arch/openrisc/kernel/irq.c

   1 /*
   2  * OpenRISC irq.c
   3  *
   4  * Linux architectural port borrowing liberally from similar works of
   5  * others.  All original copyrights apply as per the original source
   6  * declaration.
   7  *
   8  * Modifications for the OpenRISC architecture:
   9  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  10  *
  11  *      This program is free software; you can redistribute it and/or
  12  *      modify it under the terms of the GNU General Public License
  13  *      as published by the Free Software Foundation; either version
  14  *      2 of the License, or (at your option) any later version.
  15  */
  16
  17 #include <linux/interrupt.h>
  18 #include <linux/init.h>
  19 #include <linux/of.h>
  20 #include <linux/ftrace.h>
  21 #include <linux/irq.h>
  22 #include <linux/export.h>
  23 #include <linux/irqdomain.h>
  24 #include <linux/irqflags.h>
  25
  26 /* read interrupt enabled status */
  27 unsigned long arch_local_save_flags(void)
  28 {
  29         return mfspr(SPR_SR) & (SPR_SR_IEE|SPR_SR_TEE);
  30 }
  31 EXPORT_SYMBOL(arch_local_save_flags);
  32
  33 /* set interrupt enabled status */
  34 void arch_local_irq_restore(unsigned long flags)
  35 {
  36         mtspr(SPR_SR, ((mfspr(SPR_SR) & ~(SPR_SR_IEE|SPR_SR_TEE)) | flags));
  37 }
  38 EXPORT_SYMBOL(arch_local_irq_restore);
  39
  40
  41 /* OR1K PIC implementation */
  42
  43 /* We're a couple of cycles faster than the generic implementations with
  44  * these 'fast' versions.
  45  */
  46
  47 static void or1k_pic_mask(struct irq_data *data)
  48 {
  49         mtspr(SPR_PICMR, mfspr(SPR_PICMR) & ~(1UL << data->hwirq));
  50 }
  51
  52 static void or1k_pic_unmask(struct irq_data *data)
  53 {
  54         mtspr(SPR_PICMR, mfspr(SPR_PICMR) | (1UL << data->hwirq));
  55 }
  56
  57 static void or1k_pic_ack(struct irq_data *data)
  58 {
  59         /* EDGE-triggered interrupts need to be ack'ed in order to clear
  60          * the latch.
  61          * LEVEL-triggered interrupts do not need to be ack'ed; however,
  62          * ack'ing the interrupt has no ill-effect and is quicker than
  63          * trying to figure out what type it is...
  64          */
  65
  66         /* The OpenRISC 1000 spec says to write a 1 to the bit to ack the
  67          * interrupt, but the OR1200 does this backwards and requires a 0
  68          * to be written...
  69          */
  70
  71 #ifdef CONFIG_OR1K_1200
  72         /* There are two oddities with the OR1200 PIC implementation:
  73          * i)  LEVEL-triggered interrupts are latched and need to be cleared
  74          * ii) the interrupt latch is cleared by writing a 0 to the bit,
  75          *     as opposed to a 1 as mandated by the spec
  76          */
  77
  78         mtspr(SPR_PICSR, mfspr(SPR_PICSR) & ~(1UL << data->hwirq));
  79 #else
  80         WARN(1, "Interrupt handling possibly broken\n");
  81         mtspr(SPR_PICSR, (1UL << data->hwirq));
  82 #endif
  83 }
  84
  85 static void or1k_pic_mask_ack(struct irq_data *data)
  86 {
  87         /* Comments for pic_ack apply here, too */
  88
  89 #ifdef CONFIG_OR1K_1200
  90         mtspr(SPR_PICMR, mfspr(SPR_PICMR) & ~(1UL << data->hwirq));
  91         mtspr(SPR_PICSR, mfspr(SPR_PICSR) & ~(1UL << data->hwirq));
  92 #else
  93         WARN(1, "Interrupt handling possibly broken\n");
  94         mtspr(SPR_PICMR, (1UL << data->hwirq));
  95         mtspr(SPR_PICSR, (1UL << data->hwirq));
  96 #endif
  97 }
  98
  99 #if 0
 100 static int or1k_pic_set_type(struct irq_data *data, unsigned int flow_type)
 101 {
 102         /* There's nothing to do in the PIC configuration when changing
 103          * flow type.  Level and edge-triggered interrupts are both
 104          * supported, but it's PIC-implementation specific which type
 105          * is handled. */
 106
 107         return irq_setup_alt_chip(data, flow_type);
 108 }
 109 #endif
 110
 111 static struct irq_chip or1k_dev = {
 112         .name = "or1k-PIC",
 113         .irq_unmask = or1k_pic_unmask,
 114         .irq_mask = or1k_pic_mask,
 115         .irq_ack = or1k_pic_ack,
 116         .irq_mask_ack = or1k_pic_mask_ack,
 117 };
 118
 119 static struct irq_domain *root_domain;
 120
 121 static inline int pic_get_irq(int first)
 122 {
 123         int hwirq;
 124
 125         hwirq = ffs(mfspr(SPR_PICSR) >> first);
 126         if (!hwirq)
 127                 return NO_IRQ;
 128         else
 129                 hwirq = hwirq + first -1;
 130
 131         return irq_find_mapping(root_domain, hwirq);
 132 }
 133
 134
 135 static int or1k_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
 136 {
 137         irq_set_chip_and_handler_name(irq, &or1k_dev,
 138                                       handle_level_irq, "level");
 139         irq_set_status_flags(irq, IRQ_LEVEL | IRQ_NOPROBE);
 140
 141         return 0;
 142 }
 143
 144 static const struct irq_domain_ops or1k_irq_domain_ops = {
 145         .xlate = irq_domain_xlate_onecell,
 146         .map = or1k_map,
 147 };
 148
 149 /*
 150  * This sets up the IRQ domain for the PIC built in to the OpenRISC
 151  * 1000 CPU.  This is the "root" domain as these are the interrupts
 152  * that directly trigger an exception in the CPU.
 153  */
 154 static void __init or1k_irq_init(void)
 155 {
 156         struct device_node *intc = NULL;
 157
 158         /* The interrupt controller device node is mandatory */
 159         intc = of_find_compatible_node(NULL, NULL, "opencores,or1k-pic");
 160         BUG_ON(!intc);
 161
 162         /* Disable all interrupts until explicitly requested */
 163         mtspr(SPR_PICMR, (0UL));
 164
 165         root_domain = irq_domain_add_linear(intc, 32,
 166                                             &or1k_irq_domain_ops, NULL);
 167 }
 168
 169 void __init init_IRQ(void)
 170 {
 171         or1k_irq_init();
 172 }
 173
 174 void __irq_entry do_IRQ(struct pt_regs *regs)
 175 {
 176         int irq = -1;
 177         struct pt_regs *old_regs = set_irq_regs(regs);
 178
 179         irq_enter();
 180
 181         while ((irq = pic_get_irq(irq + 1)) != NO_IRQ)
 182                 generic_handle_irq(irq);
 183
 184         irq_exit();
 185         set_irq_regs(old_regs);
 186 }