mmap.c

___________C Code - user space______________

int *src = (int *)mmap (NULL, 4096, PROT_READ, MAP_SHARED, m_fd, 0);

___________Kernel space driver_______________

/*
 *
 *      BIN FILE SYSFS - for mmap'ing. share mem b/w userspace, kernel and PRU
 *
 */


#define BIN_ATTR(_name,_mode,_size,_read,_write,_mmap) { \
       .attr = { .name  =  __stringify(_name),  .mode = _mode  },   \
       .size = _size,                                         \
       .read   = _read,                                      \
       .write  = _write,                                      \
       .mmap = _mmap,                                   \
}


void pru_vma_open(struct vm_area_struct *vma)
{
        printk(KERN_NOTICE "PRU Speak VMA open, virt %lx, phys %lx\n",
            vma->vm_start, vma->vm_pgoff);
}

void pru_vma_close(struct vm_area_struct *vma)
{
        printk(KERN_NOTICE "PRU Speak VMA close.\n");
}

static struct vm_operations_struct pru_remap_vm_ops = {
        .open =  pru_vma_open,
        .close = pru_vma_close,
};

static ssize_t bin_file_read(struct file * f, struct kobject *kobj, struct bin_attribute *attr, char *buffer, loff_t pos, size_t size)
{
        printk(KERN_INFO "READ called on BIN FILE\n");
        return (ssize_t)0;
}

static ssize_t bin_file_write(struct file *f, struct kobject *kobj, struct bin_attribute *attr, char *buffer, loff_t pos, size_t size)
{
        printk(KERN_INFO "WRITE called on BIN FILE\n");
        return size;
}

static int bin_file_mmap(struct file *f, struct kobject *kobj, struct bin_attribute *attr,  struct vm_area_struct *vma)
{
        //printk(KERN_INFO "MMAP called on BIN FILE, PAGE_SHIFT value : %d\n", PAGE_SHIFT);
        if (remap_pfn_range(vma, vma->vm_start,(unsigned long)((int)shm.paddr >> PAGE_SHIFT), vma->vm_end - vma->vm_start, vma->vm_page_prot))
        {
                printk("MMAP failed\n");
                return -EAGAIN;
        }

        vma->vm_ops = &pru_remap_vm_ops;
        pru_vma_open(vma);

        printk("physical address that was to be maped %x\n: ", (int)shm.paddr);
        printk("MMAP successful\n");
        return 0;
}

static struct bin_attribute pru_speak_bin_attr = BIN_ATTR(pru_speak_binfile, S_IWUSR | S_IRUGO, PAGE_SIZE, 
                                                            bin_file_read, bin_file_write, bin_file_mmap);