source: rtems/cpukit/libdrvmgr/drvmgr_translate.c @ bef5e23e

/* Driver Manager Driver Translate Interface Implementation
 *
 * COPYRIGHT (c) 2010 Cobham Gaisler AB.
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://www.rtems.org/license/LICENSE.
 */

/*
 * Used by device drivers. The functions rely on that the parent bus driver
 * has implemented the neccessary operations correctly.
 *
 * The translate functions are used to translate addresses between buses
 * for DMA cores located on a "remote" bus, or for memory-mapped obtaining
 * an address that can be used to access an remote bus.
 *
 * For example, PCI I/O might be memory-mapped at the PCI Host bridge,
 * say address 0xfff10000-0xfff1ffff is mapped to the PCI I/O address
 * of 0x00000000-0x0000ffff. The PCI Host bridge driver may then set up
 * a map so that a driver that get PCI address 0x100 can translate that
 * into 0xfff10100.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <drvmgr/drvmgr.h>
#include "drvmgr_internal.h"

unsigned int drvmgr_translate_bus(
        struct drvmgr_bus *from,
        struct drvmgr_bus *to,
        int reverse,
        void *src_address,
        void **dst_address)
{
        struct drvmgr_bus *path[16];
        int dir, levels, i;
        void *dst, *from_adr, *to_adr;
        struct drvmgr_map_entry *map;
        struct drvmgr_bus *bus;
        unsigned int sz;
        struct drvmgr_bus *bus_bot, *bus_top;

        dst = src_address;
        sz = 0xffffffff;

        if (from == to) /* no need translating addresses when on same bus */
                goto out;

        /* Always find translation path from remote bus towards root bus. All
         * buses have root bus has parent at some level
         */
        if (from->depth > to->depth) {
                bus_bot = from;
                bus_top = to;
                dir = 0;
        } else {
                bus_bot = to;
                bus_top = from;
                dir = 1;
        }
        levels = bus_bot->depth - bus_top->depth;
        if (levels >= 16)
                return 0; /* Does not support such a big depth */
        i = 0;
        while ((bus_bot != NULL) && bus_bot != bus_top) {
                if (dir)
                        path[(levels - 1) - i] = bus_bot;
                else
                        path[i] = bus_bot;
                i++;
                bus_bot = bus_bot->dev->parent;
        }
        if (bus_bot == NULL)
                return 0; /* from -> to is not linearly connected */

        for (i = 0; i < levels; i++) {
                bus = path[i];

                if ((dir && reverse) || (!dir && !reverse))
                        map = bus->maps_up;
                else
                        map = bus->maps_down;

                if (map == NULL)
                        continue; /* No translation needed - 1:1 mapping */

                if (map == DRVMGR_TRANSLATE_NO_BRIDGE) {
                        sz = 0;
                        break; /* No bridge interface in this direction */
                }

                while (map->size != 0) {
                        if (reverse) {
                                /* Opposite direction */
                                from_adr = map->to_adr;
                                to_adr = map->from_adr;
                        } else {
                                from_adr = map->from_adr;
                                to_adr = map->to_adr;
                        }

                        if ((dst >= from_adr) &&
                            (dst <= (from_adr + (map->size - 1)))) {
                                if (((from_adr + (map->size - 1)) - dst) < sz)
                                        sz = (from_adr + (map->size - 1)) - dst;
                                dst = (dst - from_adr) + to_adr;
                                break;
                        }
                        map++;
                }
                /* quit if no matching translation information */
                if (map->size == 0) {
                        sz = 0;
                        break;
                }
        }

out:
        if (dst_address)
                *dst_address = dst;

        return sz;
}

unsigned int drvmgr_translate(
        struct drvmgr_dev *dev,
        unsigned int options,
        void *src_address,
        void **dst_address)
{
        struct drvmgr_bus *to, *from;
        int rev = 0;

        rev = (~options) & 1;
        if ((options == CPUMEM_TO_DMA) || (options == DMAMEM_FROM_CPU)) {
                from = drvmgr.root_dev.bus;
                to = dev->parent;
        } else { /* CPUMEM_FROM_DMA || DMAMEM_TO_CPU */
                from = dev->parent;
                to = drvmgr.root_dev.bus;
        }

        return drvmgr_translate_bus(from, to, rev, src_address, dst_address);
}