/*
 * TLB support routines.
 *
 * Copyright (C) 1998, 1999 Hewlett-Packard Co
 * Copyright (C) 1998, 1999 David Mosberger-Tang <davidm@hpl.hp.com>
 */
#include <linux/config.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/mm.h>

#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/pal.h>

#define SUPPORTED_PGBITS (			\
		1 << _PAGE_SIZE_256M |		\
		1 << _PAGE_SIZE_64M  |		\
		1 << _PAGE_SIZE_16M  |		\
		1 << _PAGE_SIZE_4M   |		\
		1 << _PAGE_SIZE_1M   |		\
		1 << _PAGE_SIZE_256K |		\
		1 << _PAGE_SIZE_64K  |		\
		1 << _PAGE_SIZE_16K  |		\
		1 << _PAGE_SIZE_8K   |		\
		1 << _PAGE_SIZE_4K )

static void wrap_context (struct mm_struct *mm);

unsigned long ia64_next_context = (1UL << IA64_HW_CONTEXT_BITS) + 1;

 /*
  * Put everything in a struct so we avoid the global offset table whenever
  * possible.
  */
ia64_ptce_info_t ia64_ptce_info;

/*
 * Seralize usage of ptc.g 
 */
spinlock_t ptcg_lock = SPIN_LOCK_UNLOCKED; /* see <asm/pgtable.h> */

void
get_new_mmu_context (struct mm_struct *mm)
{
	if ((ia64_next_context & IA64_HW_CONTEXT_MASK) == 0) {
		wrap_context(mm);
	}
	mm->context = ia64_next_context++;
}

/*
 * This is where we handle the case where (ia64_next_context &
 * IA64_HW_CONTEXT_MASK) == 0.  Whenever this happens, we need to
 * flush the entire TLB and skip over region id number 0, which is
 * used by the kernel.
 */
static void
wrap_context (struct mm_struct *mm)
{
	struct task_struct *task;

	/*
	 * We wrapped back to the first region id so we nuke the TLB
	 * so we can switch to the next generation of region ids.
	 */
	__flush_tlb_all();
	if (ia64_next_context++ == 0) {
		/*
		 * Oops, we've used up all 64 bits of the context
		 * space---walk through task table to ensure we don't
		 * get tricked into using an old context.  If this
		 * happens, the machine has been running for a long,
		 * long time!
		 */
		ia64_next_context = (1UL << IA64_HW_CONTEXT_BITS) + 1;

		read_lock(&tasklist_lock);
		for_each_task (task) {
			if (task->mm == mm)
				continue;
			flush_tlb_mm(mm);
		}
		read_unlock(&tasklist_lock);
	}
}

void
__flush_tlb_all (void)
{
	unsigned long i, j, flags, count0, count1, stride0, stride1, addr = ia64_ptce_info.base;

	count0  = ia64_ptce_info.count[0];
	count1  = ia64_ptce_info.count[1];
	stride0 = ia64_ptce_info.stride[0];
	stride1 = ia64_ptce_info.stride[1];

	__save_and_cli(flags);
	for (i = 0; i < count0; ++i) {
		for (j = 0; j < count1; ++j) {
			asm volatile ("ptc.e %0" :: "r"(addr));
			addr += stride1;
		}
		addr += stride0;
	}
	__restore_flags(flags);
	ia64_insn_group_barrier();
	ia64_srlz_i();			/* srlz.i implies srlz.d */
	ia64_insn_group_barrier();
}

void
flush_tlb_range (struct mm_struct *mm, unsigned long start, unsigned long end)
{
	unsigned long size = end - start;
	unsigned long nbits;

	if (mm != current->active_mm) {
		/* this doesn't happen often, if at all, so it's not worth optimizing for... */
		mm->context = 0;
		return;
	}

	nbits = ia64_fls(size + 0xfff);
	if (((1UL << nbits) & SUPPORTED_PGBITS) == 0) {
		if (nbits > _PAGE_SIZE_256M)
			nbits = _PAGE_SIZE_256M;
		else
			/*
			 * Some page sizes are not implemented in the
			 * IA-64 arch, so if we get asked to clear an
			 * unsupported page size, round up to the
			 * nearest page size.  Note that we depend on
			 * the fact that if page size N is not
			 * implemented, 2*N _is_ implemented.
			 */
			++nbits;
		if (((1UL << nbits) & SUPPORTED_PGBITS) == 0)
			panic("flush_tlb_range: BUG: nbits=%lu\n", nbits);
	}
	start &= ~((1UL << nbits) - 1);

	spin_lock(&ptcg_lock);
	do {
#ifdef CONFIG_SMP
		__asm__ __volatile__ ("ptc.g %0,%1;;srlz.i;;"
				      :: "r"(start), "r"(nbits<<2) : "memory");
#else
		__asm__ __volatile__ ("ptc.l %0,%1" :: "r"(start), "r"(nbits<<2) : "memory");
#endif
		start += (1UL << nbits);
	} while (start < end);
	spin_unlock(&ptcg_lock);
	ia64_insn_group_barrier();
	ia64_srlz_i();			/* srlz.i implies srlz.d */
	ia64_insn_group_barrier();
}

void
ia64_tlb_init (void)
{
	ia64_get_ptce(&ia64_ptce_info);
	__flush_tlb_all();		/* nuke left overs from bootstrapping... */
}