Part Number: AM3358
Hello All,
I was just experimenting with mmu in beaglebone-black armv7.
Goal: To access an led with its virtual address.
In my bare-metal program i was able to switch on and off the led. Now once i turn on the mmu , i am unable switch it on using its virtual address.
note:(i am putting all the code directly into sram and executing it from there)
I have down the following mapping in code:
.equ CM_PER_GPIO1_CLKCTRL, 0x44e000AC
.equ GPIO1_OE, 0x4804C134
.equ GPIO1_SETDATAOUT, 0x4804C194
.equ GPIO1_CLEARDATAOUT, 0x4804C190
.equ GPIO_V, 0x0804C194
.equ tlb_l1_base, 0x40200000
enable_paging:
ldr r0, =tlb_l1_base
mcr p15, 0, r0, c2, c0, 0
/*
ldr r0, =0x48001008
ldr r1, =0x48000c02
str r1, [r0]
*/
ldr r4, =0x00100000
ldr r2, =0x40010c02
ldr r3, =1000
.loop_mmu:
str r2, [r0], #4 /*0th 0x40000000 so for 80th index for 0x48000000*/
add r2, r2, r4 /*GPIO should be at 0x080*/
subs r3, #1
bne .loop_mmu
mov r0, #0x3
mcr p15, 0, r0, c3, c0, 0
mrc p15, 0, r0, c1, c0, 0
orr r0, r0, #0x1
mcr p15, 0, r0, c1, c0, 0
mov pc, lr
v_switch_led_on:
ldr r0, =GPIO1_V /*trying to switch on the led*/
ldr r2, [r0]
orr r2, r2, #0x200000
str r2, [r0]
mov pc,lr
I was hoping it to work, as the pte looks fine. Could you please help in figuring out the problem ?
