arch/mn10300/kernel/irq.c

   1 /* MN10300 Arch-specific interrupt handling
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11 #include <linux/module.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/kernel_stat.h>
  14 #include <linux/seq_file.h>
  15 #include <asm/setup.h>
  16
  17 unsigned long __mn10300_irq_enabled_epsw = EPSW_IE | EPSW_IM_7;
  18 EXPORT_SYMBOL(__mn10300_irq_enabled_epsw);
  19
  20 atomic_t irq_err_count;
  21
  22 /*
  23  * MN10300 interrupt controller operations
  24  */
  25 static void mn10300_cpupic_ack(unsigned int irq)
  26 {
  27         u16 tmp;
  28         *(volatile u8 *) &GxICR(irq) = GxICR_DETECT;
  29         tmp = GxICR(irq);
  30 }
  31
  32 static void mn10300_cpupic_mask(unsigned int irq)
  33 {
  34         u16 tmp = GxICR(irq);
  35         GxICR(irq) = (tmp & GxICR_LEVEL);
  36         tmp = GxICR(irq);
  37 }
  38
  39 static void mn10300_cpupic_mask_ack(unsigned int irq)
  40 {
  41         u16 tmp = GxICR(irq);
  42         GxICR(irq) = (tmp & GxICR_LEVEL) | GxICR_DETECT;
  43         tmp = GxICR(irq);
  44 }
  45
  46 static void mn10300_cpupic_unmask(unsigned int irq)
  47 {
  48         u16 tmp = GxICR(irq);
  49         GxICR(irq) = (tmp & GxICR_LEVEL) | GxICR_ENABLE;
  50         tmp = GxICR(irq);
  51 }
  52
  53 static void mn10300_cpupic_unmask_clear(unsigned int irq)
  54 {
  55         /* the MN10300 PIC latches its interrupt request bit, even after the
  56          * device has ceased to assert its interrupt line and the interrupt
  57          * channel has been disabled in the PIC, so for level-triggered
  58          * interrupts we need to clear the request bit when we re-enable */
  59         u16 tmp = GxICR(irq);
  60         GxICR(irq) = (tmp & GxICR_LEVEL) | GxICR_ENABLE | GxICR_DETECT;
  61         tmp = GxICR(irq);
  62 }
  63
  64 /*
  65  * MN10300 PIC level-triggered IRQ handling.
  66  *
  67  * The PIC has no 'ACK' function per se.  It is possible to clear individual
  68  * channel latches, but each latch relatches whether or not the channel is
  69  * masked, so we need to clear the latch when we unmask the channel.
  70  *
  71  * Also for this reason, we don't supply an ack() op (it's unused anyway if
  72  * mask_ack() is provided), and mask_ack() just masks.
  73  */
  74 static struct irq_chip mn10300_cpu_pic_level = {
  75         .name           = "cpu_l",
  76         .disable        = mn10300_cpupic_mask,
  77         .enable         = mn10300_cpupic_unmask_clear,
  78         .ack            = NULL,
  79         .mask           = mn10300_cpupic_mask,
  80         .mask_ack       = mn10300_cpupic_mask,
  81         .unmask         = mn10300_cpupic_unmask_clear,
  82 };
  83
  84 /*
  85  * MN10300 PIC edge-triggered IRQ handling.
  86  *
  87  * We use the latch clearing function of the PIC as the 'ACK' function.
  88  */
  89 static struct irq_chip mn10300_cpu_pic_edge = {
  90         .name           = "cpu_e",
  91         .disable        = mn10300_cpupic_mask,
  92         .enable         = mn10300_cpupic_unmask,
  93         .ack            = mn10300_cpupic_ack,
  94         .mask           = mn10300_cpupic_mask,
  95         .mask_ack       = mn10300_cpupic_mask_ack,
  96         .unmask         = mn10300_cpupic_unmask,
  97 };
  98
  99 /*
 100  * 'what should we do if we get a hw irq event on an illegal vector'.
 101  * each architecture has to answer this themselves.
 102  */
 103 void ack_bad_irq(int irq)
 104 {
 105         printk(KERN_WARNING "unexpected IRQ trap at vector %02x\n", irq);
 106 }
 107
 108 /*
 109  * change the level at which an IRQ executes
 110  * - must not be called whilst interrupts are being processed!
 111  */
 112 void set_intr_level(int irq, u16 level)
 113 {
 114         u16 tmp;
 115
 116         if (in_interrupt())
 117                 BUG();
 118
 119         tmp = GxICR(irq);
 120         GxICR(irq) = (tmp & GxICR_ENABLE) | level;
 121         tmp = GxICR(irq);
 122 }
 123
 124 /*
 125  * mark an interrupt to be ACK'd after interrupt handlers have been run rather
 126  * than before
 127  * - see Documentation/mn10300/features.txt
 128  */
 129 void set_intr_postackable(int irq)
 130 {
 131         set_irq_chip_and_handler(irq, &mn10300_cpu_pic_level,
 132                                  handle_level_irq);
 133 }
 134
 135 /*
 136  * initialise the interrupt system
 137  */
 138 void __init init_IRQ(void)
 139 {
 140         int irq;
 141
 142         for (irq = 0; irq < NR_IRQS; irq++)
 143                 if (irq_desc[irq].chip == &no_irq_chip)
 144                         /* due to the PIC latching interrupt requests, even
 145                          * when the IRQ is disabled, IRQ_PENDING is superfluous
 146                          * and we can use handle_level_irq() for edge-triggered
 147                          * interrupts */
 148                         set_irq_chip_and_handler(irq, &mn10300_cpu_pic_edge,
 149                                                  handle_level_irq);
 150         unit_init_IRQ();
 151 }
 152
 153 /*
 154  * handle normal device IRQs
 155  */
 156 asmlinkage void do_IRQ(void)
 157 {
 158         unsigned long sp, epsw, irq_disabled_epsw, old_irq_enabled_epsw;
 159         int irq;
 160
 161         sp = current_stack_pointer();
 162         if (sp - (sp & ~(THREAD_SIZE - 1)) < STACK_WARN)
 163                 BUG();
 164
 165         /* make sure local_irq_enable() doesn't muck up the interrupt priority
 166          * setting in EPSW */
 167         old_irq_enabled_epsw = __mn10300_irq_enabled_epsw;
 168         local_save_flags(epsw);
 169         __mn10300_irq_enabled_epsw = EPSW_IE | (EPSW_IM & epsw);
 170         irq_disabled_epsw = EPSW_IE | MN10300_CLI_LEVEL;
 171
 172         __IRQ_STAT(smp_processor_id(), __irq_count)++;
 173
 174         irq_enter();
 175
 176         for (;;) {
 177                 /* ask the interrupt controller for the next IRQ to process
 178                  * - the result we get depends on EPSW.IM
 179                  */
 180                 irq = IAGR & IAGR_GN;
 181                 if (!irq)
 182                         break;
 183
 184                 local_irq_restore(irq_disabled_epsw);
 185
 186                 generic_handle_irq(irq >> 2);
 187
 188                 /* restore IRQ controls for IAGR access */
 189                 local_irq_restore(epsw);
 190         }
 191
 192         __mn10300_irq_enabled_epsw = old_irq_enabled_epsw;
 193
 194         irq_exit();
 195 }
 196
 197 /*
 198  * Display interrupt management information through /proc/interrupts
 199  */
 200 int show_interrupts(struct seq_file *p, void *v)
 201 {
 202         int i = *(loff_t *) v, j, cpu;
 203         struct irqaction *action;
 204         unsigned long flags;
 205
 206         switch (i) {
 207                 /* display column title bar naming CPUs */
 208         case 0:
 209                 seq_printf(p, "           ");
 210                 for (j = 0; j < NR_CPUS; j++)
 211                         if (cpu_online(j))
 212                                 seq_printf(p, "CPU%d       ", j);
 213                 seq_putc(p, '\n');
 214                 break;
 215
 216                 /* display information rows, one per active CPU */
 217         case 1 ... NR_IRQS - 1:
 218                 raw_spin_lock_irqsave(&irq_desc[i].lock, flags);
 219
 220                 action = irq_desc[i].action;
 221                 if (action) {
 222                         seq_printf(p, "%3d: ", i);
 223                         for_each_present_cpu(cpu)
 224                                 seq_printf(p, "%10u ", kstat_irqs_cpu(i, cpu));
 225                         seq_printf(p, " %14s.%u", irq_desc[i].chip->name,
 226                                    (GxICR(i) & GxICR_LEVEL) >>
 227                                    GxICR_LEVEL_SHIFT);
 228                         seq_printf(p, "  %s", action->name);
 229
 230                         for (action = action->next;
 231                              action;
 232                              action = action->next)
 233                                 seq_printf(p, ", %s", action->name);
 234
 235                         seq_putc(p, '\n');
 236                 }
 237
 238                 raw_spin_unlock_irqrestore(&irq_desc[i].lock, flags);
 239                 break;
 240
 241                 /* polish off with NMI and error counters */
 242         case NR_IRQS:
 243                 seq_printf(p, "NMI: ");
 244                 for (j = 0; j < NR_CPUS; j++)
 245                         if (cpu_online(j))
 246                                 seq_printf(p, "%10u ", nmi_count(j));
 247                 seq_putc(p, '\n');
 248
 249                 seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
 250                 break;
 251         }
 252
 253         return 0;
 254 }