/*
 * For documentation on the i460 AGP interface, see Chapter 7 (AGP Subsystem) of
 * the "Intel 460GTX Chipset Software Developer's Manual":
 * http://www.intel.com/design/archives/itanium/downloads/248704.htm 
 */
/*
 * 460GX support by Chris Ahna <christopher.j.ahna@intel.com>
 * Clean up & simplification by David Mosberger-Tang <davidm@hpl.hp.com>
 */
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/agp_backend.h>
#include <linux/log2.h>

#include "agp.h"

#define INTEL_I460_BAPBASE              0x98
#define INTEL_I460_GXBCTL               0xa0
#define INTEL_I460_AGPSIZ               0xa2
#define INTEL_I460_ATTBASE              0xfe200000
#define INTEL_I460_GATT_VALID           (1UL << 24)
#define INTEL_I460_GATT_COHERENT        (1UL << 25)

/*
 * The i460 can operate with large (4MB) pages, but there is no sane way to support this
 * within the current kernel/DRM environment, so we disable the relevant code for now.
 * See also comments in ia64_alloc_page()...
 */
#define I460_LARGE_IO_PAGES             0

#if I460_LARGE_IO_PAGES
# define I460_IO_PAGE_SHIFT             i460.io_page_shift
#else
# define I460_IO_PAGE_SHIFT             12
#endif

#define I460_IOPAGES_PER_KPAGE          (PAGE_SIZE >> I460_IO_PAGE_SHIFT)
#define I460_KPAGES_PER_IOPAGE          (1 << (I460_IO_PAGE_SHIFT - PAGE_SHIFT))
#define I460_SRAM_IO_DISABLE            (1 << 4)
#define I460_BAPBASE_ENABLE             (1 << 3)
#define I460_AGPSIZ_MASK                0x7
#define I460_4M_PS                      (1 << 1)

/* Control bits for Out-Of-GART coherency and Burst Write Combining */
#define I460_GXBCTL_OOG         (1UL << 0)
#define I460_GXBCTL_BWC         (1UL << 2)

/*
 * gatt_table entries are 32-bits wide on the i460; the generic code ought to declare the
 * gatt_table and gatt_table_real pointers a "void *"...
 */
#define RD_GATT(index)          readl((u32 *) i460.gatt + (index))
#define WR_GATT(index, val)     writel((val), (u32 *) i460.gatt + (index))
/*
 * The 460 spec says we have to read the last location written to make sure that all
 * writes have taken effect
 */
#define WR_FLUSH_GATT(index)    RD_GATT(index)

static unsigned long i460_mask_memory (struct agp_bridge_data *bridge,
                                       dma_addr_t addr, int type);

static struct {
        void *gatt;                             /* ioremap'd GATT area */

        /* i460 supports multiple GART page sizes, so GART pageshift is dynamic: */
        u8 io_page_shift;

        /* BIOS configures chipset to one of 2 possible apbase values: */
        u8 dynamic_apbase;

        /* structure for tracking partial use of 4MB GART pages: */
        struct lp_desc {
                unsigned long *alloced_map;     /* bitmap of kernel-pages in use */
                int refcount;                   /* number of kernel pages using the large page */
                u64 paddr;                      /* physical address of large page */
                struct page *page;              /* page pointer */
        } *lp_desc;
} i460;

static const struct aper_size_info_8 i460_sizes[3] =
{
        /*
         * The 32GB aperture is only available with a 4M GART page size.  Due to the
         * dynamic GART page size, we can't figure out page_order or num_entries until
         * runtime.
         */
        {32768, 0, 0, 4},
        {1024, 0, 0, 2},
        {256, 0, 0, 1}
};

static struct gatt_mask i460_masks[] =
{
        {
          .mask = INTEL_I460_GATT_VALID | INTEL_I460_GATT_COHERENT,
          .type = 0
        }
};

static int i460_fetch_size (void)
{
        int i;
        u8 temp;
        struct aper_size_info_8 *values;

        /* Determine the GART page size */
        pci_read_config_byte(agp_bridge->dev, INTEL_I460_GXBCTL, &temp);
        i460.io_page_shift = (temp & I460_4M_PS) ? 22 : 12;
        pr_debug("i460_fetch_size: io_page_shift=%d\n", i460.io_page_shift);

        if (i460.io_page_shift != I460_IO_PAGE_SHIFT) {
                printk(KERN_ERR PFX
                        "I/O (GART) page-size %luKB doesn't match expected "
                                "size %luKB\n",
                        1UL << (i460.io_page_shift - 10),
                        1UL << (I460_IO_PAGE_SHIFT));
                return 0;
        }

        values = A_SIZE_8(agp_bridge->driver->aperture_sizes);

        pci_read_config_byte(agp_bridge->dev, INTEL_I460_AGPSIZ, &temp);

        /* Exit now if the IO drivers for the GART SRAMS are turned off */
        if (temp & I460_SRAM_IO_DISABLE) {
                printk(KERN_ERR PFX "GART SRAMS disabled on 460GX chipset\n");
                printk(KERN_ERR PFX "AGPGART operation not possible\n");
                return 0;
        }

        /* Make sure we don't try to create an 2 ^ 23 entry GATT */
        if ((i460.io_page_shift == 0) && ((temp & I460_AGPSIZ_MASK) == 4)) {
                printk(KERN_ERR PFX "We can't have a 32GB aperture with 4KB GART pages\n");
                return 0;
        }

        /* Determine the proper APBASE register */
        if (temp & I460_BAPBASE_ENABLE)
                i460.dynamic_apbase = INTEL_I460_BAPBASE;
        else
                i460.dynamic_apbase = AGP_APBASE;

        for (i = 0; i < agp_bridge->driver->num_aperture_sizes; i++) {
                /*
                 * Dynamically calculate the proper num_entries and page_order values for
                 * the define aperture sizes. Take care not to shift off the end of
                 * values[i].size.
                 */
                values[i].num_entries = (values[i].size << 8) >> (I460_IO_PAGE_SHIFT - 12);
                values[i].page_order = ilog2((sizeof(u32)*values[i].num_entries) >> PAGE_SHIFT);
        }

        for (i = 0; i < agp_bridge->driver->num_aperture_sizes; i++) {
                /* Neglect control bits when matching up size_value */
                if ((temp & I460_AGPSIZ_MASK) == values[i].size_value) {
                        agp_bridge->previous_size = agp_bridge->current_size = (void *) (values + i);
                        agp_bridge->aperture_size_idx = i;
                        return values[i].size;
                }
        }

        return 0;
}

/* There isn't anything to do here since 460 has no GART TLB. */
static void i460_tlb_flush (struct agp_memory *mem)
{
        return;
}

/*
 * This utility function is needed to prevent corruption of the control bits
 * which are stored along with the aperture size in 460's AGPSIZ register
 */
static void i460_write_agpsiz (u8 size_value)
{
        u8 temp;

        pci_read_config_byte(agp_bridge->dev, INTEL_I460_AGPSIZ, &temp);
        pci_write_config_byte(agp_bridge->dev, INTEL_I460_AGPSIZ,
                              ((temp & ~I460_AGPSIZ_MASK) | size_value));
}

static void i460_cleanup (void)
{
        struct aper_size_info_8 *previous_size;

        previous_size = A_SIZE_8(agp_bridge->previous_size);
        i460_write_agpsiz(previous_size->size_value);

        if (I460_IO_PAGE_SHIFT > PAGE_SHIFT)
                kfree(i460.lp_desc);
}

static int i460_configure (void)
{
        union {
                u32 small[2];
                u64 large;
        } temp;
        size_t size;
        u8 scratch;
        struct aper_size_info_8 *current_size;

        temp.large = 0;

        current_size = A_SIZE_8(agp_bridge->current_size);
        i460_write_agpsiz(current_size->size_value);

        /*
         * Do the necessary rigmarole to read all eight bytes of APBASE.
         * This has to be done since the AGP aperture can be above 4GB on
         * 460 based systems.
         */
        pci_read_config_dword(agp_bridge->dev, i460.dynamic_apbase, &(temp.small[0]));
        pci_read_config_dword(agp_bridge->dev, i460.dynamic_apbase + 4, &(temp.small[1]));

        /* Clear BAR control bits */
        agp_bridge->gart_bus_addr = temp.large & ~((1UL << 3) - 1);

        pci_read_config_byte(agp_bridge->dev, INTEL_I460_GXBCTL, &scratch);
        pci_write_config_byte(agp_bridge->dev, INTEL_I460_GXBCTL,
                              (scratch & 0x02) | I460_GXBCTL_OOG | I460_GXBCTL_BWC);

        /*
         * Initialize partial allocation trackers if a GART page is bigger than a kernel
         * page.
         */
        if (I460_IO_PAGE_SHIFT > PAGE_SHIFT) {
                size = current_size->num_entries * sizeof(i460.lp_desc[0]);
                i460.lp_desc = kzalloc(size, GFP_KERNEL);
                if (!i460.lp_desc)
                        return -ENOMEM;
        }
        return 0;
}

static int i460_create_gatt_table (struct agp_bridge_data *bridge)
{
        int page_order, num_entries, i;
        void *temp;

        /*
         * Load up the fixed address of the GART SRAMS which hold our GATT table.
         */
        temp = agp_bridge->current_size;
        page_order = A_SIZE_8(temp)->page_order;
        num_entries = A_SIZE_8(temp)->num_entries;

        i460.gatt = ioremap(INTEL_I460_ATTBASE, PAGE_SIZE << page_order);
        if (!i460.gatt) {
                printk(KERN_ERR PFX "ioremap failed\n");
                return -ENOMEM;
        }

        /* These are no good, the should be removed from the agp_bridge strucure... */
        agp_bridge->gatt_table_real = NULL;
        agp_bridge->gatt_table = NULL;
        agp_bridge->gatt_bus_addr = 0;

        for (i = 0; i < num_entries; ++i)
                WR_GATT(i, 0);
        WR_FLUSH_GATT(i - 1);
        return 0;
}

static int i460_free_gatt_table (struct agp_bridge_data *bridge)
{
        int num_entries, i;
        void *temp;

        temp = agp_bridge->current_size;

        num_entries = A_SIZE_8(temp)->num_entries;

        for (i = 0; i < num_entries; ++i)
                WR_GATT(i, 0);
        WR_FLUSH_GATT(num_entries - 1);

        iounmap(i460.gatt);
        return 0;
}

/*
 * The following functions are called when the I/O (GART) page size is smaller than
 * PAGE_SIZE.
 */

static int i460_insert_memory_small_io_page (struct agp_memory *mem,
                                off_t pg_start, int type)
{
        unsigned long paddr, io_pg_start, io_page_size;
        int i, j, k, num_entries;
        void *temp;

        pr_debug("i460_insert_memory_small_io_page(mem=%p, pg_start=%ld, type=%d, paddr0=0x%lx)\n",
                 mem, pg_start, type, page_to_phys(mem->pages[0]));

        if (type >= AGP_USER_TYPES || mem->type >= AGP_USER_TYPES)
                return -EINVAL;

        io_pg_start = I460_IOPAGES_PER_KPAGE * pg_start;

        temp = agp_bridge->current_size;
        num_entries = A_SIZE_8(temp)->num_entries;

        if ((io_pg_start + I460_IOPAGES_PER_KPAGE * mem->page_count) > num_entries) {
                printk(KERN_ERR PFX "Looks like we're out of AGP memory\n");
                return -EINVAL;
        }

        j = io_pg_start;
        while (j < (io_pg_start + I460_IOPAGES_PER_KPAGE * mem->page_count)) {
                if (!PGE_EMPTY(agp_bridge, RD_GATT(j))) {
                        pr_debug("i460_insert_memory_small_io_page: GATT[%d]=0x%x is busy\n",
                                 j, RD_GATT(j));
                        return -EBUSY;
                }
                j++;
        }

        io_page_size = 1UL << I460_IO_PAGE_SHIFT;
        for (i = 0, j = io_pg_start; i < mem->page_count; i++) {
                paddr = page_to_phys(mem->pages[i]);
                for (k = 0; k < I460_IOPAGES_PER_KPAGE; k++, j++, paddr += io_page_size)
                        WR_GATT(j, i460_mask_memory(agp_bridge, paddr, mem->type));
        }
        WR_FLUSH_GATT(j - 1);
        return 0;
}

static int i460_remove_memory_small_io_page(struct agp_memory *mem,
                                off_t pg_start, int type)
{
        int i;

        pr_debug("i460_remove_memory_small_io_page(mem=%p, pg_start=%ld, type=%d)\n",
                 mem, pg_start, type);

        pg_start = I460_IOPAGES_PER_KPAGE * pg_start;

        for (i = pg_start; i < (pg_start + I460_IOPAGES_PER_KPAGE * mem->page_count); i++)
                WR_GATT(i, 0);
        WR_FLUSH_GATT(i - 1);
        return 0;
}

#if I460_LARGE_IO_PAGES

/*
 * These functions are called when the I/O (GART) page size exceeds PAGE_SIZE.
 *
 * This situation is interesting since AGP memory allocations that are smaller than a
 * single GART page are possible.  The i460.lp_desc array tracks partial allocation of the
 * large GART pages to work around this issue.
 *
 * i460.lp_desc[pg_num].refcount tracks the number of kernel pages in use within GART page
 * pg_num.  i460.lp_desc[pg_num].paddr is the physical address of the large page and
 * i460.lp_desc[pg_num].alloced_map is a bitmap of kernel pages that are in use (allocated).
 */

static int i460_alloc_large_page (struct lp_desc *lp)
{
        unsigned long order = I460_IO_PAGE_SHIFT - PAGE_SHIFT;
        size_t map_size;

        lp->page = alloc_pages(GFP_KERNEL, order);
        if (!lp->page) {
                printk(KERN_ERR PFX "Couldn't alloc 4M GART page...\n");
                return -ENOMEM;
        }

        map_size = ((I460_KPAGES_PER_IOPAGE + BITS_PER_LONG - 1) & -BITS_PER_LONG)/8;
        lp->alloced_map = kzalloc(map_size, GFP_KERNEL);
        if (!lp->alloced_map) {
                __free_pages(lp->page, order);
                printk(KERN_ERR PFX "Out of memory, we're in trouble...\n");
                return -ENOMEM;
        }

        lp->paddr = page_to_phys(lp->page);
        lp->refcount = 0;
        atomic_add(I460_KPAGES_PER_IOPAGE, &agp_bridge->current_memory_agp);
        return 0;
}

static void i460_free_large_page (struct lp_desc *lp)
{
        kfree(lp->alloced_map);
        lp->alloced_map = NULL;

        __free_pages(lp->page, I460_IO_PAGE_SHIFT - PAGE_SHIFT);
        atomic_sub(I460_KPAGES_PER_IOPAGE, &agp_bridge->current_memory_agp);
}

static int i460_insert_memory_large_io_page (struct agp_memory *mem,
                                off_t pg_start, int type)
{
        int i, start_offset, end_offset, idx, pg, num_entries;
        struct lp_desc *start, *end, *lp;
        void *temp;

        if (type >= AGP_USER_TYPES || mem->type >= AGP_USER_TYPES)
                return -EINVAL;

        temp = agp_bridge->current_size;
        num_entries = A_SIZE_8(temp)->num_entries;

        /* Figure out what pg_start means in terms of our large GART pages */
        start = &i460.lp_desc[pg_start / I460_KPAGES_PER_IOPAGE];
        end = &i460.lp_desc[(pg_start + mem->page_count - 1) / I460_KPAGES_PER_IOPAGE];
        start_offset = pg_start % I460_KPAGES_PER_IOPAGE;
        end_offset = (pg_start + mem->page_count - 1) % I460_KPAGES_PER_IOPAGE;

        if (end > i460.lp_desc + num_entries) {
                printk(KERN_ERR PFX "Looks like we're out of AGP memory\n");
                return -EINVAL;
        }

        /* Check if the requested region of the aperture is free */
        for (lp = start; lp <= end; ++lp) {
                if (!lp->alloced_map)
                        continue;       /* OK, the entire large page is available... */

                for (idx = ((lp == start) ? start_offset : 0);
                     idx < ((lp == end) ? (end_offset + 1) : I460_KPAGES_PER_IOPAGE);
                     idx++)
                {
                        if (test_bit(idx, lp->alloced_map))
                                return -EBUSY;
                }
        }

        for (lp = start, i = 0; lp <= end; ++lp) {
                if (!lp->alloced_map) {
                        /* Allocate new GART pages... */
                        if (i460_alloc_large_page(lp) < 0)
                                return -ENOMEM;
                        pg = lp - i460.lp_desc;
                        WR_GATT(pg, i460_mask_memory(agp_bridge,
                                                     lp->paddr, 0));
                        WR_FLUSH_GATT(pg);
                }

                for (idx = ((lp == start) ? start_offset : 0);
                     idx < ((lp == end) ? (end_offset + 1) : I460_KPAGES_PER_IOPAGE);
                     idx++, i++)
                {
                        mem->pages[i] = lp->page;
                        __set_bit(idx, lp->alloced_map);
                        ++lp->refcount;
                }
        }
        return 0;
}

static int i460_remove_memory_large_io_page (struct agp_memory *mem,
                                off_t pg_start, int type)
{
        int i, pg, start_offset, end_offset, idx, num_entries;
        struct lp_desc *start, *end, *lp;
        void *temp;

        temp = agp_bridge->current_size;
        num_entries = A_SIZE_8(temp)->num_entries;

        /* Figure out what pg_start means in terms of our large GART pages */
        start = &i460.lp_desc[pg_start / I460_KPAGES_PER_IOPAGE];
        end = &i460.lp_desc[(pg_start + mem->page_count - 1) / I460_KPAGES_PER_IOPAGE];
        start_offset = pg_start % I460_KPAGES_PER_IOPAGE;
        end_offset = (pg_start + mem->page_count - 1) % I460_KPAGES_PER_IOPAGE;

        for (i = 0, lp = start; lp <= end; ++lp) {
                for (idx = ((lp == start) ? start_offset : 0);
                     idx < ((lp == end) ? (end_offset + 1) : I460_KPAGES_PER_IOPAGE);
                     idx++, i++)
                {
                        mem->pages[i] = NULL;
                        __clear_bit(idx, lp->alloced_map);
                        --lp->refcount;
                }

                /* Free GART pages if they are unused */
                if (lp->refcount == 0) {
                        pg = lp - i460.lp_desc;
                        WR_GATT(pg, 0);
                        WR_FLUSH_GATT(pg);
                        i460_free_large_page(lp);
                }
        }
        return 0;
}

/* Wrapper routines to call the approriate {small_io_page,large_io_page} function */

static int i460_insert_memory (struct agp_memory *mem,
                                off_t pg_start, int type)
{
        if (I460_IO_PAGE_SHIFT <= PAGE_SHIFT)
                return i460_insert_memory_small_io_page(mem, pg_start, type);
        else
                return i460_insert_memory_large_io_page(mem, pg_start, type);
}

static int i460_remove_memory (struct agp_memory *mem,
                                off_t pg_start, int type)
{
        if (I460_IO_PAGE_SHIFT <= PAGE_SHIFT)
                return i460_remove_memory_small_io_page(mem, pg_start, type);
        else
                return i460_remove_memory_large_io_page(mem, pg_start, type);
}

/*
 * If the I/O (GART) page size is bigger than the kernel page size, we don't want to
 * allocate memory until we know where it is to be bound in the aperture (a
 * multi-kernel-page alloc might fit inside of an already allocated GART page).
 *
 * Let's just hope nobody counts on the allocated AGP memory being there before bind time
 * (I don't think current drivers do)...
 */
static struct page *i460_alloc_page (struct agp_bridge_data *bridge)
{
        void *page;

        if (I460_IO_PAGE_SHIFT <= PAGE_SHIFT) {
                page = agp_generic_alloc_page(agp_bridge);
        } else
                /* Returning NULL would cause problems */
                /* AK: really dubious code. */
                page = (void *)~0UL;
        return page;
}

static void i460_destroy_page (struct page *page, int flags)
{
        if (I460_IO_PAGE_SHIFT <= PAGE_SHIFT) {
                agp_generic_destroy_page(page, flags);
        }
}

#endif /* I460_LARGE_IO_PAGES */

static unsigned long i460_mask_memory (struct agp_bridge_data *bridge,
                                       dma_addr_t addr, int type)
{
        /* Make sure the returned address is a valid GATT entry */
        return bridge->driver->masks[0].mask
                | (((addr & ~((1 << I460_IO_PAGE_SHIFT) - 1)) & 0xfffff000) >> 12);
}

const struct agp_bridge_driver intel_i460_driver = {
        .owner                  = THIS_MODULE,
        .aperture_sizes         = i460_sizes,
        .size_type              = U8_APER_SIZE,
        .num_aperture_sizes     = 3,
        .configure              = i460_configure,
        .fetch_size             = i460_fetch_size,
        .cleanup                = i460_cleanup,
        .tlb_flush              = i460_tlb_flush,
        .mask_memory            = i460_mask_memory,
        .masks                  = i460_masks,
        .agp_enable             = agp_generic_enable,
        .cache_flush            = global_cache_flush,
        .create_gatt_table      = i460_create_gatt_table,
        .free_gatt_table        = i460_free_gatt_table,
#if I460_LARGE_IO_PAGES
        .insert_memory          = i460_insert_memory,
        .remove_memory          = i460_remove_memory,
        .agp_alloc_page         = i460_alloc_page,
        .agp_destroy_page       = i460_destroy_page,
#else
        .insert_memory          = i460_insert_memory_small_io_page,
        .remove_memory          = i460_remove_memory_small_io_page,
        .agp_alloc_page         = agp_generic_alloc_page,
        .agp_alloc_pages        = agp_generic_alloc_pages,
        .agp_destroy_page       = agp_generic_destroy_page,
        .agp_destroy_pages      = agp_generic_destroy_pages,
#endif
        .alloc_by_type          = agp_generic_alloc_by_type,
        .free_by_type           = agp_generic_free_by_type,
        .agp_type_to_mask_type  = agp_generic_type_to_mask_type,
        .cant_use_aperture      = true,
};

static int agp_intel_i460_probe(struct pci_dev *pdev,
                                const struct pci_device_id *ent)
{
        struct agp_bridge_data *bridge;
        u8 cap_ptr;

        cap_ptr = pci_find_capability(pdev, PCI_CAP_ID_AGP);
        if (!cap_ptr)
                return -ENODEV;

        bridge = agp_alloc_bridge();
        if (!bridge)
                return -ENOMEM;

        bridge->driver = &intel_i460_driver;
        bridge->dev = pdev;
        bridge->capndx = cap_ptr;

        printk(KERN_INFO PFX "Detected Intel 460GX chipset\n");

        pci_set_drvdata(pdev, bridge);
        return agp_add_bridge(bridge);
}

static void agp_intel_i460_remove(struct pci_dev *pdev)
{
        struct agp_bridge_data *bridge = pci_get_drvdata(pdev);

        agp_remove_bridge(bridge);
        agp_put_bridge(bridge);
}

static struct pci_device_id agp_intel_i460_pci_table[] = {
        {
        .class          = (PCI_CLASS_BRIDGE_HOST << 8),
        .class_mask     = ~0,
        .vendor         = PCI_VENDOR_ID_INTEL,
        .device         = PCI_DEVICE_ID_INTEL_84460GX,
        .subvendor      = PCI_ANY_ID,
        .subdevice      = PCI_ANY_ID,
        },
        { }
};

MODULE_DEVICE_TABLE(pci, agp_intel_i460_pci_table);

static struct pci_driver agp_intel_i460_pci_driver = {
        .name           = "agpgart-intel-i460",
        .id_table       = agp_intel_i460_pci_table,
        .probe          = agp_intel_i460_probe,
        .remove         = agp_intel_i460_remove,
};

static int __init agp_intel_i460_init(void)
{
        if (agp_off)
                return -EINVAL;
        return pci_register_driver(&agp_intel_i460_pci_driver);
}

static void __exit agp_intel_i460_cleanup(void)
{
        pci_unregister_driver(&agp_intel_i460_pci_driver);
}

module_init(agp_intel_i460_init);
module_exit(agp_intel_i460_cleanup);

MODULE_AUTHOR("Chris Ahna <Christopher.J.Ahna@intel.com>");
MODULE_LICENSE("GPL and additional rights");