// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * arch/powerpc/sysdev/dart_iommu.c
 *
 * Copyright (C) 2004 Olof Johansson <olof@lixom.net>, IBM Corporation
 * Copyright (C) 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 *                    IBM Corporation
 *
 * Based on pSeries_iommu.c:
 * Copyright (C) 2001 Mike Corrigan & Dave Engebretsen, IBM Corporation
 * Copyright (C) 2004 Olof Johansson <olof@lixom.net>, IBM Corporation
 *
 * Dynamic DMA mapping support, Apple U3, U4 & IBM CPC925 "DART" iommu.
 */

#include <linux/init.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/pci.h>
#include <linux/dma-mapping.h>
#include <linux/vmalloc.h>
#include <linux/suspend.h>
#include <linux/memblock.h>
#include <linux/gfp.h>
#include <linux/kmemleak.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/iommu.h>
#include <asm/pci-bridge.h>
#include <asm/machdep.h>
#include <asm/cacheflush.h>
#include <asm/ppc-pci.h>

#include "dart.h"

/* DART table address and size */
static u32 *dart_tablebase;
static unsigned long dart_tablesize;

/* Mapped base address for the dart */
static unsigned int __iomem *dart;

/* Dummy val that entries are set to when unused */
static unsigned int dart_emptyval;

static struct iommu_table iommu_table_dart;
static int iommu_table_dart_inited;
static int dart_dirty;
static int dart_is_u4;

#define DART_U4_BYPASS_BASE     0x8000000000ull

#define DBG(...)

static DEFINE_SPINLOCK(invalidate_lock);

static inline void dart_tlb_invalidate_all(void)
{
        unsigned long l = 0;
        unsigned int reg, inv_bit;
        unsigned long limit;
        unsigned long flags;

        spin_lock_irqsave(&invalidate_lock, flags);

        DBG("dart: flush\n");

        /* To invalidate the DART, set the DARTCNTL_FLUSHTLB bit in the
         * control register and wait for it to clear.
         *
         * Gotcha: Sometimes, the DART won't detect that the bit gets
         * set. If so, clear it and set it again.
         */

        limit = 0;

        inv_bit = dart_is_u4 ? DART_CNTL_U4_FLUSHTLB : DART_CNTL_U3_FLUSHTLB;
retry:
        l = 0;
        reg = DART_IN(DART_CNTL);
        reg |= inv_bit;
        DART_OUT(DART_CNTL, reg);

        while ((DART_IN(DART_CNTL) & inv_bit) && l < (1L << limit))
                l++;
        if (l == (1L << limit)) {
                if (limit < 4) {
                        limit++;
                        reg = DART_IN(DART_CNTL);
                        reg &= ~inv_bit;
                        DART_OUT(DART_CNTL, reg);
                        goto retry;
                } else
                        panic("DART: TLB did not flush after waiting a long "
                              "time. Buggy U3 ?");
        }

        spin_unlock_irqrestore(&invalidate_lock, flags);
}

static inline void dart_tlb_invalidate_one(unsigned long bus_rpn)
{
        unsigned int reg;
        unsigned int l, limit;
        unsigned long flags;

        spin_lock_irqsave(&invalidate_lock, flags);

        reg = DART_CNTL_U4_ENABLE | DART_CNTL_U4_IONE |
                (bus_rpn & DART_CNTL_U4_IONE_MASK);
        DART_OUT(DART_CNTL, reg);

        limit = 0;
wait_more:
        l = 0;
        while ((DART_IN(DART_CNTL) & DART_CNTL_U4_IONE) && l < (1L << limit)) {
                rmb();
                l++;
        }

        if (l == (1L << limit)) {
                if (limit < 4) {
                        limit++;
                        goto wait_more;
                } else
                        panic("DART: TLB did not flush after waiting a long "
                              "time. Buggy U4 ?");
        }

        spin_unlock_irqrestore(&invalidate_lock, flags);
}

static void dart_cache_sync(unsigned int *base, unsigned int count)
{
        /*
         * We add 1 to the number of entries to flush, following a
         * comment in Darwin indicating that the memory controller
         * can prefetch unmapped memory under some circumstances.
         */
        unsigned long start = (unsigned long)base;
        unsigned long end = start + (count + 1) * sizeof(unsigned int);
        unsigned int tmp;

        /* Perform a standard cache flush */
        flush_dcache_range(start, end);

        /*
         * Perform the sequence described in the CPC925 manual to
         * ensure all the data gets to a point the cache incoherent
         * DART hardware will see.
         */
        asm volatile(" sync;"
                     " isync;"
                     " dcbf 0,%1;"
                     " sync;"
                     " isync;"
                     " lwz %0,0(%1);"
                     " isync" : "=r" (tmp) : "r" (end) : "memory");
}

static void dart_flush(struct iommu_table *tbl)
{
        mb();
        if (dart_dirty) {
                dart_tlb_invalidate_all();
                dart_dirty = 0;
        }
}

static int dart_build(struct iommu_table *tbl, long index,
                       long npages, unsigned long uaddr,
                       enum dma_data_direction direction,
                       unsigned long attrs)
{
        unsigned int *dp, *orig_dp;
        unsigned int rpn;
        long l;

        DBG("dart: build at: %lx, %lx, addr: %x\n", index, npages, uaddr);

        orig_dp = dp = ((unsigned int*)tbl->it_base) + index;

        /* On U3, all memory is contiguous, so we can move this
         * out of the loop.
         */
        l = npages;
        while (l--) {
                rpn = __pa(uaddr) >> DART_PAGE_SHIFT;

                *(dp++) = DARTMAP_VALID | (rpn & DARTMAP_RPNMASK);

                uaddr += DART_PAGE_SIZE;
        }
        dart_cache_sync(orig_dp, npages);

        if (dart_is_u4) {
                rpn = index;
                while (npages--)
                        dart_tlb_invalidate_one(rpn++);
        } else {
                dart_dirty = 1;
        }
        return 0;
}


static void dart_free(struct iommu_table *tbl, long index, long npages)
{
        unsigned int *dp, *orig_dp;
        long orig_npages = npages;

        /* We don't worry about flushing the TLB cache. The only drawback of
         * not doing it is that we won't catch buggy device drivers doing
         * bad DMAs, but then no 32-bit architecture ever does either.
         */

        DBG("dart: free at: %lx, %lx\n", index, npages);

        orig_dp = dp  = ((unsigned int *)tbl->it_base) + index;

        while (npages--)
                *(dp++) = dart_emptyval;

        dart_cache_sync(orig_dp, orig_npages);
}

static void allocate_dart(void)
{
        unsigned long tmp;

        /* 512 pages (2MB) is max DART tablesize. */
        dart_tablesize = 1UL << 21;

        /*
         * 16MB (1 << 24) alignment. We allocate a full 16Mb chuck since we
         * will blow up an entire large page anyway in the kernel mapping.
         */
        dart_tablebase = memblock_alloc_try_nid_raw(SZ_16M, SZ_16M,
                                        MEMBLOCK_LOW_LIMIT, SZ_2G,
                                        NUMA_NO_NODE);
        if (!dart_tablebase)
                panic("Failed to allocate 16MB below 2GB for DART table\n");

        /* There is no point scanning the DART space for leaks*/
        kmemleak_no_scan((void *)dart_tablebase);

        /* Allocate a spare page to map all invalid DART pages. We need to do
         * that to work around what looks like a problem with the HT bridge
         * prefetching into invalid pages and corrupting data
         */
        tmp = memblock_phys_alloc(DART_PAGE_SIZE, DART_PAGE_SIZE);
        if (!tmp)
                panic("DART: table allocation failed\n");

        dart_emptyval = DARTMAP_VALID | ((tmp >> DART_PAGE_SHIFT) &
                                         DARTMAP_RPNMASK);

        printk(KERN_INFO "DART table allocated at: %p\n", dart_tablebase);
}

static int __init dart_init(struct device_node *dart_node)
{
        unsigned int i;
        unsigned long base, size;
        struct resource r;

        /* IOMMU disabled by the user ? bail out */
        if (iommu_is_off)
                return -ENODEV;

        /*
         * Only use the DART if the machine has more than 1GB of RAM
         * or if requested with iommu=on on cmdline.
         *
         * 1GB of RAM is picked as limit because some default devices
         * (i.e. Airport Extreme) have 30 bit address range limits.
         */

        if (!iommu_force_on && memblock_end_of_DRAM() <= 0x40000000ull)
                return -ENODEV;

        /* Get DART registers */
        if (of_address_to_resource(dart_node, 0, &r))
                panic("DART: can't get register base ! ");

        /* Map in DART registers */
        dart = ioremap(r.start, resource_size(&r));
        if (dart == NULL)
                panic("DART: Cannot map registers!");

        /* Allocate the DART and dummy page */
        allocate_dart();

        /* Fill initial table */
        for (i = 0; i < dart_tablesize/4; i++)
                dart_tablebase[i] = dart_emptyval;

        /* Push to memory */
        dart_cache_sync(dart_tablebase, dart_tablesize / sizeof(u32));

        /* Initialize DART with table base and enable it. */
        base = ((unsigned long)dart_tablebase) >> DART_PAGE_SHIFT;
        size = dart_tablesize >> DART_PAGE_SHIFT;
        if (dart_is_u4) {
                size &= DART_SIZE_U4_SIZE_MASK;
                DART_OUT(DART_BASE_U4, base);
                DART_OUT(DART_SIZE_U4, size);
                DART_OUT(DART_CNTL, DART_CNTL_U4_ENABLE);
        } else {
                size &= DART_CNTL_U3_SIZE_MASK;
                DART_OUT(DART_CNTL,
                         DART_CNTL_U3_ENABLE |
                         (base << DART_CNTL_U3_BASE_SHIFT) |
                         (size << DART_CNTL_U3_SIZE_SHIFT));
        }

        /* Invalidate DART to get rid of possible stale TLBs */
        dart_tlb_invalidate_all();

        printk(KERN_INFO "DART IOMMU initialized for %s type chipset\n",
               dart_is_u4 ? "U4" : "U3");

        return 0;
}

static struct iommu_table_ops iommu_dart_ops = {
        .set = dart_build,
        .clear = dart_free,
        .flush = dart_flush,
};

static void iommu_table_dart_setup(void)
{
        iommu_table_dart.it_busno = 0;
        iommu_table_dart.it_offset = 0;
        /* it_size is in number of entries */
        iommu_table_dart.it_size = dart_tablesize / sizeof(u32);
        iommu_table_dart.it_page_shift = IOMMU_PAGE_SHIFT_4K;

        /* Initialize the common IOMMU code */
        iommu_table_dart.it_base = (unsigned long)dart_tablebase;
        iommu_table_dart.it_index = 0;
        iommu_table_dart.it_blocksize = 1;
        iommu_table_dart.it_ops = &iommu_dart_ops;
        if (!iommu_init_table(&iommu_table_dart, -1, 0, 0))
                panic("Failed to initialize iommu table");

        /* Reserve the last page of the DART to avoid possible prefetch
         * past the DART mapped area
         */
        set_bit(iommu_table_dart.it_size - 1, iommu_table_dart.it_map);
}

static void pci_dma_bus_setup_dart(struct pci_bus *bus)
{
        if (!iommu_table_dart_inited) {
                iommu_table_dart_inited = 1;
                iommu_table_dart_setup();
        }
}

static bool dart_device_on_pcie(struct device *dev)
{
        struct device_node *np = of_node_get(dev->of_node);

        while(np) {
                if (of_device_is_compatible(np, "U4-pcie") ||
                    of_device_is_compatible(np, "u4-pcie")) {
                        of_node_put(np);
                        return true;
                }
                np = of_get_next_parent(np);
        }
        return false;
}

static void pci_dma_dev_setup_dart(struct pci_dev *dev)
{
        if (dart_is_u4 && dart_device_on_pcie(&dev->dev))
                dev->dev.archdata.dma_offset = DART_U4_BYPASS_BASE;
        set_iommu_table_base(&dev->dev, &iommu_table_dart);
}

static bool iommu_bypass_supported_dart(struct pci_dev *dev, u64 mask)
{
        return dart_is_u4 &&
                dart_device_on_pcie(&dev->dev) &&
                mask >= DMA_BIT_MASK(40);
}

void __init iommu_init_early_dart(struct pci_controller_ops *controller_ops)
{
        struct device_node *dn;

        /* Find the DART in the device-tree */
        dn = of_find_compatible_node(NULL, "dart", "u3-dart");
        if (dn == NULL) {
                dn = of_find_compatible_node(NULL, "dart", "u4-dart");
                if (dn == NULL)
                        return; /* use default direct_dma_ops */
                dart_is_u4 = 1;
        }

        /* Initialize the DART HW */
        if (dart_init(dn) != 0)
                return;

        /*
         * U4 supports a DART bypass, we use it for 64-bit capable devices to
         * improve performance.  However, that only works for devices connected
         * to the U4 own PCIe interface, not bridged through hypertransport.
         * We need the device to support at least 40 bits of addresses.
         */
        controller_ops->dma_dev_setup = pci_dma_dev_setup_dart;
        controller_ops->dma_bus_setup = pci_dma_bus_setup_dart;
        controller_ops->iommu_bypass_supported = iommu_bypass_supported_dart;

        /* Setup pci_dma ops */
        set_pci_dma_ops(&dma_iommu_ops);
}

#ifdef CONFIG_PM
static void iommu_dart_restore(void)
{
        dart_cache_sync(dart_tablebase, dart_tablesize / sizeof(u32));
        dart_tlb_invalidate_all();
}

static int __init iommu_init_late_dart(void)
{
        if (!dart_tablebase)
                return 0;

        ppc_md.iommu_restore = iommu_dart_restore;

        return 0;
}

late_initcall(iommu_init_late_dart);
#endif /* CONFIG_PM */