/*
 * 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.
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#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 <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"

/* Physical base address and size of the DART table */
unsigned long dart_tablebase; /* exported to htab_initialize */
static unsigned long dart_tablesize;

/* Virtual base address of the DART table */
static u32 *dart_vbase;
#ifdef CONFIG_PM
static u32 *dart_copy;
#endif

/* 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_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,
		       struct dma_attrs *attrs)
{
	unsigned int *dp;
	unsigned int rpn;
	long l;

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

	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;
	}

	/* make sure all updates have reached memory */
	mb();
	in_be32((unsigned __iomem *)dp);
	mb();

	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;

	/* 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);

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

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


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

	if (dart_tablebase == 0 || dart_tablesize == 0) {
		printk(KERN_INFO "DART: table not allocated, using "
		       "direct DMA\n");
		return -ENODEV;
	}

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

	/* Make sure nothing from the DART range remains in the CPU cache
	 * from a previous mapping that existed before the kernel took
	 * over
	 */
	flush_dcache_phys_range(dart_tablebase,
				dart_tablebase + dart_tablesize);

	/* 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_alloc(DART_PAGE_SIZE, DART_PAGE_SIZE);
	dart_emptyval = DARTMAP_VALID | ((tmp >> DART_PAGE_SHIFT) &
					 DARTMAP_RPNMASK);

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

	/* Map in DART table */
	dart_vbase = ioremap(__pa(dart_tablebase), dart_tablesize);

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

	/* Initialize DART with table base and enable it. */
	base = 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 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_vbase;
	iommu_table_dart.it_index = 0;
	iommu_table_dart.it_blocksize = 1;
	iommu_init_table(&iommu_table_dart, -1);

	/* 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 dma_dev_setup_dart(struct device *dev)
{
	/* We only have one iommu table on the mac for now, which makes
	 * things simple. Setup all PCI devices to point to this table
	 */
	if (get_dma_ops(dev) == &dma_direct_ops)
		set_dma_offset(dev, DART_U4_BYPASS_BASE);
	else
		set_iommu_table_base(dev, &iommu_table_dart);
}

static void pci_dma_dev_setup_dart(struct pci_dev *dev)
{
	dma_dev_setup_dart(&dev->dev);
}

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 int dart_dma_set_mask(struct device *dev, u64 dma_mask)
{
	if (!dev->dma_mask || !dma_supported(dev, dma_mask))
		return -EIO;

	/* U4 supports a DART bypass, we use it for 64-bit capable
	 * devices to improve performances. However, that only works
	 * for devices connected to U4 own PCIe interface, not bridged
	 * through hypertransport. We need the device to support at
	 * least 40 bits of addresses.
	 */
	if (dart_device_on_pcie(dev) && dma_mask >= DMA_BIT_MASK(40)) {
		dev_info(dev, "Using 64-bit DMA iommu bypass\n");
		set_dma_ops(dev, &dma_direct_ops);
	} else {
		dev_info(dev, "Using 32-bit DMA via iommu\n");
		set_dma_ops(dev, &dma_iommu_ops);
	}
	dma_dev_setup_dart(dev);

	*dev->dma_mask = dma_mask;
	return 0;
}

void __init iommu_init_early_dart(void)
{
	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)
		goto bail;

	/* Setup low level TCE operations for the core IOMMU code */
	ppc_md.tce_build = dart_build;
	ppc_md.tce_free  = dart_free;
	ppc_md.tce_flush = dart_flush;

	/* Setup bypass if supported */
	if (dart_is_u4)
		ppc_md.dma_set_mask = dart_dma_set_mask;

	ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_dart;
	ppc_md.pci_dma_bus_setup = pci_dma_bus_setup_dart;

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

 bail:
	/* If init failed, use direct iommu and null setup functions */
	ppc_md.pci_dma_dev_setup = NULL;
	ppc_md.pci_dma_bus_setup = NULL;

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

#ifdef CONFIG_PM
static void iommu_dart_save(void)
{
	memcpy(dart_copy, dart_vbase, 2*1024*1024);
}

static void iommu_dart_restore(void)
{
	memcpy(dart_vbase, dart_copy, 2*1024*1024);
	dart_tlb_invalidate_all();
}

static int __init iommu_init_late_dart(void)
{
	unsigned long tbasepfn;
	struct page *p;

	/* if no dart table exists then we won't need to save it
	 * and the area has also not been reserved */
	if (!dart_tablebase)
		return 0;

	tbasepfn = __pa(dart_tablebase) >> PAGE_SHIFT;
	register_nosave_region_late(tbasepfn,
				    tbasepfn + ((1<<24) >> PAGE_SHIFT));

	/* For suspend we need to copy the dart contents because
	 * it is not part of the regular mapping (see above) and
	 * thus not saved automatically. The memory for this copy
	 * must be allocated early because we need 2 MB. */
	p = alloc_pages(GFP_KERNEL, 21 - PAGE_SHIFT);
	BUG_ON(!p);
	dart_copy = page_address(p);

	ppc_md.iommu_save = iommu_dart_save;
	ppc_md.iommu_restore = iommu_dart_restore;

	return 0;
}

late_initcall(iommu_init_late_dart);
#endif

void __init alloc_dart_table(void)
{
	/* Only reserve DART space if 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_is_off)
		return;

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

	/* 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 = (unsigned long)
		__va(memblock_alloc_base(1UL<<24, 1UL<<24, 0x80000000L));
	/*
	 * The DART space is later unmapped from the kernel linear mapping and
	 * accessing dart_tablebase during kmemleak scanning will fault.
	 */
	kmemleak_no_scan((void *)dart_tablebase);

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