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/spinlock.h>
  14 #include <asm/mcip.h>
  15
  16 static char smp_cpuinfo_buf[128];
  17 static int idu_detected;
  18
  19 static DEFINE_RAW_SPINLOCK(mcip_lock);
  20
  21 /*
  22  * Any SMP specific init any CPU does when it comes up.
  23  * Here we setup the CPU to enable Inter-Processor-Interrupts
  24  * Called for each CPU
  25  * -Master      : init_IRQ()
  26  * -Other(s)    : start_kernel_secondary()
  27  */
  28 void mcip_init_smp(unsigned int cpu)
  29 {
  30         smp_ipi_irq_setup(cpu, IPI_IRQ);
  31 }
  32
  33 static void mcip_ipi_send(int cpu)
  34 {
  35         unsigned long flags;
  36         int ipi_was_pending;
  37
  38         /*
  39          * NOTE: We must spin here if the other cpu hasn't yet
  40          * serviced a previous message. This can burn lots
  41          * of time, but we MUST follows this protocol or
  42          * ipi messages can be lost!!!
  43          * Also, we must release the lock in this loop because
  44          * the other side may get to this same loop and not
  45          * be able to ack -- thus causing deadlock.
  46          */
  47
  48         do {
  49                 raw_spin_lock_irqsave(&mcip_lock, flags);
  50                 __mcip_cmd(CMD_INTRPT_READ_STATUS, cpu);
  51                 ipi_was_pending = read_aux_reg(ARC_REG_MCIP_READBACK);
  52                 if (ipi_was_pending == 0)
  53                         break; /* break out but keep lock */
  54                 raw_spin_unlock_irqrestore(&mcip_lock, flags);
  55         } while (1);
  56
  57         __mcip_cmd(CMD_INTRPT_GENERATE_IRQ, cpu);
  58         raw_spin_unlock_irqrestore(&mcip_lock, flags);
  59
  60 #ifdef CONFIG_ARC_IPI_DBG
  61         if (ipi_was_pending)
  62                 pr_info("IPI ACK delayed from cpu %d\n", cpu);
  63 #endif
  64 }
  65
  66 static void mcip_ipi_clear(int irq)
  67 {
  68         unsigned int cpu, c;
  69         unsigned long flags;
  70         unsigned int __maybe_unused copy;
  71
  72         raw_spin_lock_irqsave(&mcip_lock, flags);
  73
  74         /* Who sent the IPI */
  75         __mcip_cmd(CMD_INTRPT_CHECK_SOURCE, 0);
  76
  77         copy = cpu = read_aux_reg(ARC_REG_MCIP_READBACK);       /* 1,2,4,8... */
  78
  79         /*
  80          * In rare case, multiple concurrent IPIs sent to same target can
  81          * possibly be coalesced by MCIP into 1 asserted IRQ, so @cpus can be
  82          * "vectored" (multiple bits sets) as opposed to typical single bit
  83          */
  84         do {
  85                 c = __ffs(cpu);                 /* 0,1,2,3 */
  86                 __mcip_cmd(CMD_INTRPT_GENERATE_ACK, c);
  87                 cpu &= ~(1U << c);
  88         } while (cpu);
  89
  90         raw_spin_unlock_irqrestore(&mcip_lock, flags);
  91
  92 #ifdef CONFIG_ARC_IPI_DBG
  93         if (c != __ffs(copy))
  94                 pr_info("IPIs from %x coalesced to %x\n",
  95                         copy, raw_smp_processor_id());
  96 #endif
  97 }
  98
  99 volatile int wake_flag;
 100
 101 static void mcip_wakeup_cpu(int cpu, unsigned long pc)
 102 {
 103         BUG_ON(cpu == 0);
 104         wake_flag = cpu;
 105 }
 106
 107 void arc_platform_smp_wait_to_boot(int cpu)
 108 {
 109         while (wake_flag != cpu)
 110                 ;
 111
 112         wake_flag = 0;
 113         __asm__ __volatile__("j @first_lines_of_secondary       \n");
 114 }
 115
 116 struct plat_smp_ops plat_smp_ops = {
 117         .info           = smp_cpuinfo_buf,
 118         .cpu_kick       = mcip_wakeup_cpu,
 119         .ipi_send       = mcip_ipi_send,
 120         .ipi_clear      = mcip_ipi_clear,
 121 };
 122
 123 void mcip_init_early_smp(void)
 124 {
 125 #define IS_AVAIL1(var, str)    ((var) ? str : "")
 126
 127         struct mcip_bcr {
 128 #ifdef CONFIG_CPU_BIG_ENDIAN
 129                 unsigned int pad3:8,
 130                              idu:1, llm:1, num_cores:6,
 131                              iocoh:1,  grtc:1, dbg:1, pad2:1,
 132                              msg:1, sem:1, ipi:1, pad:1,
 133                              ver:8;
 134 #else
 135                 unsigned int ver:8,
 136                              pad:1, ipi:1, sem:1, msg:1,
 137                              pad2:1, dbg:1, grtc:1, iocoh:1,
 138                              num_cores:6, llm:1, idu:1,
 139                              pad3:8;
 140 #endif
 141         } mp;
 142
 143         READ_BCR(ARC_REG_MCIP_BCR, mp);
 144
 145         sprintf(smp_cpuinfo_buf,
 146                 "Extn [SMP]\t: ARConnect (v%d): %d cores with %s%s%s%s\n",
 147                 mp.ver, mp.num_cores,
 148                 IS_AVAIL1(mp.ipi, "IPI "),
 149                 IS_AVAIL1(mp.idu, "IDU "),
 150                 IS_AVAIL1(mp.dbg, "DEBUG "),
 151                 IS_AVAIL1(mp.grtc, "GRTC"));
 152
 153         idu_detected = mp.idu;
 154
 155         if (mp.dbg) {
 156                 __mcip_cmd_data(CMD_DEBUG_SET_SELECT, 0, 0xf);
 157                 __mcip_cmd_data(CMD_DEBUG_SET_MASK, 0xf, 0xf);
 158         }
 159
 160         if (IS_ENABLED(CONFIG_ARC_HAS_GRTC) && !mp.grtc)
 161                 panic("kernel trying to use non-existent GRTC\n");
 162 }
 163
 164 /***************************************************************************
 165  * ARCv2 Interrupt Distribution Unit (IDU)
 166  *
 167  * Connects external "COMMON" IRQs to core intc, providing:
 168  *  -dynamic routing (IRQ affinity)
 169  *  -load balancing (Round Robin interrupt distribution)
 170  *  -1:N distribution
 171  *
 172  * It physically resides in the MCIP hw block
 173  */
 174
 175 #include <linux/irqchip.h>
 176 #include <linux/of.h>
 177 #include <linux/of_irq.h>
 178
 179 /*
 180  * Set the DEST for @cmn_irq to @cpu_mask (1 bit per core)
 181  */
 182 static void idu_set_dest(unsigned int cmn_irq, unsigned int cpu_mask)
 183 {
 184         __mcip_cmd_data(CMD_IDU_SET_DEST, cmn_irq, cpu_mask);
 185 }
 186
 187 static void idu_set_mode(unsigned int cmn_irq, unsigned int lvl,
 188                            unsigned int distr)
 189 {
 190         union {
 191                 unsigned int word;
 192                 struct {
 193                         unsigned int distr:2, pad:2, lvl:1, pad2:27;
 194                 };
 195         } data;
 196
 197         data.distr = distr;
 198         data.lvl = lvl;
 199         __mcip_cmd_data(CMD_IDU_SET_MODE, cmn_irq, data.word);
 200 }
 201
 202 static void idu_irq_mask(struct irq_data *data)
 203 {
 204         unsigned long flags;
 205
 206         raw_spin_lock_irqsave(&mcip_lock, flags);
 207         __mcip_cmd_data(CMD_IDU_SET_MASK, data->hwirq, 1);
 208         raw_spin_unlock_irqrestore(&mcip_lock, flags);
 209 }
 210
 211 static void idu_irq_unmask(struct irq_data *data)
 212 {
 213         unsigned long flags;
 214
 215         raw_spin_lock_irqsave(&mcip_lock, flags);
 216         __mcip_cmd_data(CMD_IDU_SET_MASK, data->hwirq, 0);
 217         raw_spin_unlock_irqrestore(&mcip_lock, flags);
 218 }
 219
 220 #ifdef CONFIG_SMP
 221 static int
 222 idu_irq_set_affinity(struct irq_data *data, const struct cpumask *cpumask,
 223                      bool force)
 224 {
 225         unsigned long flags;
 226         cpumask_t online;
 227
 228         /* errout if no online cpu per @cpumask */
 229         if (!cpumask_and(&online, cpumask, cpu_online_mask))
 230                 return -EINVAL;
 231
 232         raw_spin_lock_irqsave(&mcip_lock, flags);
 233
 234         idu_set_dest(data->hwirq, cpumask_bits(&online)[0]);
 235         idu_set_mode(data->hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_RR);
 236
 237         raw_spin_unlock_irqrestore(&mcip_lock, flags);
 238
 239         return IRQ_SET_MASK_OK;
 240 }
 241 #endif
 242
 243 static struct irq_chip idu_irq_chip = {
 244         .name                   = "MCIP IDU Intc",
 245         .irq_mask               = idu_irq_mask,
 246         .irq_unmask             = idu_irq_unmask,
 247 #ifdef CONFIG_SMP
 248         .irq_set_affinity       = idu_irq_set_affinity,
 249 #endif
 250
 251 };
 252
 253 static int idu_first_irq;
 254
 255 static void idu_cascade_isr(unsigned int __core_irq, struct irq_desc *desc)
 256 {
 257         struct irq_domain *domain = irq_desc_get_handler_data(desc);
 258         unsigned int core_irq = irq_desc_get_irq(desc);
 259         unsigned int idu_irq;
 260
 261         idu_irq = core_irq - idu_first_irq;
 262         generic_handle_irq(irq_find_mapping(domain, idu_irq));
 263 }
 264
 265 static int idu_irq_map(struct irq_domain *d, unsigned int virq, irq_hw_number_t hwirq)
 266 {
 267         irq_set_chip_and_handler(virq, &idu_irq_chip, handle_level_irq);
 268         irq_set_status_flags(virq, IRQ_MOVE_PCNTXT);
 269
 270         return 0;
 271 }
 272
 273 static int idu_irq_xlate(struct irq_domain *d, struct device_node *n,
 274                          const u32 *intspec, unsigned int intsize,
 275                          irq_hw_number_t *out_hwirq, unsigned int *out_type)
 276 {
 277         irq_hw_number_t hwirq = *out_hwirq = intspec[0];
 278         int distri = intspec[1];
 279         unsigned long flags;
 280
 281         *out_type = IRQ_TYPE_NONE;
 282
 283         /* XXX: validate distribution scheme again online cpu mask */
 284         if (distri == 0) {
 285                 /* 0 - Round Robin to all cpus, otherwise 1 bit per core */
 286                 raw_spin_lock_irqsave(&mcip_lock, flags);
 287                 idu_set_dest(hwirq, BIT(num_online_cpus()) - 1);
 288                 idu_set_mode(hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_RR);
 289                 raw_spin_unlock_irqrestore(&mcip_lock, flags);
 290         } else {
 291                 /*
 292                  * DEST based distribution for Level Triggered intr can only
 293                  * have 1 CPU, so generalize it to always contain 1 cpu
 294                  */
 295                 int cpu = ffs(distri);
 296
 297                 if (cpu != fls(distri))
 298                         pr_warn("IDU irq %lx distri mode set to cpu %x\n",
 299                                 hwirq, cpu);
 300
 301                 raw_spin_lock_irqsave(&mcip_lock, flags);
 302                 idu_set_dest(hwirq, cpu);
 303                 idu_set_mode(hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_DEST);
 304                 raw_spin_unlock_irqrestore(&mcip_lock, flags);
 305         }
 306
 307         return 0;
 308 }
 309
 310 static const struct irq_domain_ops idu_irq_ops = {
 311         .xlate  = idu_irq_xlate,
 312         .map    = idu_irq_map,
 313 };
 314
 315 /*
 316  * [16, 23]: Statically assigned always private-per-core (Timers, WDT, IPI)
 317  * [24, 23+C]: If C > 0 then "C" common IRQs
 318  * [24+C, N]: Not statically assigned, private-per-core
 319  */
 320
 321
 322 static int __init
 323 idu_of_init(struct device_node *intc, struct device_node *parent)
 324 {
 325         struct irq_domain *domain;
 326         /* Read IDU BCR to confirm nr_irqs */
 327         int nr_irqs = of_irq_count(intc);
 328         int i, irq;
 329
 330         if (!idu_detected)
 331                 panic("IDU not detected, but DeviceTree using it");
 332
 333         pr_info("MCIP: IDU referenced from Devicetree %d irqs\n", nr_irqs);
 334
 335         domain = irq_domain_add_linear(intc, nr_irqs, &idu_irq_ops, NULL);
 336
 337         /* Parent interrupts (core-intc) are already mapped */
 338
 339         for (i = 0; i < nr_irqs; i++) {
 340                 /*
 341                  * Return parent uplink IRQs (towards core intc) 24,25,.....
 342                  * this step has been done before already
 343                  * however we need it to get the parent virq and set IDU handler
 344                  * as first level isr
 345                  */
 346                 irq = irq_of_parse_and_map(intc, i);
 347                 if (!i)
 348                         idu_first_irq = irq;
 349
 350                 irq_set_chained_handler_and_data(irq, idu_cascade_isr, domain);
 351         }
 352
 353         __mcip_cmd(CMD_IDU_ENABLE, 0);
 354
 355         return 0;
 356 }
 357 IRQCHIP_DECLARE(arcv2_idu_intc, "snps,archs-idu-intc", idu_of_init);