dma-swiotlb.c

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/*
 * Contains routines needed to support swiotlb for ppc.
 *
 * Copyright (C) 2009-2010 Freescale Semiconductor, Inc.
 * Author: Becky Bruce
 *
 * 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.
 *
 */

#include <linux/dma-mapping.h>
#include <linux/memblock.h>
#include <linux/pfn.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pci.h>

#include <asm/machdep.h>
#include <asm/swiotlb.h>
#include <asm/dma.h>

unsigned int ppc_swiotlb_enable;

static u64 swiotlb_powerpc_get_required(struct device *dev)
{
    u64 end, mask, max_direct_dma_addr = dev->archdata.max_direct_dma_addr;

    end = memblock_end_of_DRAM();
    if (max_direct_dma_addr && end > max_direct_dma_addr)
        end = max_direct_dma_addr;
    end += get_dma_offset(dev);

    mask = 1ULL << (fls64(end) - 1);
    mask += mask - 1;

    return mask;
}

/*
 * At the moment, all platforms that use this code only require
 * swiotlb to be used if we're operating on HIGHMEM.  Since
 * we don't ever call anything other than map_sg, unmap_sg,
 * map_page, and unmap_page on highmem, use normal dma_ops
 * for everything else.
 */
struct dma_map_ops swiotlb_dma_ops = {
    .alloc = dma_direct_alloc_coherent,
    .free = dma_direct_free_coherent,
    .mmap = dma_direct_mmap_coherent,
    .map_sg = swiotlb_map_sg_attrs,
    .unmap_sg = swiotlb_unmap_sg_attrs,
    .dma_supported = swiotlb_dma_supported,
    .map_page = swiotlb_map_page,
    .unmap_page = swiotlb_unmap_page,
    .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
    .sync_single_for_device = swiotlb_sync_single_for_device,
    .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
    .sync_sg_for_device = swiotlb_sync_sg_for_device,
    .mapping_error = swiotlb_dma_mapping_error,
    .get_required_mask = swiotlb_powerpc_get_required,
};

void pci_dma_dev_setup_swiotlb(struct pci_dev *pdev)
{
    struct pci_controller *hose;
    struct dev_archdata *sd;

    hose = pci_bus_to_host(pdev->bus);
    sd = &pdev->dev.archdata;
    sd->max_direct_dma_addr =
        hose->dma_window_base_cur + hose->dma_window_size;
}

static int ppc_swiotlb_bus_notify(struct notifier_block *nb,
                  unsigned long action, void *data)
{
    struct device *dev = data;
    struct dev_archdata *sd;

    /* We are only intereted in device addition */
    if (action != BUS_NOTIFY_ADD_DEVICE)
        return 0;

    sd = &dev->archdata;
    sd->max_direct_dma_addr = 0;

    /* May need to bounce if the device can't address all of DRAM */
    if ((dma_get_mask(dev) + 1) < memblock_end_of_DRAM())
        set_dma_ops(dev, &swiotlb_dma_ops);

    return NOTIFY_DONE;
}

static struct notifier_block ppc_swiotlb_plat_bus_notifier = {
    .notifier_call = ppc_swiotlb_bus_notify,
    .priority = 0,
};

int __init swiotlb_setup_bus_notifier(void)
{
    bus_register_notifier(&platform_bus_type,
                  &ppc_swiotlb_plat_bus_notifier);
    return 0;
}

void swiotlb_detect_4g(void)
{
    if ((memblock_end_of_DRAM() - 1) > 0xffffffff)
        ppc_swiotlb_enable = 1;
}

static int __init swiotlb_late_init(void)
{
    if (ppc_swiotlb_enable) {
        swiotlb_print_info();
        set_pci_dma_ops(&swiotlb_dma_ops);
        ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb;
    } else {
        swiotlb_free();
    }

    return 0;
}
subsys_initcall(swiotlb_late_init);