Hi guys I'm a beginner in Android and Linux kernel. As an entry point to
Android first of all I have to deal with the Linux kernel so one of the
first tasks that I have to do is a simple driver runnable or configurable as
module or embedded into the kernel (this configuration has been done within
the menuconfig). Let me introduce my source code that I tried:
#define PROCFS_MAX_SIZE 80
#define procfs_name "calc1"
static struct proc_dir_entry *Our_Proc_File;
static unsigned long procfs_buffer_size = 0;
int procfile_read (char *buffer, char **buffer_location, off_t offset, int
buffer_length, int *eof, void *data)
{
int ret;
if (offset > 0) // we have finished to read, return 0
ret = 0;
else // fill the buffer, return the buffer size
ret = sprintf(buffer, "%s= %d\n",equation,solution);
//variables defined somewhere else
return ret;
}
// This function is called with the /proc file is written
int procfile_write(struct file *file, const char *buffer, unsigned long
count, void *data)
{
int i;
procfs_buffer_size = count;
for (i=0; i<count-1; i++)
equation[i]= buffer[i];
equation[i]= '\0';
calc1(); //this function is defined somewhere else
return procfs_buffer_size;
}
int init_module()
{
Our_Proc_File = create_proc_entry(procfs_name, 0644, NULL);
if (Our_Proc_File == NULL)
{
remove_proc_entry(procfs_name, &proc_root);
printk(KERN_ALERT "Error: Not initialize /proc/%s\n",
procfs_name);
return -ENOMEM;
}
Our_Proc_File->read_proc = procfile_read;
Our_Proc_File->write_proc = procfile_write;
Our_Proc_File->owner = THIS_MODULE;
Our_Proc_File->mode = S_IFREG | S_IRUGO;
Our_Proc_File->uid = 0;
Our_Proc_File->gid = 0;
Our_Proc_File->size = 37;
printk(KERN_ALERT "/proc/%s created\n", procfs_name);
return 0; // everything is ok
}
void cleanup_module()
{
remove_proc_entry(procfs_name, &proc_root);
printk(KERN_ALERT "/proc/%s removed\n", procfs_name);
}
MODULE_LICENSE("Dual BSD/GPL");RT_SYMBOL(procfile_write);
This works fine as module an initializing with insmod & ending with rmmod
constructs. the main goal is that, if it's a module avoid the needed of the
uses of insmod/rmmod constructs or....... if this is embedded into the
kernel....I coulded find and use this driver.
If any one can help me to fix that I'll be really grateful:
- How to link or init the module without using the insmod/rmmod constructs,
and
- If the driver (module) is embedded into th kernel, where is it placed or
haw to use it.
In advance many thaks for any help,
Best regards.
Reno.
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