arch/arc/kernel/irq.c

   1 /*
   2  * Copyright (C) 2011-12 Synopsys, Inc. (www.synopsys.com)
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  */
   9
  10 #include <linux/interrupt.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/irqdomain.h>
  14 #include <asm/sections.h>
  15 #include <asm/irq.h>
  16 #include <asm/mach_desc.h>
  17
  18 /*
  19  * Early Hardware specific Interrupt setup
  20  * -Called very early (start_kernel -> setup_arch -> setup_processor)
  21  * -Platform Independent (must for any ARC700)
  22  * -Needed for each CPU (hence not foldable into init_IRQ)
  23  *
  24  * what it does ?
  25  * -setup Vector Table Base Reg - in case Linux not linked at 0x8000_0000
  26  * -Disable all IRQs (on CPU side)
  27  * -Optionally, setup the High priority Interrupts as Level 2 IRQs
  28  */
  29 void __init arc_init_IRQ(void)
  30 {
  31         int level_mask = 0;
  32
  33         write_aux_reg(AUX_INTR_VEC_BASE, _int_vec_base_lds);
  34
  35         /* Disable all IRQs: enable them as devices request */
  36         write_aux_reg(AUX_IENABLE, 0);
  37
  38        /* setup any high priority Interrupts (Level2 in ARCompact jargon) */
  39 #ifdef CONFIG_ARC_IRQ3_LV2
  40         level_mask |= (1 << 3);
  41 #endif
  42 #ifdef CONFIG_ARC_IRQ5_LV2
  43         level_mask |= (1 << 5);
  44 #endif
  45 #ifdef CONFIG_ARC_IRQ6_LV2
  46         level_mask |= (1 << 6);
  47 #endif
  48
  49         if (level_mask) {
  50                 pr_info("Level-2 interrupts bitset %x\n", level_mask);
  51                 write_aux_reg(AUX_IRQ_LEV, level_mask);
  52         }
  53 }
  54
  55 /*
  56  * ARC700 core includes a simple on-chip intc supporting
  57  * -per IRQ enable/disable
  58  * -2 levels of interrupts (high/low)
  59  * -all interrupts being level triggered
  60  *
  61  * To reduce platform code, we assume all IRQs directly hooked-up into intc.
  62  * Platforms with external intc, hence cascaded IRQs, are free to over-ride
  63  * below, per IRQ.
  64  */
  65
  66 static void arc_mask_irq(struct irq_data *data)
  67 {
  68         arch_mask_irq(data->irq);
  69 }
  70
  71 static void arc_unmask_irq(struct irq_data *data)
  72 {
  73         arch_unmask_irq(data->irq);
  74 }
  75
  76 static struct irq_chip onchip_intc = {
  77         .name           = "ARC In-core Intc",
  78         .irq_mask       = arc_mask_irq,
  79         .irq_unmask     = arc_unmask_irq,
  80 };
  81
  82 static int arc_intc_domain_map(struct irq_domain *d, unsigned int irq,
  83                                 irq_hw_number_t hw)
  84 {
  85         if (irq == TIMER0_IRQ)
  86                 irq_set_chip_and_handler(irq, &onchip_intc, handle_percpu_irq);
  87         else
  88                 irq_set_chip_and_handler(irq, &onchip_intc, handle_level_irq);
  89
  90         return 0;
  91 }
  92
  93 static const struct irq_domain_ops arc_intc_domain_ops = {
  94         .xlate = irq_domain_xlate_onecell,
  95         .map = arc_intc_domain_map,
  96 };
  97
  98 static struct irq_domain *root_domain;
  99
 100 void __init init_onchip_IRQ(void)
 101 {
 102         struct device_node *intc = NULL;
 103
 104         intc = of_find_compatible_node(NULL, NULL, "snps,arc700-intc");
 105         if (!intc)
 106                 panic("DeviceTree Missing incore intc\n");
 107
 108         root_domain = irq_domain_add_legacy(intc, NR_IRQS, 0, 0,
 109                                             &arc_intc_domain_ops, NULL);
 110
 111         if (!root_domain)
 112                 panic("root irq domain not avail\n");
 113
 114         /* with this we don't need to export root_domain */
 115         irq_set_default_host(root_domain);
 116 }
 117
 118 /*
 119  * Late Interrupt system init called from start_kernel for Boot CPU only
 120  *
 121  * Since slab must already be initialized, platforms can start doing any
 122  * needed request_irq( )s
 123  */
 124 void __init init_IRQ(void)
 125 {
 126         init_onchip_IRQ();
 127
 128         /* Any external intc can be setup here */
 129         if (machine_desc->init_irq)
 130                 machine_desc->init_irq();
 131
 132 #ifdef CONFIG_SMP
 133         /* Master CPU can initialize it's side of IPI */
 134         if (machine_desc->init_smp)
 135                 machine_desc->init_smp(smp_processor_id());
 136 #endif
 137 }
 138
 139 /*
 140  * "C" Entry point for any ARC ISR, called from low level vector handler
 141  * @irq is the vector number read from ICAUSE reg of on-chip intc
 142  */
 143 void arch_do_IRQ(unsigned int irq, struct pt_regs *regs)
 144 {
 145         struct pt_regs *old_regs = set_irq_regs(regs);
 146
 147         irq_enter();
 148         generic_handle_irq(irq);
 149         irq_exit();
 150         set_irq_regs(old_regs);
 151 }
 152
 153 int __init get_hw_config_num_irq(void)
 154 {
 155         uint32_t val = read_aux_reg(ARC_REG_VECBASE_BCR);
 156
 157         switch (val & 0x03) {
 158         case 0:
 159                 return 16;
 160         case 1:
 161                 return 32;
 162         case 2:
 163                 return 8;
 164         default:
 165                 return 0;
 166         }
 167
 168         return 0;
 169 }
 170
 171 /*
 172  * arch_local_irq_enable - Enable interrupts.
 173  *
 174  * 1. Explicitly called to re-enable interrupts
 175  * 2. Implicitly called from spin_unlock_irq, write_unlock_irq etc
 176  *    which maybe in hard ISR itself
 177  *
 178  * Semantics of this function change depending on where it is called from:
 179  *
 180  * -If called from hard-ISR, it must not invert interrupt priorities
 181  *  e.g. suppose TIMER is high priority (Level 2) IRQ
 182  *    Time hard-ISR, timer_interrupt( ) calls spin_unlock_irq several times.
 183  *    Here local_irq_enable( ) shd not re-enable lower priority interrupts
 184  * -If called from soft-ISR, it must re-enable all interrupts
 185  *    soft ISR are low prioity jobs which can be very slow, thus all IRQs
 186  *    must be enabled while they run.
 187  *    Now hardware context wise we may still be in L2 ISR (not done rtie)
 188  *    still we must re-enable both L1 and L2 IRQs
 189  *  Another twist is prev scenario with flow being
 190  *     L1 ISR ==> interrupted by L2 ISR  ==> L2 soft ISR
 191  *     here we must not re-enable Ll as prev Ll Interrupt's h/w context will get
 192  *     over-written (this is deficiency in ARC700 Interrupt mechanism)
 193  */
 194
 195 #ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS    /* Complex version for 2 IRQ levels */
 196
 197 void arch_local_irq_enable(void)
 198 {
 199
 200         unsigned long flags;
 201         flags = arch_local_save_flags();
 202
 203         /* Allow both L1 and L2 at the onset */
 204         flags |= (STATUS_E1_MASK | STATUS_E2_MASK);
 205
 206         /* Called from hard ISR (between irq_enter and irq_exit) */
 207         if (in_irq()) {
 208
 209                 /* If in L2 ISR, don't re-enable any further IRQs as this can
 210                  * cause IRQ priorities to get upside down. e.g. it could allow
 211                  * L1 be taken while in L2 hard ISR which is wrong not only in
 212                  * theory, it can also cause the dreaded L1-L2-L1 scenario
 213                  */
 214                 if (flags & STATUS_A2_MASK)
 215                         flags &= ~(STATUS_E1_MASK | STATUS_E2_MASK);
 216
 217                 /* Even if in L1 ISR, allowe Higher prio L2 IRQs */
 218                 else if (flags & STATUS_A1_MASK)
 219                         flags &= ~(STATUS_E1_MASK);
 220         }
 221
 222         /* called from soft IRQ, ideally we want to re-enable all levels */
 223
 224         else if (in_softirq()) {
 225
 226                 /* However if this is case of L1 interrupted by L2,
 227                  * re-enabling both may cause whaco L1-L2-L1 scenario
 228                  * because ARC700 allows level 1 to interrupt an active L2 ISR
 229                  * Thus we disable both
 230                  * However some code, executing in soft ISR wants some IRQs
 231                  * to be enabled so we re-enable L2 only
 232                  *
 233                  * How do we determine L1 intr by L2
 234                  *  -A2 is set (means in L2 ISR)
 235                  *  -E1 is set in this ISR's pt_regs->status32 which is
 236                  *      saved copy of status32_l2 when l2 ISR happened
 237                  */
 238                 struct pt_regs *pt = get_irq_regs();
 239                 if ((flags & STATUS_A2_MASK) && pt &&
 240                     (pt->status32 & STATUS_A1_MASK)) {
 241                         /*flags &= ~(STATUS_E1_MASK | STATUS_E2_MASK); */
 242                         flags &= ~(STATUS_E1_MASK);
 243                 }
 244         }
 245
 246         arch_local_irq_restore(flags);
 247 }
 248
 249 #else /* ! CONFIG_ARC_COMPACT_IRQ_LEVELS */
 250
 251 /*
 252  * Simpler version for only 1 level of interrupt
 253  * Here we only Worry about Level 1 Bits
 254  */
 255 void arch_local_irq_enable(void)
 256 {
 257         unsigned long flags;
 258
 259         /*
 260          * ARC IDE Drivers tries to re-enable interrupts from hard-isr
 261          * context which is simply wrong
 262          */
 263         if (in_irq()) {
 264                 WARN_ONCE(1, "IRQ enabled from hard-isr");
 265                 return;
 266         }
 267
 268         flags = arch_local_save_flags();
 269         flags |= (STATUS_E1_MASK | STATUS_E2_MASK);
 270         arch_local_irq_restore(flags);
 271 }
 272 #endif
 273 EXPORT_SYMBOL(arch_local_irq_enable);