Accessing Linux Drivers

Question

Simply put, can a user space application access device drivers running in kernel mode? If I want to read from the I2C Linux character driver, can a basic C executable (extensionless) do that or do I need to develop a kernel module specifically for that task? If a basic C app can access the I2C character driver, what does that gcc makefile look like?

Answer 1

Yes. User space application can access the kernel driver if the driver is character device or the driver exposing the stream interfaces.

Specific to i2c, user space application can write and reads to the i2c device via sysfs api. Refer the kernel document here https://www.kernel.org/doc/Documentation/i2c/dev-interface