sw/device/examples/sram_program/sram_program.c

// Copyright lowRISC contributors.
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0

#include <stdint.h>

#include "sw/device/lib/base/macros.h"
#include "sw/device/lib/base/memory.h"
#include "sw/device/lib/dif/dif_uart.h"
#include "sw/device/lib/runtime/log.h"
#include "sw/device/lib/runtime/print.h"
#include "sw/device/lib/testing/test_framework/check.h"

#include "hw/top_earlgrey/sw/autogen/top_earlgrey.h"

static dif_uart_t uart0;

enum {
  kSramStart = TOP_EARLGREY_SRAM_CTRL_MAIN_RAM_BASE_ADDR,
  kSramEnd = TOP_EARLGREY_SRAM_CTRL_MAIN_RAM_BASE_ADDR +
             TOP_EARLGREY_SRAM_CTRL_MAIN_RAM_SIZE_BYTES,
};

void sram_main() {
  // Initialize UART.
  CHECK_DIF_OK(dif_uart_init(
      mmio_region_from_addr(TOP_EARLGREY_UART0_BASE_ADDR), &uart0));
  CHECK_DIF_OK(
      dif_uart_configure(&uart0, (dif_uart_config_t){
                                     .baudrate = kUartBaudrate,
                                     .clk_freq_hz = kClockFreqPeripheralHz,
                                     .parity_enable = kDifToggleDisabled,
                                     .parity = kDifUartParityEven,
                                 }));
  base_uart_stdout(&uart0);

  // Read the program counter and check that we are executing from SRAM.
  uint32_t pc = 0;
  asm("auipc %[pc], 0;" : [pc] "=r"(pc));
  LOG_INFO("PC: %p, SRAM: [%p, %p)", pc, kSramStart, kSramEnd);
  CHECK(pc >= kSramStart && pc < kSramEnd, "PC is outside the main SRAM");
}