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      1 /*	$NetBSD: softintr.c,v 1.18 2020/11/21 21:27:09 thorpej Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2001 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by IWAMOTO Toshihiro.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: softintr.c,v 1.18 2020/11/21 21:27:09 thorpej Exp $");
     34 
     35 #include <sys/param.h>
     36 #include <sys/systm.h>
     37 #include <sys/syslog.h>
     38 #include <sys/kmem.h>
     39 
     40 #include <machine/cpu.h>
     41 #include <arm/cpufunc.h>
     42 #include <machine/intr.h>
     43 
     44 void softintr_free(void *);
     45 void softintr_dispatch(int);
     46 
     47 struct softintr_handler {
     48 	struct softintr_handler *sh_vlink;	/* vertical link */
     49 	struct softintr_handler *sh_hlink;	/* horizontal link */
     50 
     51 	void (*sh_fun)(void *);
     52 	void *sh_arg;
     53 	int sh_level;
     54 
     55 	int sh_pending;
     56 };
     57 
     58 struct softintr_handler *softintrs;
     59 struct softintr_handler *softintr_pending;
     60 
     61 void *
     62 softintr_establish(int level, void (*fun)(void *), void *arg)
     63 {
     64 	struct softintr_handler *sh;
     65 
     66 	sh = kmem_alloc(sizeof(*sh), KM_SLEEP);
     67 	sh->sh_fun = fun;
     68 	sh->sh_level = ipl_to_spl(level);
     69 	sh->sh_arg = arg;
     70 	sh->sh_pending = 0;
     71 
     72 	return sh;
     73 }
     74 
     75 void
     76 softintr_disestablish(void *cookie)
     77 {
     78 	struct softintr_handler *sh = cookie;
     79 	u_int saved_cpsr;
     80 
     81 	saved_cpsr = SetCPSR(I32_bit, I32_bit);
     82 	if (sh->sh_pending) {
     83 		sh->sh_fun = softintr_free;
     84 		sh->sh_arg = sh;
     85 		SetCPSR(I32_bit, I32_bit & saved_cpsr);
     86 	} else {
     87 		SetCPSR(I32_bit, I32_bit & saved_cpsr);
     88 		kmem_free(sh, sizeof(*sh));
     89 	}
     90 }
     91 
     92 void
     93 softintr_free(void *arg)
     94 {
     95 	struct softintr_handler *sh = arg;
     96 
     97 	kmem_free(sh, sizeof(*sh));
     98 }
     99 
    100 void
    101 softintr_schedule(void *cookie)
    102 {
    103 	struct softintr_handler **p, *sh = cookie;
    104 	register int pending, saved_cpsr;
    105 
    106 	pending = 1;
    107 	__asm("swp %0, %0, [%1]" : "+r" (pending) : "r" (&sh->sh_pending));
    108 
    109 	if (pending)
    110 		return;
    111 
    112 	sh->sh_vlink = NULL;
    113 	sh->sh_hlink = NULL;
    114 
    115 #ifdef __GNUC__
    116 	__asm volatile("mrs %0, cpsr\n orr r1, %0, %1\n msr cpsr_a;;, r1" :
    117 	    "=r" (saved_cpsr) : "i" (I32_bit) : "r1");
    118 #else
    119 	saved_cpsr = SetCPSR(I32_bit, I32_bit);
    120 #endif
    121 	p = &softintr_pending;
    122 
    123 	for (;; p = &(*p)->sh_vlink) {
    124 		if (*p == NULL)
    125 			goto set_and_exit;
    126 
    127 		if ((*p)->sh_level <= sh->sh_level)
    128 			break;
    129 	}
    130 
    131 	if ((*p)->sh_level == sh->sh_level) {
    132 		sh->sh_hlink = *p;
    133 		sh->sh_vlink = (*p)->sh_vlink;
    134 		goto set_and_exit;
    135 	}
    136 
    137 	sh->sh_vlink = *p;
    138 set_and_exit:
    139 	*p = sh;
    140 #ifdef __GNUC__
    141 	__asm volatile("msr cpsr_c, %0" : : "r" (saved_cpsr));
    142 #else
    143 	SetCPSR(I32_bit, I32_bit & saved_cpsr);
    144 #endif
    145 	return;
    146 }
    147 
    148 void
    149 softintr_dispatch(int s)
    150 {
    151 	struct softintr_handler *sh, *sh1;
    152 	register int saved_cpsr;
    153 
    154 	while (1) {
    155 		/* Protect list operation from interrupts */
    156 #ifdef __GNUC__
    157 		__asm volatile("mrs %0, cpsr\n orr r1, %0, %1\n"
    158 		    " msr cpsr_all, r1" : "=r" (saved_cpsr) :
    159 		    "i" (I32_bit) : "r1");
    160 #else
    161 		saved_cpsr = SetCPSR(I32_bit, I32_bit);
    162 #endif
    163 
    164 		if (softintr_pending == NULL ||
    165 		    softintr_pending->sh_level <= s) {
    166 #ifdef __GNUC__
    167 			__asm("msr cpsr_c, %0" : : "r" (saved_cpsr));
    168 #else
    169 			SetCPSR(I32_bit, I32_bit & saved_cpsr);
    170 #endif
    171 			splx(s);
    172 			return;
    173 		}
    174 		sh = softintr_pending;
    175 		softintr_pending = softintr_pending->sh_vlink;
    176 
    177 		if (sh->sh_level > current_spl_level)
    178 			raisespl(sh->sh_level);
    179 #ifdef __GNUC__
    180 		__asm volatile("msr cpsr_c, %0" : : "r" (saved_cpsr));
    181 #else
    182 		SetCPSR(I32_bit, I32_bit & saved_cpsr);
    183 #endif
    184 		if (sh->sh_level < current_spl_level)
    185 			lowerspl(sh->sh_level);
    186 
    187 		while (1) {
    188 			/* The order is important */
    189 			sh1 = sh->sh_hlink;
    190 			sh->sh_pending = 0;
    191 
    192 			(sh->sh_fun)(sh->sh_arg);
    193 			if (sh1 == NULL)
    194 				break;
    195 			sh = sh1;
    196 		}
    197 	}
    198 	splx(s);
    199 }
    200