arch/tile/kernel/irq.c

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/irq.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/uaccess.h>
  21 #include <hv/drv_pcie_rc_intf.h>
  22 #include <arch/spr_def.h>
  23 #include <asm/traps.h>
  24
  25 /* Bit-flag stored in irq_desc->chip_data to indicate HW-cleared irqs. */
  26 #define IS_HW_CLEARED 1
  27
  28 /*
  29  * The set of interrupts we enable for arch_local_irq_enable().
  30  * This is initialized to have just a single interrupt that the kernel
  31  * doesn't actually use as a sentinel.  During kernel init,
  32  * interrupts are added as the kernel gets prepared to support them.
  33  * NOTE: we could probably initialize them all statically up front.
  34  */
  35 DEFINE_PER_CPU(unsigned long long, interrupts_enabled_mask) =
  36   INITIAL_INTERRUPTS_ENABLED;
  37 EXPORT_PER_CPU_SYMBOL(interrupts_enabled_mask);
  38
  39 /* Define per-tile device interrupt statistics state. */
  40 DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
  41 EXPORT_PER_CPU_SYMBOL(irq_stat);
  42
  43 /*
  44  * Define per-tile irq disable mask; the hardware/HV only has a single
  45  * mask that we use to implement both masking and disabling.
  46  */
  47 static DEFINE_PER_CPU(unsigned long, irq_disable_mask)
  48         ____cacheline_internodealigned_in_smp;
  49
  50 /*
  51  * Per-tile IRQ nesting depth.  Used to make sure we enable newly
  52  * enabled IRQs before exiting the outermost interrupt.
  53  */
  54 static DEFINE_PER_CPU(int, irq_depth);
  55
  56 /* State for allocating IRQs on Gx. */
  57 #if CHIP_HAS_IPI()
  58 static unsigned long available_irqs = ((1UL << NR_IRQS) - 1) &
  59                                       (~(1UL << IRQ_RESCHEDULE));
  60 static DEFINE_SPINLOCK(available_irqs_lock);
  61 #endif
  62
  63 #if CHIP_HAS_IPI()
  64 /* Use SPRs to manipulate device interrupts. */
  65 #define mask_irqs(irq_mask) __insn_mtspr(SPR_IPI_MASK_SET_K, irq_mask)
  66 #define unmask_irqs(irq_mask) __insn_mtspr(SPR_IPI_MASK_RESET_K, irq_mask)
  67 #define clear_irqs(irq_mask) __insn_mtspr(SPR_IPI_EVENT_RESET_K, irq_mask)
  68 #else
  69 /* Use HV to manipulate device interrupts. */
  70 #define mask_irqs(irq_mask) hv_disable_intr(irq_mask)
  71 #define unmask_irqs(irq_mask) hv_enable_intr(irq_mask)
  72 #define clear_irqs(irq_mask) hv_clear_intr(irq_mask)
  73 #endif
  74
  75 /*
  76  * The interrupt handling path, implemented in terms of HV interrupt
  77  * emulation on TILEPro, and IPI hardware on TILE-Gx.
  78  * Entered with interrupts disabled.
  79  */
  80 void tile_dev_intr(struct pt_regs *regs, int intnum)
  81 {
  82         int depth = __get_cpu_var(irq_depth)++;
  83         unsigned long original_irqs;
  84         unsigned long remaining_irqs;
  85         struct pt_regs *old_regs;
  86
  87 #if CHIP_HAS_IPI()
  88         /*
  89          * Pending interrupts are listed in an SPR.  We might be
  90          * nested, so be sure to only handle irqs that weren't already
  91          * masked by a previous interrupt.  Then, mask out the ones
  92          * we're going to handle.
  93          */
  94         unsigned long masked = __insn_mfspr(SPR_IPI_MASK_K);
  95         original_irqs = __insn_mfspr(SPR_IPI_EVENT_K) & ~masked;
  96         __insn_mtspr(SPR_IPI_MASK_SET_K, original_irqs);
  97 #else
  98         /*
  99          * Hypervisor performs the equivalent of the Gx code above and
 100          * then puts the pending interrupt mask into a system save reg
 101          * for us to find.
 102          */
 103         original_irqs = __insn_mfspr(SPR_SYSTEM_SAVE_K_3);
 104 #endif
 105         remaining_irqs = original_irqs;
 106
 107         /* Track time spent here in an interrupt context. */
 108         old_regs = set_irq_regs(regs);
 109         irq_enter();
 110
 111 #ifdef CONFIG_DEBUG_STACKOVERFLOW
 112         /* Debugging check for stack overflow: less than 1/8th stack free? */
 113         {
 114                 long sp = stack_pointer - (long) current_thread_info();
 115                 if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
 116                         pr_emerg("tile_dev_intr: "
 117                                "stack overflow: %ld\n",
 118                                sp - sizeof(struct thread_info));
 119                         dump_stack();
 120                 }
 121         }
 122 #endif
 123         while (remaining_irqs) {
 124                 unsigned long irq = __ffs(remaining_irqs);
 125                 remaining_irqs &= ~(1UL << irq);
 126
 127                 /* Count device irqs; Linux IPIs are counted elsewhere. */
 128                 if (irq != IRQ_RESCHEDULE)
 129                         __get_cpu_var(irq_stat).irq_dev_intr_count++;
 130
 131                 generic_handle_irq(irq);
 132         }
 133
 134         /*
 135          * If we weren't nested, turn on all enabled interrupts,
 136          * including any that were reenabled during interrupt
 137          * handling.
 138          */
 139         if (depth == 0)
 140                 unmask_irqs(~__get_cpu_var(irq_disable_mask));
 141
 142         __get_cpu_var(irq_depth)--;
 143
 144         /*
 145          * Track time spent against the current process again and
 146          * process any softirqs if they are waiting.
 147          */
 148         irq_exit();
 149         set_irq_regs(old_regs);
 150 }
 151
 152
 153 /*
 154  * Remove an irq from the disabled mask.  If we're in an interrupt
 155  * context, defer enabling the HW interrupt until we leave.
 156  */
 157 static void tile_irq_chip_enable(struct irq_data *d)
 158 {
 159         get_cpu_var(irq_disable_mask) &= ~(1UL << d->irq);
 160         if (__get_cpu_var(irq_depth) == 0)
 161                 unmask_irqs(1UL << d->irq);
 162         put_cpu_var(irq_disable_mask);
 163 }
 164
 165 /*
 166  * Add an irq to the disabled mask.  We disable the HW interrupt
 167  * immediately so that there's no possibility of it firing.  If we're
 168  * in an interrupt context, the return path is careful to avoid
 169  * unmasking a newly disabled interrupt.
 170  */
 171 static void tile_irq_chip_disable(struct irq_data *d)
 172 {
 173         get_cpu_var(irq_disable_mask) |= (1UL << d->irq);
 174         mask_irqs(1UL << d->irq);
 175         put_cpu_var(irq_disable_mask);
 176 }
 177
 178 /* Mask an interrupt. */
 179 static void tile_irq_chip_mask(struct irq_data *d)
 180 {
 181         mask_irqs(1UL << d->irq);
 182 }
 183
 184 /* Unmask an interrupt. */
 185 static void tile_irq_chip_unmask(struct irq_data *d)
 186 {
 187         unmask_irqs(1UL << d->irq);
 188 }
 189
 190 /*
 191  * Clear an interrupt before processing it so that any new assertions
 192  * will trigger another irq.
 193  */
 194 static void tile_irq_chip_ack(struct irq_data *d)
 195 {
 196         if ((unsigned long)irq_data_get_irq_chip_data(d) != IS_HW_CLEARED)
 197                 clear_irqs(1UL << d->irq);
 198 }
 199
 200 /*
 201  * For per-cpu interrupts, we need to avoid unmasking any interrupts
 202  * that we disabled via disable_percpu_irq().
 203  */
 204 static void tile_irq_chip_eoi(struct irq_data *d)
 205 {
 206         if (!(__get_cpu_var(irq_disable_mask) & (1UL << d->irq)))
 207                 unmask_irqs(1UL << d->irq);
 208 }
 209
 210 static struct irq_chip tile_irq_chip = {
 211         .name = "tile_irq_chip",
 212         .irq_enable = tile_irq_chip_enable,
 213         .irq_disable = tile_irq_chip_disable,
 214         .irq_ack = tile_irq_chip_ack,
 215         .irq_eoi = tile_irq_chip_eoi,
 216         .irq_mask = tile_irq_chip_mask,
 217         .irq_unmask = tile_irq_chip_unmask,
 218 };
 219
 220 void __init init_IRQ(void)
 221 {
 222         ipi_init();
 223 }
 224
 225 void setup_irq_regs(void)
 226 {
 227         /* Enable interrupt delivery. */
 228         unmask_irqs(~0UL);
 229 #if CHIP_HAS_IPI()
 230         arch_local_irq_unmask(INT_IPI_K);
 231 #endif
 232 }
 233
 234 void tile_irq_activate(unsigned int irq, int tile_irq_type)
 235 {
 236         /*
 237          * We use handle_level_irq() by default because the pending
 238          * interrupt vector (whether modeled by the HV on
 239          * TILEPro or implemented in hardware on TILE-Gx) has
 240          * level-style semantics for each bit.  An interrupt fires
 241          * whenever a bit is high, not just at edges.
 242          */
 243         irq_flow_handler_t handle = handle_level_irq;
 244         if (tile_irq_type == TILE_IRQ_PERCPU)
 245                 handle = handle_percpu_irq;
 246         irq_set_chip_and_handler(irq, &tile_irq_chip, handle);
 247
 248         /*
 249          * Flag interrupts that are hardware-cleared so that ack()
 250          * won't clear them.
 251          */
 252         if (tile_irq_type == TILE_IRQ_HW_CLEAR)
 253                 irq_set_chip_data(irq, (void *)IS_HW_CLEARED);
 254 }
 255 EXPORT_SYMBOL(tile_irq_activate);
 256
 257
 258 void ack_bad_irq(unsigned int irq)
 259 {
 260         pr_err("unexpected IRQ trap at vector %02x\n", irq);
 261 }
 262
 263 /*
 264  * Generic, controller-independent functions:
 265  */
 266
 267 #if CHIP_HAS_IPI()
 268 int create_irq(void)
 269 {
 270         unsigned long flags;
 271         int result;
 272
 273         spin_lock_irqsave(&available_irqs_lock, flags);
 274         if (available_irqs == 0)
 275                 result = -ENOMEM;
 276         else {
 277                 result = __ffs(available_irqs);
 278                 available_irqs &= ~(1UL << result);
 279                 dynamic_irq_init(result);
 280         }
 281         spin_unlock_irqrestore(&available_irqs_lock, flags);
 282
 283         return result;
 284 }
 285 EXPORT_SYMBOL(create_irq);
 286
 287 void destroy_irq(unsigned int irq)
 288 {
 289         unsigned long flags;
 290
 291         spin_lock_irqsave(&available_irqs_lock, flags);
 292         available_irqs |= (1UL << irq);
 293         dynamic_irq_cleanup(irq);
 294         spin_unlock_irqrestore(&available_irqs_lock, flags);
 295 }
 296 EXPORT_SYMBOL(destroy_irq);
 297 #endif