drivers/irqchip/irq-bcm2835.c

   1 /*
   2  * Copyright 2010 Broadcom
   3  * Copyright 2012 Simon Arlott, Chris Boot, Stephen Warren
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * Quirk 1: Shortcut interrupts don't set the bank 1/2 register pending bits
  16  *
  17  * If an interrupt fires on bank 1 that isn't in the shortcuts list, bit 8
  18  * on bank 0 is set to signify that an interrupt in bank 1 has fired, and
  19  * to look in the bank 1 status register for more information.
  20  *
  21  * If an interrupt fires on bank 1 that _is_ in the shortcuts list, its
  22  * shortcut bit in bank 0 is set as well as its interrupt bit in the bank 1
  23  * status register, but bank 0 bit 8 is _not_ set.
  24  *
  25  * Quirk 2: You can't mask the register 1/2 pending interrupts
  26  *
  27  * In a proper cascaded interrupt controller, the interrupt lines with
  28  * cascaded interrupt controllers on them are just normal interrupt lines.
  29  * You can mask the interrupts and get on with things. With this controller
  30  * you can't do that.
  31  *
  32  * Quirk 3: The shortcut interrupts can't be (un)masked in bank 0
  33  *
  34  * Those interrupts that have shortcuts can only be masked/unmasked in
  35  * their respective banks' enable/disable registers. Doing so in the bank 0
  36  * enable/disable registers has no effect.
  37  *
  38  * The FIQ control register:
  39  *  Bits 0-6: IRQ (index in order of interrupts from banks 1, 2, then 0)
  40  *  Bit    7: Enable FIQ generation
  41  *  Bits  8+: Unused
  42  *
  43  * An interrupt must be disabled before configuring it for FIQ generation
  44  * otherwise both handlers will fire at the same time!
  45  */
  46
  47 #include <linux/io.h>
  48 #include <linux/slab.h>
  49 #include <linux/of_address.h>
  50 #include <linux/of_irq.h>
  51 #include <linux/irqchip.h>
  52 #include <linux/irqdomain.h>
  53
  54 #include <asm/exception.h>
  55 #include <asm/mach/irq.h>
  56
  57 /* Put the bank and irq (32 bits) into the hwirq */
  58 #define MAKE_HWIRQ(b, n)        ((b << 5) | (n))
  59 #define HWIRQ_BANK(i)           (i >> 5)
  60 #define HWIRQ_BIT(i)            BIT(i & 0x1f)
  61
  62 #define NR_IRQS_BANK0           8
  63 #define BANK0_HWIRQ_MASK        0xff
  64 /* Shortcuts can't be disabled so any unknown new ones need to be masked */
  65 #define SHORTCUT1_MASK          0x00007c00
  66 #define SHORTCUT2_MASK          0x001f8000
  67 #define SHORTCUT_SHIFT          10
  68 #define BANK1_HWIRQ             BIT(8)
  69 #define BANK2_HWIRQ             BIT(9)
  70 #define BANK0_VALID_MASK        (BANK0_HWIRQ_MASK | BANK1_HWIRQ | BANK2_HWIRQ \
  71                                         | SHORTCUT1_MASK | SHORTCUT2_MASK)
  72
  73 #define REG_FIQ_CONTROL         0x0c
  74
  75 #define NR_BANKS                3
  76 #define IRQS_PER_BANK           32
  77
  78 static const int reg_pending[] __initconst = { 0x00, 0x04, 0x08 };
  79 static const int reg_enable[] __initconst = { 0x18, 0x10, 0x14 };
  80 static const int reg_disable[] __initconst = { 0x24, 0x1c, 0x20 };
  81 static const int bank_irqs[] __initconst = { 8, 32, 32 };
  82
  83 static const int shortcuts[] = {
  84         7, 9, 10, 18, 19,               /* Bank 1 */
  85         21, 22, 23, 24, 25, 30          /* Bank 2 */
  86 };
  87
  88 struct armctrl_ic {
  89         void __iomem *base;
  90         void __iomem *pending[NR_BANKS];
  91         void __iomem *enable[NR_BANKS];
  92         void __iomem *disable[NR_BANKS];
  93         struct irq_domain *domain;
  94 };
  95
  96 static struct armctrl_ic intc __read_mostly;
  97 static void __exception_irq_entry bcm2835_handle_irq(
  98         struct pt_regs *regs);
  99
 100 static void armctrl_mask_irq(struct irq_data *d)
 101 {
 102         writel_relaxed(HWIRQ_BIT(d->hwirq), intc.disable[HWIRQ_BANK(d->hwirq)]);
 103 }
 104
 105 static void armctrl_unmask_irq(struct irq_data *d)
 106 {
 107         writel_relaxed(HWIRQ_BIT(d->hwirq), intc.enable[HWIRQ_BANK(d->hwirq)]);
 108 }
 109
 110 static struct irq_chip armctrl_chip = {
 111         .name = "ARMCTRL-level",
 112         .irq_mask = armctrl_mask_irq,
 113         .irq_unmask = armctrl_unmask_irq
 114 };
 115
 116 static int armctrl_xlate(struct irq_domain *d, struct device_node *ctrlr,
 117         const u32 *intspec, unsigned int intsize,
 118         unsigned long *out_hwirq, unsigned int *out_type)
 119 {
 120         if (WARN_ON(intsize != 2))
 121                 return -EINVAL;
 122
 123         if (WARN_ON(intspec[0] >= NR_BANKS))
 124                 return -EINVAL;
 125
 126         if (WARN_ON(intspec[1] >= IRQS_PER_BANK))
 127                 return -EINVAL;
 128
 129         if (WARN_ON(intspec[0] == 0 && intspec[1] >= NR_IRQS_BANK0))
 130                 return -EINVAL;
 131
 132         *out_hwirq = MAKE_HWIRQ(intspec[0], intspec[1]);
 133         *out_type = IRQ_TYPE_NONE;
 134         return 0;
 135 }
 136
 137 static const struct irq_domain_ops armctrl_ops = {
 138         .xlate = armctrl_xlate
 139 };
 140
 141 static int __init armctrl_of_init(struct device_node *node,
 142         struct device_node *parent)
 143 {
 144         void __iomem *base;
 145         int irq, b, i;
 146
 147         base = of_iomap(node, 0);
 148         if (!base)
 149                 panic("%s: unable to map IC registers\n",
 150                         node->full_name);
 151
 152         intc.domain = irq_domain_add_linear(node, MAKE_HWIRQ(NR_BANKS, 0),
 153                         &armctrl_ops, NULL);
 154         if (!intc.domain)
 155                 panic("%s: unable to create IRQ domain\n", node->full_name);
 156
 157         for (b = 0; b < NR_BANKS; b++) {
 158                 intc.pending[b] = base + reg_pending[b];
 159                 intc.enable[b] = base + reg_enable[b];
 160                 intc.disable[b] = base + reg_disable[b];
 161
 162                 for (i = 0; i < bank_irqs[b]; i++) {
 163                         irq = irq_create_mapping(intc.domain, MAKE_HWIRQ(b, i));
 164                         BUG_ON(irq <= 0);
 165                         irq_set_chip_and_handler(irq, &armctrl_chip,
 166                                 handle_level_irq);
 167                         set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
 168                 }
 169         }
 170
 171         set_handle_irq(bcm2835_handle_irq);
 172         return 0;
 173 }
 174
 175 /*
 176  * Handle each interrupt across the entire interrupt controller.  This reads the
 177  * status register before handling each interrupt, which is necessary given that
 178  * handle_IRQ may briefly re-enable interrupts for soft IRQ handling.
 179  */
 180
 181 static u32 armctrl_translate_bank(int bank)
 182 {
 183         u32 stat = readl_relaxed(intc.pending[bank]);
 184
 185         return MAKE_HWIRQ(bank, ffs(stat) - 1);
 186 }
 187
 188 static u32 armctrl_translate_shortcut(int bank, u32 stat)
 189 {
 190         return MAKE_HWIRQ(bank, shortcuts[ffs(stat >> SHORTCUT_SHIFT) - 1]);
 191 }
 192
 193 static u32 get_next_armctrl_hwirq(void)
 194 {
 195         u32 stat = readl_relaxed(intc.pending[0]) & BANK0_VALID_MASK;
 196
 197         if (stat == 0)
 198                 return ~0;
 199         else if (stat & BANK0_HWIRQ_MASK)
 200                 return MAKE_HWIRQ(0, ffs(stat & BANK0_HWIRQ_MASK) - 1);
 201         else if (stat & SHORTCUT1_MASK)
 202                 return armctrl_translate_shortcut(1, stat & SHORTCUT1_MASK);
 203         else if (stat & SHORTCUT2_MASK)
 204                 return armctrl_translate_shortcut(2, stat & SHORTCUT2_MASK);
 205         else if (stat & BANK1_HWIRQ)
 206                 return armctrl_translate_bank(1);
 207         else if (stat & BANK2_HWIRQ)
 208                 return armctrl_translate_bank(2);
 209         else
 210                 BUG();
 211 }
 212
 213 static void __exception_irq_entry bcm2835_handle_irq(
 214         struct pt_regs *regs)
 215 {
 216         u32 hwirq;
 217
 218         while ((hwirq = get_next_armctrl_hwirq()) != ~0)
 219                 handle_IRQ(irq_linear_revmap(intc.domain, hwirq), regs);
 220 }
 221
 222 IRQCHIP_DECLARE(bcm2835_armctrl_ic, "brcm,bcm2835-armctrl-ic", armctrl_of_init);