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  • // SPDX-License-Identifier: GPL-2.0+
    
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    /*
     * Copyright (c) 2015 Google, Inc
     * Written by Simon Glass <sjg@chromium.org>
     */
    
    #include <common.h>
    #include <command.h>
    #include <errno.h>
    
    static int test_get_timer(void)
    {
    	ulong base, start, next, diff;
    	int iter;
    
    	base = get_timer(0);
    	start = get_timer(0);
    	for (iter = 0; iter < 10; iter++) {
    		do {
    			next = get_timer(0);
    		} while (start == next);
    
    		if (start + 1 != next) {
    			printf("%s: iter=%d, start=%lu, next=%lu, expected a difference of 1\n",
    			       __func__, iter, start, next);
    			return -EINVAL;
    		}
    		start++;
    	}
    
    	/*
    	 * Check that get_timer(base) matches our elapsed time, allowing that
    	 * an extra millisecond may have passed.
    	 */
    	diff = get_timer(base);
    	if (diff != iter && diff != iter + 1) {
    		printf("%s: expected get_timer(base) to match elapsed time: diff=%lu, expected=%d\n",
    		       __func__, diff, iter);
    			return -EINVAL;
    	}
    
    	return 0;
    }
    
    static int test_timer_get_us(void)
    {
    	ulong prev, next, min = 1000000;
    	long delta;
    	int iter;
    
    	/* Find the minimum delta we can measure, in microseconds */
    	prev = timer_get_us();
    	for (iter = 0; iter < 100; ) {
    		next = timer_get_us();
    		if (next != prev) {
    			delta = next - prev;
    			if (delta < 0) {
    				printf("%s: timer_get_us() went backwards from %lu to %lu\n",
    				       __func__, prev, next);
    				return -EINVAL;
    			} else if (delta != 0) {
    				if (delta < min)
    					min = delta;
    				prev = next;
    				iter++;
    			}
    		}
    	}
    
    	if (min != 1) {
    		printf("%s: Minimum microsecond delta should be 1 but is %lu\n",
    		       __func__, min);
    		return -EINVAL;
    	}
    
    	return 0;
    }
    
    static int test_time_comparison(void)
    {
    	ulong start_us, end_us, delta_us;
    	long error;
    	ulong start;
    
    	start = get_timer(0);
    	start_us = timer_get_us();
    	while (get_timer(start) < 1000)
    		;
    	end_us = timer_get_us();
    	delta_us = end_us - start_us;
    	error = delta_us - 1000000;
    	printf("%s: Microsecond time for 1 second: %lu, error = %ld\n",
    	       __func__, delta_us, error);
    	if (abs(error) > 1000)
    		return -EINVAL;
    
    	return 0;
    }
    
    static int test_udelay(void)
    {
    	long error;
    	ulong start, delta;
    	int iter;
    
    	start = get_timer(0);
    	for (iter = 0; iter < 1000; iter++)
    		udelay(1000);
    	delta = get_timer(start);
    	error = delta - 1000;
    	printf("%s: Delay time for 1000 udelay(1000): %lu ms, error = %ld\n",
    	       __func__, delta, error);
    	if (abs(error) > 100)
    		return -EINVAL;
    
    	return 0;
    }
    
    
    int do_ut_time(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
    
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    {
    	int ret = 0;
    
    	ret |= test_get_timer();
    	ret |= test_timer_get_us();
    	ret |= test_time_comparison();
    	ret |= test_udelay();
    
    	printf("Test %s\n", ret ? "failed" : "passed");
    
    	return ret ? CMD_RET_FAILURE : CMD_RET_SUCCESS;
    }