/*
 * arch/sh/mm/pmb.c
 *
 * Privileged Space Mapping Buffer (PMB) Support.
 *
 * Copyright (C) 2005 - 2011  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/syscore_ops.h>
#include <linux/cpu.h>
#include <linux/module.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 <linux/pgtable.h>
#include <asm/cacheflush.h>
#include <linux/sizes.h>
#include <linux/uaccess.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;

        raw_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 requirements are met.
                 */
                if (size <= span) {
                        read_unlock(&pmb_rwlock);
                        return true;
                }
        }

        read_unlock(&pmb_rwlock);
        return false;
}

static bool pmb_size_valid(unsigned long size)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(pmb_sizes); i++)
                if (pmb_sizes[i].size == size)
                        return true;

        return false;
}

static inline bool pmb_addr_valid(unsigned long addr, unsigned long size)
{
        return (addr >= P1SEG && (addr + size - 1) < P3SEG);
}

static inline bool pmb_prot_valid(pgprot_t prot)
{
        return (pgprot_val(prot) & _PAGE_USER) == 0;
}

static int pmb_size_to_flags(unsigned long size)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(pmb_sizes); i++)
                if (pmb_sizes[i].size == size)
                        return pmb_sizes[i].flag;

        return 0;
}

static int pmb_alloc_entry(void)
{
        int pos;

        pos = find_first_zero_bit(pmb_map, NR_PMB_ENTRIES);
        if (pos >= 0 && pos < NR_PMB_ENTRIES)
                __set_bit(pos, pmb_map);
        else
                pos = -ENOSPC;

        return pos;
}

static struct pmb_entry *pmb_alloc(unsigned long vpn, unsigned long ppn,
                                   unsigned long flags, int entry)
{
        struct pmb_entry *pmbe;
        unsigned long irqflags;
        void *ret = NULL;
        int pos;

        write_lock_irqsave(&pmb_rwlock, irqflags);

        if (entry == PMB_NO_ENTRY) {
                pos = pmb_alloc_entry();
                if (unlikely(pos < 0)) {
                        ret = ERR_PTR(pos);
                        goto out;
                }
        } else {
                if (__test_and_set_bit(entry, pmb_map)) {
                        ret = ERR_PTR(-ENOSPC);
                        goto out;
                }

                pos = entry;
        }

        write_unlock_irqrestore(&pmb_rwlock, irqflags);

        pmbe = &pmb_entry_list[pos];

        memset(pmbe, 0, sizeof(struct pmb_entry));

        raw_spin_lock_init(&pmbe->lock);

        pmbe->vpn       = vpn;
        pmbe->ppn       = ppn;
        pmbe->flags     = flags;
        pmbe->entry     = pos;

        return pmbe;

out:
        write_unlock_irqrestore(&pmb_rwlock, irqflags);
        return ret;
}

static void pmb_free(struct pmb_entry *pmbe)
{
        __clear_bit(pmbe->entry, pmb_map);

        pmbe->entry     = PMB_NO_ENTRY;
        pmbe->link      = NULL;
}

/*
 * Must be run uncached.
 */
static void __set_pmb_entry(struct pmb_entry *pmbe)
{
        unsigned long addr, data;

        addr = mk_pmb_addr(pmbe->entry);
        data = mk_pmb_data(pmbe->entry);

        jump_to_uncached();

        /* Set V-bit */
        __raw_writel(pmbe->vpn | PMB_V, addr);
        __raw_writel(pmbe->ppn | pmbe->flags | PMB_V, data);

        back_to_cached();
}

static void __clear_pmb_entry(struct pmb_entry *pmbe)
{
        unsigned long addr, data;
        unsigned long addr_val, data_val;

        addr = mk_pmb_addr(pmbe->entry);
        data = mk_pmb_data(pmbe->entry);

        addr_val = __raw_readl(addr);
        data_val = __raw_readl(data);

        /* Clear V-bit */
        writel_uncached(addr_val & ~PMB_V, addr);
        writel_uncached(data_val & ~PMB_V, data);
}

#ifdef CONFIG_PM
static void set_pmb_entry(struct pmb_entry *pmbe)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&pmbe->lock, flags);
        __set_pmb_entry(pmbe);
        raw_spin_unlock_irqrestore(&pmbe->lock, flags);
}
#endif /* CONFIG_PM */

int pmb_bolt_mapping(unsigned long vaddr, phys_addr_t phys,
                     unsigned long size, pgprot_t prot)
{
        struct pmb_entry *pmbp, *pmbe;
        unsigned long orig_addr, orig_size;
        unsigned long flags, pmb_flags;
        int i, mapped;

        if (size < SZ_16M)
                return -EINVAL;
        if (!pmb_addr_valid(vaddr, size))
                return -EFAULT;
        if (pmb_mapping_exists(vaddr, phys, size))
                return 0;

        orig_addr = vaddr;
        orig_size = size;

        flush_tlb_kernel_range(vaddr, vaddr + size);

        pmb_flags = pgprot_to_pmb_flags(prot);
        pmbp = NULL;

        do {
                for (i = mapped = 0; i < ARRAY_SIZE(pmb_sizes); i++) {
                        if (size < pmb_sizes[i].size)
                                continue;

                        pmbe = pmb_alloc(vaddr, phys, pmb_flags |
                                         pmb_sizes[i].flag, PMB_NO_ENTRY);
                        if (IS_ERR(pmbe)) {
                                pmb_unmap_entry(pmbp, mapped);
                                return PTR_ERR(pmbe);
                        }

                        raw_spin_lock_irqsave(&pmbe->lock, flags);

                        pmbe->size = pmb_sizes[i].size;

                        __set_pmb_entry(pmbe);

                        phys    += pmbe->size;
                        vaddr   += pmbe->size;
                        size    -= pmbe->size;

                        /*
                         * Link adjacent entries that span multiple PMB
                         * entries for easier tear-down.
                         */
                        if (likely(pmbp)) {
                                raw_spin_lock_nested(&pmbp->lock,
                                                     SINGLE_DEPTH_NESTING);
                                pmbp->link = pmbe;
                                raw_spin_unlock(&pmbp->lock);
                        }

                        pmbp = pmbe;

                        /*
                         * Instead of trying smaller sizes on every
                         * iteration (even if we succeed in allocating
                         * space), try using pmb_sizes[i].size again.
                         */
                        i--;
                        mapped++;

                        raw_spin_unlock_irqrestore(&pmbe->lock, flags);
                }
        } while (size >= SZ_16M);

        flush_cache_vmap(orig_addr, orig_addr + orig_size);

        return 0;
}

void __iomem *pmb_remap_caller(phys_addr_t phys, unsigned long size,
                               pgprot_t prot, void *caller)
{
        unsigned long vaddr;
        phys_addr_t offset, last_addr;
        phys_addr_t align_mask;
        unsigned long aligned;
        struct vm_struct *area;
        int i, ret;

        if (!pmb_iomapping_enabled)
                return NULL;

        /*
         * Small mappings need to go through the TLB.
         */
        if (size < SZ_16M)
                return ERR_PTR(-EINVAL);
        if (!pmb_prot_valid(prot))
                return ERR_PTR(-EINVAL);

        for (i = 0; i < ARRAY_SIZE(pmb_sizes); i++)
                if (size >= pmb_sizes[i].size)
                        break;

        last_addr = phys + size;
        align_mask = ~(pmb_sizes[i].size - 1);
        offset = phys & ~align_mask;
        phys &= align_mask;
        aligned = ALIGN(last_addr, pmb_sizes[i].size) - phys;

        /*
         * XXX: This should really start from uncached_end, but this
         * causes the MMU to reset, so for now we restrict it to the
         * 0xb000...0xc000 range.
         */
        area = __get_vm_area_caller(aligned, VM_IOREMAP, 0xb0000000,
                                    P3SEG, caller);
        if (!area)
                return NULL;

        area->phys_addr = phys;
        vaddr = (unsigned long)area->addr;

        ret = pmb_bolt_mapping(vaddr, phys, size, prot);
        if (unlikely(ret != 0))
                return ERR_PTR(ret);

        return (void __iomem *)(offset + (char *)vaddr);
}

int pmb_unmap(void __iomem *addr)
{
        struct pmb_entry *pmbe = NULL;
        unsigned long vaddr = (unsigned long __force)addr;
        int i, found = 0;

        read_lock(&pmb_rwlock);

        for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
                if (test_bit(i, pmb_map)) {
                        pmbe = &pmb_entry_list[i];
                        if (pmbe->vpn == vaddr) {
                                found = 1;
                                break;
                        }
                }
        }

        read_unlock(&pmb_rwlock);

        if (found) {
                pmb_unmap_entry(pmbe, NR_PMB_ENTRIES);
                return 0;
        }

        return -EINVAL;
}

static void __pmb_unmap_entry(struct pmb_entry *pmbe, int depth)
{
        do {
                struct pmb_entry *pmblink = pmbe;

                /*
                 * We may be called before this pmb_entry has been
                 * entered into the PMB table via set_pmb_entry(), but
                 * that's OK because we've allocated a unique slot for
                 * this entry in pmb_alloc() (even if we haven't filled
                 * it yet).
                 *
                 * Therefore, calling __clear_pmb_entry() is safe as no
                 * other mapping can be using that slot.
                 */
                __clear_pmb_entry(pmbe);

                flush_cache_vunmap(pmbe->vpn, pmbe->vpn + pmbe->size);

                pmbe = pmblink->link;

                pmb_free(pmblink);
        } while (pmbe && --depth);
}

static void pmb_unmap_entry(struct pmb_entry *pmbe, int depth)
{
        unsigned long flags;

        if (unlikely(!pmbe))
                return;

        write_lock_irqsave(&pmb_rwlock, flags);
        __pmb_unmap_entry(pmbe, depth);
        write_unlock_irqrestore(&pmb_rwlock, flags);
}

static void __init pmb_notify(void)
{
        int i;

        pr_info("PMB: boot mappings:\n");

        read_lock(&pmb_rwlock);

        for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
                struct pmb_entry *pmbe;

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

                pmbe = &pmb_entry_list[i];

                pr_info("       0x%08lx -> 0x%08lx [ %4ldMB %2scached ]\n",
                        pmbe->vpn >> PAGE_SHIFT, pmbe->ppn >> PAGE_SHIFT,
                        pmbe->size >> 20, (pmbe->flags & PMB_C) ? "" : "un");
        }

        read_unlock(&pmb_rwlock);
}

/*
 * Sync our software copy of the PMB mappings with those in hardware. The
 * mappings in the hardware PMB were either set up by the bootloader or
 * very early on by the kernel.
 */
static void __init pmb_synchronize(void)
{
        struct pmb_entry *pmbp = NULL;
        int i, j;

        /*
         * Run through the initial boot mappings, log the established
         * ones, and blow away anything that falls outside of the valid
         * PPN range. Specifically, we only care about existing mappings
         * that impact the cached/uncached sections.
         *
         * Note that touching these can be a bit of a minefield; the boot
         * loader can establish multi-page mappings with the same caching
         * attributes, so we need to ensure that we aren't modifying a
         * mapping that we're presently executing from, or may execute
         * from in the case of straddling page boundaries.
         *
         * In the future we will have to tidy up after the boot loader by
         * jumping between the cached and uncached mappings and tearing
         * down alternating mappings while executing from the other.
         */
        for (i = 0; i < NR_PMB_ENTRIES; i++) {
                unsigned long addr, data;
                unsigned long addr_val, data_val;
                unsigned long ppn, vpn, flags;
                unsigned long irqflags;
                unsigned int size;
                struct pmb_entry *pmbe;

                addr = mk_pmb_addr(i);
                data = mk_pmb_data(i);

                addr_val = __raw_readl(addr);
                data_val = __raw_readl(data);

                /*
                 * Skip over any bogus entries
                 */
                if (!(data_val & PMB_V) || !(addr_val & PMB_V))
                        continue;

                ppn = data_val & PMB_PFN_MASK;
                vpn = addr_val & PMB_PFN_MASK;

                /*
                 * Only preserve in-range mappings.
                 */
                if (!pmb_ppn_in_range(ppn)) {
                        /*
                         * Invalidate anything out of bounds.
                         */
                        writel_uncached(addr_val & ~PMB_V, addr);
                        writel_uncached(data_val & ~PMB_V, data);
                        continue;
                }

                /*
                 * Update the caching attributes if necessary
                 */
                if (data_val & PMB_C) {
                        data_val &= ~PMB_CACHE_MASK;
                        data_val |= pmb_cache_flags();

                        writel_uncached(data_val, data);
                }

                size = data_val & PMB_SZ_MASK;
                flags = size | (data_val & PMB_CACHE_MASK);

                pmbe = pmb_alloc(vpn, ppn, flags, i);
                if (IS_ERR(pmbe)) {
                        WARN_ON_ONCE(1);
                        continue;
                }

                raw_spin_lock_irqsave(&pmbe->lock, irqflags);

                for (j = 0; j < ARRAY_SIZE(pmb_sizes); j++)
                        if (pmb_sizes[j].flag == size)
                                pmbe->size = pmb_sizes[j].size;

                if (pmbp) {
                        raw_spin_lock_nested(&pmbp->lock, SINGLE_DEPTH_NESTING);
                        /*
                         * Compare the previous entry against the current one to
                         * see if the entries span a contiguous mapping. If so,
                         * setup the entry links accordingly. Compound mappings
                         * are later coalesced.
                         */
                        if (pmb_can_merge(pmbp, pmbe))
                                pmbp->link = pmbe;
                        raw_spin_unlock(&pmbp->lock);
                }

                pmbp = pmbe;

                raw_spin_unlock_irqrestore(&pmbe->lock, irqflags);
        }
}

static void __init pmb_merge(struct pmb_entry *head)
{
        unsigned long span, newsize;
        struct pmb_entry *tail;
        int i = 1, depth = 0;

        span = newsize = head->size;

        tail = head->link;
        while (tail) {
                span += tail->size;

                if (pmb_size_valid(span)) {
                        newsize = span;
                        depth = i;
                }

                /* This is the end of the line.. */
                if (!tail->link)
                        break;

                tail = tail->link;
                i++;
        }

        /*
         * The merged page size must be valid.
         */
        if (!depth || !pmb_size_valid(newsize))
                return;

        head->flags &= ~PMB_SZ_MASK;
        head->flags |= pmb_size_to_flags(newsize);

        head->size = newsize;

        __pmb_unmap_entry(head->link, depth);
        __set_pmb_entry(head);
}

static void __init pmb_coalesce(void)
{
        unsigned long flags;
        int i;

        write_lock_irqsave(&pmb_rwlock, flags);

        for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
                struct pmb_entry *pmbe;

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

                pmbe = &pmb_entry_list[i];

                /*
                 * We're only interested in compound mappings
                 */
                if (!pmbe->link)
                        continue;

                /*
                 * Nothing to do if it already uses the largest possible
                 * page size.
                 */
                if (pmbe->size == SZ_512M)
                        continue;

                pmb_merge(pmbe);
        }

        write_unlock_irqrestore(&pmb_rwlock, flags);
}

#ifdef CONFIG_UNCACHED_MAPPING
static void __init pmb_resize(void)
{
        int i;

        /*
         * If the uncached mapping was constructed by the kernel, it will
         * already be a reasonable size.
         */
        if (uncached_size == SZ_16M)
                return;

        read_lock(&pmb_rwlock);

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

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

                pmbe = &pmb_entry_list[i];

                if (pmbe->vpn != uncached_start)
                        continue;

                /*
                 * Found it, now resize it.
                 */
                raw_spin_lock_irqsave(&pmbe->lock, flags);

                pmbe->size = SZ_16M;
                pmbe->flags &= ~PMB_SZ_MASK;
                pmbe->flags |= pmb_size_to_flags(pmbe->size);

                uncached_resize(pmbe->size);

                __set_pmb_entry(pmbe);

                raw_spin_unlock_irqrestore(&pmbe->lock, flags);
        }

        read_unlock(&pmb_rwlock);
}
#endif

static int __init early_pmb(char *p)
{
        if (!p)
                return 0;

        if (strstr(p, "iomap"))
                pmb_iomapping_enabled = 1;

        return 0;
}
early_param("pmb", early_pmb);

void __init pmb_init(void)
{
        /* Synchronize software state */
        pmb_synchronize();

        /* Attempt to combine compound mappings */
        pmb_coalesce();

#ifdef CONFIG_UNCACHED_MAPPING
        /* Resize initial mappings, if necessary */
        pmb_resize();
#endif

        /* Log them */
        pmb_notify();

        writel_uncached(0, PMB_IRMCR);

        /* Flush out the TLB */
        local_flush_tlb_all();
        ctrl_barrier();
}

bool __in_29bit_mode(void)
{
        return (__raw_readl(PMB_PASCR) & PASCR_SE) == 0;
}

static int pmb_debugfs_show(struct seq_file *file, void *iter)
{
        int i;

        seq_printf(file, "V: Valid, C: Cacheable, WT: Write-Through\n"
                         "CB: Copy-Back, B: Buffered, UB: Unbuffered\n");
        seq_printf(file, "ety   vpn  ppn  size   flags\n");

        for (i = 0; i < NR_PMB_ENTRIES; i++) {
                unsigned long addr, data;
                unsigned int size;
                char *sz_str = NULL;

                addr = __raw_readl(mk_pmb_addr(i));
                data = __raw_readl(mk_pmb_data(i));

                size = data & PMB_SZ_MASK;
                sz_str = (size == PMB_SZ_16M)  ? " 16MB":
                         (size == PMB_SZ_64M)  ? " 64MB":
                         (size == PMB_SZ_128M) ? "128MB":
                                                 "512MB";

                /* 02: V 0x88 0x08 128MB C CB  B */
                seq_printf(file, "%02d: %c 0x%02lx 0x%02lx %s %c %s %s\n",
                           i, ((addr & PMB_V) && (data & PMB_V)) ? 'V' : ' ',
                           (addr >> 24) & 0xff, (data >> 24) & 0xff,
                           sz_str, (data & PMB_C) ? 'C' : ' ',
                           (data & PMB_WT) ? "WT" : "CB",
                           (data & PMB_UB) ? "UB" : " B");
        }

        return 0;
}

DEFINE_SHOW_ATTRIBUTE(pmb_debugfs);

static int __init pmb_debugfs_init(void)
{
        debugfs_create_file("pmb", S_IFREG | S_IRUGO, arch_debugfs_dir, NULL,
                            &pmb_debugfs_fops);
        return 0;
}
subsys_initcall(pmb_debugfs_init);

#ifdef CONFIG_PM
static void pmb_syscore_resume(void *data)
{
        struct pmb_entry *pmbe;
        int i;

        read_lock(&pmb_rwlock);

        for (i = 0; i < ARRAY_SIZE(pmb_entry_list); i++) {
                if (test_bit(i, pmb_map)) {
                        pmbe = &pmb_entry_list[i];
                        set_pmb_entry(pmbe);
                }
        }

        read_unlock(&pmb_rwlock);
}

static const struct syscore_ops pmb_syscore_ops = {
        .resume = pmb_syscore_resume,
};

static struct syscore pmb_syscore = {
        .ops = &pmb_syscore_ops,
};

static int __init pmb_sysdev_init(void)
{
        register_syscore(&pmb_syscore);
        return 0;
}
subsys_initcall(pmb_sysdev_init);
#endif