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 #define FIQ_OFFSET ({ \ 51 extern void *vector_fiq_offset; \ 52 (unsigned)&vector_fiq_offset; \ 53 }) 54 55 static unsigned long no_fiq_insn; 56 57 /* Default reacquire function 58 * - we always relinquish FIQ control 59 * - we always reacquire FIQ control 60 */ 61 static int fiq_def_op(void *ref, int relinquish) 62 { 63 if (!relinquish) 64 set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn)); 65 66 return 0; 67 } 68 69 static struct fiq_handler default_owner = { 70 .name = "default", 71 .fiq_op = fiq_def_op, 72 }; 73 74 static struct fiq_handler *current_fiq = &default_owner; 75 76 int show_fiq_list(struct seq_file *p, int prec) 77 { 78 if (current_fiq != &default_owner) 79 seq_printf(p, "%*s: %s\n", prec, "FIQ", 80 current_fiq->name); 81 82 return 0; 83 } 84 85 void set_fiq_handler(void *start, unsigned int length) 86 { 87 void *base = vectors_page; 88 unsigned offset = FIQ_OFFSET; 89 90 memcpy(base + offset, start, length); 91 if (!cache_is_vipt_nonaliasing()) 92 flush_icache_range(base + offset, offset + length); 93 flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length); 94 } 95 96 int claim_fiq(struct fiq_handler *f) 97 { 98 int ret = 0; 99 100 if (current_fiq) { 101 ret = -EBUSY; 102 103 if (current_fiq->fiq_op != NULL) 104 ret = current_fiq->fiq_op(current_fiq->dev_id, 1); 105 } 106 107 if (!ret) { 108 f->next = current_fiq; 109 current_fiq = f; 110 } 111 112 return ret; 113 } 114 115 void release_fiq(struct fiq_handler *f) 116 { 117 if (current_fiq != f) { 118 printk(KERN_ERR "%s FIQ trying to release %s FIQ\n", 119 f->name, current_fiq->name); 120 dump_stack(); 121 return; 122 } 123 124 do 125 current_fiq = current_fiq->next; 126 while (current_fiq->fiq_op(current_fiq->dev_id, 0)); 127 } 128 129 static int fiq_start; 130 131 void enable_fiq(int fiq) 132 { 133 enable_irq(fiq + fiq_start); 134 } 135 136 void disable_fiq(int fiq) 137 { 138 disable_irq(fiq + fiq_start); 139 } 140 141 EXPORT_SYMBOL(set_fiq_handler); 142 EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ 143 EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */ 144 EXPORT_SYMBOL(claim_fiq); 145 EXPORT_SYMBOL(release_fiq); 146 EXPORT_SYMBOL(enable_fiq); 147 EXPORT_SYMBOL(disable_fiq); 148 149 void __init init_FIQ(int start) 150 { 151 unsigned offset = FIQ_OFFSET; 152 no_fiq_insn = *(unsigned long *)(0xffff0000 + offset); 153 fiq_start = start; 154 } 155