cc3200: Use peripheral driver library functions from ROM

Previously, CC3200 drivers had two options to use the peripheral
driver library APIs:
1) Build driverlib SDK files in Zephyr, in ext/hal/ti/cc3200/*
2) Link directly with the driverlib.a, from an externally installed
   TI CC3200 SDK.

A new option is added to replace option 2), and is now the default:
3) Use the driverlib functions already provided in ROM.

This enables a savings in code size, which will depend on the
types of device drivers configured and the number of SDK
APIs actually used.

A rom_report build of the shell sample application showed
a savings of about 2kb in code space using this new config option.

Change-Id: Ie1ede6f7aacd23db20f5292e776f1dfeab5c7fe0
Signed-off-by: Gil Pitney <gil.pitney@linaro.org>
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>

arch/arm/soc/ti_simplelink/cc32xx/Kconfig.defconfig.cc3200

@@ -20,9 +20,6 @@ config FLASH_SIZE
 config CC3200SDK_LIBRARY
 	def_bool n
 
-config CC3200SDK_INSTALL_PATH
-	default ""
-
 config NUM_IRQS
 	int
 	# must be >= the highest interrupt number used

boards/arm/cc3200_launchxl/cc3200_launchxl_defconfig

@@ -22,4 +22,4 @@ CONFIG_CONSOLE=y
 CONFIG_UART_CONSOLE=y
 
 # Enable CC3200 SDK driver files
-CONFIG_CC3200SDK_BUILTIN=y
+CONFIG_CC3200SDK_ROM_DRIVERLIB=y

ext/hal/Kbuild

@@ -1,4 +1,4 @@
 obj-$(CONFIG_HAS_KSDK) += ksdk/
 obj-$(CONFIG_QMSI_BUILTIN) += qmsi/
 obj-$(CONFIG_HAS_STM32CUBE) += st/stm32cube/
-obj-$(CONFIG_CC3200SDK_BUILTIN) += ti/cc3200sdk/
+obj-$(CONFIG_HAS_CC3200SDK) += ti/cc3200sdk/

ext/hal/ti/cc3200sdk/Kbuild

@@ -1,17 +1,18 @@
-# CC3200 SDK builds driverlib with level 0 optimization (-O0).
+# CONFIG_CC3200SDK_BUILTIN can be used for debugging purposes.
-# Zephyr uses -Os optimization level, which causes issues
+# In that case, the CC3200 SDK driverlib must be built with level 0
-# with the uart module: characters are garbled on output.
+# optimization (-O0) for the uart module to work properly.
-# Until this is resolved with the vendor, we keep -O0 here,
+# Note the default build for Zephyr is CONFIG_CC3200SDK_ROM_DRIVERLIB=y
-# to ensure correct operation.
+# which uses the ROM versions of the APIs instead.
 ccflags-$(CONFIG_CC3200SDK_BUILTIN) += -O0
-ccflags-$(CONFIG_CC3200SDK_BUILTIN) += -D$(COMPILER)
+ccflags-$(CONFIG_HAS_CC3200SDK) += -D$(COMPILER)
 obj-$(CONFIG_CC3200SDK_BUILTIN) += driverlib/gpio.o
 obj-$(CONFIG_CC3200SDK_BUILTIN) += driverlib/interrupt.o
 obj-$(CONFIG_CC3200SDK_BUILTIN) += driverlib/pin.o
-obj-$(CONFIG_CC3200SDK_BUILTIN) += driverlib/prcm.o
 obj-$(CONFIG_CC3200SDK_BUILTIN) += driverlib/uart.o
-obj-$(CONFIG_CC3200SDK_BUILTIN) += driverlib/utils.o
 obj-$(CONFIG_CC3200SDK_BUILTIN) += driverlib/udma.o
 # spi.c warns on parens
 CFLAGS_spi.o += -Wno-parentheses
 obj-$(CONFIG_CC3200SDK_BUILTIN) += driverlib/spi.o
+# Need prcm and utils for PRCMCC3200MCUInit which is not in ROM
+obj-$(CONFIG_HAS_CC3200SDK) += driverlib/utils.o
+obj-$(CONFIG_HAS_CC3200SDK) += driverlib/prcm.o

ext/hal/ti/cc3200sdk/Kconfig

@@ -19,18 +19,11 @@ config CC3200SDK_BUILTIN
         help
         Link with local CC3200 SDK driverlib sources.
 
-config CC3200SDK_LIBRARY
+config CC3200SDK_ROM_DRIVERLIB
-	bool "Link with CC3200 SDK static driver library"
+        bool "Use the Peripheral Driver library functions in ROM"
-	default n
+        default n
-	select CC3200SDK
+        select CC3200SDK
-	help
+        help
-	The CC3200 SDK provides a static library (libdriver.a)
+        Vector to CC3200 SDK driverlib APIs in ROM.
-	which implements peripheral APIs for the CC3200.
-
-config CC3200SDK_INSTALL_PATH
-	depends on CC3200SDK_LIBRARY
-	string "CC3200 SDK install path"
-	help
-	This option holds the path where the CC3200 SDK is installed.
 
 endif

ext/hal/ti/cc3200sdk/Makefile

@@ -1,11 +1,9 @@
-ifdef CONFIG_CC3200SDK_LIBRARY
+ifdef CONFIG_HAS_CC3200SDK
-ZEPHYRINCLUDE += -I$(CONFIG_CC3200SDK_INSTALL_PATH)
-LIB_INCLUDE_DIR += -L$(CONFIG_CC3200SDK_INSTALL_PATH:"%"=%)/driverlib/gcc/exe
-ALL_LIBS += driver
-endif  # CONFIG_CC3200SDK_LIBRARY
-
-ifdef CONFIG_CC3200SDK_BUILTIN
 ZEPHYRINCLUDE +=-I$(srctree)/ext/hal/ti/cc3200sdk
 ZEPHYRINCLUDE +=-I$(srctree)/ext/hal/ti/cc3200sdk/inc
 ZEPHYRINCLUDE +=-I$(srctree)/ext/hal/ti/cc3200sdk/driverlib
-endif # CONFIG_CC3200_BUILTIN
+endif # CONFIG_HAS_CC3200SDK
+
+ifdef CONFIG_CC3200SDK_ROM_DRIVERLIB
+KBUILD_CFLAGS += -DTARGET_IS_CC3200
+endif  # CONFIG_CC3200SDK_ROM_DRIVERLIB

ext/hal/ti/cc3200sdk/README

@@ -10,8 +10,30 @@ from:
 Files in driverlib/ and inc/ are copied from an SDK installation
 (without modification).
 
-Setting CONFIG_CC3200SDK_BUILTIN allows building those files within
+After setting CONFIG_HAS_CC3200SDK=y in Kconfig, there are two methods
-the Zephyr ext/hal/ subdirectory.
+for using the peripheral driver library:
 
-Setting CONFIG_CC3200SDK_INSTALL_PATH and CONFIG_CC3200SDK_LIBRARY enables
+1) (Default) Use the driverlib functions in ROM instead of RAM.
-linking with the library provided by the CC3200 SDK, installed separately.
+
+TI provides the driver library functions burned into ROM at the factory,
+or updated via a service pack patch, thus saving application code space.
+
+For the zephyr shell sample, for example, this resulted in a savings of
+about 2Kb in code space.
+
+Setting CONFIG_CC3200SDK_ROM_DRIVERLIB enables all driverlib APIs prefixed by
+"MAP_" to vector to those functions already existing in ROM.
+
+See: Section 6.2.2 "Linking User Application with ROM APIs",
+     CC3200 Programmer's Guide, www.ti.com/lit/pdf/swru369
+
+2) Use the driver library functions built from the CC3200SDK files in Zephyr.
+
+Setting CONFIG_CC3200SDK_BUILTIN allows building those files within
+the Zephyr ext/hal/ti/ subdirectory. Though this will take more code space
+than using the ROM driverlib functions, this may be useful for debugging
+purposes.
+
+Applications can use the two configurations simultaneously:  For example, calling
+APIs without the "MAP_" prefix would call into Zephyr-built driver lib functions in
+RAM, while calling APIs with the "MAP_" prefix would call into the ROM.