1 /* 2 * linux/arch/arm/kernel/fiq.c 3 * 4 * Copyright (C) 1998 Russell King 5 * Copyright (C) 1998, 1999 Phil Blundell 6 * 7 * FIQ support written by Philip Blundell <philb@gnu.org>, 1998. 8 * 9 * FIQ support re-written by Russell King to be more generic 10 * 11 * We now properly support a method by which the FIQ handlers can 12 * be stacked onto the vector. We still do not support sharing 13 * the FIQ vector itself. 14 * 15 * Operation is as follows: 16 * 1. Owner A claims FIQ: 17 * - default_fiq relinquishes control. 18 * 2. Owner A: 19 * - inserts code. 20 * - sets any registers, 21 * - enables FIQ. 22 * 3. Owner B claims FIQ: 23 * - if owner A has a relinquish function. 24 * - disable FIQs. 25 * - saves any registers. 26 * - returns zero. 27 * 4. Owner B: 28 * - inserts code. 29 * - sets any registers, 30 * - enables FIQ. 31 * 5. Owner B releases FIQ: 32 * - Owner A is asked to reacquire FIQ: 33 * - inserts code. 34 * - restores saved registers. 35 * - enables FIQ. 36 * 6. Goto 3 37 */ 38 #include <linux/module.h> 39 #include <linux/kernel.h> 40 #include <linux/init.h> 41 #include <linux/interrupt.h> 42 #include <linux/seq_file.h> 43 44 #include <asm/cacheflush.h> 45 #include <asm/cp15.h> 46 #include <asm/fiq.h> 47 #include <asm/irq.h> 48 #include <asm/traps.h> 49 50 static unsigned long no_fiq_insn; 51 52 /* Default reacquire function 53 * - we always relinquish FIQ control 54 * - we always reacquire FIQ control 55 */ 56 static int fiq_def_op(void *ref, int relinquish) 57 { 58 if (!relinquish) 59 set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn)); 60 61 return 0; 62 } 63 64 static struct fiq_handler default_owner = { 65 .name = "default", 66 .fiq_op = fiq_def_op, 67 }; 68 69 static struct fiq_handler *current_fiq = &default_owner; 70 71 int show_fiq_list(struct seq_file *p, int prec) 72 { 73 if (current_fiq != &default_owner) 74 seq_printf(p, "%*s: %s\n", prec, "FIQ", 75 current_fiq->name); 76 77 return 0; 78 } 79 80 void set_fiq_handler(void *start, unsigned int length) 81 { 82 #if defined(CONFIG_CPU_USE_DOMAINS) 83 memcpy((void *)0xffff001c, start, length); 84 #else 85 memcpy(vectors_page + 0x1c, start, length); 86 #endif 87 flush_icache_range(0xffff001c, 0xffff001c + length); 88 if (!vectors_high()) 89 flush_icache_range(0x1c, 0x1c + length); 90 } 91 92 int claim_fiq(struct fiq_handler *f) 93 { 94 int ret = 0; 95 96 if (current_fiq) { 97 ret = -EBUSY; 98 99 if (current_fiq->fiq_op != NULL) 100 ret = current_fiq->fiq_op(current_fiq->dev_id, 1); 101 } 102 103 if (!ret) { 104 f->next = current_fiq; 105 current_fiq = f; 106 } 107 108 return ret; 109 } 110 111 void release_fiq(struct fiq_handler *f) 112 { 113 if (current_fiq != f) { 114 printk(KERN_ERR "%s FIQ trying to release %s FIQ\n", 115 f->name, current_fiq->name); 116 dump_stack(); 117 return; 118 } 119 120 do 121 current_fiq = current_fiq->next; 122 while (current_fiq->fiq_op(current_fiq->dev_id, 0)); 123 } 124 125 static int fiq_start; 126 127 void enable_fiq(int fiq) 128 { 129 enable_irq(fiq + fiq_start); 130 } 131 132 void disable_fiq(int fiq) 133 { 134 disable_irq(fiq + fiq_start); 135 } 136 137 EXPORT_SYMBOL(set_fiq_handler); 138 EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ 139 EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */ 140 EXPORT_SYMBOL(claim_fiq); 141 EXPORT_SYMBOL(release_fiq); 142 EXPORT_SYMBOL(enable_fiq); 143 EXPORT_SYMBOL(disable_fiq); 144 145 void __init init_FIQ(int start) 146 { 147 no_fiq_insn = *(unsigned long *)0xffff001c; 148 fiq_start = start; 149 } 150