GPIO Raspberry Type B with MainLine Kernel - module

Question

I have compiled uboot and a mainline kernel downloaded from kernel.org to run on a Raspberry Type B Module. I have a problem using the GPIO Interface. I am writing a module to manage two I/O's one of them should generate irq. When I call gpio_to_irq() or any other gpio related kernel api, the call always fail (return code -517 or -22). The same code, running on the raspberry kernel downloaded from the github RPI repository works. The mainline kernel, however, support BCM2835 that is the Soc used on RPI. Where is my approch wrong ? How does the gpio_api calls fail ? If I manually find the GPIO number (Virq) and I requests it with request_irq() everything works fine even with the mainline kernel from kernel.org.
The mainline kernel version is 4.11 while the rpi kernel version from github is 4.9.26. Here is the init function of the module:
I apologize for this. I will try to be more in toych now. Linux version (mainline) is 4.11 while the rpi linux version is 4.9.26. This is the init function of the module:
static int __init hello_init(void)
{
int result;
int temp;
printk(KERN_INFO "Hello world!\n");
printk(KERN_INFO "%s\n",Version);
/* Registering device */
result = register_chrdev(memory_major, "Bisio", &memory_fops);
if (result < 0)
{
printk(KERN_INFO "Memory Driver: Cannot Obtain Major Number %d\n", memory_major);
return -1;
}
/* Allocating memory for the buffer */
memory_buffer = kmalloc(MEMSIZE, GFP_KERNEL);
if (!memory_buffer) {
return -ENOMEM;
}
memset(memory_buffer, 0, MEMSIZE);
result = gpio_request(23,"MyIO");
printk(KERN_INFO "gpio_request: %d\n",result);
result = gpio_direction_input(23);
printk(KERN_INFO "gpio_direction_input: %d\n",result);
result = gpio_to_irq(23);
printk(KERN_INFO "gpio_to_irq: %d\n",result);
return 0; // Non-zero return means that the module couldn't be loaded.
}
Doing a insmod for this module I get:
[ 109.792257] nothing: loading out-of-tree module taints kernel.
[ 109.820350] Hello world!
[ 109.829341] Driver Version 1.27 - 10/09/2015 - 10:20
[ 109.841344] gpio_request: -517
[ 109.850737] gpio_direction_input: 0
[ 109.860187] gpio_to_irq: -22
while, doing the same with the rpi kernel (compiled with the same gcc crosscompiler version (5.20 soft float) works correctly and here is the output of the same init function:
[ 47.927565] nothing: loading out-of-tree module taints kernel.
[ 47.939771] Hello world!
[ 47.942333] Driver Version 1.27 - 10/09/2015 - 10:20
[ 47.947411] gpio_request: 0
[ 47.952798] gpio_direction_input: 0
[ 47.956314] gpio_to_irq: 183
what I am missing ?
Any help will be appreciated.
Regards
Marco Bisio