// SPDX-License-Identifier: GPL-2.0
/*
** PARISC 1.1 Dynamic DMA mapping support.
** This implementation is for PA-RISC platforms that do not support
** I/O TLBs (aka DMA address translation hardware).
** See Documentation/core-api/dma-api-howto.rst for interface definitions.
**
**      (c) Copyright 1999,2000 Hewlett-Packard Company
**      (c) Copyright 2000 Grant Grundler
**      (c) Copyright 2000 Philipp Rumpf <prumpf@tux.org>
**      (c) Copyright 2000 John Marvin
**
** "leveraged" from 2.3.47: arch/ia64/kernel/pci-dma.c.
** (I assume it's from David Mosberger-Tang but there was no Copyright)
**
** AFAIK, all PA7100LC and PA7300LC platforms can use this code.
**
** - ggg
*/

#include <linux/init.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/dma-direct.h>
#include <linux/dma-map-ops.h>

#include <asm/cacheflush.h>
#include <asm/dma.h>    /* for DMA_CHUNK_SIZE */
#include <asm/io.h>
#include <asm/page.h>   /* get_order */
#include <linux/uaccess.h>
#include <asm/tlbflush.h>       /* for purge_tlb_*() macros */

static struct proc_dir_entry * proc_gsc_root __read_mostly = NULL;
static unsigned long pcxl_used_bytes __read_mostly;
static unsigned long pcxl_used_pages __read_mostly;

unsigned long pcxl_dma_start __ro_after_init; /* pcxl dma mapping area start */
static DEFINE_SPINLOCK(pcxl_res_lock);
static char    *pcxl_res_map;
static int     pcxl_res_hint;
static int     pcxl_res_size;

#ifdef DEBUG_PCXL_RESOURCE
#define DBG_RES(x...)   printk(x)
#else
#define DBG_RES(x...)
#endif


/*
** Dump a hex representation of the resource map.
*/

#ifdef DUMP_RESMAP
static
void dump_resmap(void)
{
        u_long *res_ptr = (unsigned long *)pcxl_res_map;
        u_long i = 0;

        printk("res_map: ");
        for(; i < (pcxl_res_size / sizeof(unsigned long)); ++i, ++res_ptr)
                printk("%08lx ", *res_ptr);

        printk("\n");
}
#else
static inline void dump_resmap(void) {;}
#endif

static inline int map_pte_uncached(pte_t * pte,
                unsigned long vaddr,
                unsigned long size, unsigned long *paddr_ptr)
{
        unsigned long end;
        unsigned long orig_vaddr = vaddr;

        vaddr &= ~PMD_MASK;
        end = vaddr + size;
        if (end > PMD_SIZE)
                end = PMD_SIZE;
        do {
                unsigned long flags;

                if (!pte_none(*pte))
                        printk(KERN_ERR "map_pte_uncached: page already exists\n");
                purge_tlb_start(flags);
                set_pte(pte, __mk_pte(*paddr_ptr, PAGE_KERNEL_UNC));
                pdtlb(SR_KERNEL, orig_vaddr);
                purge_tlb_end(flags);
                vaddr += PAGE_SIZE;
                orig_vaddr += PAGE_SIZE;
                (*paddr_ptr) += PAGE_SIZE;
                pte++;
        } while (vaddr < end);
        return 0;
}

static inline int map_pmd_uncached(pmd_t * pmd, unsigned long vaddr,
                unsigned long size, unsigned long *paddr_ptr)
{
        unsigned long end;
        unsigned long orig_vaddr = vaddr;

        vaddr &= ~PGDIR_MASK;
        end = vaddr + size;
        if (end > PGDIR_SIZE)
                end = PGDIR_SIZE;
        do {
                pte_t * pte = pte_alloc_kernel(pmd, vaddr);
                if (!pte)
                        return -ENOMEM;
                if (map_pte_uncached(pte, orig_vaddr, end - vaddr, paddr_ptr))
                        return -ENOMEM;
                vaddr = (vaddr + PMD_SIZE) & PMD_MASK;
                orig_vaddr += PMD_SIZE;
                pmd++;
        } while (vaddr < end);
        return 0;
}

static inline int map_uncached_pages(unsigned long vaddr, unsigned long size,
                unsigned long paddr)
{
        pgd_t * dir;
        unsigned long end = vaddr + size;

        dir = pgd_offset_k(vaddr);
        do {
                p4d_t *p4d;
                pud_t *pud;
                pmd_t *pmd;

                p4d = p4d_offset(dir, vaddr);
                pud = pud_offset(p4d, vaddr);
                pmd = pmd_alloc(NULL, pud, vaddr);

                if (!pmd)
                        return -ENOMEM;
                if (map_pmd_uncached(pmd, vaddr, end - vaddr, &paddr))
                        return -ENOMEM;
                vaddr = vaddr + PGDIR_SIZE;
                dir++;
        } while (vaddr && (vaddr < end));
        return 0;
}

static inline void unmap_uncached_pte(pmd_t * pmd, unsigned long vaddr,
                unsigned long size)
{
        pte_t * pte;
        unsigned long end;
        unsigned long orig_vaddr = vaddr;

        if (pmd_none(*pmd))
                return;
        if (pmd_bad(*pmd)) {
                pmd_ERROR(*pmd);
                pmd_clear(pmd);
                return;
        }
        pte = pte_offset_kernel(pmd, vaddr);
        vaddr &= ~PMD_MASK;
        end = vaddr + size;
        if (end > PMD_SIZE)
                end = PMD_SIZE;
        do {
                unsigned long flags;
                pte_t page = *pte;

                pte_clear(&init_mm, vaddr, pte);
                purge_tlb_start(flags);
                pdtlb(SR_KERNEL, orig_vaddr);
                purge_tlb_end(flags);
                vaddr += PAGE_SIZE;
                orig_vaddr += PAGE_SIZE;
                pte++;
                if (pte_none(page) || pte_present(page))
                        continue;
                printk(KERN_CRIT "Whee.. Swapped out page in kernel page table\n");
        } while (vaddr < end);
}

static inline void unmap_uncached_pmd(pgd_t * dir, unsigned long vaddr,
                unsigned long size)
{
        pmd_t * pmd;
        unsigned long end;
        unsigned long orig_vaddr = vaddr;

        if (pgd_none(*dir))
                return;
        if (pgd_bad(*dir)) {
                pgd_ERROR(*dir);
                pgd_clear(dir);
                return;
        }
        pmd = pmd_offset(pud_offset(p4d_offset(dir, vaddr), vaddr), vaddr);
        vaddr &= ~PGDIR_MASK;
        end = vaddr + size;
        if (end > PGDIR_SIZE)
                end = PGDIR_SIZE;
        do {
                unmap_uncached_pte(pmd, orig_vaddr, end - vaddr);
                vaddr = (vaddr + PMD_SIZE) & PMD_MASK;
                orig_vaddr += PMD_SIZE;
                pmd++;
        } while (vaddr < end);
}

static void unmap_uncached_pages(unsigned long vaddr, unsigned long size)
{
        pgd_t * dir;
        unsigned long end = vaddr + size;

        dir = pgd_offset_k(vaddr);
        do {
                unmap_uncached_pmd(dir, vaddr, end - vaddr);
                vaddr = vaddr + PGDIR_SIZE;
                dir++;
        } while (vaddr && (vaddr < end));
}

#define PCXL_SEARCH_LOOP(idx, mask, size)  \
       for(; res_ptr < res_end; ++res_ptr) \
       { \
               if(0 == ((*res_ptr) & mask)) { \
                       *res_ptr |= mask; \
                       idx = (int)((u_long)res_ptr - (u_long)pcxl_res_map); \
                       pcxl_res_hint = idx + (size >> 3); \
                       goto resource_found; \
               } \
       }

#define PCXL_FIND_FREE_MAPPING(idx, mask, size)  { \
       u##size *res_ptr = (u##size *)&(pcxl_res_map[pcxl_res_hint & ~((size >> 3) - 1)]); \
       u##size *res_end = (u##size *)&pcxl_res_map[pcxl_res_size]; \
       PCXL_SEARCH_LOOP(idx, mask, size); \
       res_ptr = (u##size *)&pcxl_res_map[0]; \
       PCXL_SEARCH_LOOP(idx, mask, size); \
}

static unsigned long
pcxl_alloc_range(size_t size)
{
        int res_idx;
        u_long mask, flags;
        unsigned int pages_needed = size >> PAGE_SHIFT;

        mask = (u_long) -1L;
        mask >>= BITS_PER_LONG - pages_needed;

        DBG_RES("pcxl_alloc_range() size: %d pages_needed %d pages_mask 0x%08lx\n", 
                size, pages_needed, mask);

        spin_lock_irqsave(&pcxl_res_lock, flags);

        if(pages_needed <= 8) {
                PCXL_FIND_FREE_MAPPING(res_idx, mask, 8);
        } else if(pages_needed <= 16) {
                PCXL_FIND_FREE_MAPPING(res_idx, mask, 16);
        } else if(pages_needed <= 32) {
                PCXL_FIND_FREE_MAPPING(res_idx, mask, 32);
        } else {
                panic("%s: pcxl_alloc_range() Too many pages to map.\n",
                      __FILE__);
        }

        dump_resmap();
        panic("%s: pcxl_alloc_range() out of dma mapping resources\n",
              __FILE__);
        
resource_found:
        
        DBG_RES("pcxl_alloc_range() res_idx %d mask 0x%08lx res_hint: %d\n",
                res_idx, mask, pcxl_res_hint);

        pcxl_used_pages += pages_needed;
        pcxl_used_bytes += ((pages_needed >> 3) ? (pages_needed >> 3) : 1);

        spin_unlock_irqrestore(&pcxl_res_lock, flags);

        dump_resmap();

        /* 
        ** return the corresponding vaddr in the pcxl dma map
        */
        return (pcxl_dma_start + (res_idx << (PAGE_SHIFT + 3)));
}

#define PCXL_FREE_MAPPINGS(idx, m, size) \
                u##size *res_ptr = (u##size *)&(pcxl_res_map[(idx) + (((size >> 3) - 1) & (~((size >> 3) - 1)))]); \
                /* BUG_ON((*res_ptr & m) != m); */ \
                *res_ptr &= ~m;

/*
** clear bits in the pcxl resource map
*/
static void
pcxl_free_range(unsigned long vaddr, size_t size)
{
        u_long mask, flags;
        unsigned int res_idx = (vaddr - pcxl_dma_start) >> (PAGE_SHIFT + 3);
        unsigned int pages_mapped = size >> PAGE_SHIFT;

        mask = (u_long) -1L;
        mask >>= BITS_PER_LONG - pages_mapped;

        DBG_RES("pcxl_free_range() res_idx: %d size: %d pages_mapped %d mask 0x%08lx\n", 
                res_idx, size, pages_mapped, mask);

        spin_lock_irqsave(&pcxl_res_lock, flags);

        if(pages_mapped <= 8) {
                PCXL_FREE_MAPPINGS(res_idx, mask, 8);
        } else if(pages_mapped <= 16) {
                PCXL_FREE_MAPPINGS(res_idx, mask, 16);
        } else if(pages_mapped <= 32) {
                PCXL_FREE_MAPPINGS(res_idx, mask, 32);
        } else {
                panic("%s: pcxl_free_range() Too many pages to unmap.\n",
                      __FILE__);
        }
        
        pcxl_used_pages -= (pages_mapped ? pages_mapped : 1);
        pcxl_used_bytes -= ((pages_mapped >> 3) ? (pages_mapped >> 3) : 1);

        spin_unlock_irqrestore(&pcxl_res_lock, flags);

        dump_resmap();
}

static int __maybe_unused proc_pcxl_dma_show(struct seq_file *m, void *v)
{
#if 0
        u_long i = 0;
        unsigned long *res_ptr = (u_long *)pcxl_res_map;
#endif
        unsigned long total_pages = pcxl_res_size << 3;   /* 8 bits per byte */

        seq_printf(m, "\nDMA Mapping Area size    : %d bytes (%ld pages)\n",
                PCXL_DMA_MAP_SIZE, total_pages);

        seq_printf(m, "Resource bitmap : %d bytes\n", pcxl_res_size);

        seq_puts(m,  "            total:    free:    used:   % used:\n");
        seq_printf(m, "blocks  %8d %8ld %8ld %8ld%%\n", pcxl_res_size,
                pcxl_res_size - pcxl_used_bytes, pcxl_used_bytes,
                (pcxl_used_bytes * 100) / pcxl_res_size);

        seq_printf(m, "pages   %8ld %8ld %8ld %8ld%%\n", total_pages,
                total_pages - pcxl_used_pages, pcxl_used_pages,
                (pcxl_used_pages * 100 / total_pages));

#if 0
        seq_puts(m, "\nResource bitmap:");

        for(; i < (pcxl_res_size / sizeof(u_long)); ++i, ++res_ptr) {
                if ((i & 7) == 0)
                    seq_puts(m,"\n   ");
                seq_printf(m, "%s %08lx", buf, *res_ptr);
        }
#endif
        seq_putc(m, '\n');
        return 0;
}

static int __init
pcxl_dma_init(void)
{
        if (pcxl_dma_start == 0)
                return 0;

        pcxl_res_size = PCXL_DMA_MAP_SIZE >> (PAGE_SHIFT + 3);
        pcxl_res_hint = 0;
        pcxl_res_map = (char *)__get_free_pages(GFP_KERNEL,
                                            get_order(pcxl_res_size));
        memset(pcxl_res_map, 0, pcxl_res_size);
        proc_gsc_root = proc_mkdir("bus/gsc", NULL);
        if (!proc_gsc_root)
                printk(KERN_WARNING
                        "pcxl_dma_init: Unable to create gsc /proc dir entry\n");
        else {
                struct proc_dir_entry* ent;
                ent = proc_create_single("pcxl_dma", 0, proc_gsc_root,
                                proc_pcxl_dma_show);
                if (!ent)
                        printk(KERN_WARNING
                                "pci-dma.c: Unable to create pcxl_dma /proc entry.\n");
        }
        return 0;
}

__initcall(pcxl_dma_init);

void *arch_dma_alloc(struct device *dev, size_t size,
                dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
        unsigned long vaddr;
        unsigned long paddr;
        int order;

        if (boot_cpu_data.cpu_type != pcxl2 && boot_cpu_data.cpu_type != pcxl)
                return NULL;

        order = get_order(size);
        size = 1 << (order + PAGE_SHIFT);
        vaddr = pcxl_alloc_range(size);
        paddr = __get_free_pages(gfp | __GFP_ZERO, order);
        flush_kernel_dcache_range(paddr, size);
        paddr = __pa(paddr);
        map_uncached_pages(vaddr, size, paddr);
        *dma_handle = (dma_addr_t) paddr;

        return (void *)vaddr;
}

void arch_dma_free(struct device *dev, size_t size, void *vaddr,
                dma_addr_t dma_handle, unsigned long attrs)
{
        int order = get_order(size);

        WARN_ON_ONCE(boot_cpu_data.cpu_type != pcxl2 &&
                     boot_cpu_data.cpu_type != pcxl);

        size = 1 << (order + PAGE_SHIFT);
        unmap_uncached_pages((unsigned long)vaddr, size);
        pcxl_free_range((unsigned long)vaddr, size);

        free_pages((unsigned long)__va(dma_handle), order);
}

void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
                enum dma_data_direction dir)
{
        /*
         * fdc: The data cache line is written back to memory, if and only if
         * it is dirty, and then invalidated from the data cache.
         */
        flush_kernel_dcache_range((unsigned long)phys_to_virt(paddr), size);
}

void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
                enum dma_data_direction dir)
{
        unsigned long addr = (unsigned long) phys_to_virt(paddr);

        switch (dir) {
        case DMA_TO_DEVICE:
        case DMA_BIDIRECTIONAL:
                flush_kernel_dcache_range(addr, size);
                return;
        case DMA_FROM_DEVICE:
                purge_kernel_dcache_range_asm(addr, addr + size);
                return;
        default:
                BUG();
        }
}