make the common runtime optional

In order to achieve really tiny firmwares, make our runtime (tasks,
hooks, muxed timers, GPIO abstraction ...) optional.
Add 2 new build options for it : CONFIG_COMMON_RUNTIME and
CONFIG_COMMON_GPIO which are enabled by default, and ensure all the
source files are built according to the right configuration variable.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BRANCH=none
BUG=none
TEST=make buildall
build a minimal board with no runtime.

Change-Id: Icb621cbe0a75b3a320cb53c3267d6e578cd3c32f
Reviewed-on: https://chromium-review.googlesource.com/189403
Reviewed-by: Vic Yang <victoryang@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>

11 files changed, 49 insertions, 10 deletions

diff --git a/chip/stm32/build.mk b/chip/stm32/build.mk
index 2b0477518c..a4ce0f4bda 100644
--- a/chip/stm32/build.mk
+++ b/chip/stm32/build.mk
@@ -25,11 +25,14 @@ I2C_FAMILY=$(subst stm32f0,stm32l,$(CHIP_FAMILY))
 # Select between 16-bit and 32-bit timer for clock source
 TIMER_TYPE=$(if $(CONFIG_STM_HWTIMER32),32,)
 
-chip-y=dma.o hwtimer$(TIMER_TYPE).o system.o uart.o
-chip-y+=jtag-$(CHIP_FAMILY).o clock-$(CHIP_FAMILY).o gpio-$(CHIP_FAMILY).o
+chip-y=dma.o system.o
+chip-y+=jtag-$(CHIP_FAMILY).o clock-$(CHIP_FAMILY).o
 chip-$(CONFIG_SPI)+=spi.o
+chip-$(CONFIG_COMMON_GPIO)+=gpio-$(CHIP_FAMILY).o
+chip-$(CONFIG_COMMON_TIMER)+=hwtimer$(TIMER_TYPE).o
 chip-$(CONFIG_I2C)+=i2c-$(I2C_FAMILY).o
 chip-$(CONFIG_WATCHDOG)+=watchdog.o
+chip-$(HAS_TASK_CONSOLE)+=uart.o
 chip-$(HAS_TASK_KEYSCAN)+=keyboard_raw.o
 chip-$(HAS_TASK_POWERLED)+=power_led.o
 chip-$(CONFIG_FLASH)+=flash-$(FLASH_FAMILY).o
diff --git a/common/build.mk b/common/build.mk
index e2697c8c1c..cab075503a 100644
--- a/common/build.mk
+++ b/common/build.mk
@@ -6,9 +6,8 @@
 # Common files build
 #
 
-common-y=main.o util.o console_output.o uart_buffering.o
-common-y+=memory_commands.o shared_mem.o system.o hooks.o
-common-y+=gpio.o version.o printf.o queue.o
+common-y=util.o
+common-y+=version.o printf.o queue.o
 
 common-$(CONFIG_ACCEL_CALIBRATE)+=motion_calibrate.o
 common-$(CONFIG_ADC)+=adc.o
@@ -30,7 +29,9 @@ common-$(CONFIG_CHARGER_V2)+=charge_state_v2.o
 # for ARM, not the charger driver for the tps65090.  Rename.
 common-$(CONFIG_CHARGER_TPS65090)+=pmu_tps65090_charger.o
 common-$(CONFIG_CMD_I2CWEDGE)+=i2c_wedge.o
+common-$(CONFIG_COMMON_GPIO)+=gpio.o
 common-$(CONFIG_COMMON_PANIC_OUTPUT)+=panic_output.o
+common-$(CONFIG_COMMON_RUNTIME)+=hooks.o main.o system.o shared_mem.o
 common-$(CONFIG_COMMON_TIMER)+=timer.o
 common-$(CONFIG_PMU_POWERINFO)+=pmu_tps65090_powerinfo.o
 common-$(CONFIG_PMU_TPS65090)+=pmu_tps65090.o
@@ -64,7 +65,8 @@ common-$(CONFIG_USB_PORT_POWER_SMART)+=usb_port_power_smart.o
 common-$(CONFIG_VBOOT_HASH)+=sha256.o vboot_hash.o
 common-$(CONFIG_WIRELESS)+=wireless.o
 common-$(HAS_TASK_CHIPSET)+=chipset.o throttle_ap.o
-common-$(HAS_TASK_CONSOLE)+=console.o
+common-$(HAS_TASK_CONSOLE)+=console.o console_output.o uart_buffering.o
+common-$(HAS_TASK_CONSOLE)+=memory_commands.o
 common-$(HAS_TASK_HOSTCMD)+=acpi.o host_command.o host_event_commands.o
 common-$(HAS_TASK_KEYSCAN)+=keyboard_scan.o
 common-$(HAS_TASK_LIGHTBAR)+=lightbar.o
diff --git a/core/cortex-m/build.mk b/core/cortex-m/build.mk
index 741ec005cc..5306865984 100644
--- a/core/cortex-m/build.mk
+++ b/core/cortex-m/build.mk
@@ -17,6 +17,8 @@ CFLAGS_CPU+=-mthumb -Os -mno-sched-prolog
 CFLAGS_CPU+=-mno-unaligned-access
 CFLAGS_CPU+=$(CFLAGS_FPU-y)
 
-core-y=cpu.o init.o panic.o switch.o task.o
+core-y=cpu.o init.o
+core-$(CONFIG_COMMON_PANIC_OUTPUT)+=panic.o
+core-$(CONFIG_COMMON_RUNTIME)+=switch.o task.o
 core-$(CONFIG_WATCHDOG)+=watchdog.o
 core-$(CONFIG_MPU)+=mpu.o
diff --git a/core/cortex-m/init.S b/core/cortex-m/init.S
index 78c2307545..00072c7f0f 100644
--- a/core/cortex-m/init.S
+++ b/core/cortex-m/init.S
@@ -374,8 +374,12 @@ fini_loop:
 /* Default exception handler */
 .thumb_func
 default_handler:
+#ifdef CONFIG_COMMON_PANIC_OUTPUT
 	b exception_panic
+#endif
+	b reset
 
+.align 2
 _bss_start:
 .long __bss_start
 _bss_end:
diff --git a/core/cortex-m/task.c b/core/cortex-m/task.c
index c0cbc84d59..5e309ef4cb 100644
--- a/core/cortex-m/task.c
+++ b/core/cortex-m/task.c
@@ -330,7 +330,7 @@ static uint32_t __wait_evt(int timeout_us, task_id_t resched)
 	task_ *tsk = current_task;
 	task_id_t me = tsk - tasks;
 	uint32_t evt;
-	int ret;
+	int ret __attribute__((unused));
 
 	ASSERT(!in_interrupt_context());
 
diff --git a/core/cortex-m0/build.mk b/core/cortex-m0/build.mk
index 6ee39c5669..9b5d63bb4d 100644
--- a/core/cortex-m0/build.mk
+++ b/core/cortex-m0/build.mk
@@ -13,5 +13,7 @@ CROSS_COMPILE?=arm-none-eabi-
 CFLAGS_CPU+=-mthumb -Os -mno-sched-prolog
 CFLAGS_CPU+=-mno-unaligned-access
 
-core-y=cpu.o init.o panic.o switch.o task.o thumb_case.o div.o
+core-y=cpu.o init.o thumb_case.o div.o
+core-$(CONFIG_COMMON_PANIC_OUTPUT)+=panic.o
+core-$(CONFIG_COMMON_RUNTIME)+=switch.o task.o
 core-$(CONFIG_WATCHDOG)+=watchdog.o
diff --git a/core/cortex-m0/init.S b/core/cortex-m0/init.S
index f868435157..98bdb89e19 100644
--- a/core/cortex-m0/init.S
+++ b/core/cortex-m0/init.S
@@ -133,8 +133,12 @@ fini_loop:
 /* Default exception handler */
 .thumb_func
 default_handler:
+#ifdef CONFIG_COMMON_PANIC_OUTPUT
 	b exception_panic
+#endif
+	b reset
 
+.align 2
 _bss_start:
 .long __bss_start
 _bss_end:
diff --git a/core/cortex-m0/task.c b/core/cortex-m0/task.c
index 5072a9741e..b067e25f62 100644
--- a/core/cortex-m0/task.c
+++ b/core/cortex-m0/task.c
@@ -318,7 +318,7 @@ static uint32_t __wait_evt(int timeout_us, task_id_t resched)
 	task_ *tsk = current_task;
 	task_id_t me = tsk - tasks;
 	uint32_t evt;
-	int ret;
+	int ret __attribute__((unused));
 
 	ASSERT(!in_interrupt_context());
 
diff --git a/include/config.h b/include/config.h
index a80d256db6..8cfbb38a80 100644
--- a/include/config.h
+++ b/include/config.h
@@ -267,6 +267,18 @@
 /* Provide common core code to output panic information without interrupts. */
 #define CONFIG_COMMON_PANIC_OUTPUT
 
+/*
+ * Provide the default GPIO abstraction layer.
+ * You want this unless you are doing a really tiny firmware.
+ */
+#define CONFIG_COMMON_GPIO
+
+/*
+ * Provide common runtime layer code (tasks, hooks ...)
+ * You want this unless you are doing a really tiny firmware.
+ */
+#define CONFIG_COMMON_RUNTIME
+
 /* Provide common core code to handle the operating system timers. */
 #define CONFIG_COMMON_TIMER
 
diff --git a/include/hooks.h b/include/hooks.h
index fb3e6c236b..944d44bd06 100644
--- a/include/hooks.h
+++ b/include/hooks.h
@@ -192,6 +192,7 @@ void hook_notify(enum hook_type type);
  */
 int hook_call_deferred(void (*routine)(void), int us);
 
+#ifdef CONFIG_COMMON_RUNTIME
 /**
  * Register a hook routine.
  *
@@ -248,4 +249,9 @@ struct deferred_data {
 	__attribute__((section(".rodata.deferred")))			\
 	     = {routine}
 
+#else /* CONFIG_COMMON_RUNTIME */
+#define DECLARE_HOOK(t, func, p) void unused_hook_##func(void) { func(); }
+#define DECLARE_DEFERRED(func) void unused_deferred_##func(void) { func(); }
+#endif /* CONFIG_COMMON_RUNTIME */
+
 #endif  /* __CROS_EC_HOOKS_H */
diff --git a/include/task.h b/include/task.h
index 4cbd60b857..723c6f0ad6 100644
--- a/include/task.h
+++ b/include/task.h
@@ -205,6 +205,10 @@ struct irq_priority {
  * Implement the DECLARE_IRQ(irq, routine, priority) macro which is
  * a core specific helper macro to declare an interrupt handler "routine".
  */
+#ifdef CONFIG_COMMON_RUNTIME
 #include "irq_handler.h"
+#else
+#define DECLARE_IRQ(irq, routine, priority)
+#endif
 
 #endif  /* __CROS_EC_TASK_H */