ARM: cp15: setup mmu and enable dcache

arch/arm/lib/cache-cp15.c static void cp_delay (void) · line 76

I think you need to invalidate caches, TLB, branch-prediction array etc before enabling MMU. I don't think the caches are guaranteed to be invalidated at power on reset.

Please find below some experimental(but working) code I had written for enabling MMU and caches for an internal project. It's written for the ARM RVCT tool chain. So, it will not compile straight away on GCC.

It has code for invalidating caches, TLB, Branch prediction array etc. Also, it uses macros for the bit fields in the SCTLR register. However, the L1 D$ cleaning is not generic. It assumes the size and organization of the L1 cache. arch/arm/cpu/armv7/omap3/cache.S has a more generic implementation of invalidating the entire L1 D$.

In case you find it useful, you are welcome to reuse any part of this code. If you want me to create a patch myself I am open to do that too.

Best regards,
Aneesh

Mmu.c:

/*
* (C) Copyright 2008
* Texas Instruments, <www.ti.com>
* Author:
* Aneesh V <[email protected]>
*
* 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's version 2 of
* the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/

#include <utils.h>

#ifdef MMU_ENABLED

extern unsigned int pagetable[1024*4];
extern unsigned int Vector(void);

#define PAGE_TAB_SECTION_CONSTANTS 0x40002
#define NS_BIT_1 0x80000
#define nG_0 0
#define S_BIT_1 0x010000
#define AP_FULL_ACCESS 0x00C00
#define DOMAIN_0 0
#define XN_1 0x10
#define TEX_C_B_NORMAL_I_WBWA_O_WBWA 0x05004
#define TEX_C_B_NORMAL_I_WBWA_O_NC 0x04004
#define TEX_C_B_NORMAL_I_NC_O_NC 0x01002
#define TEX_C_B_NORMAL_SHARABLE_DEVICE 0x4

#define SECTION_ENTRY_FULL_ACCESS_FULL_CACHED (PAGE_TAB_SECTION_CONSTANTS|NS_BIT_1|nG_0|S_BIT_1|AP_FULL_ACCESS|DOMAIN_0|TEX_C_B_NORMAL_I_WBWA_O_WBWA) #define SECTION_ENTRY_FULL_ACCESS_FULL_CACHED_NON_SHARED (PAGE_TAB_SECTION_CONSTANTS|NS_BIT_1|nG_0|AP_FULL_ACCESS|DOMAIN_0|TEX_C_B_NORMAL_I_WBWA_O_WBWA) #define SECTION_ENTRY_FULL_ACCESS_NORMAL_NC (PAGE_TAB_SECTION_CONSTANTS|NS_BIT_1|nG_0|S_BIT_1|AP_FULL_ACCESS|DOMAIN_0|TEX_C_B_NORMAL_I_NC_O_NC) #define SECTION_ENTRY_FULL_ACCESS_SHARED_DEVICE (PAGE_TAB_SECTION_CONSTANTS|NS_BIT_1|nG_0|S_BIT_1|AP_FULL_ACCESS|DOMAIN_0|TEX_C_B_NORMAL_SHARABLE_DEVICE)

#define M_BIT_1 0x1

#define C_BIT_1  0x4
#define Z_BIT_1  0x800
#define I_BIT_1  0x1000
#define V_BIT_1  0x2000

#define SCTRL_VALUE (M_BIT_1|C_BIT_1|Z_BIT_1|I_BIT_1|V_BIT_1) //#define SCTRL_VALUE (M_BIT_1|Z_BIT_1|I_BIT_1|V_BIT_1)

__asm void setvector(void);
void setup_pagetable(unsigned int *pagetable, unsigned int devicemem_attr, unsigned int code_and_data); __asm unsigned int setup_vector(unsigned int (*vector)(void));
__asm unsigned int setup_ttbr0(unsigned int ttbr0value);
__asm unsigned int setup_ttbr1(unsigned int ttbr1value);
__asm unsigned int setup_ttbrc(unsigned int ttbrc_value);
__asm unsigned int setup_dacr(unsigned int dacr_value);
__asm unsigned int setup_sctlr(unsigned int sctlrr_value);
__asm void invalidate_caches(void);
__asm void barriers(void);
__asm void enable_pl310(void);
void invalidate_dcache_setway(unsigned int setway);
void stresstestaftermmu(void);

__asm unsigned int setup_prrr(unsigned int prrr_value)

{
    MCR p15,0,r0,c10,c2,0 ; Read CP15 Primary Region Remap Register
    bx lr
}

__asm unsigned int setup_nmrr(unsigned int nmrr_value)

{
    MCR p15,0,r0,c10,c2,1 ; Read CP15 Normal Memory Remap Register
    bx lr
}

void enablemmu(void)

{
    int set, way, setway;

    volatile int i = 10;

    setup_pagetable(pagetable, SECTION_ENTRY_FULL_ACCESS_SHARED_DEVICE, SECTION_ENTRY_FULL_ACCESS_FULL_CACHED);

    printf("page table address 0x%08x\r\n", pagetable);
    invalidate_caches();
    printf("Cache and TLB invalidation done..\r\n");


    //All TTBR permission values(RGN etc) are 0's. So nothing else to be done for TTBR0 value.
    setup_ttbr0(((unsigned int)pagetable) | 0x48);
    setup_ttbr1(((unsigned int)pagetable) | 0x48);

    //TTBRC is 1(N=1)
    setup_ttbrc(1);

    setup_dacr(1);
    setup_vector(Vector);
    //Only I and M bit set in SCR
    for(set=0; set<256; set++)
    {
        for(way=0; way<4; way++)
        {
            setway = way << 30;
            setway |= set << 5;
            invalidate_dcache_setway(setway);
        }
    }
    printf("Data cache invalidation done..\r\n");

    //Enable L2
    enable_pl310();

    barriers();
    setup_sctlr(SCTRL_VALUE); //Enable everything except I$ and D$
    printf("mmu enabled..\r\n");

    printf("If you are seeing this mmu and caches are working fine..\r\n");
}

__asm void invalidate_dcache_setway(unsigned int setway) {
MCR p15, 0, r0, c7, c6, 2 ; invalidate (aka purge) by set/way
bx lr
}

__asm void barriers(void)

{
    DCD     0xF57FF04F                  ; DSBSY (full system DSB)
    DCD     0xF57FF06F                  ; ISBSY (full system ISB)
    bx lr
}
//__asm int setuppagetables
__asm void invalidate_caches(void)
{
    mov     r1, #0
    mcr     p15, 0, r1, c8, c7, 0   ; Invalidate entire unified TLB
    mcr     p15, 0, r1, c8, c6, 0   ; Invalidate entire data TLB
    mcr     p15, 0, r1, c8, c5, 0   ; Invalidate entire instruction TLB
    mcr     p15, 0, r1, c7, c5, 6   ; Invalidate entire branch prediction array
    mcr     p15, 0, r1, c7, c5, 0   ; Invalidate icache

bx lr
}

__asm unsigned int setup_dacr(unsigned int dacr_value)
{
MCR p15,0,r0,c3,c0,0 ; Write CP15 Domain Access Control Register MRC p15,0,r0,c3,c0,0 ; Read CP15 Domain Access Control Register bx lr
}

__asm unsigned int setup_ttbrc(unsigned int ttbrc_value) {

    MCR p15, 0, r0, c2, c0, 2 //Write TTBRC - N=0
    MRC p15, 0, r0, c2, c0, 2 //Write TTBRC - N=0
    bx lr
}

__asm unsigned int setup_ttbr0(unsigned int ttbr0value) {

    //Only TTBR0 is used.
    MCR p15, 0, r0, c2, c0, 0 //Write TTBR0
    MRC p15, 0, r0, c2, c0, 0 //Write TTBR0
    bx lr
}

__asm unsigned int setup_ttbr1(unsigned int ttbr1value) {

//Only TTBR0 is used.
MCR p15, 0,r0, c2, c0, 1 ;Write Translation Table Base Register 1
MRC p15, 0,r0, c2, c0, 1 ;Read Translation Table Base Register 1
bx lr
}

__asm unsigned int setup_vector(unsigned int (*vector)(void))

{
    MCR p15,0,r0,c12,c0,0 ; Set VBAR
    MRC p15,0,r0,c12,c0,0 ; Read VBAR
    bx lr

}

__asm unsigned int setup_sctlr(unsigned int sctlr_value)

{
    MCR p15,0,r0,c1,c0,0 ; Write CP15 System Control Register
    DCD     0xF57FF04F                  ; DSBSY (full system DSB)
    DCD     0xF57FF06F                  ; ISBSY (full system ISB)
    MRC p15,0,r0,c1,c0,0 ; Read CP15 System Control Register
    bx lr
}

__asm void enable_pl310(void)

{
        STMFD   sp!, {r4-r12,lr}
        MOV     r0, #1
        LDR     r12, =0x102
        DCD     0xE1600070			; call ROM Code API to enable PL310 on ZEBU/Si
        ldmfd   sp!, {r4-r12,pc}
}

void setup_pagetable(unsigned int *pagetable, unsigned int devicemem_attr, unsigned int code_and_data)

{
    int i;
    //volatile int j=10;
    printf(">setup_pagetable - device mem: 0x%x code_data: 0x%x\r\n",  devicemem_attr, code_and_data);
//    while(j);
    for (i=0; i<2*1024; i++)
    {
            pagetable[i] = (i << 20) | devicemem_attr;
    }
#if 1    
    for(; i<2*1024+256; i++)
    {
            pagetable[i] = (i << 20) | code_and_data;
    }
    for(; i<2*1024+512; i++)
    {
            pagetable[i] = (i << 20) | code_and_data;
    }

#endif

    for (; i<4*1024; i++)
    {
            pagetable[i] = (i << 20) | code_and_data;
    }

    pagetable[0x403] = (0x403 << 20) | code_and_data;

    
    printf("section entry for 0x00000000 - 0x%08x\r\n",  pagetable[0]);
    printf("section entry for 0x80000000 - 0x%08x\r\n",  pagetable[0x800]);
}

#endif