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HowToPortTizenRTOnWiFiChipset.md

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How to port TizenRT on new WiFi chipset

There are two cases to consider towards porting TizenRT on a new WiFi chipset. The specific case depends on the vendor's decision to either use their proprietary supplicant codebase, or to directly use TizenRT's WiFi solution.

Below are mentioned the two cases in detail. Additionally, we provide guidelines on how to interface TizenRT's WiFi Manager to the newly added chipset. Lastly, instructions are provided to incorporate the WiFi chipset driver in TizenRT's code tree. Specifically, details are provided to interface driver to network stack, and to get/set WiFi configuration from a higher abstraction layer.

How to add external WiFi library

External vendors may choose to build TizenRT application that includes their compiled WiFi libary, rather than opting for TizenRT's wpa_supplicant. To support external and independently compiled WiFi supplicant libraries, they must be added to TizenRT.
For details on how to add libraries, please refer to How to add Static Library.

How to use WPA_SUPPLICANT

If the developer wishes to use TizenRT's wpa_supplicant for WiFi-based applications, then following changes need to be performed at wpa_suppliant.

Supplicant

Changes in external directory for a new WiFi board to include new chipset driver.

  1. Make sure you have defined CONFIG_DRIVER_<DRIVER_NAME> in external/wpa_supplicant/Kconfig. Refer to the example below for CONFIG_DRIVER_T20, which is subject to the condition that CONFIG_SCSC_WLAN is enabled already.
config DRIVER_T20
	bool "Driver T20 for SLSI WiFi"
	default y
	depends on SCSC_WLAN
  1. Add new chipset driver under external/wpa_supplicant/src/drivers/, and name it as driver_<driver_name>.c. Select this file for build in external/wpa_supplicant/src/drivers/Make.defs, depending on the Kconfig that is defined for your WiFi driver. An example is shown for LSI WiFi:
ifeq ($(CONFIG_DRIVER_T20), y)
CSCRS += driver_t20.c
endif

Inside driver_<driver_name>.c, declare a driver structure variable named wpa_driver_<driver_name>_ops. wpa_driver_<driver_name>_ops is a structure of type wpa_driver_ops that is declared in external/wpa_supplicant/src/drivers/driver.h. The wpa_driver_ops structure contains function pointers to the specific WiFi driver that the supplicant links to. As an example, refer to the wpa_driver_t20_ops structure declared in external/wpa_supplicant/src/drivers/driver_t20.c for the LSI WiFi chipset.

const struct wpa_driver_ops wpa_driver_t20_ops = {
	.name = "slsi_t20",
	.desc = "SLSI T20 Driver",
	.init2 = slsi_t20_init,
	.deinit = slsi_t20_deinit,
	.get_mac_addr = slsi_get_mac_addr,
	.get_capa = slsi_t20_get_capa,
	.scan2 = slsi_hw_scan,…
}
  1. Add the driver structure variable created in step 2 to the wpa_drivers list in external/wpa_supplicant/src/drivers/drivers.c, as shown below:
#ifdef CONFIG_DRIVER_<DRIVER_NAME>
extern struct wpa_driver_ops wpa_driver_<driver_name>_ops;	/* driver_<driver_name>.c */
#endif

const struct wpa_driver_ops *const wpa_drivers[] = {
#ifdef CONFIG_DRIVER_<DRIVER_NAME>
	&wpa_driver_<DRIVER_NAME>_ops,
#endif
...
}

This links the supplicant to the relevant WiFi driver.

Interfacing to WiFi Manager

TizenRT features a generic WiFi Manager framework (API located at framework/inc/wifi_manager) for applications. The WiFi Manager framework implements specific WiFi utility functions that will directly talk to the WiFi supplicant software. Also, in case of a proprietary WiFi API used over WiFi supplicant, the developer should invoke those APIs using the WiFi utility functions. TizenRT provides a standard API for WiFi utilities, which is declared under framework/src/wifi_manager/wifi_utils.h. Please make sure you create a new WiFi utility file named wifi_utils_<supplicant_prefix>.c in the same folder, and interface to the WiFi supplicant, using the API in wifi_utils.h. Developers are encouraged to consult wifi_utils_wpa.c as a reference implementation that interfaces to TizenRT's WPA_SUPPLICANT. Finally, to build the utility file that you have created, please edit framework/src/wifi_manager/Make.defs, and add the following lines as shown below:

ifeq ($(CONFIG_<SUPPLICANT_LIBRARY_NAME>), y)
CSRCS += wifi_utils_<supplicant_prefix>.c
endif

Incorporating WiFi Chipset Driver

The WiFi driver source files should reside under a newly created os/driver/wireless/<wifi_driver_name> folder. Please follow the steps below to initialize the driver and interface it with the overlying network stack.

WiFi Driver Initialization

This driver should be initialized from the main board's initialization routine. An example initialization can be found under os/arch/arm/src/sidk_s5jt200/src/s5jt200_boot.c:

void board_initialize(void) {
...
#ifdef CONFIG_SCSC_WLAN
	slldbg("Initialize SCSC driver\n");
	slsi_driver_initialize();
#endif
}

Make sure you create your board-specific files at os/arch/arm/src/<board_name>/src/<board>_boot.c, and call the driver initialization function as shown in the example above.

Next, inside your board specific directory, create a <board>_wlan.c file. This file should include following functionalities:

1. Interfacing the WiFi driver to the Network Stack

In TizenRT, the netif structure links the WiFi driver to the overlying network layer. Netif creation should be called from the WiFi driver initialization function. Please make sure you have implemented netif.c and netif.h files in your driver code for this purpose. An example netif creation can be found under up_wlan_init function in os/arch/arm/src/sidk_s5jt200/s5jt200_wlan.c file. In this case, during bootup, up_wlan_init is invoked from the driver initialization routine, and creates the netif structure. The up_wlan_init function is shown below for reference:

static err_t wlan_init(struct netif *netif)
{
	netif->name[0] = IFNAME0;
	netif->name[1] = IFNAME1;

	snprintf(netif->d_ifname, IFNAMSIZ, "%c%c%d", netif->name[0], netif->name[1], netif->num);

	netif->flags = NETIF_FLAG_ETHARP | NETIF_FLAG_ETHERNET | NETIF_FLAG_BROADCAST | NETIF_FLAG_IGMP;

	return ERR_OK;
}

void up_wlan_init(struct netif *dev)
{
	struct ip_addr ipaddr;
	struct ip_addr netmask;
	struct ip_addr gw;

	/* Start LWIP network thread */
	ipaddr.addr = inet_addr("0.0.0.0");
	netmask.addr = inet_addr("255.255.255.255");
	gw.addr = inet_addr("0.0.0.0");

	netif_set_default(dev);

	wlan_netif = netif_add(dev, &ipaddr, &netmask, &gw,
					NULL, wlan_init, tcpip_input);
	wlan_netif->flags |= NETIF_FLAG_IGMP;
}

2. WiFi configuration data

Please define two functions for reading and writing WiFi configuration data, as up_wlan_read_config and up_wlan_write_config functions. The prototype and implementation for the functions are vendor-specific. As a reference, please refer to the up_wlan_read_config function in os/arch/arm/src/sidk_s5jt200/s5jt200_wlan.c.

3. Getting WiFi MAC address and the WiFi firmware address.

Please refer to the functions up_wlan_get_mac_addr and up_wlan_get_firmware in os/arch/arm/src/sidk_s5jt200/s5jt200_wlan.c.