examples/platform/openiotsdk/tf-m/targets/an552/native_drivers/mpu_armv8m_drv.c

/*
 * Copyright (c) 2017-2021, Arm Limited. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 *
 */

#include "mpu_armv8m_drv.h"
#include "cmsis.h"

/*
 * FixMe:
 * This is a beta quality driver for MPU in v8M. To be finalized.
 */

enum mpu_armv8m_error_t mpu_armv8m_enable(struct mpu_armv8m_dev_t * dev, uint32_t privdef_en, uint32_t hfnmi_en)
{
    /*No error checking*/

    MPU_Type * mpu = (MPU_Type *) dev->base;

    /*
     * FixMe: Set 3 pre-defined MAIR_ATTR for memory. The attributes come
     * from default memory map, need to check if fine-tune is necessary.
     *
     * MAIR0_0: Peripheral, Device-nGnRE.
     * MAIR0_1: Code, WT RA. Same attr for Outer and Inner.
     * MAIR0_2: SRAM, WBWA RA. Same attr for Outer and Inner.
     */
    mpu->MAIR0 = (MPU_ARMV8M_MAIR_ATTR_DEVICE_VAL << MPU_MAIR0_Attr0_Pos) | (MPU_ARMV8M_MAIR_ATTR_CODE_VAL << MPU_MAIR0_Attr1_Pos) |
        (MPU_ARMV8M_MAIR_ATTR_DATA_VAL << MPU_MAIR0_Attr2_Pos);

    mpu->CTRL = (privdef_en ? MPU_CTRL_PRIVDEFENA_Msk : 0) | (hfnmi_en ? MPU_CTRL_HFNMIENA_Msk : 0);

    /*Ensure all configuration is written before enable*/

    mpu->CTRL |= MPU_CTRL_ENABLE_Msk;

    /* Enable MPU before next instruction */
    __DSB();
    __ISB();
    return MPU_ARMV8M_OK;
}

enum mpu_armv8m_error_t mpu_armv8m_disable(struct mpu_armv8m_dev_t * dev)
{
    MPU_Type * mpu = (MPU_Type *) dev->base;

    /* Reset all fields as enable does full setup */
    mpu->CTRL = 0;

    return MPU_ARMV8M_OK;
}

enum mpu_armv8m_error_t mpu_armv8m_region_enable(struct mpu_armv8m_dev_t * dev, struct mpu_armv8m_region_cfg_t * region_cfg)
{
    MPU_Type * mpu = (MPU_Type *) dev->base;

    enum mpu_armv8m_error_t ret_val = MPU_ARMV8M_OK;
    uint32_t ctrl_before;
    uint32_t base_cfg;
    uint32_t limit_cfg;

    /*FIXME : Add complete error checking*/
    if ((region_cfg->region_base & ~MPU_RBAR_BASE_Msk) != 0)
    {
        return MPU_ARMV8M_ERROR;
    }
    /* region_limit doesn't need to be aligned but the scatter
     * file needs to be setup to ensure that partitions do not overlap.
     */

    ctrl_before = mpu->CTRL;
    mpu->CTRL   = 0;

    mpu->RNR = region_cfg->region_nr & MPU_RNR_REGION_Msk;

    /* This 0s the lower bits of the base address */
    base_cfg = region_cfg->region_base & MPU_RBAR_BASE_Msk;
    base_cfg |= (region_cfg->attr_sh << MPU_RBAR_SH_Pos) & MPU_RBAR_SH_Msk;
    base_cfg |= (region_cfg->attr_access << MPU_RBAR_AP_Pos) & MPU_RBAR_AP_Msk;
    base_cfg |= (region_cfg->attr_exec << MPU_RBAR_XN_Pos) & MPU_RBAR_XN_Msk;

    mpu->RBAR = base_cfg;

    /*This 0s the lower bits of base address but they are treated as 1 */
    limit_cfg = (region_cfg->region_limit - 1) & MPU_RLAR_LIMIT_Msk;

    limit_cfg |= (region_cfg->region_attridx << MPU_RLAR_AttrIndx_Pos) & MPU_RLAR_AttrIndx_Msk;

#ifdef TFM_PXN_ENABLE
    limit_cfg |= (region_cfg->attr_pxn << MPU_RLAR_PXN_Pos) & MPU_RLAR_PXN_Msk;
#endif

    limit_cfg |= MPU_RLAR_EN_Msk;

    mpu->RLAR = limit_cfg;

    /*Restore main MPU control*/
    mpu->CTRL = ctrl_before;

    /* Enable MPU before the next instruction */
    __DSB();
    __ISB();

    return ret_val;
}

enum mpu_armv8m_error_t mpu_armv8m_region_disable(struct mpu_armv8m_dev_t * dev, uint32_t region_nr)
{

    MPU_Type * mpu = (MPU_Type *) dev->base;

    enum mpu_armv8m_error_t ret_val = MPU_ARMV8M_OK;
    uint32_t ctrl_before;

    /*FIXME : Add complete error checking*/

    ctrl_before = mpu->CTRL;
    mpu->CTRL   = 0;

    mpu->RNR = region_nr & MPU_RNR_REGION_Msk;

    mpu->RBAR = 0;
    mpu->RLAR = 0;

    /*Restore main MPU control*/
    mpu->CTRL = ctrl_before;

    return ret_val;
}

enum mpu_armv8m_error_t mpu_armv8m_clean(struct mpu_armv8m_dev_t * dev)
{
    MPU_Type * mpu = (MPU_Type *) dev->base;
    uint32_t i     = (mpu->TYPE & MPU_TYPE_DREGION_Msk) >> MPU_TYPE_DREGION_Pos;

    while (i > 0)
    {
        mpu_armv8m_region_disable(dev, i - 1);
        i--;
    }

    return MPU_ARMV8M_OK;
}