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 #include <linux/perf_event.h>
  25
  26 /* Bit-flag stored in irq_desc->chip_data to indicate HW-cleared irqs. */
  27 #define IS_HW_CLEARED 1
  28
  29 /*
  30  * The set of interrupts we enable for arch_local_irq_enable().
  31  * This is initialized to have just a single interrupt that the kernel
  32  * doesn't actually use as a sentinel.  During kernel init,
  33  * interrupts are added as the kernel gets prepared to support them.
  34  * NOTE: we could probably initialize them all statically up front.
  35  */
  36 DEFINE_PER_CPU(unsigned long long, interrupts_enabled_mask) =
  37   INITIAL_INTERRUPTS_ENABLED;
  38 EXPORT_PER_CPU_SYMBOL(interrupts_enabled_mask);
  39
  40 /* Define per-tile device interrupt statistics state. */
  41 DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
  42 EXPORT_PER_CPU_SYMBOL(irq_stat);
  43
  44 /*
  45  * Define per-tile irq disable mask; the hardware/HV only has a single
  46  * mask that we use to implement both masking and disabling.
  47  */
  48 static DEFINE_PER_CPU(unsigned long, irq_disable_mask)
  49         ____cacheline_internodealigned_in_smp;
  50
  51 /*
  52  * Per-tile IRQ nesting depth.  Used to make sure we enable newly
  53  * enabled IRQs before exiting the outermost interrupt.
  54  */
  55 static DEFINE_PER_CPU(int, irq_depth);
  56
  57 #if CHIP_HAS_IPI()
  58 /* Use SPRs to manipulate device interrupts. */
  59 #define mask_irqs(irq_mask) __insn_mtspr(SPR_IPI_MASK_SET_K, irq_mask)
  60 #define unmask_irqs(irq_mask) __insn_mtspr(SPR_IPI_MASK_RESET_K, irq_mask)
  61 #define clear_irqs(irq_mask) __insn_mtspr(SPR_IPI_EVENT_RESET_K, irq_mask)
  62 #else
  63 /* Use HV to manipulate device interrupts. */
  64 #define mask_irqs(irq_mask) hv_disable_intr(irq_mask)
  65 #define unmask_irqs(irq_mask) hv_enable_intr(irq_mask)
  66 #define clear_irqs(irq_mask) hv_clear_intr(irq_mask)
  67 #endif
  68
  69 /*
  70  * The interrupt handling path, implemented in terms of HV interrupt
  71  * emulation on TILEPro, and IPI hardware on TILE-Gx.
  72  * Entered with interrupts disabled.
  73  */
  74 void tile_dev_intr(struct pt_regs *regs, int intnum)
  75 {
  76         int depth = __this_cpu_inc_return(irq_depth);
  77         unsigned long original_irqs;
  78         unsigned long remaining_irqs;
  79         struct pt_regs *old_regs;
  80
  81 #if CHIP_HAS_IPI()
  82         /*
  83          * Pending interrupts are listed in an SPR.  We might be
  84          * nested, so be sure to only handle irqs that weren't already
  85          * masked by a previous interrupt.  Then, mask out the ones
  86          * we're going to handle.
  87          */
  88         unsigned long masked = __insn_mfspr(SPR_IPI_MASK_K);
  89         original_irqs = __insn_mfspr(SPR_IPI_EVENT_K) & ~masked;
  90         __insn_mtspr(SPR_IPI_MASK_SET_K, original_irqs);
  91 #else
  92         /*
  93          * Hypervisor performs the equivalent of the Gx code above and
  94          * then puts the pending interrupt mask into a system save reg
  95          * for us to find.
  96          */
  97         original_irqs = __insn_mfspr(SPR_SYSTEM_SAVE_K_3);
  98 #endif
  99         remaining_irqs = original_irqs;
 100
 101         /* Track time spent here in an interrupt context. */
 102         old_regs = set_irq_regs(regs);
 103         irq_enter();
 104
 105 #ifdef CONFIG_DEBUG_STACKOVERFLOW
 106         /* Debugging check for stack overflow: less than 1/8th stack free? */
 107         {
 108                 long sp = stack_pointer - (long) current_thread_info();
 109                 if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
 110                         pr_emerg("%s: stack overflow: %ld\n",
 111                                  __func__, sp - sizeof(struct thread_info));
 112                         dump_stack();
 113                 }
 114         }
 115 #endif
 116         while (remaining_irqs) {
 117                 unsigned long irq = __ffs(remaining_irqs);
 118                 remaining_irqs &= ~(1UL << irq);
 119
 120                 /* Count device irqs; Linux IPIs are counted elsewhere. */
 121                 if (irq != IRQ_RESCHEDULE)
 122                         __this_cpu_inc(irq_stat.irq_dev_intr_count);
 123
 124                 generic_handle_irq(irq);
 125         }
 126
 127         /*
 128          * If we weren't nested, turn on all enabled interrupts,
 129          * including any that were reenabled during interrupt
 130          * handling.
 131          */
 132         if (depth == 1)
 133                 unmask_irqs(~__this_cpu_read(irq_disable_mask));
 134
 135         __this_cpu_dec(irq_depth);
 136
 137         /*
 138          * Track time spent against the current process again and
 139          * process any softirqs if they are waiting.
 140          */
 141         irq_exit();
 142         set_irq_regs(old_regs);
 143 }
 144
 145
 146 /*
 147  * Remove an irq from the disabled mask.  If we're in an interrupt
 148  * context, defer enabling the HW interrupt until we leave.
 149  */
 150 static void tile_irq_chip_enable(struct irq_data *d)
 151 {
 152         get_cpu_var(irq_disable_mask) &= ~(1UL << d->irq);
 153         if (__this_cpu_read(irq_depth) == 0)
 154                 unmask_irqs(1UL << d->irq);
 155         put_cpu_var(irq_disable_mask);
 156 }
 157
 158 /*
 159  * Add an irq to the disabled mask.  We disable the HW interrupt
 160  * immediately so that there's no possibility of it firing.  If we're
 161  * in an interrupt context, the return path is careful to avoid
 162  * unmasking a newly disabled interrupt.
 163  */
 164 static void tile_irq_chip_disable(struct irq_data *d)
 165 {
 166         get_cpu_var(irq_disable_mask) |= (1UL << d->irq);
 167         mask_irqs(1UL << d->irq);
 168         put_cpu_var(irq_disable_mask);
 169 }
 170
 171 /* Mask an interrupt. */
 172 static void tile_irq_chip_mask(struct irq_data *d)
 173 {
 174         mask_irqs(1UL << d->irq);
 175 }
 176
 177 /* Unmask an interrupt. */
 178 static void tile_irq_chip_unmask(struct irq_data *d)
 179 {
 180         unmask_irqs(1UL << d->irq);
 181 }
 182
 183 /*
 184  * Clear an interrupt before processing it so that any new assertions
 185  * will trigger another irq.
 186  */
 187 static void tile_irq_chip_ack(struct irq_data *d)
 188 {
 189         if ((unsigned long)irq_data_get_irq_chip_data(d) != IS_HW_CLEARED)
 190                 clear_irqs(1UL << d->irq);
 191 }
 192
 193 /*
 194  * For per-cpu interrupts, we need to avoid unmasking any interrupts
 195  * that we disabled via disable_percpu_irq().
 196  */
 197 static void tile_irq_chip_eoi(struct irq_data *d)
 198 {
 199         if (!(__this_cpu_read(irq_disable_mask) & (1UL << d->irq)))
 200                 unmask_irqs(1UL << d->irq);
 201 }
 202
 203 static struct irq_chip tile_irq_chip = {
 204         .name = "tile_irq_chip",
 205         .irq_enable = tile_irq_chip_enable,
 206         .irq_disable = tile_irq_chip_disable,
 207         .irq_ack = tile_irq_chip_ack,
 208         .irq_eoi = tile_irq_chip_eoi,
 209         .irq_mask = tile_irq_chip_mask,
 210         .irq_unmask = tile_irq_chip_unmask,
 211 };
 212
 213 void __init init_IRQ(void)
 214 {
 215         ipi_init();
 216 }
 217
 218 void setup_irq_regs(void)
 219 {
 220         /* Enable interrupt delivery. */
 221         unmask_irqs(~0UL);
 222 #if CHIP_HAS_IPI()
 223         arch_local_irq_unmask(INT_IPI_K);
 224 #endif
 225 }
 226
 227 void tile_irq_activate(unsigned int irq, int tile_irq_type)
 228 {
 229         /*
 230          * We use handle_level_irq() by default because the pending
 231          * interrupt vector (whether modeled by the HV on
 232          * TILEPro or implemented in hardware on TILE-Gx) has
 233          * level-style semantics for each bit.  An interrupt fires
 234          * whenever a bit is high, not just at edges.
 235          */
 236         irq_flow_handler_t handle = handle_level_irq;
 237         if (tile_irq_type == TILE_IRQ_PERCPU)
 238                 handle = handle_percpu_irq;
 239         irq_set_chip_and_handler(irq, &tile_irq_chip, handle);
 240
 241         /*
 242          * Flag interrupts that are hardware-cleared so that ack()
 243          * won't clear them.
 244          */
 245         if (tile_irq_type == TILE_IRQ_HW_CLEAR)
 246                 irq_set_chip_data(irq, (void *)IS_HW_CLEARED);
 247 }
 248 EXPORT_SYMBOL(tile_irq_activate);
 249
 250
 251 void ack_bad_irq(unsigned int irq)
 252 {
 253         pr_err("unexpected IRQ trap at vector %02x\n", irq);
 254 }
 255
 256 /*
 257  * /proc/interrupts printing:
 258  */
 259 int arch_show_interrupts(struct seq_file *p, int prec)
 260 {
 261 #ifdef CONFIG_PERF_EVENTS
 262         int i;
 263
 264         seq_printf(p, "%*s: ", prec, "PMI");
 265
 266         for_each_online_cpu(i)
 267                 seq_printf(p, "%10llu ", per_cpu(perf_irqs, i));
 268         seq_puts(p, "  perf_events\n");
 269 #endif
 270         return 0;
 271 }
 272
 273 #if CHIP_HAS_IPI()
 274 int arch_setup_hwirq(unsigned int irq, int node)
 275 {
 276         return irq >= NR_IRQS ? -EINVAL : 0;
 277 }
 278
 279 void arch_teardown_hwirq(unsigned int irq) { }
 280 #endif