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 dfl_fiq_insn; 56 static struct pt_regs dfl_fiq_regs; 57 58 /* Default reacquire function 59 * - we always relinquish FIQ control 60 * - we always reacquire FIQ control 61 */ 62 static int fiq_def_op(void *ref, int relinquish) 63 { 64 if (!relinquish) { 65 /* Restore default handler and registers */ 66 local_fiq_disable(); 67 set_fiq_regs(&dfl_fiq_regs); 68 set_fiq_handler(&dfl_fiq_insn, sizeof(dfl_fiq_insn)); 69 local_fiq_enable(); 70 71 /* FIXME: notify irq controller to standard enable FIQs */ 72 } 73 74 return 0; 75 } 76 77 static struct fiq_handler default_owner = { 78 .name = "default", 79 .fiq_op = fiq_def_op, 80 }; 81 82 static struct fiq_handler *current_fiq = &default_owner; 83 84 int show_fiq_list(struct seq_file *p, int prec) 85 { 86 if (current_fiq != &default_owner) 87 seq_printf(p, "%*s: %s\n", prec, "FIQ", 88 current_fiq->name); 89 90 return 0; 91 } 92 93 void set_fiq_handler(void *start, unsigned int length) 94 { 95 void *base = vectors_page; 96 unsigned offset = FIQ_OFFSET; 97 98 memcpy(base + offset, start, length); 99 if (!cache_is_vipt_nonaliasing()) 100 flush_icache_range((unsigned long)base + offset, offset + 101 length); 102 flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length); 103 } 104 105 int claim_fiq(struct fiq_handler *f) 106 { 107 int ret = 0; 108 109 if (current_fiq) { 110 ret = -EBUSY; 111 112 if (current_fiq->fiq_op != NULL) 113 ret = current_fiq->fiq_op(current_fiq->dev_id, 1); 114 } 115 116 if (!ret) { 117 f->next = current_fiq; 118 current_fiq = f; 119 } 120 121 return ret; 122 } 123 124 void release_fiq(struct fiq_handler *f) 125 { 126 if (current_fiq != f) { 127 pr_err("%s FIQ trying to release %s FIQ\n", 128 f->name, current_fiq->name); 129 dump_stack(); 130 return; 131 } 132 133 do 134 current_fiq = current_fiq->next; 135 while (current_fiq->fiq_op(current_fiq->dev_id, 0)); 136 } 137 138 static int fiq_start; 139 140 void enable_fiq(int fiq) 141 { 142 enable_irq(fiq + fiq_start); 143 } 144 145 void disable_fiq(int fiq) 146 { 147 disable_irq(fiq + fiq_start); 148 } 149 150 EXPORT_SYMBOL(set_fiq_handler); 151 EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ 152 EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */ 153 EXPORT_SYMBOL(claim_fiq); 154 EXPORT_SYMBOL(release_fiq); 155 EXPORT_SYMBOL(enable_fiq); 156 EXPORT_SYMBOL(disable_fiq); 157 158 void __init init_FIQ(int start) 159 { 160 unsigned offset = FIQ_OFFSET; 161 dfl_fiq_insn = *(unsigned long *)(0xffff0000 + offset); 162 get_fiq_regs(&dfl_fiq_regs); 163 fiq_start = start; 164 } 165