Linux Device Driver

Question

I have problem concerning about my module it it installed/initialized correctly but the other parts of the driver is not installed or showing up in the output.

   static struct i2c_driver qt2120_dev {
       .probe = qt2120_probe,
       .remove = qt2120_remove,
       .owner = {
           .name = qt2120,
           .module = THIS_MODULE, 
       }
       ....           
   }

  static __init qt2120_init(){
       prink("********init******");
       .......
  }
  module_init(qt2120_init)

  static int qt2120_probe(){
       prink("********probe******");
       .......     
  }

  static __devinit qt2120_remove(){
       prink("********probe******");
       .......     
  }

Only "/**init*" appeared in the output. The module has been installed to the i2c according to the output.

  "bus: i2c. qt2120 as qt2120/input"

Something is wrong with module because the printk's in probe and remove never at all.

I also changed in the MAKEFILE @CONFIG_AT2120 += qt2160.o with qt2120.o as the module

Is there something wrong with my configuration? qt2120.c is very similar to qt2160.c in code aurora.

Well, `prink` is not valid, so maybe your latest compile attempt failed and you actually installed an earlier version. And no, you should not have changed .o to .c in the Makefile either. — Chris Stratton, Jun 06 '13 at 15:48

score 2 · Answer 1 · answered Jul 22 '13 at 13:04

Probe and remove function is not calling because you have not registered your driver with i2c subsystem. Register your driver using i2c_add_driver() API. In your case,

static int __init qt2120_init(void)
{
    return i2c_add_driver(&qt2120_dev);
}

static void __exit qt2120_remove(void)
{
    return i2c_del_driver(&qt2120_dev);
}

score 2 · Answer 2 · answered Apr 22 '15 at 09:57

First you need to make ,I2C driver registering the 'struct i2c_driver' structure with the I2C core using i2c_add_driver(addr_of_struct i2c_driver).

static const struct i2c_device_id sample_i2c_id[] = {
  { "qt2120", 0 },
  { }
};
static struct i2c_driver qt2120_dev = {
   .probe = qt2120_probe,
   .remove = qt2120_remove,
   .id_table = sample_i2c_id,
   .driver   = {
        .name = "qt2120",
    },
 ....           
};

You need to add .id_table entry . The id_table member allows us to tell the framework which I2C slaves chips we support.

After matching .id_table entry.Driver calls probe function.

Use following links for reference:

Understanding of i2c driver : http://www.embedded-bits.co.uk/2009/i2c-in-the-2632-linux-kernel/

Sample code: https://code.google.com/p/ldd-templates/source/browse/drivers/i2c/sample-i2c-client.c

Linux Device Driver

2 Answers2