kernel: Fix usage of CONFIG_SYS_CLOCK_EXISTS

When compiling the kernel with CONFIG_SYS_CLOCK_TICKS_PER_SEC=0,
the CONFIG_SYS_CLOCK_EXISTS internal variable is unset.
This completely disables timer handling in the kernel, but a couple of
spots missed the required conditional compilation.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

arch/arm/core/cortex_m/vector_table.S

@@ -66,5 +66,9 @@ SECTION_SUBSEC_FUNC(exc_vector_table,_vector_table_section,_vector_table)
 #endif /* CONFIG_ARMV6_M_ARMV8_M_BASELINE */
     .word __reserved
     .word __pendsv
+#if defined(CONFIG_SYS_CLOCK_EXISTS)
     .word z_clock_isr
+#else
+    .word __reserved
+#endif
 

kernel/Kconfig

@@ -557,6 +557,8 @@ config SYS_CLOCK_TICKS_PER_SEC
 	  granularity, not necessarily the number or frequency of
 	  interrupts delivered to the kernel.
 
+	  A value of 0 completely disables timer support in the kernel.
+
 config SYS_CLOCK_HW_CYCLES_PER_SEC
 	int "System clock's h/w timer frequency"
 	help

kernel/work_q.c

@@ -19,7 +19,9 @@
 
 #define WORKQUEUE_THREAD_NAME	"workqueue"
 
+#ifdef CONFIG_SYS_CLOCK_EXISTS
 static struct k_spinlock lock;
+#endif
 
 extern void z_work_q_main(void *work_q_ptr, void *p2, void *p3);
 

subsys/power/reboot.c

@@ -21,7 +21,9 @@ extern void sys_clock_disable(void);
 void sys_reboot(int type)
 {
 	(void)irq_lock();
+#ifdef CONFIG_SYS_CLOCK_EXISTS
 	sys_clock_disable();
+#endif
 
 	sys_arch_reboot(type);