msgboxin.c

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <stdint.h>
#include "rpmsg.h"

/*
// The ioctl number, replace with exact value from your kernel (may vary, typically defined in rpmsg_chrdev.h)
#define RPMSG_CREATE_EPT_IOCTL 0x4020b009  

struct rpmsg_endpoint_info {
    char name[32];
    uint32_t src_addr;
    uint32_t dst_addr;
};
*/

int main() {
    int ctrlfd, rpmsgfd;
    struct rpmsg_endpoint_info ept_info;
    ssize_t len;
    char rx_buf[512];
    char tx_buf[512] = "Hello DSP from Linux!";

    // Fill endpoint info (customize src/dst addresses as needed!)
    memset(&ept_info, 0, sizeof(ept_info));
    //strncpy(ept_info.name, "msgbox-channel", sizeof(ept_info.name));
    //strncpy(ept_info.name, "sunxi,dsp-msgbox", sizeof(ept_info.name));
    //strncpy(ept_info.name, "rpmsg_chrdev", sizeof(ept_info.name));
    //strncpy(ept_info.name, "sunxi,msgbox-amp", sizeof(ept_info.name));
    strncpy(ept_info.name, "amp", sizeof(ept_info.name));

    // Example addresses. Match these to those used in DSP firmware and dts 'msgbox' node.
    ept_info.src_addr = 0x01;
    ept_info.dst_addr = 0x01;

    // Open the control device
    ctrlfd = open("/dev/rpmsg_ctrl0", O_RDWR);
    if (ctrlfd < 0) {
        perror("open /dev/rpmsg_ctrl0");
        return 1;
    }

    // Issue the ioctl to create the endpoint
    if (ioctl(ctrlfd, RPMSG_CREATE_EPT_IOCTL, &ept_info) < 0) {
        perror("ioctl RPMSG_CREATE_EPT_IOCTL");
        close(ctrlfd);
        return 1;
    }
    close(ctrlfd);

    // Now /dev/rpmsg0 should exist
    rpmsgfd = open("/dev/rpmsg0", O_RDWR);
    if (rpmsgfd < 0) {
        perror("open /dev/rpmsg0");
        return 1;
    }
/*
    // Write message to DSP
    len = write(rpmsgfd, tx_buf, strlen(tx_buf));
    if (len < 0) {
        perror("write to /dev/rpmsg0");
        close(rpmsgfd);
        return 1;
    }
    printf("Sent %zd bytes: %s\n", len, tx_buf);
*/
while ( 1 ) {
    // Read message from DSP
    len = read(rpmsgfd, rx_buf, sizeof(rx_buf) - 1);
    if (len < 0) {
        perror("read from /dev/rpmsg0");
        close(rpmsgfd);
        return 1;
    }
    rx_buf[len] = '\0';
    printf("Received %zd bytes: %s\n", len, rx_buf);
}
    close(rpmsgfd);
    return 0;
}