When driver probe is called?

6 Answers. 6. 42. Long story short: the probe() function of the driver is called as a result of calling the register_driver for that specific bus. More precisely, it’s called by the probe() of that bus_type structure.

How probe function is called in Linux?

Probing is done when the probe() method is called by function pointer inside a structure which is used to device binding with default or custom platform data regarding to device.

What is the functionality of probe function?

The purpose of the probe routine is to detect devices residing on the bus and to create device nodes corresponding to these devices. The probe routine specifies resource requirements as device node properties so that the bus driver can reserve resources required to initialize the device. …

What is a platform device?

Platform devices are given a name, used in driver binding, and a list of resources such as addresses and IRQs: struct platform_device { const char *name; u32 id; struct device dev; u32 num_resources; struct resource *resource; };

What are the basic structures in Linux devices?

Basic Structures in Linux Devices

struct bus_type.
struct device.
struct device_driver.

What is kernel probe?

5 Kernel Probes Kernel probes are a set of tools to collect Linux kernel debugging and performance information. To use kernel probes, you typically need to write or obtain a specific kernel module. Such modules include both the init and the exit function.

What is Of_match_table?

OF match style is the first matching mechanism performed by the platform core in order to match devices with their drivers. It uses a device tree’s compatible property to match the device entry in of_match_table , which is a field of the struct driver substructure.

What is the function used to register a device?

Device driver registration. driver_register() is the low-level function used to register a device driver with the bus.

What is a KProbe?

There are two types of probes in the kernel as of now, called “KProbes” and “JProbes.” A KProbe is defined by a pre-handler and a post-handler. When a KProbe is installed at a particular instruction and that instruction is executed, the pre-handler is executed just before the execution of the probed instruction.

How does Linux platform driver probe function work?

When the platform_driver_probe() function is called, the operating system scans through the list of available platform devices and checks if the driver.name matches with the device name. If yes, it calls the driver probe function with the platform data.

How is the device driver independent of the platform?

This way, the device driver can be made independent of the platform and hence can be used across multiple platforms. For example, the below example implements functions for power ON/OFF the device and for doing the device reset. This is done by calling platform_device_register () function with the device instance as shown below.

What does the platform driver do in Linux?

Platform Driver The platform driver implements a probe function that is called by the OS when this driver is inserted. Since the driver is supposed to be platform independent, it depends on the platform_data functions to set up the device and make it operational.

What happens if platform device is not found?

If the device is not found, the driver is simply ignored. Platform device driver works a bit differently than normal hot-pluggable device driver. Platform device is either directly mounted on the board or part of the SoC and hence can’t be physically removed.

When driver probe is called?