kernel: remove single thread support

arch/Kconfig

@@ -126,7 +126,6 @@ config DYNAMIC_OBJECTS
 
 config SIMPLE_FATAL_ERROR_HANDLER
 	bool "Simple system fatal error handler"
-	default y if !MULTITHREADING
 	help
 	  Provides an implementation of _SysFatalErrorHandler() that hard hangs
 	  instead of aborting the faulting thread, and does not print anything,

drivers/flash/soc_flash_nrf.c

@@ -65,17 +65,8 @@ static int erase_op(void *context); /* instance of flash_op_handler_t */
 static int erase_in_timeslice(u32_t addr, u32_t size);
 #endif /* CONFIG_SOC_FLASH_NRF_RADIO_SYNC */
 
-#if defined(CONFIG_MULTITHREADING)
 /* semaphore for locking flash resources (tickers) */
 static struct k_sem sem_lock;
-#define SYNC_INIT() k_sem_init(&sem_lock, 1, 1)
-#define SYNC_LOCK() k_sem_take(&sem_lock, K_FOREVER)
-#define SYNC_UNLOCK() k_sem_give(&sem_lock)
-#else
-#define SYNC_INIT()
-#define SYNC_LOCK()
-#define SYNC_UNLOCK()
-#endif
 
 static int write(off_t addr, const void *data, size_t len);
 static int erase(u32_t addr, u32_t size);
@@ -131,7 +122,7 @@ static int flash_nrf_write(struct device *dev, off_t addr,
 		return 0;
 	}
 
-	SYNC_LOCK();
+	k_sem_take(&sem_lock, K_FOREVER);
 
 #if defined(CONFIG_SOC_FLASH_NRF_RADIO_SYNC)
 	if (ticker_is_initialized(0)) {
@@ -142,7 +133,7 @@ static int flash_nrf_write(struct device *dev, off_t addr,
 		ret = write(addr, data, len);
 	}
 
-	SYNC_UNLOCK();
+	k_sem_give(&sem_lock);
 
 	return ret;
 }
@@ -166,7 +157,7 @@ static int flash_nrf_erase(struct device *dev, off_t addr, size_t size)
 		return 0;
 	}
 
-	SYNC_LOCK();
+	k_sem_take(&sem_lock, K_FOREVER);
 
 #if defined(CONFIG_SOC_FLASH_NRF_RADIO_SYNC)
 	if (ticker_is_initialized(0)) {
@@ -177,14 +168,14 @@ static int flash_nrf_erase(struct device *dev, off_t addr, size_t size)
 		ret = erase(addr, size);
 	}
 
-	SYNC_UNLOCK();
+	k_sem_give(&sem_lock);
 
 	return ret;
 }
 
 static int flash_nrf_write_protection(struct device *dev, bool enable)
 {
-	SYNC_LOCK();
+	k_sem_take(&sem_lock, K_FOREVER);
 
 	if (enable) {
 		NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;
@@ -193,7 +184,7 @@ static int flash_nrf_write_protection(struct device *dev, bool enable)
 	}
 	nvmc_wait_ready();
 
-	SYNC_UNLOCK();
+	k_sem_give(&sem_lock);
 
 	return 0;
 }
@@ -225,7 +216,7 @@ static int nrf_flash_init(struct device *dev)
 {
 	dev->driver_api = &flash_nrf_api;
 
-	SYNC_INIT();
+	k_sem_init(&sem_lock, 1, 1);
 
 #if defined(CONFIG_SOC_FLASH_NRF_RADIO_SYNC)
 	k_sem_init(&sem_sync, 0, 1);

drivers/flash/spi_flash_w25qxxdv.c

@@ -14,17 +14,6 @@
 #include "spi_flash_w25qxxdv.h"
 #include "flash_priv.h"
 
-#if defined(CONFIG_MULTITHREADING)
-#define SYNC_INIT() k_sem_init( \
-		&((struct spi_flash_data *)dev->driver_data)->sem, 1, UINT_MAX)
-#define SYNC_LOCK() k_sem_take(&driver_data->sem, K_FOREVER)
-#define SYNC_UNLOCK() k_sem_give(&driver_data->sem)
-#else
-#define SYNC_INIT()
-#define SYNC_LOCK()
-#define SYNC_UNLOCK()
-#endif
-
 static int spi_flash_wb_access(struct spi_flash_data *ctx,
 			       u8_t cmd, bool addressed, off_t offset,
 			       void *data, size_t length, bool write)
@@ -134,14 +123,14 @@ static int spi_flash_wb_read(struct device *dev, off_t offset, void *data,
 		return -ENODEV;
 	}
 
-	SYNC_LOCK();
+	k_sem_take(&driver_data->sem, K_FOREVER);
 
 	wait_for_flash_idle(dev);
 
 	ret = spi_flash_wb_access(driver_data, W25QXXDV_CMD_READ,
 				  true, offset, data, len, false);
 
-	SYNC_UNLOCK();
+	k_sem_give(&driver_data->sem);
 
 	return ret;
 }
@@ -157,13 +146,13 @@ static int spi_flash_wb_write(struct device *dev, off_t offset,
 		return -ENOTSUP;
 	}
 
-	SYNC_LOCK();
+	k_sem_take(&driver_data->sem, K_FOREVER);
 
 	wait_for_flash_idle(dev);
 
 	reg = spi_flash_wb_reg_read(dev, W25QXXDV_CMD_RDSR);
 	if (!(reg & W25QXXDV_WEL_BIT)) {
-		SYNC_UNLOCK();
+		k_sem_give(&driver_data->sem);
 		return -EIO;
 	}
 
@@ -176,7 +165,7 @@ static int spi_flash_wb_write(struct device *dev, off_t offset,
 	ret = spi_flash_wb_access(driver_data, W25QXXDV_CMD_PP,
 				  true, offset, (void *)data, len, true);
 
-	SYNC_UNLOCK();
+	k_sem_give(&driver_data->sem);
 
 	return ret;
 }
@@ -187,7 +176,7 @@ static int spi_flash_wb_write_protection_set(struct device *dev, bool enable)
 	u8_t reg = 0;
 	int ret;
 
-	SYNC_LOCK();
+	k_sem_take(&driver_data->sem, K_FOREVER);
 
 	wait_for_flash_idle(dev);
 
@@ -199,7 +188,7 @@ static int spi_flash_wb_write_protection_set(struct device *dev, bool enable)
 
 	ret = spi_flash_wb_reg_write(dev, reg);
 
-	SYNC_UNLOCK();
+	k_sem_give(&driver_data->sem);
 
 	return ret;
 }
@@ -263,12 +252,12 @@ static int spi_flash_wb_erase(struct device *dev, off_t offset, size_t size)
 		return -ENODEV;
 	}
 
-	SYNC_LOCK();
+	k_sem_take(&driver_data->sem, K_FOREVER);
 
 	reg = spi_flash_wb_reg_read(dev, W25QXXDV_CMD_RDSR);
 
 	if (!(reg & W25QXXDV_WEL_BIT)) {
-		SYNC_UNLOCK();
+		k_sem_give(&driver_data->sem);
 		return -EIO;
 	}
 
@@ -303,7 +292,7 @@ static int spi_flash_wb_erase(struct device *dev, off_t offset, size_t size)
 		}
 	}
 
-	SYNC_UNLOCK();
+	k_sem_give(&driver_data->sem);
 
 	return ret;
 }
@@ -351,9 +340,10 @@ static int spi_flash_wb_configure(struct device *dev)
 
 static int spi_flash_init(struct device *dev)
 {
+	struct spi_flash_data *data = dev->driver_data;
 	int ret;
 
-	SYNC_INIT();
+	k_sem_init(&data->sem, 1, UINT_MAX);
 
 	ret = spi_flash_wb_configure(dev);
 	if (!ret) {

drivers/flash/spi_flash_w25qxxdv.h

@@ -20,9 +20,7 @@ struct spi_flash_data {
 	struct spi_cs_control cs_ctrl;
 #endif /* CONFIG_SPI_FLASH_W25QXXDV_GPIO_SPI_CS */
 	struct spi_config spi_cfg;
-#if defined(CONFIG_MULTITHREADING)
 	struct k_sem sem;
-#endif /* CONFIG_MULTITHREADING */
 };
 
 

ext/hal/ti/simplelink/Kconfig

@@ -9,7 +9,6 @@ config HAS_CC3220SDK
 config SIMPLELINK_HOST_DRIVER
 	bool "Build the SimpleLink WiFi Host Driver"
 	depends on HAS_CC3220SDK
-	depends on MULTITHREADING
 	select NEWLIB_LIBC
 	select ERRNO
 	help

include/kernel.h

@@ -4597,17 +4597,10 @@ extern void _sys_power_save_idle_exit(s32_t ticks);
  * private APIs that are utilized by one or more public APIs
  */
 
-#ifdef CONFIG_MULTITHREADING
 /**
  * @internal
  */
 extern void _init_static_threads(void);
-#else
-/**
- * @internal
- */
-#define _init_static_threads() do { } while (false)
-#endif
 
 /**
  * @internal

kernel/Kconfig

@@ -9,22 +9,8 @@
 
 menu "General Kernel Options"
 
-config MULTITHREADING
-	bool "Multi-threading"
-	default y
-	help
-	  If disabled, only the main thread is available, so a main() function
-	  must be provided. Interrupts are available. Kernel objects will most
-	  probably not behave as expected, especially with regards to pending,
-	  since the main thread cannot pend, it being the only thread in the
-	  system.
-
-	  Many drivers and subsystems will not work with this option; use only
-	  when you REALLY know what you are doing.
-
 config NUM_COOP_PRIORITIES
-	int "Number of coop priorities" if MULTITHREADING
-	default 1 if !MULTITHREADING
+	int "Number of coop priorities"
 	default 16
 	range 0 128
 	help
@@ -52,8 +38,7 @@ config NUM_COOP_PRIORITIES
 	  priority, and be the only thread at that priority.
 
 config NUM_PREEMPT_PRIORITIES
-	int "Number of preemptible priorities" if MULTITHREADING
-	default 0 if !MULTITHREADING
+	int "Number of preemptible priorities"
 	default 15
 	range 0 128
 	help

kernel/include/ksched.h

@@ -11,7 +11,6 @@
 #include <tracing.h>
 #include <stdbool.h>
 
-#ifdef CONFIG_MULTITHREADING
 #define _VALID_PRIO(prio, entry_point) \
 	(((prio) == K_IDLE_PRIO && _is_idle_thread(entry_point)) || \
 		 (_is_prio_higher_or_equal((prio), \
@@ -26,10 +25,6 @@
 		 K_LOWEST_APPLICATION_THREAD_PRIO, \
 		 K_HIGHEST_APPLICATION_THREAD_PRIO); \
 	} while (false)
-#else
-#define _VALID_PRIO(prio, entry_point) ((prio) == -1)
-#define _ASSERT_VALID_PRIO(prio, entry_point) __ASSERT((prio) == -1, "")
-#endif
 
 void _sched_init(void);
 void _add_thread_to_ready_q(struct k_thread *thread);

kernel/init.c

@@ -244,7 +244,6 @@ void __weak main(void)
 	/* NOP default main() if the application does not provide one. */
 }
 
-#if defined(CONFIG_MULTITHREADING)
 static void init_idle_thread(struct k_thread *thr, k_thread_stack_t *stack)
 {
 #ifdef CONFIG_SMP
@@ -256,7 +255,6 @@ static void init_idle_thread(struct k_thread *thr, k_thread_stack_t *stack)
 			  K_LOWEST_THREAD_PRIO, K_ESSENTIAL, IDLE_THREAD_NAME);
 	_mark_thread_as_started(thr);
 }
-#endif
 
 /**
  *
@@ -270,7 +268,6 @@ static void init_idle_thread(struct k_thread *thr, k_thread_stack_t *stack)
  *
  * @return N/A
  */
-#ifdef CONFIG_MULTITHREADING
 static void prepare_multithreading(struct k_thread *dummy_thread)
 {
 #ifdef CONFIG_ARCH_HAS_CUSTOM_SWAP_TO_MAIN
@@ -322,11 +319,9 @@ static void prepare_multithreading(struct k_thread *dummy_thread)
 	_mark_thread_as_started(_main_thread);
 	_ready_thread(_main_thread);
 
-#ifdef CONFIG_MULTITHREADING
 	init_idle_thread(_idle_thread, _idle_stack);
 	_kernel.cpus[0].idle_thread = _idle_thread;
 	sys_trace_thread_create(_idle_thread);
-#endif
 
 #if defined(CONFIG_SMP) && CONFIG_MP_NUM_CPUS > 1
 	init_idle_thread(_idle_thread1, _idle_stack1);
@@ -371,7 +366,6 @@ static void switch_to_main_thread(void)
 	(void)_Swap(irq_lock());
 #endif
 }
-#endif /* CONFIG_MULTITHREDING */
 
 u32_t z_early_boot_rand32_get(void)
 {
@@ -429,7 +423,6 @@ extern uintptr_t __stack_chk_guard;
  */
 FUNC_NORETURN void _Cstart(void)
 {
-#ifdef CONFIG_MULTITHREADING
 #ifdef CONFIG_ARCH_HAS_CUSTOM_SWAP_TO_MAIN
 	struct k_thread *dummy_thread = NULL;
 #else
@@ -440,7 +433,6 @@ FUNC_NORETURN void _Cstart(void)
 	struct k_thread *dummy_thread = (struct k_thread *)&dummy_thread_memory;
 
 	(void)memset(dummy_thread_memory, 0, sizeof(dummy_thread_memory));
-#endif
 #endif
 	/*
 	 * The interrupt library needs to be initialized early since a series
@@ -467,16 +459,8 @@ FUNC_NORETURN void _Cstart(void)
 	__stack_chk_guard = z_early_boot_rand32_get();
 #endif
 
-#ifdef CONFIG_MULTITHREADING
 	prepare_multithreading(dummy_thread);
 	switch_to_main_thread();
-#else
-	bg_thread_main(NULL, NULL, NULL);
-
-	irq_lock();
-	while (true) {
-	}
-#endif
 
 	/*
 	 * Compiler can't tell that the above routines won't return and issues

kernel/sched.c

@@ -803,7 +803,6 @@ Z_SYSCALL_HANDLER0_SIMPLE_VOID(k_yield);
 
 void _impl_k_sleep(s32_t duration)
 {
-#ifdef CONFIG_MULTITHREADING
 	/* volatile to guarantee that irq_lock() is executed after ticks is
 	 * populated
 	 */
@@ -828,7 +827,6 @@ void _impl_k_sleep(s32_t duration)
 	_add_thread_timeout(_current, NULL, ticks);
 
 	(void)_Swap(key);
-#endif
 }
 
 #ifdef CONFIG_USERSPACE