net: wifi: Add support for regulatory domain configuration

Wi-Fi bands are regulated by a governing body depending on operating
country, add support for the user to provide a country of operation as a
hint to the Wi-Fi chipset.

Ideally if the chipset supports this is all handled internally, in that
case "get" is useful but for testing and other usecases add a "set" as
well, similar to "iw reg set" or "country_code=" configuration in
hostapd/wpa_supplicant in Linux world.

This add a new offload API operation "reg_domain" that can be used to
either get or set the regulatory information.

The validation is left to the underlying chipset, shell only does basic
validation, (XY/00).

This is just a regulatory hint to the chipset, there could be other
regulatory hints e.g., beacon that can override this configuration, so,
an additional option to force this setting despite other hints is also
given for testing purposes.

FYI, the standard database used is [1].

[1] - https://git.kernel.org/pub/scm/linux/kernel/git/sforshee/wireless-regdb.git/tree/db.txt

Signed-off-by: Krishna T <krishna.t@nordicsemi.no>

subsys/net/l2/wifi/wifi_mgmt.c

@@ -293,3 +293,24 @@ void wifi_mgmt_raise_twt_event(struct net_if *iface, struct wifi_twt_params *twt
 					iface, twt_params,
 					sizeof(struct wifi_twt_params));
 }
+
+static int wifi_reg_domain(uint32_t mgmt_request, struct net_if *iface,
+			   void *data, size_t len)
+{
+	const struct device *dev = net_if_get_device(iface);
+	struct net_wifi_mgmt_offload *off_api =
+			(struct net_wifi_mgmt_offload *) dev->api;
+	struct wifi_reg_domain *reg_domain = data;
+
+	if (off_api == NULL || off_api->reg_domain == NULL) {
+		return -ENOTSUP;
+	}
+
+	if (!data || len != sizeof(*reg_domain)) {
+		return -EINVAL;
+	}
+
+	return off_api->reg_domain(dev, reg_domain);
+}
+
+NET_MGMT_REGISTER_REQUEST_HANDLER(NET_REQUEST_WIFI_REG_DOMAIN, wifi_reg_domain);

subsys/net/l2/wifi/wifi_shell.c

@@ -735,6 +735,67 @@ static int cmd_wifi_ap_disable(const struct shell *sh, size_t argc,
 	return 0;
 }
 
+
+static int cmd_wifi_reg_domain(const struct shell *sh, size_t argc,
+			       char *argv[])
+{
+	struct net_if *iface = net_if_get_default();
+	struct wifi_reg_domain regd = {0};
+	int ret;
+
+	if (argc == 1) {
+		regd.oper = WIFI_MGMT_GET;
+	} else if (argc >= 2 && argc <= 3) {
+		regd.oper = WIFI_MGMT_SET;
+		if (strlen(argv[1]) != 2) {
+			shell_fprintf(sh, SHELL_WARNING,
+				"Invalid reg domain: Length should be two letters/digits\n");
+			return -ENOEXEC;
+		}
+
+		/* Two letter country code with special case of 00 for WORLD */
+		if (((argv[1][0] < 'A' || argv[1][0] > 'Z') ||
+			(argv[1][1] < 'A' || argv[1][1] > 'Z')) &&
+			(argv[1][0] != '0' || argv[1][1] != '0')) {
+			shell_fprintf(sh, SHELL_WARNING, "Invalid reg domain %c%c\n", argv[1][0],
+				argv[1][1]);
+			return -ENOEXEC;
+		}
+		regd.country_code[0] = argv[1][0];
+		regd.country_code[1] = argv[1][1];
+
+		if (argc == 3) {
+			if (strncmp(argv[2], "-f", 2) == 0) {
+				regd.force = true;
+			} else {
+				shell_fprintf(sh, SHELL_WARNING, "Invalid option %s\n", argv[2]);
+				return -ENOEXEC;
+			}
+		}
+	} else {
+		shell_help(sh);
+		return -ENOEXEC;
+	}
+
+	ret = net_mgmt(NET_REQUEST_WIFI_REG_DOMAIN, iface,
+		       &regd, sizeof(regd));
+	if (ret) {
+		shell_fprintf(sh, SHELL_WARNING, "Cannot %s Regulatory domain: %d\n",
+			regd.oper == WIFI_MGMT_GET ? "get" : "set", ret);
+		return -ENOEXEC;
+	}
+
+	if (regd.oper == WIFI_MGMT_GET) {
+		shell_fprintf(sh, SHELL_NORMAL, "Wi-Fi Regulatory domain is: %c%c\n",
+			regd.country_code[0], regd.country_code[1]);
+	} else {
+		shell_fprintf(sh, SHELL_NORMAL, "Wi-Fi Regulatory domain set to: %c%c\n",
+			regd.country_code[0], regd.country_code[1]);
+	}
+
+	return 0;
+}
+
 SHELL_STATIC_SUBCMD_SET_CREATE(wifi_cmd_ap,
 	SHELL_CMD(disable, NULL,
 		  "Disable Access Point mode",
@@ -785,6 +846,13 @@ SHELL_STATIC_SUBCMD_SET_CREATE(wifi_commands,
 	SHELL_CMD(statistics, NULL, "Wi-Fi interface statistics", cmd_wifi_stats),
 	SHELL_CMD(status, NULL, "Status of the Wi-Fi interface", cmd_wifi_status),
 	SHELL_CMD(twt, &wifi_twt_ops, "Manage TWT flows", NULL),
+	SHELL_CMD(ap, &wifi_cmd_ap, "Access Point mode commands", NULL),
+	SHELL_CMD(reg_domain, NULL,
+		"Set or Get Wi-Fi regulatory domain\n"
+		"Usage: wifi reg_domain [ISO/IEC 3166-1 alpha2] [-f]\n"
+		"-f: Force to use this regulatory hint over any other regulatory hints\n"
+		"Note: This may cause regulatory compliance issues, use it at your own risk.",
+		cmd_wifi_reg_domain),
 	SHELL_SUBCMD_SET_END
 );