Milkymist MMU

/*
 * Milkymist SoC (Software)
 * Copyright (C) 2012 Yann Sionneau <yann.sionneau@gmail.com>
 *
 * 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, version 3 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, see <http://www.gnu.org/licenses/>.
 */

#include <hal/mmu.h>
#include <base/mmu.h>
#include <base/stdio.h>

#ifdef __ASSEMBLER__
#define MMPTR(x) x
#else
#define MMPTR(x) (*((volatile unsigned int *)(x)))
#endif
#define CSR_UART_RXTX       MMPTR(0xe0000000)

void f(void) {
    char c = '@';
    CSR_UART_RXTX = c;
//  asm volatile("bi f" ::: ); // We intinitely loop to f()
    asm volatile("xor r0, r0, r0\n\t"
             "xor r0, r0, r0" ::: );
}

void itlbtest(void) {
    register unsigned int stack, f_addr;
    unsigned int *p;
    unsigned int *pdest;
    unsigned int addr;

    asm volatile("mv %0, sp" : "=r"(stack) :: );
    printf("stack == 0x%08X\n", stack);

    printf("f() is located at 0x%p\n", f);

    f_addr = 0x44004000;
    printf("Mapping f() into virtual memory at 0x%08X [physical == 0x%08X]\n", f_addr, f_addr+0x1000);

//  for (addr = 0x00860000 ; addr <= 0x00874000 ; addr += 0x1000)
//      mmu_map(addr, addr, DTLB_MAPPING | MAPPING_CAN_READ);

    mmu_map(stack, stack, DTLB_MAPPING | MAPPING_CAN_READ | MAPPING_CAN_WRITE);
    mmu_map(f_addr, f_addr + 0x1000, ITLB_MAPPING | MAPPING_CAN_READ);
    mmu_map(itlbtest, itlbtest, ITLB_MAPPING | MAPPING_CAN_READ);
    mmu_map(call_function_with_itlb_enabled, call_function_with_itlb_enabled, ITLB_MAPPING | MAPPING_CAN_READ);
    puts("Mapping DONE");

//  mmu_itlb_invalidate_line(f_addr);

    // We copy f's code to 0x44005000
    for (p = f, pdest = 0x44005000 ; p < f + 0x1000 ; p++, pdest++)
        *pdest = *p;
    puts("Copy DONE");

    asm volatile("wcsr DCC, r0\n\t"
             "xor r0, r0, r0\n\t"
             "xor r0, r0, r0\n\t"
             "xor r0, r0, r0\n\t"
             "xor r0, r0, r0");
    asm volatile("wcsr ICC, r0\n\t"
             "xor r0, r0, r0");
    puts("Instruction and Data caches have been invalidated");

    call_function_with_itlb_enabled(f_addr);
    disable_dtlb();
    disable_itlb();
    puts("Call DONE");
}

00865a44 <f>:
  865a44:   34 02 00 40     mvi r2,64
  865a48:   78 01 e0 00     mvhi r1,0xe000
  865a4c:   58 22 00 00     sw (r1+0),r2
  865a50:   98 00 00 00     xor r0,r0,r0
  865a54:   98 00 00 00     xor r0,r0,r0
  865a58:   c3 a0 00 00     ret