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/fiq.h> 46 #include <asm/irq.h> 47 #include <asm/system.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 /* 93 * Taking an interrupt in FIQ mode is death, so both these functions 94 * disable irqs for the duration. Note - these functions are almost 95 * entirely coded in assembly. 96 */ 97 void __naked set_fiq_regs(struct pt_regs *regs) 98 { 99 register unsigned long tmp; 100 asm volatile ( 101 "mov ip, sp\n\ 102 stmfd sp!, {fp, ip, lr, pc}\n\ 103 sub fp, ip, #4\n\ 104 mrs %0, cpsr\n\ 105 msr cpsr_c, %2 @ select FIQ mode\n\ 106 mov r0, r0\n\ 107 ldmia %1, {r8 - r14}\n\ 108 msr cpsr_c, %0 @ return to SVC mode\n\ 109 mov r0, r0\n\ 110 ldmfd sp, {fp, sp, pc}" 111 : "=&r" (tmp) 112 : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE)); 113 } 114 115 void __naked get_fiq_regs(struct pt_regs *regs) 116 { 117 register unsigned long tmp; 118 asm volatile ( 119 "mov ip, sp\n\ 120 stmfd sp!, {fp, ip, lr, pc}\n\ 121 sub fp, ip, #4\n\ 122 mrs %0, cpsr\n\ 123 msr cpsr_c, %2 @ select FIQ mode\n\ 124 mov r0, r0\n\ 125 stmia %1, {r8 - r14}\n\ 126 msr cpsr_c, %0 @ return to SVC mode\n\ 127 mov r0, r0\n\ 128 ldmfd sp, {fp, sp, pc}" 129 : "=&r" (tmp) 130 : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE)); 131 } 132 133 int claim_fiq(struct fiq_handler *f) 134 { 135 int ret = 0; 136 137 if (current_fiq) { 138 ret = -EBUSY; 139 140 if (current_fiq->fiq_op != NULL) 141 ret = current_fiq->fiq_op(current_fiq->dev_id, 1); 142 } 143 144 if (!ret) { 145 f->next = current_fiq; 146 current_fiq = f; 147 } 148 149 return ret; 150 } 151 152 void release_fiq(struct fiq_handler *f) 153 { 154 if (current_fiq != f) { 155 printk(KERN_ERR "%s FIQ trying to release %s FIQ\n", 156 f->name, current_fiq->name); 157 dump_stack(); 158 return; 159 } 160 161 do 162 current_fiq = current_fiq->next; 163 while (current_fiq->fiq_op(current_fiq->dev_id, 0)); 164 } 165 166 void enable_fiq(int fiq) 167 { 168 enable_irq(fiq + FIQ_START); 169 } 170 171 void disable_fiq(int fiq) 172 { 173 disable_irq(fiq + FIQ_START); 174 } 175 176 EXPORT_SYMBOL(set_fiq_handler); 177 EXPORT_SYMBOL(set_fiq_regs); 178 EXPORT_SYMBOL(get_fiq_regs); 179 EXPORT_SYMBOL(claim_fiq); 180 EXPORT_SYMBOL(release_fiq); 181 EXPORT_SYMBOL(enable_fiq); 182 EXPORT_SYMBOL(disable_fiq); 183 184 void __init init_FIQ(void) 185 { 186 no_fiq_insn = *(unsigned long *)0xffff001c; 187 } 188