/*
 *  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 files_struct init_files = INIT_FILES;
static struct signal_struct init_signals = INIT_SIGNALS;
struct mm_struct init_mm = INIT_MM;

union task_union init_task_union __attribute__((section("init_task")))
	 = { task: INIT_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__
int
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.  */
		barrier();
		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();
	}
}

struct halt_info {
	int	mode;
	char *	restart_cmd;
};

static void
halt_processor(void * generic_ptr)
{
	struct percpu_struct * cpup;
	struct halt_info * how = (struct halt_info *)generic_ptr;
	unsigned long *flags;
	int cpuid = smp_processor_id();

	/* No point in taking interrupts anymore. */
	__cli();

	cpup = (struct percpu_struct *)
			((unsigned long)hwrpb + hwrpb->processor_offset
			 + hwrpb->processor_size * cpuid);
	flags = &cpup->flags;

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

#ifdef __SMP__
	/* Secondaries halt here. */
	if (cpuid != smp_boot_cpuid) {
		*flags |= 0x00040000UL; /* "remain halted" */
		clear_bit(cpuid, &cpu_present_mask);
		halt();
	}
#endif /* __SMP__ */

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

		/* 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);
	}
#endif /* CONFIG_RTC */

	if (how->mode == LINUX_REBOOT_CMD_RESTART) {
		if (!how->restart_cmd) {
			*flags |= 0x00020000UL; /* "cold bootstrap" */
			cpup->ipc_buffer[0] = 0;
		} else {
		  /* NOTE: this could really only work when returning
		     into MILO, rather than SRM console. The latter
		     does NOT look at the ipc_buffer to get a new
		     boot command. It could be done by using callbacks
		     to change some of the SRM environment variables,
		     but that is beyond our capabilities at this time.
		     At the moment, SRM will use the last boot device,
		     but the file and flags will be the defaults, when
		     doing a "warm" bootstrap.
		  */
			*flags |=  0x00030000UL; /* "warm bootstrap" */
			strncpy((char *)cpup->ipc_buffer,
				how->restart_cmd,
				sizeof(cpup->ipc_buffer));
		}
	} else
		*flags |=  0x00040000UL; /* "remain halted" */

#ifdef __SMP__
	/* Wait for the secondaries to halt. */
	clear_bit(smp_boot_cpuid, &cpu_present_mask);
	while (cpu_present_mask)
		/* Make sure we sample memory and not a register. */
		barrier();
#endif /* __SMP__ */

        /* If booted from SRM, reset some of the original environment. */
	if (alpha_using_srm) {
#ifdef CONFIG_DUMMY_CONSOLE
		/* This has the effect of resetting the VGA video origin.  */
		take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
#endif
		reset_for_srm();
		set_hae(srm_hae);
	}
	else if (how->mode != LINUX_REBOOT_CMD_RESTART &&
		 how->mode != LINUX_REBOOT_CMD_RESTART2) {
		/* 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;
	}

	/* PRIMARY */
	halt();
}

void
generic_kill_arch(int mode, char * restart_cmd)
{
	struct halt_info copy_of_args;

	copy_of_args.mode = mode;
	copy_of_args.restart_cmd = restart_cmd;
#ifdef __SMP__
	/* A secondary can't wait here for the primary to finish, can it now? */
	smp_call_function(halt_processor, (void *)&copy_of_args, 1, 0);
#endif /* __SMP__ */
	halt_processor(&copy_of_args);
}

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;

	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;
}
