Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) /* calibrate.c: default delay calibration
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4)  * Excised from init/main.c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5)  *  Copyright (C) 1991, 1992  Linus Torvalds
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8) #include <linux/jiffies.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) #include <linux/delay.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) #include <linux/init.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) #include <linux/timex.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12) #include <linux/smp.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) #include <linux/percpu.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) unsigned long lpj_fine;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) unsigned long preset_lpj;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) static int __init lpj_setup(char *str)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19) 	preset_lpj = simple_strtoul(str,NULL,0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20) 	return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23) __setup("lpj=", lpj_setup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) #ifdef ARCH_HAS_READ_CURRENT_TIMER
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) /* This routine uses the read_current_timer() routine and gets the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28)  * loops per jiffy directly, instead of guessing it using delay().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29)  * Also, this code tries to handle non-maskable asynchronous events
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30)  * (like SMIs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) #define DELAY_CALIBRATION_TICKS			((HZ < 100) ? 1 : (HZ/100))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) #define MAX_DIRECT_CALIBRATION_RETRIES		5
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) static unsigned long calibrate_delay_direct(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) 	unsigned long pre_start, start, post_start;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) 	unsigned long pre_end, end, post_end;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) 	unsigned long start_jiffies;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) 	unsigned long timer_rate_min, timer_rate_max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) 	unsigned long good_timer_sum = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) 	unsigned long good_timer_count = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) 	unsigned long measured_times[MAX_DIRECT_CALIBRATION_RETRIES];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) 	int max = -1; /* index of measured_times with max/min values or not set */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) 	int min = -1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) 	int i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) 	if (read_current_timer(&pre_start) < 0 )
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) 	 * A simple loop like
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) 	 *	while ( jiffies < start_jiffies+1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) 	 *		start = read_current_timer();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55) 	 * will not do. As we don't really know whether jiffy switch
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) 	 * happened first or timer_value was read first. And some asynchronous
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) 	 * event can happen between these two events introducing errors in lpj.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) 	 * So, we do
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) 	 * 1. pre_start <- When we are sure that jiffy switch hasn't happened
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) 	 * 2. check jiffy switch
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) 	 * 3. start <- timer value before or after jiffy switch
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 	 * 4. post_start <- When we are sure that jiffy switch has happened
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 	 * Note, we don't know anything about order of 2 and 3.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 	 * Now, by looking at post_start and pre_start difference, we can
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) 	 * check whether any asynchronous event happened or not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) 	for (i = 0; i < MAX_DIRECT_CALIBRATION_RETRIES; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) 		pre_start = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 		read_current_timer(&start);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 		start_jiffies = jiffies;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 		while (time_before_eq(jiffies, start_jiffies + 1)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) 			pre_start = start;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) 			read_current_timer(&start);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) 		read_current_timer(&post_start);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) 		pre_end = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) 		end = post_start;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) 		while (time_before_eq(jiffies, start_jiffies + 1 +
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 					       DELAY_CALIBRATION_TICKS)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) 			pre_end = end;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) 			read_current_timer(&end);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) 		read_current_timer(&post_end);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) 		timer_rate_max = (post_end - pre_start) /
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 					DELAY_CALIBRATION_TICKS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 		timer_rate_min = (pre_end - post_start) /
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 					DELAY_CALIBRATION_TICKS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) 		 * If the upper limit and lower limit of the timer_rate is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) 		 * >= 12.5% apart, redo calibration.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 		if (start >= post_end)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) 			printk(KERN_NOTICE "calibrate_delay_direct() ignoring "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) 					"timer_rate as we had a TSC wrap around"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) 					" start=%lu >=post_end=%lu\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 				start, post_end);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) 		if (start < post_end && pre_start != 0 && pre_end != 0 &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) 		    (timer_rate_max - timer_rate_min) < (timer_rate_max >> 3)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) 			good_timer_count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) 			good_timer_sum += timer_rate_max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) 			measured_times[i] = timer_rate_max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) 			if (max < 0 || timer_rate_max > measured_times[max])
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) 				max = i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) 			if (min < 0 || timer_rate_max < measured_times[min])
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) 				min = i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) 		} else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 			measured_times[i] = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) 	 * Find the maximum & minimum - if they differ too much throw out the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 	 * one with the largest difference from the mean and try again...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) 	while (good_timer_count > 1) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) 		unsigned long estimate;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 		unsigned long maxdiff;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 		/* compute the estimate */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) 		estimate = (good_timer_sum/good_timer_count);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 		maxdiff = estimate >> 3;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) 		/* if range is within 12% let's take it */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) 		if ((measured_times[max] - measured_times[min]) < maxdiff)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) 			return estimate;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) 		/* ok - drop the worse value and try again... */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) 		good_timer_sum = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 		good_timer_count = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) 		if ((measured_times[max] - estimate) <
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 				(estimate - measured_times[min])) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) 			printk(KERN_NOTICE "calibrate_delay_direct() dropping "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) 					"min bogoMips estimate %d = %lu\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) 				min, measured_times[min]);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 			measured_times[min] = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 			min = max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 		} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 			printk(KERN_NOTICE "calibrate_delay_direct() dropping "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 					"max bogoMips estimate %d = %lu\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 				max, measured_times[max]);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 			measured_times[max] = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) 			max = min;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) 		for (i = 0; i < MAX_DIRECT_CALIBRATION_RETRIES; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) 			if (measured_times[i] == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) 				continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) 			good_timer_count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 			good_timer_sum += measured_times[i];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) 			if (measured_times[i] < measured_times[min])
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) 				min = i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 			if (measured_times[i] > measured_times[max])
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 				max = i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) 	printk(KERN_NOTICE "calibrate_delay_direct() failed to get a good "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 	       "estimate for loops_per_jiffy.\nProbably due to long platform "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) 		"interrupts. Consider using \"lpj=\" boot option.\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) #else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) static unsigned long calibrate_delay_direct(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177)  * This is the number of bits of precision for the loops_per_jiffy.  Each
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178)  * time we refine our estimate after the first takes 1.5/HZ seconds, so try
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179)  * to start with a good estimate.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180)  * For the boot cpu we can skip the delay calibration and assign it a value
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181)  * calculated based on the timer frequency.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182)  * For the rest of the CPUs we cannot assume that the timer frequency is same as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183)  * the cpu frequency, hence do the calibration for those.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) #define LPS_PREC 8
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) static unsigned long calibrate_delay_converge(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) 	/* First stage - slowly accelerate to find initial bounds */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) 	unsigned long lpj, lpj_base, ticks, loopadd, loopadd_base, chop_limit;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) 	int trials = 0, band = 0, trial_in_band = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 	lpj = (1<<12);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) 	/* wait for "start of" clock tick */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) 	ticks = jiffies;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) 	while (ticks == jiffies)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) 		; /* nothing */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) 	/* Go .. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) 	ticks = jiffies;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) 	do {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) 		if (++trial_in_band == (1<<band)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) 			++band;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) 			trial_in_band = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) 		__delay(lpj * band);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) 		trials += band;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) 	} while (ticks == jiffies);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) 	 * We overshot, so retreat to a clear underestimate. Then estimate
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) 	 * the largest likely undershoot. This defines our chop bounds.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) 	trials -= band;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) 	loopadd_base = lpj * band;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) 	lpj_base = lpj * trials;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) recalibrate:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) 	lpj = lpj_base;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) 	loopadd = loopadd_base;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) 	 * Do a binary approximation to get lpj set to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) 	 * equal one clock (up to LPS_PREC bits)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) 	chop_limit = lpj >> LPS_PREC;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) 	while (loopadd > chop_limit) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) 		lpj += loopadd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) 		ticks = jiffies;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) 		while (ticks == jiffies)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) 			; /* nothing */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) 		ticks = jiffies;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) 		__delay(lpj);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) 		if (jiffies != ticks)	/* longer than 1 tick */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) 			lpj -= loopadd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) 		loopadd >>= 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) 	 * If we incremented every single time possible, presume we've
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) 	 * massively underestimated initially, and retry with a higher
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) 	 * start, and larger range. (Only seen on x86_64, due to SMIs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) 	if (lpj + loopadd * 2 == lpj_base + loopadd_base * 2) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) 		lpj_base = lpj;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) 		loopadd_base <<= 2;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) 		goto recalibrate;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) 	return lpj;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) static DEFINE_PER_CPU(unsigned long, cpu_loops_per_jiffy) = { 0 };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254)  * Check if cpu calibration delay is already known. For example,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255)  * some processors with multi-core sockets may have all cores
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256)  * with the same calibration delay.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258)  * Architectures should override this function if a faster calibration
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259)  * method is available.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) unsigned long __attribute__((weak)) calibrate_delay_is_known(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267)  * Indicate the cpu delay calibration is done. This can be used by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268)  * architectures to stop accepting delay timer registrations after this point.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) void __attribute__((weak)) calibration_delay_done(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) void calibrate_delay(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) 	unsigned long lpj;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) 	static bool printed;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) 	int this_cpu = smp_processor_id();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) 	if (per_cpu(cpu_loops_per_jiffy, this_cpu)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) 		lpj = per_cpu(cpu_loops_per_jiffy, this_cpu);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) 		if (!printed)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) 			pr_info("Calibrating delay loop (skipped) "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) 				"already calibrated this CPU");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) 	} else if (preset_lpj) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) 		lpj = preset_lpj;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) 		if (!printed)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) 			pr_info("Calibrating delay loop (skipped) "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) 				"preset value.. ");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) 	} else if ((!printed) && lpj_fine) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) 		lpj = lpj_fine;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) 		pr_info("Calibrating delay loop (skipped), "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) 			"value calculated using timer frequency.. ");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) 	} else if ((lpj = calibrate_delay_is_known())) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) 		;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) 	} else if ((lpj = calibrate_delay_direct()) != 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) 		if (!printed)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) 			pr_info("Calibrating delay using timer "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) 				"specific routine.. ");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) 	} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) 		if (!printed)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) 			pr_info("Calibrating delay loop... ");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) 		lpj = calibrate_delay_converge();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) 	per_cpu(cpu_loops_per_jiffy, this_cpu) = lpj;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) 	if (!printed)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) 		pr_cont("%lu.%02lu BogoMIPS (lpj=%lu)\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) 			lpj/(500000/HZ),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310) 			(lpj/(5000/HZ)) % 100, lpj);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) 	loops_per_jiffy = lpj;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) 	printed = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) 	calibration_delay_done();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316) }