// SPDX-License-Identifier: GPL-2.0
/*
 * io-unit.c:  IO-UNIT specific routines for memory management.
 *
 * Copyright (C) 1997,1998 Jakub Jelinek    (jj@sunsite.mff.cuni.cz)
 */
 
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/bitops.h>
#include <linux/dma-map-ops.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>

#include <asm/io.h>
#include <asm/io-unit.h>
#include <asm/mxcc.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/dma.h>
#include <asm/oplib.h>

#include "mm_32.h"

/* #define IOUNIT_DEBUG */
#ifdef IOUNIT_DEBUG
#define IOD(x) printk(x)
#else
#define IOD(x) do { } while (0)
#endif

#define IOPERM        (IOUPTE_CACHE | IOUPTE_WRITE | IOUPTE_VALID)
#define MKIOPTE(phys) __iopte((((phys)>>4) & IOUPTE_PAGE) | IOPERM)

static const struct dma_map_ops iounit_dma_ops;

static void __init iounit_iommu_init(struct platform_device *op)
{
        struct iounit_struct *iounit;
        iopte_t __iomem *xpt;
        iopte_t __iomem *xptend;

        iounit = kzalloc_obj(struct iounit_struct, GFP_ATOMIC);
        if (!iounit) {
                prom_printf("SUN4D: Cannot alloc iounit, halting.\n");
                prom_halt();
        }

        iounit->limit[0] = IOUNIT_BMAP1_START;
        iounit->limit[1] = IOUNIT_BMAP2_START;
        iounit->limit[2] = IOUNIT_BMAPM_START;
        iounit->limit[3] = IOUNIT_BMAPM_END;
        iounit->rotor[1] = IOUNIT_BMAP2_START;
        iounit->rotor[2] = IOUNIT_BMAPM_START;

        xpt = of_ioremap(&op->resource[2], 0, PAGE_SIZE * 16, "XPT");
        if (!xpt) {
                prom_printf("SUN4D: Cannot map External Page Table.");
                prom_halt();
        }
        
        op->dev.archdata.iommu = iounit;
        iounit->page_table = xpt;
        spin_lock_init(&iounit->lock);

        xptend = iounit->page_table + (16 * PAGE_SIZE) / sizeof(iopte_t);
        for (; xpt < xptend; xpt++)
                sbus_writel(0, xpt);

        op->dev.dma_ops = &iounit_dma_ops;
}

static int __init iounit_init(void)
{
        extern void sun4d_init_sbi_irq(void);
        struct device_node *dp;

        for_each_node_by_name(dp, "sbi") {
                struct platform_device *op = of_find_device_by_node(dp);

                iounit_iommu_init(op);
                of_propagate_archdata(op);
        }

        sun4d_init_sbi_irq();

        return 0;
}

subsys_initcall(iounit_init);

/* One has to hold iounit->lock to call this */
static dma_addr_t iounit_get_area(struct iounit_struct *iounit,
                                  phys_addr_t phys, int size)
{
        int i, j, k, npages;
        unsigned long rotor, scan, limit;
        iopte_t iopte;

        npages = (offset_in_page(phys) + size + (PAGE_SIZE - 1)) >> PAGE_SHIFT;

        /* A tiny bit of magic ingredience :) */
        switch (npages) {
        case 1: i = 0x0231; break;
        case 2: i = 0x0132; break;
        default: i = 0x0213; break;
        }
        
        IOD(("%s(%pa,%d[%d])=", __func__, &phys, size, npages));
        
next:   j = (i & 15);
        rotor = iounit->rotor[j - 1];
        limit = iounit->limit[j];
        scan = rotor;
nexti:  scan = find_next_zero_bit(iounit->bmap, limit, scan);
        if (scan + npages > limit) {
                if (limit != rotor) {
                        limit = rotor;
                        scan = iounit->limit[j - 1];
                        goto nexti;
                }
                i >>= 4;
                if (!(i & 15))
                        panic("iounit_get_area: Couldn't find free iopte slots for (%pa,%d)\n",
                              &phys, size);
                goto next;
        }
        for (k = 1, scan++; k < npages; k++)
                if (test_bit(scan++, iounit->bmap))
                        goto nexti;
        iounit->rotor[j - 1] = (scan < limit) ? scan : iounit->limit[j - 1];
        scan -= npages;
        iopte = MKIOPTE(phys & PAGE_MASK);
        phys = IOUNIT_DMA_BASE + (scan << PAGE_SHIFT) + offset_in_page(phys);
        for (k = 0; k < npages; k++, iopte = __iopte(iopte_val(iopte) + 0x100), scan++) {
                set_bit(scan, iounit->bmap);
                sbus_writel(iopte_val(iopte), &iounit->page_table[scan]);
        }
        IOD(("%pa\n", &phys));
        return phys;
}

static dma_addr_t iounit_map_phys(struct device *dev, phys_addr_t phys,
                size_t len, enum dma_data_direction dir, unsigned long attrs)
{
        struct iounit_struct *iounit = dev->archdata.iommu;
        unsigned long flags;
        dma_addr_t ret;
        
        /* XXX So what is maxphys for us and how do drivers know it? */
        if (!len || len > 256 * 1024)
                return DMA_MAPPING_ERROR;

        spin_lock_irqsave(&iounit->lock, flags);
        ret = iounit_get_area(iounit, phys, len);
        spin_unlock_irqrestore(&iounit->lock, flags);
        return ret;
}

static int iounit_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
                enum dma_data_direction dir, unsigned long attrs)
{
        struct iounit_struct *iounit = dev->archdata.iommu;
        struct scatterlist *sg;
        unsigned long flags;
        int i;

        /* FIXME: Cache some resolved pages - often several sg entries are to the same page */
        spin_lock_irqsave(&iounit->lock, flags);
        for_each_sg(sgl, sg, nents, i) {
                sg->dma_address =
                        iounit_get_area(iounit, sg_phys(sg), sg->length);
                sg->dma_length = sg->length;
        }
        spin_unlock_irqrestore(&iounit->lock, flags);
        return nents;
}

static void iounit_unmap_phys(struct device *dev, dma_addr_t vaddr, size_t len,
                enum dma_data_direction dir, unsigned long attrs)
{
        struct iounit_struct *iounit = dev->archdata.iommu;
        unsigned long flags;
        
        spin_lock_irqsave(&iounit->lock, flags);
        len = ((vaddr & ~PAGE_MASK) + len + (PAGE_SIZE-1)) >> PAGE_SHIFT;
        vaddr = (vaddr - IOUNIT_DMA_BASE) >> PAGE_SHIFT;
        IOD(("iounit_release %08lx-%08lx\n", (long)vaddr, (long)len+vaddr));
        for (len += vaddr; vaddr < len; vaddr++)
                clear_bit(vaddr, iounit->bmap);
        spin_unlock_irqrestore(&iounit->lock, flags);
}

static void iounit_unmap_sg(struct device *dev, struct scatterlist *sgl,
                int nents, enum dma_data_direction dir, unsigned long attrs)
{
        struct iounit_struct *iounit = dev->archdata.iommu;
        unsigned long flags, vaddr, len;
        struct scatterlist *sg;
        int i;

        spin_lock_irqsave(&iounit->lock, flags);
        for_each_sg(sgl, sg, nents, i) {
                len = ((sg->dma_address & ~PAGE_MASK) + sg->length + (PAGE_SIZE-1)) >> PAGE_SHIFT;
                vaddr = (sg->dma_address - IOUNIT_DMA_BASE) >> PAGE_SHIFT;
                IOD(("iounit_release %08lx-%08lx\n", (long)vaddr, (long)len+vaddr));
                for (len += vaddr; vaddr < len; vaddr++)
                        clear_bit(vaddr, iounit->bmap);
        }
        spin_unlock_irqrestore(&iounit->lock, flags);
}

#ifdef CONFIG_SBUS
static void *iounit_alloc(struct device *dev, size_t len,
                dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
        struct iounit_struct *iounit = dev->archdata.iommu;
        unsigned long va, addr, page, end, ret;
        pgprot_t dvma_prot;
        iopte_t __iomem *iopte;

        /* XXX So what is maxphys for us and how do drivers know it? */
        if (!len || len > 256 * 1024)
                return NULL;

        len = PAGE_ALIGN(len);
        va = __get_free_pages(gfp | __GFP_ZERO, get_order(len));
        if (!va)
                return NULL;

        addr = ret = sparc_dma_alloc_resource(dev, len);
        if (!addr)
                goto out_free_pages;
        *dma_handle = addr;

        dvma_prot = __pgprot(SRMMU_CACHE | SRMMU_ET_PTE | SRMMU_PRIV);
        end = PAGE_ALIGN((addr + len));
        while(addr < end) {
                page = va;
                {
                        pmd_t *pmdp;
                        pte_t *ptep;
                        long i;

                        pmdp = pmd_off_k(addr);
                        ptep = pte_offset_kernel(pmdp, addr);

                        set_pte(ptep, mk_pte(virt_to_page(page), dvma_prot));

                        i = ((addr - IOUNIT_DMA_BASE) >> PAGE_SHIFT);

                        iopte = iounit->page_table + i;
                        sbus_writel(iopte_val(MKIOPTE(__pa(page))), iopte);
                }
                addr += PAGE_SIZE;
                va += PAGE_SIZE;
        }
        flush_cache_all();
        flush_tlb_all();

        return (void *)ret;

out_free_pages:
        free_pages(va, get_order(len));
        return NULL;
}

static void iounit_free(struct device *dev, size_t size, void *cpu_addr,
                dma_addr_t dma_addr, unsigned long attrs)
{
        /* XXX Somebody please fill this in */
}
#endif

static const struct dma_map_ops iounit_dma_ops = {
#ifdef CONFIG_SBUS
        .alloc                  = iounit_alloc,
        .free                   = iounit_free,
#endif
        .map_phys               = iounit_map_phys,
        .unmap_phys             = iounit_unmap_phys,
        .map_sg                 = iounit_map_sg,
        .unmap_sg               = iounit_unmap_sg,
};