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arch/arm/am67: Add a RAT sliding window for 36-bit DDR access.
J722S maps DDR above the first 2 GB at 0x8_8000_0000, out of reach of the 32-bit R5F, while a 64-bit Linux peer posts virtio buffers there. Dedicates RAT region 0 as a 16 MB window at 0xFE000000. am67_rat_map() re-aims it and returns a pointer plus the bytes left before the edge, so callers can split copies that straddle it. The window is Non-cacheable, since it retargets at runtime and cached lines would alias across physical blocks. A mapping is valid only until the next call; the sole user, vhost-net, is serialised on the netdev work thread. Assisted-by: Claude Code:claude-fable-5 Signed-off-by: Ulaş Sertan Kemeç <sertan.usk@gmail.com>
This commit is contained in:
Ulaş Sertan Kemeç
Xiang Xiao
parent
a2edd99159
commit
cd4fe549ee
5 changed files with 184 additions and 2 deletions
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@ -20,8 +20,14 @@
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#
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# ##############################################################################
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set(SRCS am67_boot.c am67_irq.c am67_mpuinit.c am67_pinmux.c am67_serial.c
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am67_timer.c)
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set(SRCS
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am67_boot.c
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am67_irq.c
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am67_mpuinit.c
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am67_pinmux.c
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am67_rat.c
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am67_serial.c
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am67_timer.c)
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if(CONFIG_RPTUN)
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list(APPEND SRCS am67_rptun.c)
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@ -48,3 +48,4 @@ endif
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ifeq ($(CONFIG_RPTUN),y)
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CHIP_CSRCS += am67_rptun.c
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endif
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CHIP_CSRCS += am67_rat.c
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@ -31,6 +31,7 @@
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#include <sys/param.h>
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#include "am67_mpuinit.h"
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#include "am67_rat.h"
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#include "mpu.h"
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/****************************************************************************
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@ -85,5 +86,11 @@ void am67_mpu_init(void)
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am67_ipc_shm_region(AM67_IPC_SHM0_START_ADDR, AM67_IPC_SHM0_SIZE);
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am67_ipc_shm_region(AM67_IPC_SHM1_START_ADDR, AM67_IPC_SHM1_SIZE);
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/* RAT sliding window (am67_rat.c): retargeted at runtime onto arbitrary
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* 36-bit physical blocks, so it must never be cached.
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*/
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am67_ipc_shm_region(AM67_RAT_WIN_BASE, AM67_RAT_WIN_SIZE);
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mpu_control(true);
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}
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114
arch/arm/src/am67/am67_rat.c
Normal file
114
arch/arm/src/am67/am67_rat.c
Normal file
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@ -0,0 +1,114 @@
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/****************************************************************************
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* arch/arm/src/am67/am67_rat.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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/* Region Address Translator (RAT) sliding window.
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*
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* The Cortex-R5F is a 32-bit master on a 36-bit SoC: DDR beyond the first
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* 2 GB lives at 0x8_8000_0000 and cannot be addressed by the core
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* directly. The R5FSS integrates a per-core RAT (config space at
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* 0x2ffe_0000, 4 regions) that remaps a 32-bit input window onto any
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* 36-bit output address (TRM 7.2.2.6 / 7.3.2.6.4).
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*
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* This driver dedicates one region as a 16 MB sliding window: callers ask
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* for a pointer to an arbitrary 36-bit physical address and the window is
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* re-aimed at the containing 16 MB block. The window range is mapped
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* Non-cacheable in the MPU (am67_mpuinit.c), so accesses through it are
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* also coherent with the A53 without cache maintenance.
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*
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* The single window is a shared resource: the returned pointer is only
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* valid until the next am67_rat_map() call, and callers must be
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* serialized (the sole current user is the vhost-net driver, whose
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* transmit/receive both run on the netdev work thread).
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*/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <stddef.h>
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#include <arch/barriers.h>
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#include "arm_internal.h"
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#include "am67_rat.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define AM67_RAT_BASE (0x2ffe0000ul)
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#define AM67_RAT_CTRL(n) (AM67_RAT_BASE + 0x20 + 0x10 * (n))
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#define AM67_RAT_ADDR(n) (AM67_RAT_BASE + 0x24 + 0x10 * (n))
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#define AM67_RAT_TRANS_L(n) (AM67_RAT_BASE + 0x28 + 0x10 * (n))
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#define AM67_RAT_TRANS_U(n) (AM67_RAT_BASE + 0x2c + 0x10 * (n))
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#define AM67_RAT_CTRL_EN (1ul << 31)
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#define AM67_RAT_REGION (0) /* RAT region index used for the window */
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#define AM67_RAT_WIN_LOG2 (24) /* 16 MB window */
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: am67_rat_map
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*
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* Description:
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* Return a CPU pointer to the given 36-bit physical address by sliding
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* the RAT window over its 16 MB block. If avail is non-NULL it
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* receives the number of contiguous bytes reachable from the returned
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* pointer before the window ends (callers accessing more must map
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* again at the advanced address).
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*
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* The pointer is valid only until the next call. Not reentrant.
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*
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****************************************************************************/
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FAR void *am67_rat_map(uint64_t pa, FAR size_t *avail)
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{
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static uint64_t cur_block = UINT64_MAX;
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uint64_t block = pa & ~((uint64_t)AM67_RAT_WIN_SIZE - 1);
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uint32_t offset = (uint32_t)(pa & (AM67_RAT_WIN_SIZE - 1));
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if (block != cur_block)
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{
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putreg32(0, AM67_RAT_CTRL(AM67_RAT_REGION));
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putreg32(AM67_RAT_WIN_BASE, AM67_RAT_ADDR(AM67_RAT_REGION));
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putreg32((uint32_t)block, AM67_RAT_TRANS_L(AM67_RAT_REGION));
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putreg32((uint32_t)(block >> 32), AM67_RAT_TRANS_U(AM67_RAT_REGION));
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putreg32(AM67_RAT_CTRL_EN | AM67_RAT_WIN_LOG2,
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AM67_RAT_CTRL(AM67_RAT_REGION));
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UP_DSB();
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cur_block = block;
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}
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if (avail != NULL)
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{
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*avail = AM67_RAT_WIN_SIZE - offset;
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}
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return (FAR void *)(AM67_RAT_WIN_BASE + offset);
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}
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54
arch/arm/src/am67/am67_rat.h
Normal file
54
arch/arm/src/am67/am67_rat.h
Normal file
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@ -0,0 +1,54 @@
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/****************************************************************************
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* arch/arm/src/am67/am67_rat.h
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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#ifndef __ARCH_ARM_SRC_AM67_AM67_RAT_H
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#define __ARCH_ARM_SRC_AM67_AM67_RAT_H
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <stddef.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* 32-bit address range claimed by the RAT sliding window. Must be mapped
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* Non-cacheable in the MPU (am67_mpuinit.c) and must not overlap anything
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* the firmware needs to address directly (NuttX RAM/IPC live in
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* 0xa2000000-0xa3000000).
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*/
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#define AM67_RAT_WIN_BASE (0xfe000000ul)
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#define AM67_RAT_WIN_SIZE (0x01000000ul) /* 16 MB */
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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FAR void *am67_rat_map(uint64_t pa, FAR size_t *avail);
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#endif /* __ARCH_ARM_SRC_AM67_AM67_RAT_H */
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