u-boot/arch/sparc/cpu/leon3/ambapp_low.S
Daniel Hellstrom 898cc81da3 sparc: leon3: Reimplemented AMBA Plug&Play scanning routines.
Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
2015-11-13 10:23:32 +02:00

784 lines
20 KiB
ArmAsm

/* GRLIB AMBA Plug&Play information scanning implemented without
* using memory (stack) and one register window. The code scan
* the PnP info and inserts the AHB bridges/buses into register
* i0-i5.
* The code support
* - up to 6 AHB buses
* - multiple APB buses
* - support for AHB2AHB & L2CACHE bridges
*
* (C) Copyright 2010, 2015
* Daniel Hellstrom, Cobham Gaisler, daniel@gaisler.com.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <ambapp.h>
.seg "text"
.globl _nomem_amba_init
.globl _nomem_ambapp_find_buses
.globl _nomem_find_apb
.globl _nomem_find_ahb
/* Overview
* ========
*
* _nomem_amba_init - Init AMBA bus and calls _nomem_ambapp_find_buses
* _nomem_ambapp_find_buses - Scan AMBA PnP info for AHB buses/bridges and
* place them in i0-i5, see below
* _nomem_find_apb - Find one APB device identified by VENDOR:DEVICE
* ID and an index.
* _nomem_find_ahb - Find one AHB Master or Slave device identified
* by VENDOR:DEVICE ID and an index.
* init_ahb_bridges - Local function. Clears i0-i5
* insert_ahb_bridge - Local function. Insert a new AHB bus into first
* free register in i0-i5. It also checks that the
* bus has not already been added.
* get_ahb_bridge - Local function. Get AHB bus from registers,
* return register iN, where N is defined by o0.
*
* The _nomem_find_apb and _nomem_find_ahb function requires that i0-i5
* are populated with the AHB buses of the system. The registers are
* initialized by _nomem_ambapp_find_buses.
*
* AHB Bus result and requirements of i0-i5
* ========================================
*
* i0: AHB BUS0 IOAREA, no parent bus
* i1: AHB BUS1 IOAREA, parent bus is always i0 (AHB BUS0) and bridge address
* i2: AHB BUS2 IOAREA, 3-bit parent bus number and bridge address
* i3: AHB BUS3 IOAREA, 3-bit parent bus number and bridge address
* i4: AHB BUS4 IOAREA, 3-bit parent bus number and bridge address
* i5: AHB BUS5 IOAREA, 3-bit parent bus number and bridge address
*
* AHB BUS
* -------
* Bits 31-20 (0xfff00000) contain the found bus I/O Area (AHB PnP area).
*
* 3-bit Parent bus
* ----------------
* Bits 2-0 (0x00000007) contain parent bus number. Zero if no parent
* bus, 1 = parent is AHB BUS 0 (i0), 2 = parent is AHB BUS 1 (i1)..
*
* Bridge Address
* --------------
* Bits 10-5 (0x000007e0) contain the index of the Bridge's PnP
* information on the parent. Since all bridges are found in the
* PnP information they all have a PnP entry. Together with the
* parent bus number the PnP entry can be found:
* PnPEntry = (BRIDGE_ADDRESS + (iN & 0xfff00000)) | 0x000ff800
* where N is the parent bus minus one.
*
*/
/* Function initializes the AHB Bridge I/O AREA storage. (Clears i0-i5)
*
* Arguments
* none
*
* Results
* none
*
* Clobbered
* none
*/
init_ahb_bridges:
mov %g0, %i0
mov %g0, %i1
mov %g0, %i2
mov %g0, %i3
mov %g0, %i4
retl
mov %g0, %i5
/* Function returns AHB Bridge I/O AREA for specified bus.
*
* Arguments
* - o0 = bus number
*
* Results
* - o0 = I/O AREA
*
* Clobbered
* none
*/
get_ahb_bridge:
cmp %o0, 1
be,a L1
mov %i0, %o0
cmp %o0, 2
be,a L1
mov %i1, %o0
cmp %o0, 3
be,a L1
mov %i2, %o0
cmp %o0, 4
be,a L1
mov %i3, %o0
cmp %o0, 5
be,a L1
mov %i4, %o0
cmp %o0, 6
be,a L1
mov %i5, %o0
/* o0 > 6: only 6 buses supported */
mov %g0, %o0
L1:
retl
nop
/* Function adds a AHB Bridge I/O AREA to the i0-i5 registers if
* not already added. It stores the bus PnP start information.
*
* Arguments
* - o0 = AHB Bridge I/O area
*
* Results
* none
*
* Clobbered
* o2, o3
*/
insert_ahb_bridge:
/* Check that bridge hasn't already been added */
andn %o0, 0x7ff, %o2
andn %i0, 0x7ff, %o3
cmp %o3, %o2
be L2
andn %i1, 0x7ff, %o3
cmp %o3, %o2
be L2
andn %i2, 0x7ff, %o3
cmp %o3, %o2
be L2
andn %i3, 0x7ff, %o3
cmp %o3, %o2
be L2
andn %i4, 0x7ff, %o3
cmp %o3, %o2
be L2
andn %i5, 0x7ff, %o3
cmp %o3, %o2
be L2
/* Insert into first free posistion */
cmp %i0, %g0
be,a L2
mov %o0, %i0
cmp %i1, %g0
be,a L2
mov %o0, %i1
cmp %i2, %g0
be,a L2
mov %o0, %i2
cmp %i3, %g0
be,a L2
mov %o0, %i3
cmp %i4, %g0
be,a L2
mov %o0, %i4
cmp %i5, %g0
be,a L2
mov %o0, %i5
L2:
retl
nop
/* FUNCTION int _nomem_find_ahb_bus(
* unsigned int bridge,
* int vendor_device,
* int index,
* void **pconf,
* int not_used,
* int option
* )
*
* Scans the AHB Master or Slave area for a matching VENDOR:DEVICE, the
* index is decremented when a matching device is found but index is
* greater than zero. When index is zero and a matching DEVICE:VENDOR
* is found the AHB configuration address and AHB I/O area is returned.
*
* i0-i7,l0,l1,l2,l3,l4,g2,o6 is not available for use.
* o1,o5 Must be left untouched
*
* Results
* - o0 Number of found devices (1 or 0)
* - o2 is decremented for each matching VENDOR:DEVICE found, zero if found
* - o3 Address of the AHB PnP configuration entry (Only valid if o0=1)
*
* Clobbered
* - o3 (Clobbered when no device was found)
* - o4 (Number of Devices left to search)
* - o0 (Bus ID, PnP ID, Device)
*/
_nomem_find_ahb_bus:
/* Get the number of Slaves/Masters.
* Only AHB Bus 0 has 64 AHB Masters/Slaves the
* other AHB buses has 16 slaves and 16 masters.
*/
add %g0, 16, %o4 /* Defaulting to 16 */
andcc %o0, 0x7, %g0 /* 3-bit bus id */
be,a .L_maxloops_detected
add %g0, 64, %o4 /* AHB Bus 0 has 64 AHB Masters/Slaves */
.L_maxloops_detected:
/* Get start address of AHB Slave or AHB Master area depending on what
* we are searching for.
*/
andn %o0, 0x7ff, %o0 /* Remove Bus ID and 5-bit AHB/AHB
* Bridge PnP Address to get I/O Area */
set AMBA_CONF_AREA, %o3
or %o3, %o0, %o3 /* Master area address */
cmp %o5, DEV_AHB_SLV
be,a .L_conf_area_calculated
or %o3, AMBA_AHB_SLAVE_CONF_AREA, %o3 /* Add 0x800 to get to slave area */
.L_conf_area_calculated:
/* Iterate over all AHB device and try to find matching DEVICE:VENDOR
* o1 - VENDOR|DEVICE
* o2 - Index
* o3 - Current AHB Device Configuration address
* o5 - Type (leave untouched)
*
* o4 - Number of AHB device left to process
* o0 - tmp
*/
.L_process_one_conf:
ld [%o3], %o0
andn %o0, 0xfff, %o0
cmp %o0, 0 /* No device if zero */
beq .L_next_conf
cmp %o1, 0 /* If VENDOR:DEVICE==0, consider all matching */
beq .L_process_ahb_dev_found
cmp %o0, %o1 /* Does VENDOR and DEVICE Match? */
bne .L_next_conf
nop
.L_process_ahb_dev_found:
/* Found a Matching VENDOR:DEVICE, index must also match */
cmp %o2, %g0
bne .L_next_conf
dec %o2
/* Index matches also, return happy with o3 set to AHB Conf Address */
mov %g0, %o2
retl
add %g0, 1, %o0
.L_next_conf:
subcc %o4, 1, %o4 /* One device has been processed,
* Are there more devices to process? */
bne .L_process_one_conf
add %o3, AMBA_AHB_CONF_LENGH, %o3 /* Next Configuration entry */
/* No Matching device found */
retl
mov %g0, %o0
/* FUNCTION int _nomem_find_ahb(
* int unused,
* int vendor_device,
* int index,
* void **pconf,
* int *ahb_bus_index,
* int option,
* )
*
* Find a AHB Master or AHB Slave device, it puts the address of the AHB PnP
* configuration in o3 (pconf), the I/O Area base address in o4 (pioarea).
*
* Calls _nomem_find_ahb_bus for every AHB bus.
*
* i0-i7, l0, l1, o6, g1, g4-g7 is not available for use.
*
* Arguments
* - o0 Unused
*
* Results
* - o0 Number of found devices (1 or 0)
* - o2 Decremented Index (Zero if found)
* - o3 Address of the AHB PnP configuration entry
* - o4 AHB Bus index the device was found on (if o0=1)
* - o5 Left untouched
*
* Clobbered
* - o0 (AHB Bridge and used by _nomem_find_ahb_bus)
* - o2 (index is decremented)
* - l2 (Current AHB Bus index)
* - g2 (return address)
*/
_nomem_find_ahb:
mov %o7, %g2 /* Save return address */
/* Scan all AHB Buses found for the AHB Master/Slave matching VENDOR:DEVICE */
clr %l2
.L_search_next_ahb_bus:
add %l2, 1, %l2
call get_ahb_bridge /* Get bus %l0 I/O Area */
mov %l2, %o0
cmp %o0, %g0
be .L_no_device_found /* If no more AHB bus is left to be scanned, proceed */
nop
call _nomem_find_ahb_bus /* Scan AHB bus %o0 for VENDOR:DEVICE. Index in o3 is decremented */
nop
cmp %o0, %g0 /* If VENDOR:DEVICE was not found scan next AHB Bus */
be .L_search_next_ahb_bus /* Do next bus is o0=0 (not found) */
nop
/* The device was found, o0 is 1 */
mov %g2, %o7 /* Restore return address */
retl
mov %l2, %o4 /* The AHB bus index the device was found on */
/* No device found matching */
.L_no_device_found:
mov %g2, %o7 /* Restore return address */
retl
mov %g0, %o0
/* FUNCTION int _nomem_find_apb_bus(
* int apbmst,
* int vendor_device,
* int index,
* void **pconf
* )
*
* Find a APB Slave device, it puts the address of the APB PnP configuration
* in o3 (pconf).
*
* Calls _nomem_find_ahb_bus for every AHB bus searching for AHB/APB Bridges.
* The AHB/APB bridges are AHB Slaves with ID GAISLER_APBMST.
*
* Results
* - o0 Number of found devices (1 or 0)
* - o2 Decremented Index
* - o3 Address of the found APB device PnP configuration entry
*
* Clobbered
* - o5 PnP VENDOR:DEVICE ID
*/
_nomem_find_apb_bus:
set AMBA_CONF_AREA, %o3
or %o0, %o3, %o3 /* Calc start of APB device PnP info */
add %g0, 16, %o0 /* o0, number of APB Slaves left to scan */
.L_process_one_apb_conf:
ld [%o3], %o5
andn %o5, 0xfff, %o5
cmp %o5, 0 /* No device if zero */
beq .L_process_apb_dev_not_found
cmp %o1, 0 /* If VENDOR:DEVICE == -1, consider all matching */
beq .L_process_apb_dev_found
cmp %o1, %o5 /* Found VENDOR:DEVICE */
bne .L_process_apb_dev_not_found
nop
.L_process_apb_dev_found:
/* Found matching device, compare index */
cmp %o2, %g0
bne .L_process_apb_dev_not_found
dec %o2
/* Matching index and VENDOR:DEVICE */
retl
add %g0, 1, %o0
.L_process_apb_dev_not_found:
subcc %o0, 1, %o0
bne .L_process_one_apb_conf
add %o3, 8, %o3
retl
mov %g0, %o0
/* FUNCTION int _nomem_find_apb(
* int unused,
* int vendor_device,
* int index,
* void **pconf,
* int *ahb_bus_index
* )
*
* Find a APB Slave device, it puts the address of the APB PnP configuration
* in o3 (pconf), the APB Master I/O Area base address in o4 (papbarea).
*
* Calls _nomem_find_ahb_bus for every AHB bus searching for AHB/APB Bridges.
* The AHB/APB bridges are AHB Slaves with ID GAISLER_APBMST.
*
* i0-i7, l0, l1, o6 is not available for use.
*
* Arguments
* - o0 Unused
*
* Results
* - o0 Number of found devices (1 or 0)
* - o2 Decremented Index if not found
* - o3 Address of the APB PnP configuration entry
* - o4 AHB Bus index of APB Bridge/APB Device
*
* Clobbered
* - o0 (AHB Bridge)
* - o2 (index is decremented)
* - l2 (APB DEV Index [7..4] : APBMST AHB Index [3..0])
* - l3 (Current AHB Bus index)
* - l4 (temporary storage for APB VENDOR:DEVICE)
* - o5 (AHB Slave ID)
* - o0 (clobbered by _nomem_find_ahb_bus)
* - g2 (Return address)
*/
_nomem_find_apb:
/* Scan all AHB Buses found for AHB/APB Bridges */
mov %o7, %g2 /* Save return address */
mov %o1, %l4 /* Save APB VENDOR:DEVICE */
sll %o2, 4, %l2 /* APB MST index = 0 */
add %g0, 1, %l3 /* AHB Bus index = 0 */
.L2_search_next_ahb_bus:
call get_ahb_bridge /* Get bus %l3 I/O Area */
mov %l3, %o0
cmp %o0, %g0
be .L2_no_device_found /* If no more AHB bus is left to be scanned, proceed */
add %g0, DEV_AHB_SLV, %o5 /* Search for AHB Slave */
sethi %hi(AMBA_PNP_ID(VENDOR_GAISLER, GAISLER_APBMST)), %o1
call _nomem_find_ahb_bus /* Scan AHB bus %o0 for VENDOR:DEVICE. Index in o3 is decremented */
and %l2, 0xf, %o2 /* Set APBMST index */
cmp %o0, %g0 /* If no AHB/APB Bridge was not found, scan next AHB Bus */
be .L_no_apb_bridge_found /* Do next bus */
nop
/* The AHB/APB Bridge was found.
* Search for the requested APB Device on the APB bus using
* find_apb_bus, it will decrement the index.
*/
ld [%o3 + AMBA_AHB_MBAR0_OFS], %o3
sll %o3, 16, %o0
and %o0, %o3, %o0 /* Address AND Address Mask */
sethi %hi(0xfff00000), %o3
and %o0, %o3, %o0 /* AHB/APB Bridge address */
srl %l2, 4, %o2 /* APB DEV Index */
call _nomem_find_apb_bus
mov %l4, %o1 /* APB VENDOR:DEVICE */
cmp %o0, %g0
be .L_apb_dev_not_found
mov %g2, %o7 /* Restore return address */
/* APB Device found
* o0 1
* o2 Index is decremented to zero
* o3 APB configuration address,
* o4 APB Bridge Configuration address.
*/
mov %g0, %o2
retl
mov %l3, %o4
.L_apb_dev_not_found:
/* Update APB DEV Index by saving output from find_apb_bus
* (index parameter) into bits [31..4] in L2.
*/
sll %o2, 4, %o2
and %l2, 0xf, %l2
or %o2, %l2, %l2
/* Try finding the next AHB/APB Bridge on the same AHB bus
* to find more APB devices
*/
ba .L2_search_next_ahb_bus /* Find next AHB/APB bridge */
inc %l2
.L_no_apb_bridge_found:
inc %l3 /* Next AHB Bus */
ba .L2_search_next_ahb_bus /* Process next AHB bus */
andn %l2, 0xf, %l2 /* Start at APB Bridge index 0 at every AHB Bus */
/* No device found matching */
.L2_no_device_found:
mov %g2, %o7 /* Restore return address */
srl %l2, 4, %o2 /* APB DEV Index */
retl
mov %g0, %o0
/* FUNCTION _nomem_amba_scan_gaisler_ahb2ahb_bridge(unsigned int bridge, int bus)
*
* Constraints:
* - o1 may not be used
* - o0, o2, o3 may be used.
*
* Arguments
* - o0 PnP Address of Bridge AHB device
* - o2 PnP ID of AHB device
*
* Results
* - o0 Address of new bus PnP area or a 1 if AHB device is no bridge
*
* Clobbered
* - o0, o2
*
*/
_nomem_amba_scan_gaisler_ahb2ahb_bridge:
andn %o2, 0xfff, %o2
sethi %hi(AMBA_PNP_ID(VENDOR_GAISLER,GAISLER_AHB2AHB)), %o3
cmp %o2, %o3
beq .L_is_ahb2ahb_bridge
nop
retl
add %g0, 1, %o0
.L_is_ahb2ahb_bridge:
/* Found a GAISLER AHB2AHB bridge */
retl
ld [%o0 + AMBA_AHB_CUSTOM1_OFS], %o0 /* Get address of bridge PnP area */
/* FUNCTION _nomem_amba_scan_gaisler_l2cache_bridge(unsigned int bridge, int bus)
*
* Constraints:
* - o1 may not be used
* - o0, o2, o3 may be used.
*
* Arguments
* - o0 PnP Address of Bridge AHB device
* - o2 PnP ID of AHB device
*
* Results
* - o0 Address of new bus PnP area or a 1 if AHB device is no bridge
*
* Clobbered
* - o0, o2
*
*/
_nomem_amba_scan_gaisler_l2cache_bridge:
andn %o2, 0xfff, %o2
sethi %hi(AMBA_PNP_ID(VENDOR_GAISLER,GAISLER_L2CACHE)), %o3
cmp %o2, %o3
beq .L_is_l2cache_bridge
nop
retl
add %g0, 1, %o0
.L_is_l2cache_bridge:
/* Found a GAISLER l2cache bridge */
retl
ld [%o0 + AMBA_AHB_CUSTOM1_OFS], %o0 /* Get address of bridge PnP area */
/* FUNCTION _nomem_amba_scan(unsigned int bridge, int bus)
*
* Constraints:
* i0-i7, l0 is used by caller
* o5-o7 may not be used.
*
* Arguments
* - o0 Bridge Information: I/O AREA and parent bus
* - o1 Bus
*
* Results
* - o0 Number of AHB bridges found
*
* Clobbered
* - o0 (Current AHB slave conf address)
* - o2 (Used by insert_bridge)
* - o3 (Used by insert_bridge)
* - l1 (Number of AHB Slaves left to process)
* - l2 (Current AHB slave conf address)
* - g2 (Return address)
*/
_nomem_amba_scan:
mov %o7, %g2 /* Save return address */
set 16, %l1
cmp %o1, 1
be,a .L2_maxloops_detected
add %g0, 64, %l1
.L2_maxloops_detected:
/* Clear 3-bit parent bus from bridge to get I/O AREA, then or
* (AMBA_CONF_AREA | AMBA_AHB_SLAVE_CONF_AREA) to get first AHB slave
* conf address.
*/
andn %o0, 0x7ff, %o0
set (AMBA_CONF_AREA | AMBA_AHB_SLAVE_CONF_AREA), %l2
or %o0, %l2, %l2
/* Scan AHB Slave area for AHB<->AHB bridges. For each AHB device
* all "bridge drivers" are called, the driver function interface:
*
* Input:
* - o0 PnP Address of Bridge AHB device
* - o2 PnP ID of AHB device
* Return values:
* - o0 Address of new bus PnP area, returning a 1 in o2 means not found
*
* Constraints:
* - o1 may not be used
* - o0, o2, o3 may be used.
*
*/
.L_scan_one_ahb_slave:
ld [%l2], %o2
cmp %o2, %g0
beq .L_scan_next_ahb_slave
nop
/* Call the GAISLER AHB2AHB bridge driver */
call _nomem_amba_scan_gaisler_ahb2ahb_bridge
mov %l2, %o0
cmp %o0, 1
bne .L_found_bridge
ld [%l2], %o2
/* Call the GAISLER L2CACHE bridge driver */
call _nomem_amba_scan_gaisler_l2cache_bridge
mov %l2, %o0
cmp %o0, 1
bne .L_found_bridge
ld [%l2], %o2
/* Insert next bridge "driver" function here */
/* The PnP ID did not match a bridge - a new bus was not found ==>
* step to next AHB device */
ba .L_scan_next_ahb_slave
nop
/* Add Found bus */
.L_found_bridge:
and %l2, 0x7e0, %o2
or %o2, %o0, %o0 /* Add AHB/AHB Bridge PnP address */
call insert_ahb_bridge /* Insert Bridge into found buses storage */
or %o1, %o0, %o0 /* Add parent bus LSB 3-bits */
.L_scan_next_ahb_slave:
/* More Slaves to process? */
subcc %l1, 1, %l1
bne .L_scan_one_ahb_slave
add %l2, AMBA_AHB_CONF_LENGH, %l2
/* No more AHB devices to process */
mov %g2, %o7 /* Restore return address */
retl
nop
/* FUNCTION _nomem_ambapp_find_buses(unsigned int ioarea)
*
* Find AMBA AHB buses.
*
* Constraints:
* i6-i7, l7 is used by caller
*
* Arguments
* - o0 Bridge Information: I/O AREA and parent bus
*
* Results
* - o0 Number of AHB bridges found
* - i0-i5 initialized
*
* Clobbered
* - o0 (Current AHB slave conf address)
* - o2 (Used by insert_bridge)
* - o3 (Used by insert_bridge)
* - l0 (Current AHB Bus)
* - l1 (Used by nomem_amba_scan)
* - l2 (Used by nomem_amba_scan)
* - l3 (Used by nomem_amba_scan)
* - l4 (Used by nomem_amba_scan)
*
* - g1 (level 1 return address)
* - g2 (Used by nomem_amba_scan)
*/
_nomem_ambapp_find_buses:
mov %o7, %g1 /* Save return address */
/* Initialize AHB Bus storage */
call init_ahb_bridges
nop
/* Insert AHB Bus 0 */
call insert_ahb_bridge
nop /* Argument already prepared by caller */
/* Scan AHB Bus 0 for AHB Bridges */
call _nomem_amba_scan
add %g0, 1, %o1
/* Scan all AHB Buses found for more AHB Bridges */
add %g0, 2, %l0
.L100_search_next_ahb_bus:
call get_ahb_bridge /* Get bus %l0 I/O Area */
mov %l0, %o0
cmp %o0, %g0
be .L100_return /* If no more AHB bus is left to be scanned, proceed */
nop
call _nomem_amba_scan /* Scan bus %l0 for AHB Bridges. i0-i7,l0 is used */
mov %l0, %o1 /* I/O AREA untouched in o0 */
ba .L100_search_next_ahb_bus /* Do next bus */
add %l0, 1, %l0
.L100_return:
mov %g1, %o7
retl
nop
/* FUNCTION _nomem_amba_init(unsigned int ioarea)
*
* Find all AHB buses
*
* Constraints:
* i6, i7, o6, o7, l7, l6, g3, g4, g5, g6, g7 is used by caller
*
* Arguments
* - o0 Bridge Information: I/O AREA and parent bus
*
* Results
* - o0 Number of AHB bridges found
*
* Clobbered
* - l0, l1, l2, l3, l4, g1, g2 (used by _nomem_ambapp_find_buses)
* - o0, o1, o2, o3 (Used as arguments)
* - o5 (return address)
* - g1 (level 1 return address)
* - g2 (level 2 return address)
*/
_nomem_amba_init:
mov %o7, %o5 /* Save return address, o5 not used */
/* Scan for buses, it will init i0-i5 */
call _nomem_ambapp_find_buses
nop
mov %o5, %o7
retl
nop
/* Call tree and their return address register
*
*_nomem_amba_scan (g1)
* -> init_ahb_bridges (o7)
* -> insert_ahb_bridge (o7)
* -> _nomem_amba_scan (g2)
* -> insert_ahb_bridge (o7)
* -> get_ahb_bridge (o7)
*
*
* -> _nomem_find_apb (g2)
* -> get_ahb_bridge (o7)
* -> _nomem_find_ahb_bus (o7)
* -> _nomem_find_apb_bus (o7)
* -> _nomem_find_ahb (g2)
* -> get_ahb_bridge (o7)
* -> _nomem_find_ahb_bus (o7)
* -> mem_handler.func() (o7)
*
*/