arch/arm/common/gic.c

   1 /*
   2  *  linux/arch/arm/common/gic.c
   3  *
   4  *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Interrupt architecture for the GIC:
  11  *
  12  * o There is one Interrupt Distributor, which receives interrupts
  13  *   from system devices and sends them to the Interrupt Controllers.
  14  *
  15  * o There is one CPU Interface per CPU, which sends interrupts sent
  16  *   by the Distributor, and interrupts generated locally, to the
  17  *   associated CPU. The base address of the CPU interface is usually
  18  *   aliased so that the same address points to different chips depending
  19  *   on the CPU it is accessed from.
  20  *
  21  * Note that IRQs 0-31 are special - they are local to each CPU.
  22  * As such, the enable set/clear, pending set/clear and active bit
  23  * registers are banked per-cpu for these sources.
  24  */
  25 #include <linux/init.h>
  26 #include <linux/kernel.h>
  27 #include <linux/list.h>
  28 #include <linux/smp.h>
  29 #include <linux/cpumask.h>
  30 #include <linux/io.h>
  31
  32 #include <asm/irq.h>
  33 #include <asm/mach/irq.h>
  34 #include <asm/hardware/gic.h>
  35
  36 static DEFINE_SPINLOCK(irq_controller_lock);
  37
  38 struct gic_chip_data {
  39         unsigned int irq_offset;
  40         void __iomem *dist_base;
  41         void __iomem *cpu_base;
  42 };
  43
  44 #ifndef MAX_GIC_NR
  45 #define MAX_GIC_NR      1
  46 #endif
  47
  48 static struct gic_chip_data gic_data[MAX_GIC_NR];
  49
  50 static inline void __iomem *gic_dist_base(unsigned int irq)
  51 {
  52         struct gic_chip_data *gic_data = get_irq_chip_data(irq);
  53         return gic_data->dist_base;
  54 }
  55
  56 static inline void __iomem *gic_cpu_base(unsigned int irq)
  57 {
  58         struct gic_chip_data *gic_data = get_irq_chip_data(irq);
  59         return gic_data->cpu_base;
  60 }
  61
  62 static inline unsigned int gic_irq(unsigned int irq)
  63 {
  64         struct gic_chip_data *gic_data = get_irq_chip_data(irq);
  65         return irq - gic_data->irq_offset;
  66 }
  67
  68 /*
  69  * Routines to acknowledge, disable and enable interrupts
  70  *
  71  * Linux assumes that when we're done with an interrupt we need to
  72  * unmask it, in the same way we need to unmask an interrupt when
  73  * we first enable it.
  74  *
  75  * The GIC has a separate notion of "end of interrupt" to re-enable
  76  * an interrupt after handling, in order to support hardware
  77  * prioritisation.
  78  *
  79  * We can make the GIC behave in the way that Linux expects by making
  80  * our "acknowledge" routine disable the interrupt, then mark it as
  81  * complete.
  82  */
  83 static void gic_ack_irq(unsigned int irq)
  84 {
  85         u32 mask = 1 << (irq % 32);
  86
  87         spin_lock(&irq_controller_lock);
  88         writel(mask, gic_dist_base(irq) + GIC_DIST_ENABLE_CLEAR + (gic_irq(irq) / 32) * 4);
  89         writel(gic_irq(irq), gic_cpu_base(irq) + GIC_CPU_EOI);
  90         spin_unlock(&irq_controller_lock);
  91 }
  92
  93 static void gic_mask_irq(unsigned int irq)
  94 {
  95         u32 mask = 1 << (irq % 32);
  96
  97         spin_lock(&irq_controller_lock);
  98         writel(mask, gic_dist_base(irq) + GIC_DIST_ENABLE_CLEAR + (gic_irq(irq) / 32) * 4);
  99         spin_unlock(&irq_controller_lock);
 100 }
 101
 102 static void gic_unmask_irq(unsigned int irq)
 103 {
 104         u32 mask = 1 << (irq % 32);
 105
 106         spin_lock(&irq_controller_lock);
 107         writel(mask, gic_dist_base(irq) + GIC_DIST_ENABLE_SET + (gic_irq(irq) / 32) * 4);
 108         spin_unlock(&irq_controller_lock);
 109 }
 110
 111 #ifdef CONFIG_SMP
 112 static void gic_set_cpu(unsigned int irq, cpumask_t mask_val)
 113 {
 114         void __iomem *reg = gic_dist_base(irq) + GIC_DIST_TARGET + (gic_irq(irq) & ~3);
 115         unsigned int shift = (irq % 4) * 8;
 116         unsigned int cpu = first_cpu(mask_val);
 117         u32 val;
 118
 119         spin_lock(&irq_controller_lock);
 120         irq_desc[irq].cpu = cpu;
 121         val = readl(reg) & ~(0xff << shift);
 122         val |= 1 << (cpu + shift);
 123         writel(val, reg);
 124         spin_unlock(&irq_controller_lock);
 125 }
 126 #endif
 127
 128 static void gic_handle_cascade_irq(unsigned int irq, struct irq_desc *desc)
 129 {
 130         struct gic_chip_data *chip_data = get_irq_data(irq);
 131         struct irq_chip *chip = get_irq_chip(irq);
 132         unsigned int cascade_irq, gic_irq;
 133         unsigned long status;
 134
 135         /* primary controller ack'ing */
 136         chip->ack(irq);
 137
 138         spin_lock(&irq_controller_lock);
 139         status = readl(chip_data->cpu_base + GIC_CPU_INTACK);
 140         spin_unlock(&irq_controller_lock);
 141
 142         gic_irq = (status & 0x3ff);
 143         if (gic_irq == 1023)
 144                 goto out;
 145
 146         cascade_irq = gic_irq + chip_data->irq_offset;
 147         if (unlikely(gic_irq < 32 || gic_irq > 1020 || cascade_irq >= NR_IRQS))
 148                 do_bad_IRQ(cascade_irq, desc);
 149         else
 150                 generic_handle_irq(cascade_irq);
 151
 152  out:
 153         /* primary controller unmasking */
 154         chip->unmask(irq);
 155 }
 156
 157 static struct irq_chip gic_chip = {
 158         .name           = "GIC",
 159         .ack            = gic_ack_irq,
 160         .mask           = gic_mask_irq,
 161         .unmask         = gic_unmask_irq,
 162 #ifdef CONFIG_SMP
 163         .set_affinity   = gic_set_cpu,
 164 #endif
 165 };
 166
 167 void __init gic_cascade_irq(unsigned int gic_nr, unsigned int irq)
 168 {
 169         if (gic_nr >= MAX_GIC_NR)
 170                 BUG();
 171         if (set_irq_data(irq, &gic_data[gic_nr]) != 0)
 172                 BUG();
 173         set_irq_chained_handler(irq, gic_handle_cascade_irq);
 174 }
 175
 176 void __init gic_dist_init(unsigned int gic_nr, void __iomem *base,
 177                           unsigned int irq_start)
 178 {
 179         unsigned int max_irq, i;
 180         u32 cpumask = 1 << smp_processor_id();
 181
 182         if (gic_nr >= MAX_GIC_NR)
 183                 BUG();
 184
 185         cpumask |= cpumask << 8;
 186         cpumask |= cpumask << 16;
 187
 188         gic_data[gic_nr].dist_base = base;
 189         gic_data[gic_nr].irq_offset = (irq_start - 1) & ~31;
 190
 191         writel(0, base + GIC_DIST_CTRL);
 192
 193         /*
 194          * Find out how many interrupts are supported.
 195          */
 196         max_irq = readl(base + GIC_DIST_CTR) & 0x1f;
 197         max_irq = (max_irq + 1) * 32;
 198
 199         /*
 200          * The GIC only supports up to 1020 interrupt sources.
 201          * Limit this to either the architected maximum, or the
 202          * platform maximum.
 203          */
 204         if (max_irq > max(1020, NR_IRQS))
 205                 max_irq = max(1020, NR_IRQS);
 206
 207         /*
 208          * Set all global interrupts to be level triggered, active low.
 209          */
 210         for (i = 32; i < max_irq; i += 16)
 211                 writel(0, base + GIC_DIST_CONFIG + i * 4 / 16);
 212
 213         /*
 214          * Set all global interrupts to this CPU only.
 215          */
 216         for (i = 32; i < max_irq; i += 4)
 217                 writel(cpumask, base + GIC_DIST_TARGET + i * 4 / 4);
 218
 219         /*
 220          * Set priority on all interrupts.
 221          */
 222         for (i = 0; i < max_irq; i += 4)
 223                 writel(0xa0a0a0a0, base + GIC_DIST_PRI + i * 4 / 4);
 224
 225         /*
 226          * Disable all interrupts.
 227          */
 228         for (i = 0; i < max_irq; i += 32)
 229                 writel(0xffffffff, base + GIC_DIST_ENABLE_CLEAR + i * 4 / 32);
 230
 231         /*
 232          * Setup the Linux IRQ subsystem.
 233          */
 234         for (i = irq_start; i < gic_data[gic_nr].irq_offset + max_irq; i++) {
 235                 set_irq_chip(i, &gic_chip);
 236                 set_irq_chip_data(i, &gic_data[gic_nr]);
 237                 set_irq_handler(i, handle_level_irq);
 238                 set_irq_flags(i, IRQF_VALID | IRQF_PROBE);
 239         }
 240
 241         writel(1, base + GIC_DIST_CTRL);
 242 }
 243
 244 void __cpuinit gic_cpu_init(unsigned int gic_nr, void __iomem *base)
 245 {
 246         if (gic_nr >= MAX_GIC_NR)
 247                 BUG();
 248
 249         gic_data[gic_nr].cpu_base = base;
 250
 251         writel(0xf0, base + GIC_CPU_PRIMASK);
 252         writel(1, base + GIC_CPU_CTRL);
 253 }
 254
 255 #ifdef CONFIG_SMP
 256 void gic_raise_softirq(cpumask_t cpumask, unsigned int irq)
 257 {
 258         unsigned long map = *cpus_addr(cpumask);
 259
 260         /* this always happens on GIC0 */
 261         writel(map << 16 | irq, gic_data[0].dist_base + GIC_DIST_SOFTINT);
 262 }
 263 #endif