path: root/arch/sh/mm/pmb.c

/*
 * arch/sh/mm/pmb.c
 *
 * Privileged Space Mapping Buffer (PMB) Support.
 *
 * Copyright (C) 2005 - 2010  Paul Mundt
 * Copyright (C) 2010  Matt Fleming
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/bitops.h>
#include <linux/debugfs.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <asm/cacheflush.h>
#include <asm/sizes.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>

struct pmb_entry;

struct pmb_entry {
	unsigned long vpn;
	unsigned long ppn;
	unsigned long flags;
	unsigned long size;

	spinlock_t lock;

	/*
	 * 0 .. NR_PMB_ENTRIES for specific entry selection, or
	 * PMB_NO_ENTRY to search for a free one
	 */
	int entry;

	/* Adjacent entry link for contiguous multi-entry mappings */
	struct pmb_entry *link;
};

static struct {
	unsigned long size;
	int flag;
} pmb_sizes[] = {
	{ .size	= SZ_512M, .flag = PMB_SZ_512M, },
	{ .size = SZ_128M, .flag = PMB_SZ_128M, },
	{ .size = SZ_64M,  .flag = PMB_SZ_64M,  },
	{ .size = SZ_16M,  .flag = PMB_SZ_16M,  },
};

static void pmb_unmap_entry(struct pmb_entry *, int depth);

static DEFINE_RWLOCK(pmb_rwlock);
static struct pmb_entry pmb_entry_list[NR_PMB_ENTRIES];
static DECLARE_BITMAP(pmb_map, NR_PMB_ENTRIES);

static unsigned int pmb_iomapping_enabled;

static __always_inline unsigned long mk_pmb_entry(unsigned int entry)
{
	return (entry & PMB_E_MASK) << PMB_E_SHIFT;
}

static __always_inline unsigned long mk_pmb_addr(unsigned int entry)
{
	return mk_pmb_entry(entry) | PMB_ADDR;
}

static __always_inline unsigned long mk_pmb_data(unsigned int entry)
{
	return mk_pmb_entry(entry) | PMB_DATA;
}

static __always_inline unsigned int pmb_ppn_in_range(unsigned long ppn)
{
	return ppn >= __pa(memory_start) && ppn < __pa(memory_end);
}

/*
 * Ensure that the PMB entries match our cache configuration.
 *
 * When we are in 32-bit address extended mode, CCR.CB becomes
 * invalid, so care must be taken to manually adjust cacheable
 * translations.
 */
static __always_inline unsigned long pmb_cache_flags(void)
{
	unsigned long flags = 0;

#if defined(CONFIG_CACHE_OFF)
	flags |= PMB_WT | PMB_UB;
#elif defined(CONFIG_CACHE_WRITETHROUGH)
	flags |= PMB_C | PMB_WT | PMB_UB;
#elif defined(CONFIG_CACHE_WRITEBACK)
	flags |= PMB_C;
#endif

	return flags;
}

/*
 * Convert typical pgprot value to the PMB equivalent
 */
static inline unsigned long pgprot_to_pmb_flags(pgprot_t prot)
{
	unsigned long pmb_flags = 0;
	u64 flags = pgprot_val(prot);

	if (flags & _PAGE_CACHABLE)
		pmb_flags |= PMB_C;
	if (flags & _PAGE_WT)
		pmb_flags |= PMB_WT | PMB_UB;

	return pmb_flags;
}

static inline bool pmb_can_merge(struct pmb_entry *a, struct pmb_entry *b)
{
	return (b->vpn == (a->vpn + a->size)) &&
	       (b->ppn == (a->ppn + a->size)) &&
	       (b->flags == a->flags);
}

static bool pmb_mapping_exists(unsigned long vaddr, phys_addr_t phys,
			       unsigned long size)
{
	int i;

	read_lock(&pmb_rwlock);

	for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
		struct pmb_entry *pmbe, *iter;
		unsigned long span;

		if (!test_bit(i, pmb_map))
			continue;

		pmbe = &pmb_entry_list[i];

		/*
		 * See if VPN and PPN are bounded by an existing mapping.
		 */
		if ((vaddr < pmbe->vpn) || (vaddr >= (pmbe->vpn + pmbe->size)))
			continue;
		if ((phys < pmbe->ppn) || (phys >= (pmbe->ppn + pmbe->size)))
			continue;

		/*
		 * Now see if we're in range of a simple mapping.
		 */
		if (size <= pmbe->size) {
			read_unlock(&pmb_rwlock);
			return true;
		}

		span = pmbe->size;

		/*
		 * Finally for sizes that involve compound mappings, walk
		 * the chain.
		 */
		for (iter = pmbe->link; iter; iter = iter->link)
			span += iter->size;

		/*
		 * Nothing else to do if the range req