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      1 /*	$NetBSD: cortex_pmc.c,v 1.9 2025/12/19 13:03:51 nia Exp $	*/
      2 
      3 /* Copyright (c) 2007 Microsoft
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
     16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     17  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     18  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
     19  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     20  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     21  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     22  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     23  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     24  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     25  * POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 
     29 /*
     30  * support for ARM cortex Performance Monitor Counters
     31  * based on arm11_pmc.c
     32  */
     33 
     34 #include <sys/cdefs.h>
     35 /* __KERNEL_RCSID(0, "$NetBSD: cortex_pmc.c,v 1.9 2025/12/19 13:03:51 nia Exp $"); */
     36 
     37 #include <sys/param.h>
     38 #include <sys/types.h>
     39 
     40 #include <sys/kernel.h>
     41 #include <sys/systm.h>
     42 #include <sys/time.h>
     43 #include <sys/timetc.h>
     44 
     45 #include <dev/clock_subr.h>
     46 
     47 #include <uvm/uvm_extern.h>
     48 
     49 #include <arm/armreg.h>
     50 #include <arm/cpufunc.h>
     51 #include <arm/arm32/machdep.h>
     52 
     53 #ifndef CORTEX_PMC_CCNT_HZ
     54 # define CORTEX_PMC_CCNT_HZ	400000000	/* 400MHz */
     55 #endif
     56 
     57 #define COUNTS_PER_USEC	(curcpu()->ci_data.cpu_cc_freq / (1000*1000))
     58 
     59 static const uint32_t counts_per_wrap = ~0UL - 1;
     60 
     61 /*
     62  * enable the PMC CCNT for delay()
     63  */
     64 void
     65 cortex_pmc_ccnt_init(void)
     66 {
     67 	if (curcpu()->ci_data.cpu_cc_freq == 0) {
     68 		curcpu()->ci_data.cpu_cc_freq = CORTEX_PMC_CCNT_HZ;
     69 	}
     70 }
     71 
     72 /*
     73  * delay - for "at least" arg usec
     74  *
     75  *	NOTE: at 400MHz we are restricted to (uint32_t)~0 "counts"
     76  *	if this is a problem, accumulate counts in LL vars
     77  */
     78 void
     79 delay(u_int arg)
     80 {
     81 	uint32_t ctrl;
     82 	uint32_t cur;
     83 	uint32_t last;
     84 	uint32_t delta = 0;
     85 	uint32_t usecs = 0;
     86 	const uint32_t counts_per_usec = COUNTS_PER_USEC;
     87 	const uint32_t delay_arg_limit = ~0UL / counts_per_usec; /* about 10 sec */
     88 
     89 	if (arg > delay_arg_limit)
     90 		panic("%s: arg %u overflow, limit is %u usec\n",
     91 		    __func__, arg, delay_arg_limit);
     92 
     93 	last = armreg_pmccntr_read();
     94 	delta = usecs = 0;
     95 	while (arg > usecs) {
     96 		cur = armreg_pmccntr_read();
     97 
     98 		/*
     99 		 * overflow flag is moved to a separate register
    100 		 * and is not read from PMC Control Register
    101 		 */
    102 		ctrl = armreg_pmovsr_read();
    103 		if (ctrl & CORTEX_CNTOFL_C) {
    104 			/*
    105 			 * Reset overflow flag for cycle counter in overflow
    106 			 * register
    107 			 */
    108 			armreg_pmovsr_write(CORTEX_CNTOFL_C);
    109 			delta += (cur + (counts_per_wrap - last));
    110 		} else {
    111 			delta += (cur - last);
    112 		}
    113 		last = cur;
    114 		if (delta >= counts_per_usec) {
    115 			usecs += delta / counts_per_usec;
    116 			delta %= counts_per_usec;
    117 		}
    118 	}
    119 }
    120