initial buildroot for linux 5.15

package/spidev_test/Config.in

@@ -0,0 +1,17 @@
+config BR2_PACKAGE_SPIDEV_TEST
+	bool "spidev_test"
+	help
+	  SPI testing utility (using spidev driver).
+
+	  This package builds and installs the userspace 'spidev_test'
+	  command. It is up to the user to ensure that the kernel
+	  configuration has all suitable options enabled to allow a
+	  proper operation of 'spidev_test'.
+
+	  The version used is based on your toolchain headers version,
+	  if it's older than 3.15 then 3.0 is used, otherwise 3.15
+	  is used.
+	  This means you won't have quad-pumped SPI support if your
+	  toolchain is too old.
+
+	  https://www.kernel.org/doc/html/latest/spi/index.html

package/spidev_test/spidev_test.hash

@@ -0,0 +1,3 @@
+# Locally calculated
+sha256 80471c330d8c0bf5ba6479c434a54a54bdd2dc59a703b9c76c2541ec04cfb8c3  spidev_test.c?id=v3.0
+sha256 3cf76b15d9a8644f3f5cbc0387cc02a7d4a392ade39788cbc6367cce98552e2f  spidev_test.c?id=v4.10

package/spidev_test/spidev_test.mk

@@ -0,0 +1,48 @@
+################################################################################
+#
+# spidev_test
+#
+################################################################################
+
+# Build the latest version that is compatible with the toolchain's kernel headers
+# v3.15+ requires SPI_TX_QUAD/SPI_RX_QUAD to build
+# Normally kernel headers can't be newer than kernel so switch based on that.
+# If you need quad-pumped spi support you need to upgrade your toolchain.
+# Note that the location of spidev_test.c changes from v4.5 onwards.
+
+ifeq ($(BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_15),y)
+SPIDEV_TEST_VERSION = 4.10
+SPIDEV_TEST_PATH = tools/spi
+else
+SPIDEV_TEST_VERSION = 3.0
+SPIDEV_TEST_PATH = Documentation/spi
+endif
+
+SPIDEV_TEST_SITE = http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/plain/$(SPIDEV_TEST_PATH)
+SPIDEV_TEST_SOURCE = spidev_test.c?id=v$(SPIDEV_TEST_VERSION)
+SPIDEV_TEST_LICENSE = GPL-2.0
+
+# musl libc requires linux/ioctl.h for _IOC_SIZEBITS. Do a sed patch to keep
+# compatibility with different spidev_test.c versions that we support.
+define SPIDEV_TEST_ADD_LINUX_IOCTL
+	$(SED) 's~^#include <sys/ioctl.h>~#include <sys/ioctl.h>\n#include <linux/ioctl.h>~' \
+		$(@D)/spidev_test.c
+endef
+
+SPIDEV_TEST_POST_PATCH_HOOKS += SPIDEV_TEST_ADD_LINUX_IOCTL
+
+define SPIDEV_TEST_EXTRACT_CMDS
+	cp $(SPIDEV_TEST_DL_DIR)/$(SPIDEV_TEST_SOURCE) $(@D)/spidev_test.c
+endef
+
+define SPIDEV_TEST_BUILD_CMDS
+	$(TARGET_MAKE_ENV) $(TARGET_CC) $(TARGET_CFLAGS) \
+		-o $(@D)/spidev_test $(@D)/spidev_test.c
+endef
+
+define SPIDEV_TEST_INSTALL_TARGET_CMDS
+	$(INSTALL) -D -m 755 $(@D)/spidev_test \
+		$(TARGET_DIR)/usr/sbin/spidev_test
+endef
+
+$(eval $(generic-package))