Intel Wi-Fi Control Path
======================================


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        Topics in this section,

                * :ref:`Learnings in this section <FreebsdDeviceDriver_wireless_fdd_wi-fi_chipset_wi-fi_control_path_step1>`

                * :ref:`Version Info <FreebsdDeviceDriver_wireless_fdd_wi-fi_chipset_wi-fi_control_path_step3>`

	       	* :ref:`Control path <FreebsdDeviceDriver_wireless_fdd_wi-fi_chipset_wi-fi_control_path_step38>`




.. _FreebsdDeviceDriver_wireless_fdd_wi-fi_chipset_wi-fi_control_path_step1:
  
.. tab-set::

   .. tab-item:: Learnings in this section

        * In this section, you are going to learn

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                * Wi-Fi Control Path


.. _FreebsdDeviceDriver_wireless_fdd_wi-fi_chipset_wi-fi_control_path_step3:

.. tab-set::
 
    .. tab-item:: Version Info

        =============================== =======================================
        #                               Version
        =============================== =======================================
        Freebsd                         14.1.0
	wpa_supplicant                  2.10
        =============================== =======================================






.. _FreebsdDeviceDriver_wireless_fdd_wi-fi_chipset_wi-fi_control_path_step38:

.. tab-set::

   .. tab-item:: Control path

	.. tab-set::

	   .. tab-item:: wpa_supplicant to wlan entry point

		.. code-block:: c

			Ex:
			const  struct wpa_driver_ops wpa_driver_bsd_ops = {
										.scan2 = wpa_driver_bsd_scan,
										};

		* Defined in /usr/src/contrib/wpa/src/drivers/driver_bsd.c

		* The ‘struct wpa_driver_ops’  is a structure in wpa_supplicant (user-space daemon) that defines a set of function pointers for various operations that the driver needs to support to interact with the Wi-Fi hardware.

		* `wpa_driver_bsd_ops` It provides an interface between wpa_supplicant and the FreeBSD kernel's Wi-Fi driver.

		.. code-block :: c

			static int wpa_driver_bsd_scan(void *priv, struct wpa_driver_scan_params *params) 


		* Defined in /usr/src/contrib/wpa/src/drivers/driver_bsd.c

		* It is a driver interaction function responsible for sending scan requests to the kernel. This function issues an IOCTL system call/command.

	.. tab-set::

	   .. tab-item:: wlan entry

		* The WLAN (Wireless Local Area Network) functionality is handled primarily through the net80211 subsystem, which provides a comprehensive framework for wireless networking based on the IEEE 802.11 standard.

		* The net80211 framework is responsible for managing the core 802.11 wireless protocol stack in FreeBSD. It handles wireless-specific tasks such as scanning for networks, authentication, association, encryption, and managing wireless data traffic.


		.. code-block:: c

			int ieee80211_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) 

		* Defined in /usr/src/sys/net80211/ieee80211_ioctl.c

		* Once the ioctl request is received, it is handled by the FreeBSD 802.11 stack. This is  the entry point in the kernel for ioctl calls related to 802.11

		.. code-block:: c
	
			Struct ieee80211com {
					   * scanning support */
					     void   (*ic_scan_start)(struct ieee80211com *)
				     };

		* Defined in /usr/src/sys/net80211/ieee80211_var.h

		* The struct ieee80211com is a structure in the FreeBSD networking stack specifically within net80211 framework, which handles 802.11 (Wi-Fi) networking.

		* It provides an interact with actual Wi-Fi hardware 

		* From ‘ic_scan_start’ as  call back and called the linux_KPI functions 


	.. tab-set::

	   .. tab-item:: wlan to iwlwifi entry point

		.. code-block:: c

			int linuxkpi_ieee80211_ifattach(struct ieee80211_hw *hw)
			{
				ic->ic_scan_start = lkpi_ic_scan_start;
			}


		* Defined in sys/compat/linuxkpi/common/src/linux_80211.c

		* The LinuxKPI (Linux Kernel Programming Interface) in FreeBSD is a compatibility layer that allows certain Linux kernel functions and drivers to work on FreeBSD by providing equivalents or mappings to FreeBSD's own kernel APIs.

		* Many hardware vendors provide Linux drivers, but not FreeBSD drivers. The LinuxKPI layer enables FreeBSD to use Linux drivers by adapting Linux kernel function calls to FreeBSD equivalents.

		* In linuxkpi called the same ieee80211_ops call back functions and then enter intel driver(iwlwifi).

		.. code-block:: c

			struct ieee80211_ops {												     
						int  (*hw_scan)(struct ieee80211_hw *, struct ieee80211_vif *, struct ieee80211_scan_request *);
					       }

		* Defined in sys/compat/linuxkpi/common/include/net/mac80211.h

		.. code-block:: c

			struct ieee80211_ops iwl_mvm_hw_ops = {
						      .hw_scan = iwl_mvm_mac_hw_scan,
								}

		* Defined in /usr/src/sys/contrib/dev/iwlwifi/mvm/mac80211.c
			
		* From the linuxkpi function finally calls the ieee80211 operation function.

		* ieee80211_ops define a set of operations (function pointers) for the 802.11 (Wi-Fi) hardware to handle various Wi-Fi tasks like scanning, association, and data transmission

		* iwl_mvm_hw_ops is the Intel-specific implementation for handling Wi-Fi hardware operations.