我想讀和我下面這些步驟ARM9(SAM9X25)寫寄存器:http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka3750.html
我用下面的代碼結束:寫入和讀取寄存器的Linux基於ARM
#include "stdio.h"
#define PIO_WPMR_BANK_D 0xFFFFFAE4 // PIO Write Protection Mode Register Bank D
#define PIO_PUER_BANK_D 0xFFFFFA64 // PIO Pull-Up Enable Register Bank D
#define PIO_PUSR_BANK_D 0xFFFFFA68 // PIO Pull-Up Status Register Bank D
#define MASK_LED7 0xFFDFFFFF // LED7 Mask
#define DESABLE_WRITE_PROTECTION_BANK_D 0x50494F00 // Desable write protection Bank D
int main(void) {
printf("test");
unsigned int volatile * const register_PIO_WPMR_BANK_D = (unsigned int *) PIO_WPMR_BANK_D;
unsigned int volatile * const register_PIO_PUSR_BANK_D = (unsigned int *) PIO_PUSR_BANK_D;
unsigned int volatile * const port_D = (unsigned int *) PIO_PUER_BANK_D;
*register_PIO_WPMR_BANK_D = DESABLE_WRITE_PROTECTION_BANK_D;
*port_D = *register_PIO_PUSR_BANK_D & MASK_LED7;
return 0; }
我交叉編譯了代碼在Ubuntu 16.04像這樣arm-linux-gnueabi-gcc gpio.c -o gpio
但我有一個Segmentation Fault
在printf
之後執行我的主板上的程序。
我知道地址是正確的......那麼,爲什麼我有這個錯誤?
這是好方法嗎?
謝謝你的幫助!
SOLUTION:
謝謝@vlk我可以讓它工作!下面是切換LED一個小例子:
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <fcntl.h>
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
#define _PIOD_BANK_D 0xA00
#define _PIO_OFFSET 0xFFFFF000
/* When executing this on the board :
long sz = sysconf(_SC_PAGESIZE);
printf("%ld\n\r",sz);
We have 4096.
*/
#define _MAP_SIZE 0x1000 // 4096
#define _WPMR_OFFSET 0x0E4 // PIO Write Protection Mode Register Bank D
#define _PIO_ENABLE 0x000
#define _PIO_DISABLE 0x004
#define _PIO_STATUS 0x008
#define _OUTPUT_ENABLE 0x010
#define _OUTPUT_DISABLE 0x014
#define _OUTPUT_STATUS 0x018
#define _FILTER_ENABLE 0x020
#define _FILTER_DISABLE 0x024
#define _FILTER_STATUS 0x028
#define _OUTPUT_DATA_SET 0x030
#define _OUTPUT_DATA_CLEAR 0x034
#define _OUTPUT_DATA_STATUS 0x038
#define _PIN_DATA_STATUS 0x03c
#define _MULTI_DRIVER_ENABLE 0x050
#define _MULTI_DRIVER_DISABLE 0x054
#define _MULTI_DRIVER_STATUS 0x058
#define _PULL_UP_DISABLE 0x060
#define _PULL_UP_ENABLE 0x064
#define _PULL_UP_STATUS 0x068
#define _PULL_DOWN_DISABLE 0x090
#define _PULL_DOWN_ENABLE 0x094
#define _PULL_DOWN_STATUS 0x098
#define _DISABLE_WRITE_PROTECTION 0x50494F00 // Desable write protection
#define LED_PIN 21
int main(void) {
volatile void *gpio_addr;
volatile unsigned int *gpio_enable_addr;
volatile unsigned int *gpio_output_mode_addr;
volatile unsigned int *gpio_output_set_addr;
volatile unsigned int *gpio_output_clear_addr;
volatile unsigned int *gpio_data_status_addr;
volatile unsigned int *gpio_write_protection_addr;
int fd = open("/dev/mem", O_RDWR|O_SYNC);
if (fd < 0){
fprintf(stderr, "Unable to open port\n\r");
exit(fd);
}
gpio_addr = mmap(NULL, _MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, _PIO_OFFSET);
if(gpio_addr == MAP_FAILED){
handle_error("mmap");
}
gpio_write_protection_addr = gpio_addr + _PIOD_BANK_D + _WPMR_OFFSET;
gpio_enable_addr = gpio_addr + _PIOD_BANK_D + _PIO_ENABLE;
gpio_output_mode_addr = gpio_addr + _PIOD_BANK_D + _OUTPUT_ENABLE;
gpio_output_set_addr = gpio_addr + _PIOD_BANK_D + _OUTPUT_DATA_SET;
gpio_output_clear_addr = gpio_addr + _PIOD_BANK_D + _OUTPUT_DATA_CLEAR;
gpio_data_status_addr = gpio_addr + _PIOD_BANK_D + _OUTPUT_DATA_STATUS;
*gpio_write_protection_addr = _DISABLE_WRITE_PROTECTION;
*gpio_enable_addr = 1 << LED_PIN;
*gpio_output_mode_addr = 1 << LED_PIN; // Output
// If LED
if((*gpio_data_status_addr & (1<<LED_PIN)) > 0){
*gpio_output_clear_addr = 1 << LED_PIN;
}else{
*gpio_output_set_addr = 1 << LED_PIN;
}
return 0;
}
編輯:
答案在評論3)。你必須改變MMAP和喜歡,所以如果你想讓它與所有的補償工作的幽會(即:mmap example):
#define _PIO_OFFSET 0xFFFFFA00 // Instead of 0xFFFFF000
#define _MAP_SIZE 0x1000 // 4096
#define _MAP_MASK (_MAP_SIZE - 1)
#define _PA_OFFSET _PIO_OFFSET & ~_MAP_MASK
而且MMAP:
gpio_addr = mmap(NULL, _MAP_SIZE + _PIO_OFFSET - _PA_OFFSET, PROT_READ | PROT_WRITE, MAP_SHARED, fd, _PA_OFFSET);
而對於分配:
gpio_enable_addr = gpio_addr + _PIO_OFFSET - (_PA_OFFSET) + _PIO_ENABLE;
閱讀:從用戶空間訪問物理地址(https://stackoverflow.com/questions/12040303/accessing-physical-address-from-user-space) –
您無法訪問他們直接從像您可以使用mmap通過操作系統打眼,或者寫一個內核驅動程序或運行baremetal,但寫它應該賽格故障的應用空間。 –