1 // SPDX-License-Identifier: GPL-2.0
17 #include <asm/r4k-timer.h>
35  * we want to have the fastest, inlined, non-debug version
36  * of a critical section, to be able to prove counter time-warps:
60 		 * another CPU) and update the previous counter timestamp.  in check_counter_warp()
82 		 * we saw a time-warp of the counter going backwards:  in check_counter_warp()
86 			max_warp = max(max_warp, prev - now);  in check_counter_warp()
90 			 * one CPU should observe time going backwards.  in check_counter_warp()
99 	WARN(!(now-start),  in check_counter_warp()
101 			now-start, end-start);  in check_counter_warp()
106  * The freshly booted CPU initiates this via an async SMP function call.
110 	unsigned int cpu = (unsigned long)__cpu;  in check_counter_sync_source()  local
116 	while (atomic_read(&start_count) != cpus - 1)  in check_counter_sync_source()
126 	while (atomic_read(&stop_count) != cpus-1)  in check_counter_sync_source()
130 	 * If the test was successful set the number of runs to zero and  in check_counter_sync_source()
137 		pr_info("Counter synchronization [CPU#%d -> CPU#%u]: passed\n",  in check_counter_sync_source()
138 			smp_processor_id(), cpu);  in check_counter_sync_source()
143 		pr_info("Counter synchronization [CPU#%d -> CPU#%u]:\n",  in check_counter_sync_source()
144 			smp_processor_id(), cpu);  in check_counter_sync_source()
151 	 * Reset it - just in case we boot another CPU later:  in check_counter_sync_source()
174 void synchronise_count_slave(int cpu)  in synchronise_count_slave()  argument
182 	/* Kick the control CPU into the counter synchronization function */  in synchronise_count_slave()
185 				 (unsigned long *)(unsigned long)cpu, 0);  in synchronise_count_slave()
188 	 * Register this CPU's participation and wait for the  in synchronise_count_slave()
189 	 * source CPU to start the measurement:  in synchronise_count_slave()
208 	 * Wait for the source CPU to print stuff:  in synchronise_count_slave()
214 	 * Reset it for the next sync test:  in synchronise_count_slave()
219 	 * Check the number of remaining test runs. If not zero, the test  in synchronise_count_slave()
221 	 * test was either successful or failed terminally.  in synchronise_count_slave()
230 	 * If the warp value of this CPU is 0, then the other CPU  in synchronise_count_slave()
235 		cur_max_warp = -gbl_max_warp;  in synchronise_count_slave()
241 	pr_debug("Counter compensate: CPU%u observed %d warp\n", cpu, cur_max_warp);  in synchronise_count_slave()