[oe] [meta-networking][PATCH v5 3/3] kernel_wireless_regdb: Add class for embedding regulatory data into older kernel

[Krzysztof Kozlowski]

Linux kernels before v4.15, allowed to be compiled with static
regulatory database if it was put under net/wireless/db.txt.

Add kernel_wireless_regdb class which allows in such cases to embed the
wireless regulatory database directly in the Linux kernel during build
process.

Usage:
1. The class should be inherited by kernel recipe (e.g. in
   linux-yocto_%.bbappend).
2. For Linux kernels up to v4.14, build kernel with CONFIG_EXPERT and
   CONFIG_CFG80211_INTERNAL_REGDB.

Signed-off-by: Krzysztof Kozlowski <krzk at kernel.org>
---
 .../classes/kernel_wireless_regdb.bbclass            | 20 ++++++++++++++++++++
 .../wireless-regdb/wireless-regdb_2018.05.31.bb      |  9 +++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 meta-networking/classes/kernel_wireless_regdb.bbclass

diff --git a/meta-networking/classes/kernel_wireless_regdb.bbclass b/meta-networking/classes/kernel_wireless_regdb.bbclass
new file mode 100644
index 000000000000..1238172bd4b7
--- /dev/null
+++ b/meta-networking/classes/kernel_wireless_regdb.bbclass
@@ -0,0 +1,20 @@
+# Linux kernels before v4.15, allowed to be compiled with static
+# regulatory database if it was put under net/wireless/db.txt.
+#
+# This class copies the regulatory plaintext database to kernel sources before
+# compiling.
+#
+# Usage:
+# 1. The class should be inherited by kernel recipe (e.g. in
+#    linux-yocto_%.bbappend).
+# 2. For Linux kernels up to v4.14, build kernel with CONFIG_EXPERT and
+#    CONFIG_CFG80211_INTERNAL_REGDB.
+
+DEPENDS += "wireless-regdb-native"
+
+SRCTREECOVEREDTASKS += "do_kernel_add_regdb"
+do_kernel_add_regdb() {
+    cp ${STAGING_LIBDIR_NATIVE}/crda/db.txt ${S}/net/wireless/db.txt
+}
+do_kernel_add_regdb[dirs] = "${S}"
+addtask kernel_add_regdb before do_build after do_configure
diff --git a/meta-networking/recipes-connectivity/wireless-regdb/wireless-regdb_2018.05.31.bb b/meta-networking/recipes-connectivity/wireless-regdb/wireless-regdb_2018.05.31.bb
index 2ae9e85427bc..d1c8d567597b 100644
--- a/meta-networking/recipes-connectivity/wireless-regdb/wireless-regdb_2018.05.31.bb
+++ b/meta-networking/recipes-connectivity/wireless-regdb/wireless-regdb_2018.05.31.bb
@@ -22,6 +22,7 @@ do_install() {
 
 # Install static regulatory DB in /lib/firmware for kernel to load.
 # This requires Linux kernel >= v4.15.
+# For kernel <= v4.14, inherit the kernel_wireless_regdb.bbclass in kernel's recipe.
 PACKAGES =+ "${PN}-static"
 RCONFLICTS_${PN} = "${PN}-static"
 
@@ -30,4 +31,12 @@ FILES_${PN}-static = " \
     ${nonarch_base_libdir}/firmware/regulatory.db.p7s \
 "
 
+# Native users might want to use the source of regulatory DB.
+# This is for example used by Linux kernel <= v4.14 and kernel_wireless_regdb.bbclass.
+do_install_append_class-native() {
+    install -m 0644 -D db.txt ${D}${libdir}/crda/db.txt
+}
+
 RSUGGESTS_${PN} = "crda"
+
+BBCLASSEXTEND = "native"
-- 
2.14.1