out:
	unlock_kernel();
	return error;
}