arch/arc/kernel/mcip.c

   1 /*
   2  * ARC ARConnect (MultiCore IP) support (formerly known as MCIP)
   3  *
   4  * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
   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
  11 #include <linux/smp.h>
  12 #include <linux/irq.h>
  13 #include <linux/irqchip/chained_irq.h>
  14 #include <linux/spinlock.h>
  15 #include <soc/arc/mcip.h>
  16 #include <asm/irqflags-arcv2.h>
  17 #include <asm/setup.h>
  18
  19 static DEFINE_RAW_SPINLOCK(mcip_lock);
  20
  21 #ifdef CONFIG_SMP
  22
  23 static char smp_cpuinfo_buf[128];
  24
  25 static void mcip_setup_per_cpu(int cpu)
  26 {
  27         smp_ipi_irq_setup(cpu, IPI_IRQ);
  28         smp_ipi_irq_setup(cpu, SOFTIRQ_IRQ);
  29 }
  30
  31 static void mcip_ipi_send(int cpu)
  32 {
  33         unsigned long flags;
  34         int ipi_was_pending;
  35
  36         /* ARConnect can only send IPI to others */
  37         if (unlikely(cpu == raw_smp_processor_id())) {
  38                 arc_softirq_trigger(SOFTIRQ_IRQ);
  39                 return;
  40         }
  41
  42         raw_spin_lock_irqsave(&mcip_lock, flags);
  43
  44         /*
  45          * If receiver already has a pending interrupt, elide sending this one.
  46          * Linux cross core calling works well with concurrent IPIs
  47          * coalesced into one
  48          * see arch/arc/kernel/smp.c: ipi_send_msg_one()
  49          */
  50         __mcip_cmd(CMD_INTRPT_READ_STATUS, cpu);
  51         ipi_was_pending = read_aux_reg(ARC_REG_MCIP_READBACK);
  52         if (!ipi_was_pending)
  53                 __mcip_cmd(CMD_INTRPT_GENERATE_IRQ, cpu);
  54
  55         raw_spin_unlock_irqrestore(&mcip_lock, flags);
  56 }
  57
  58 static void mcip_ipi_clear(int irq)
  59 {
  60         unsigned int cpu, c;
  61         unsigned long flags;
  62
  63         if (unlikely(irq == SOFTIRQ_IRQ)) {
  64                 arc_softirq_clear(irq);
  65                 return;
  66         }
  67
  68         raw_spin_lock_irqsave(&mcip_lock, flags);
  69
  70         /* Who sent the IPI */
  71         __mcip_cmd(CMD_INTRPT_CHECK_SOURCE, 0);
  72
  73         cpu = read_aux_reg(ARC_REG_MCIP_READBACK);      /* 1,2,4,8... */
  74
  75         /*
  76          * In rare case, multiple concurrent IPIs sent to same target can
  77          * possibly be coalesced by MCIP into 1 asserted IRQ, so @cpus can be
  78          * "vectored" (multiple bits sets) as opposed to typical single bit
  79          */
  80         do {
  81                 c = __ffs(cpu);                 /* 0,1,2,3 */
  82                 __mcip_cmd(CMD_INTRPT_GENERATE_ACK, c);
  83                 cpu &= ~(1U << c);
  84         } while (cpu);
  85
  86         raw_spin_unlock_irqrestore(&mcip_lock, flags);
  87 }
  88
  89 static void mcip_probe_n_setup(void)
  90 {
  91         struct mcip_bcr mp;
  92
  93         READ_BCR(ARC_REG_MCIP_BCR, mp);
  94
  95         sprintf(smp_cpuinfo_buf,
  96                 "Extn [SMP]\t: ARConnect (v%d): %d cores with %s%s%s%s%s\n",
  97                 mp.ver, mp.num_cores,
  98                 IS_AVAIL1(mp.ipi, "IPI "),
  99                 IS_AVAIL1(mp.idu, "IDU "),
 100                 IS_AVAIL1(mp.llm, "LLM "),
 101                 IS_AVAIL1(mp.dbg, "DEBUG "),
 102                 IS_AVAIL1(mp.gfrc, "GFRC"));
 103
 104         cpuinfo_arc700[0].extn.gfrc = mp.gfrc;
 105
 106         if (mp.dbg) {
 107                 __mcip_cmd_data(CMD_DEBUG_SET_SELECT, 0, 0xf);
 108                 __mcip_cmd_data(CMD_DEBUG_SET_MASK, 0xf, 0xf);
 109         }
 110 }
 111
 112 struct plat_smp_ops plat_smp_ops = {
 113         .info           = smp_cpuinfo_buf,
 114         .init_early_smp = mcip_probe_n_setup,
 115         .init_per_cpu   = mcip_setup_per_cpu,
 116         .ipi_send       = mcip_ipi_send,
 117         .ipi_clear      = mcip_ipi_clear,
 118 };
 119
 120 #endif
 121
 122 /***************************************************************************
 123  * ARCv2 Interrupt Distribution Unit (IDU)
 124  *
 125  * Connects external "COMMON" IRQs to core intc, providing:
 126  *  -dynamic routing (IRQ affinity)
 127  *  -load balancing (Round Robin interrupt distribution)
 128  *  -1:N distribution
 129  *
 130  * It physically resides in the MCIP hw block
 131  */
 132
 133 #include <linux/irqchip.h>
 134 #include <linux/of.h>
 135 #include <linux/of_irq.h>
 136
 137 /*
 138  * Set the DEST for @cmn_irq to @cpu_mask (1 bit per core)
 139  */
 140 static void idu_set_dest(unsigned int cmn_irq, unsigned int cpu_mask)
 141 {
 142         __mcip_cmd_data(CMD_IDU_SET_DEST, cmn_irq, cpu_mask);
 143 }
 144
 145 static void idu_set_mode(unsigned int cmn_irq, unsigned int lvl,
 146                            unsigned int distr)
 147 {
 148         union {
 149                 unsigned int word;
 150                 struct {
 151                         unsigned int distr:2, pad:2, lvl:1, pad2:27;
 152                 };
 153         } data;
 154
 155         data.distr = distr;
 156         data.lvl = lvl;
 157         __mcip_cmd_data(CMD_IDU_SET_MODE, cmn_irq, data.word);
 158 }
 159
 160 static void idu_irq_mask(struct irq_data *data)
 161 {
 162         unsigned long flags;
 163
 164         raw_spin_lock_irqsave(&mcip_lock, flags);
 165         __mcip_cmd_data(CMD_IDU_SET_MASK, data->hwirq, 1);
 166         raw_spin_unlock_irqrestore(&mcip_lock, flags);
 167 }
 168
 169 static void idu_irq_unmask(struct irq_data *data)
 170 {
 171         unsigned long flags;
 172
 173         raw_spin_lock_irqsave(&mcip_lock, flags);
 174         __mcip_cmd_data(CMD_IDU_SET_MASK, data->hwirq, 0);
 175         raw_spin_unlock_irqrestore(&mcip_lock, flags);
 176 }
 177
 178 static int
 179 idu_irq_set_affinity(struct irq_data *data, const struct cpumask *cpumask,
 180                      bool force)
 181 {
 182         unsigned long flags;
 183         cpumask_t online;
 184         unsigned int destination_bits;
 185         unsigned int distribution_mode;
 186
 187         /* errout if no online cpu per @cpumask */
 188         if (!cpumask_and(&online, cpumask, cpu_online_mask))
 189                 return -EINVAL;
 190
 191         raw_spin_lock_irqsave(&mcip_lock, flags);
 192
 193         destination_bits = cpumask_bits(&online)[0];
 194         idu_set_dest(data->hwirq, destination_bits);
 195
 196         if (ffs(destination_bits) == fls(destination_bits))
 197                 distribution_mode = IDU_M_DISTRI_DEST;
 198         else
 199                 distribution_mode = IDU_M_DISTRI_RR;
 200
 201         idu_set_mode(data->hwirq, IDU_M_TRIG_LEVEL, distribution_mode);
 202
 203         raw_spin_unlock_irqrestore(&mcip_lock, flags);
 204
 205         return IRQ_SET_MASK_OK;
 206 }
 207
 208 static void idu_irq_enable(struct irq_data *data)
 209 {
 210         /*
 211          * By default send all common interrupts to all available online CPUs.
 212          * The affinity of common interrupts in IDU must be set manually since
 213          * in some cases the kernel will not call irq_set_affinity() by itself:
 214          *   1. When the kernel is not configured with support of SMP.
 215          *   2. When the kernel is configured with support of SMP but upper
 216          *      interrupt controllers does not support setting of the affinity
 217          *      and cannot propagate it to IDU.
 218          */
 219         idu_irq_set_affinity(data, cpu_online_mask, false);
 220         idu_irq_unmask(data);
 221 }
 222
 223 static struct irq_chip idu_irq_chip = {
 224         .name                   = "MCIP IDU Intc",
 225         .irq_mask               = idu_irq_mask,
 226         .irq_unmask             = idu_irq_unmask,
 227         .irq_enable             = idu_irq_enable,
 228 #ifdef CONFIG_SMP
 229         .irq_set_affinity       = idu_irq_set_affinity,
 230 #endif
 231
 232 };
 233
 234 static irq_hw_number_t idu_first_hwirq;
 235
 236 static void idu_cascade_isr(struct irq_desc *desc)
 237 {
 238         struct irq_domain *idu_domain = irq_desc_get_handler_data(desc);
 239         struct irq_chip *core_chip = irq_desc_get_chip(desc);
 240         irq_hw_number_t core_hwirq = irqd_to_hwirq(irq_desc_get_irq_data(desc));
 241         irq_hw_number_t idu_hwirq = core_hwirq - idu_first_hwirq;
 242
 243         chained_irq_enter(core_chip, desc);
 244         generic_handle_irq(irq_find_mapping(idu_domain, idu_hwirq));
 245         chained_irq_exit(core_chip, desc);
 246 }
 247
 248 static int idu_irq_map(struct irq_domain *d, unsigned int virq, irq_hw_number_t hwirq)
 249 {
 250         irq_set_chip_and_handler(virq, &idu_irq_chip, handle_level_irq);
 251         irq_set_status_flags(virq, IRQ_MOVE_PCNTXT);
 252
 253         return 0;
 254 }
 255
 256 static int idu_irq_xlate(struct irq_domain *d, struct device_node *n,
 257                          const u32 *intspec, unsigned int intsize,
 258                          irq_hw_number_t *out_hwirq, unsigned int *out_type)
 259 {
 260         /*
 261          * Ignore value of interrupt distribution mode for common interrupts in
 262          * IDU which resides in intspec[1] since setting an affinity using value
 263          * from Device Tree is deprecated in ARC.
 264          */
 265         *out_hwirq = intspec[0];
 266         *out_type = IRQ_TYPE_NONE;
 267
 268         return 0;
 269 }
 270
 271 static const struct irq_domain_ops idu_irq_ops = {
 272         .xlate  = idu_irq_xlate,
 273         .map    = idu_irq_map,
 274 };
 275
 276 /*
 277  * [16, 23]: Statically assigned always private-per-core (Timers, WDT, IPI)
 278  * [24, 23+C]: If C > 0 then "C" common IRQs
 279  * [24+C, N]: Not statically assigned, private-per-core
 280  */
 281
 282
 283 static int __init
 284 idu_of_init(struct device_node *intc, struct device_node *parent)
 285 {
 286         struct irq_domain *domain;
 287         /* Read IDU BCR to confirm nr_irqs */
 288         int nr_irqs = of_irq_count(intc);
 289         int i, virq;
 290         struct mcip_bcr mp;
 291
 292         READ_BCR(ARC_REG_MCIP_BCR, mp);
 293
 294         if (!mp.idu)
 295                 panic("IDU not detected, but DeviceTree using it");
 296
 297         pr_info("MCIP: IDU referenced from Devicetree %d irqs\n", nr_irqs);
 298
 299         domain = irq_domain_add_linear(intc, nr_irqs, &idu_irq_ops, NULL);
 300
 301         /* Parent interrupts (core-intc) are already mapped */
 302
 303         for (i = 0; i < nr_irqs; i++) {
 304                 /*
 305                  * Return parent uplink IRQs (towards core intc) 24,25,.....
 306                  * this step has been done before already
 307                  * however we need it to get the parent virq and set IDU handler
 308                  * as first level isr
 309                  */
 310                 virq = irq_of_parse_and_map(intc, i);
 311                 if (!i)
 312                         idu_first_hwirq = irqd_to_hwirq(irq_get_irq_data(virq));
 313
 314                 irq_set_chained_handler_and_data(virq, idu_cascade_isr, domain);
 315         }
 316
 317         __mcip_cmd(CMD_IDU_ENABLE, 0);
 318
 319         return 0;
 320 }
 321 IRQCHIP_DECLARE(arcv2_idu_intc, "snps,archs-idu-intc", idu_of_init);