arch/mips/kernel/smp-cps.c

   1 /*
   2  * Copyright (C) 2013 Imagination Technologies
   3  * Author: Paul Burton <paul.burton@imgtec.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation;  either version 2 of the  License, or (at your
   8  * option) any later version.
   9  */
  10
  11 #include <linux/io.h>
  12 #include <linux/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/smp.h>
  15 #include <linux/types.h>
  16
  17 #include <asm/cacheflush.h>
  18 #include <asm/gic.h>
  19 #include <asm/mips-cm.h>
  20 #include <asm/mips-cpc.h>
  21 #include <asm/mips_mt.h>
  22 #include <asm/mipsregs.h>
  23 #include <asm/pm-cps.h>
  24 #include <asm/smp-cps.h>
  25 #include <asm/time.h>
  26 #include <asm/uasm.h>
  27
  28 static DECLARE_BITMAP(core_power, NR_CPUS);
  29
  30 struct core_boot_config *mips_cps_core_bootcfg;
  31
  32 static unsigned core_vpe_count(unsigned core)
  33 {
  34         unsigned cfg;
  35
  36         if (!config_enabled(CONFIG_MIPS_MT_SMP) || !cpu_has_mipsmt)
  37                 return 1;
  38
  39         write_gcr_cl_other(core << CM_GCR_Cx_OTHER_CORENUM_SHF);
  40         cfg = read_gcr_co_config() & CM_GCR_Cx_CONFIG_PVPE_MSK;
  41         return (cfg >> CM_GCR_Cx_CONFIG_PVPE_SHF) + 1;
  42 }
  43
  44 static void __init cps_smp_setup(void)
  45 {
  46         unsigned int ncores, nvpes, core_vpes;
  47         int c, v;
  48
  49         /* Detect & record VPE topology */
  50         ncores = mips_cm_numcores();
  51         pr_info("VPE topology ");
  52         for (c = nvpes = 0; c < ncores; c++) {
  53                 core_vpes = core_vpe_count(c);
  54                 pr_cont("%c%u", c ? ',' : '{', core_vpes);
  55
  56                 /* Use the number of VPEs in core 0 for smp_num_siblings */
  57                 if (!c)
  58                         smp_num_siblings = core_vpes;
  59
  60                 for (v = 0; v < min_t(int, core_vpes, NR_CPUS - nvpes); v++) {
  61                         cpu_data[nvpes + v].core = c;
  62 #ifdef CONFIG_MIPS_MT_SMP
  63                         cpu_data[nvpes + v].vpe_id = v;
  64 #endif
  65                 }
  66
  67                 nvpes += core_vpes;
  68         }
  69         pr_cont("} total %u\n", nvpes);
  70
  71         /* Indicate present CPUs (CPU being synonymous with VPE) */
  72         for (v = 0; v < min_t(unsigned, nvpes, NR_CPUS); v++) {
  73                 set_cpu_possible(v, true);
  74                 set_cpu_present(v, true);
  75                 __cpu_number_map[v] = v;
  76                 __cpu_logical_map[v] = v;
  77         }
  78
  79         /* Set a coherent default CCA (CWB) */
  80         change_c0_config(CONF_CM_CMASK, 0x5);
  81
  82         /* Core 0 is powered up (we're running on it) */
  83         bitmap_set(core_power, 0, 1);
  84
  85         /* Initialise core 0 */
  86         mips_cps_core_init();
  87
  88         /* Make core 0 coherent with everything */
  89         write_gcr_cl_coherence(0xff);
  90 }
  91
  92 static void __init cps_prepare_cpus(unsigned int max_cpus)
  93 {
  94         unsigned ncores, core_vpes, c, cca;
  95         bool cca_unsuitable;
  96         u32 *entry_code;
  97
  98         mips_mt_set_cpuoptions();
  99
 100         /* Detect whether the CCA is unsuited to multi-core SMP */
 101         cca = read_c0_config() & CONF_CM_CMASK;
 102         switch (cca) {
 103         case 0x4: /* CWBE */
 104         case 0x5: /* CWB */
 105                 /* The CCA is coherent, multi-core is fine */
 106                 cca_unsuitable = false;
 107                 break;
 108
 109         default:
 110                 /* CCA is not coherent, multi-core is not usable */
 111                 cca_unsuitable = true;
 112         }
 113
 114         /* Warn the user if the CCA prevents multi-core */
 115         ncores = mips_cm_numcores();
 116         if (cca_unsuitable && ncores > 1) {
 117                 pr_warn("Using only one core due to unsuitable CCA 0x%x\n",
 118                         cca);
 119
 120                 for_each_present_cpu(c) {
 121                         if (cpu_data[c].core)
 122                                 set_cpu_present(c, false);
 123                 }
 124         }
 125
 126         /*
 127          * Patch the start of mips_cps_core_entry to provide:
 128          *
 129          * v0 = CM base address
 130          * s0 = kseg0 CCA
 131          */
 132         entry_code = (u32 *)&mips_cps_core_entry;
 133         UASM_i_LA(&entry_code, 3, (long)mips_cm_base);
 134         uasm_i_addiu(&entry_code, 16, 0, cca);
 135         dma_cache_wback_inv((unsigned long)&mips_cps_core_entry,
 136                             (void *)entry_code - (void *)&mips_cps_core_entry);
 137
 138         /* Allocate core boot configuration structs */
 139         mips_cps_core_bootcfg = kcalloc(ncores, sizeof(*mips_cps_core_bootcfg),
 140                                         GFP_KERNEL);
 141         if (!mips_cps_core_bootcfg) {
 142                 pr_err("Failed to allocate boot config for %u cores\n", ncores);
 143                 goto err_out;
 144         }
 145
 146         /* Allocate VPE boot configuration structs */
 147         for (c = 0; c < ncores; c++) {
 148                 core_vpes = core_vpe_count(c);
 149                 mips_cps_core_bootcfg[c].vpe_config = kcalloc(core_vpes,
 150                                 sizeof(*mips_cps_core_bootcfg[c].vpe_config),
 151                                 GFP_KERNEL);
 152                 if (!mips_cps_core_bootcfg[c].vpe_config) {
 153                         pr_err("Failed to allocate %u VPE boot configs\n",
 154                                core_vpes);
 155                         goto err_out;
 156                 }
 157         }
 158
 159         /* Mark this CPU as booted */
 160         atomic_set(&mips_cps_core_bootcfg[current_cpu_data.core].vpe_mask,
 161                    1 << cpu_vpe_id(&current_cpu_data));
 162
 163         return;
 164 err_out:
 165         /* Clean up allocations */
 166         if (mips_cps_core_bootcfg) {
 167                 for (c = 0; c < ncores; c++)
 168                         kfree(mips_cps_core_bootcfg[c].vpe_config);
 169                 kfree(mips_cps_core_bootcfg);
 170                 mips_cps_core_bootcfg = NULL;
 171         }
 172
 173         /* Effectively disable SMP by declaring CPUs not present */
 174         for_each_possible_cpu(c) {
 175                 if (c == 0)
 176                         continue;
 177                 set_cpu_present(c, false);
 178         }
 179 }
 180
 181 static void boot_core(unsigned core)
 182 {
 183         u32 access;
 184
 185         /* Select the appropriate core */
 186         write_gcr_cl_other(core << CM_GCR_Cx_OTHER_CORENUM_SHF);
 187
 188         /* Set its reset vector */
 189         write_gcr_co_reset_base(CKSEG1ADDR((unsigned long)mips_cps_core_entry));
 190
 191         /* Ensure its coherency is disabled */
 192         write_gcr_co_coherence(0);
 193
 194         /* Ensure the core can access the GCRs */
 195         access = read_gcr_access();
 196         access |= 1 << (CM_GCR_ACCESS_ACCESSEN_SHF + core);
 197         write_gcr_access(access);
 198
 199         if (mips_cpc_present()) {
 200                 /* Reset the core */
 201                 mips_cpc_lock_other(core);
 202                 write_cpc_co_cmd(CPC_Cx_CMD_RESET);
 203                 mips_cpc_unlock_other();
 204         } else {
 205                 /* Take the core out of reset */
 206                 write_gcr_co_reset_release(0);
 207         }
 208
 209         /* The core is now powered up */
 210         bitmap_set(core_power, core, 1);
 211 }
 212
 213 static void remote_vpe_boot(void *dummy)
 214 {
 215         mips_cps_boot_vpes();
 216 }
 217
 218 static void cps_boot_secondary(int cpu, struct task_struct *idle)
 219 {
 220         unsigned core = cpu_data[cpu].core;
 221         unsigned vpe_id = cpu_vpe_id(&cpu_data[cpu]);
 222         struct core_boot_config *core_cfg = &mips_cps_core_bootcfg[core];
 223         struct vpe_boot_config *vpe_cfg = &core_cfg->vpe_config[vpe_id];
 224         unsigned int remote;
 225         int err;
 226
 227         vpe_cfg->pc = (unsigned long)&smp_bootstrap;
 228         vpe_cfg->sp = __KSTK_TOS(idle);
 229         vpe_cfg->gp = (unsigned long)task_thread_info(idle);
 230
 231         atomic_or(1 << cpu_vpe_id(&cpu_data[cpu]), &core_cfg->vpe_mask);
 232
 233         preempt_disable();
 234
 235         if (!test_bit(core, core_power)) {
 236                 /* Boot a VPE on a powered down core */
 237                 boot_core(core);
 238                 goto out;
 239         }
 240
 241         if (core != current_cpu_data.core) {
 242                 /* Boot a VPE on another powered up core */
 243                 for (remote = 0; remote < NR_CPUS; remote++) {
 244                         if (cpu_data[remote].core != core)
 245                                 continue;
 246                         if (cpu_online(remote))
 247                                 break;
 248                 }
 249                 BUG_ON(remote >= NR_CPUS);
 250
 251                 err = smp_call_function_single(remote, remote_vpe_boot,
 252                                                NULL, 1);
 253                 if (err)
 254                         panic("Failed to call remote CPU\n");
 255                 goto out;
 256         }
 257
 258         BUG_ON(!cpu_has_mipsmt);
 259
 260         /* Boot a VPE on this core */
 261         mips_cps_boot_vpes();
 262 out:
 263         preempt_enable();
 264 }
 265
 266 static void cps_init_secondary(void)
 267 {
 268         /* Disable MT - we only want to run 1 TC per VPE */
 269         if (cpu_has_mipsmt)
 270                 dmt();
 271
 272         change_c0_status(ST0_IM, STATUSF_IP3 | STATUSF_IP4 |
 273                                  STATUSF_IP6 | STATUSF_IP7);
 274 }
 275
 276 static void cps_smp_finish(void)
 277 {
 278         write_c0_compare(read_c0_count() + (8 * mips_hpt_frequency / HZ));
 279
 280 #ifdef CONFIG_MIPS_MT_FPAFF
 281         /* If we have an FPU, enroll ourselves in the FPU-full mask */
 282         if (cpu_has_fpu)
 283                 cpu_set(smp_processor_id(), mt_fpu_cpumask);
 284 #endif /* CONFIG_MIPS_MT_FPAFF */
 285
 286         local_irq_enable();
 287 }
 288
 289 #ifdef CONFIG_HOTPLUG_CPU
 290
 291 static int cps_cpu_disable(void)
 292 {
 293         unsigned cpu = smp_processor_id();
 294         struct core_boot_config *core_cfg;
 295
 296         if (!cpu)
 297                 return -EBUSY;
 298
 299         if (!cps_pm_support_state(CPS_PM_POWER_GATED))
 300                 return -EINVAL;
 301
 302         core_cfg = &mips_cps_core_bootcfg[current_cpu_data.core];
 303         atomic_sub(1 << cpu_vpe_id(&current_cpu_data), &core_cfg->vpe_mask);
 304         smp_mb__after_atomic();
 305         set_cpu_online(cpu, false);
 306         cpu_clear(cpu, cpu_callin_map);
 307
 308         return 0;
 309 }
 310
 311 static DECLARE_COMPLETION(cpu_death_chosen);
 312 static unsigned cpu_death_sibling;
 313 static enum {
 314         CPU_DEATH_HALT,
 315         CPU_DEATH_POWER,
 316 } cpu_death;
 317
 318 void play_dead(void)
 319 {
 320         unsigned cpu, core;
 321
 322         local_irq_disable();
 323         idle_task_exit();
 324         cpu = smp_processor_id();
 325         cpu_death = CPU_DEATH_POWER;
 326
 327         if (cpu_has_mipsmt) {
 328                 core = cpu_data[cpu].core;
 329
 330                 /* Look for another online VPE within the core */
 331                 for_each_online_cpu(cpu_death_sibling) {
 332                         if (cpu_data[cpu_death_sibling].core != core)
 333                                 continue;
 334
 335                         /*
 336                          * There is an online VPE within the core. Just halt
 337                          * this TC and leave the core alone.
 338                          */
 339                         cpu_death = CPU_DEATH_HALT;
 340                         break;
 341                 }
 342         }
 343
 344         /* This CPU has chosen its way out */
 345         complete(&cpu_death_chosen);
 346
 347         if (cpu_death == CPU_DEATH_HALT) {
 348                 /* Halt this TC */
 349                 write_c0_tchalt(TCHALT_H);
 350                 instruction_hazard();
 351         } else {
 352                 /* Power down the core */
 353                 cps_pm_enter_state(CPS_PM_POWER_GATED);
 354         }
 355
 356         /* This should never be reached */
 357         panic("Failed to offline CPU %u", cpu);
 358 }
 359
 360 static void wait_for_sibling_halt(void *ptr_cpu)
 361 {
 362         unsigned cpu = (unsigned)ptr_cpu;
 363         unsigned vpe_id = cpu_data[cpu].vpe_id;
 364         unsigned halted;
 365         unsigned long flags;
 366
 367         do {
 368                 local_irq_save(flags);
 369                 settc(vpe_id);
 370                 halted = read_tc_c0_tchalt();
 371                 local_irq_restore(flags);
 372         } while (!(halted & TCHALT_H));
 373 }
 374
 375 static void cps_cpu_die(unsigned int cpu)
 376 {
 377         unsigned core = cpu_data[cpu].core;
 378         unsigned stat;
 379         int err;
 380
 381         /* Wait for the cpu to choose its way out */
 382         if (!wait_for_completion_timeout(&cpu_death_chosen,
 383                                          msecs_to_jiffies(5000))) {
 384                 pr_err("CPU%u: didn't offline\n", cpu);
 385                 return;
 386         }
 387
 388         /*
 389          * Now wait for the CPU to actually offline. Without doing this that
 390          * offlining may race with one or more of:
 391          *
 392          *   - Onlining the CPU again.
 393          *   - Powering down the core if another VPE within it is offlined.
 394          *   - A sibling VPE entering a non-coherent state.
 395          *
 396          * In the non-MT halt case (ie. infinite loop) the CPU is doing nothing
 397          * with which we could race, so do nothing.
 398          */
 399         if (cpu_death == CPU_DEATH_POWER) {
 400                 /*
 401                  * Wait for the core to enter a powered down or clock gated
 402                  * state, the latter happening when a JTAG probe is connected
 403                  * in which case the CPC will refuse to power down the core.
 404                  */
 405                 do {
 406                         mips_cpc_lock_other(core);
 407                         stat = read_cpc_co_stat_conf();
 408                         stat &= CPC_Cx_STAT_CONF_SEQSTATE_MSK;
 409                         mips_cpc_unlock_other();
 410                 } while (stat != CPC_Cx_STAT_CONF_SEQSTATE_D0 &&
 411                          stat != CPC_Cx_STAT_CONF_SEQSTATE_D2 &&
 412                          stat != CPC_Cx_STAT_CONF_SEQSTATE_U2);
 413
 414                 /* Indicate the core is powered off */
 415                 bitmap_clear(core_power, core, 1);
 416         } else if (cpu_has_mipsmt) {
 417                 /*
 418                  * Have a CPU with access to the offlined CPUs registers wait
 419                  * for its TC to halt.
 420                  */
 421                 err = smp_call_function_single(cpu_death_sibling,
 422                                                wait_for_sibling_halt,
 423                                                (void *)cpu, 1);
 424                 if (err)
 425                         panic("Failed to call remote sibling CPU\n");
 426         }
 427 }
 428
 429 #endif /* CONFIG_HOTPLUG_CPU */
 430
 431 static struct plat_smp_ops cps_smp_ops = {
 432         .smp_setup              = cps_smp_setup,
 433         .prepare_cpus           = cps_prepare_cpus,
 434         .boot_secondary         = cps_boot_secondary,
 435         .init_secondary         = cps_init_secondary,
 436         .smp_finish             = cps_smp_finish,
 437         .send_ipi_single        = gic_send_ipi_single,
 438         .send_ipi_mask          = gic_send_ipi_mask,
 439 #ifdef CONFIG_HOTPLUG_CPU
 440         .cpu_disable            = cps_cpu_disable,
 441         .cpu_die                = cps_cpu_die,
 442 #endif
 443 };
 444
 445 bool mips_cps_smp_in_use(void)
 446 {
 447         extern struct plat_smp_ops *mp_ops;
 448         return mp_ops == &cps_smp_ops;
 449 }
 450
 451 int register_cps_smp_ops(void)
 452 {
 453         if (!mips_cm_present()) {
 454                 pr_warn("MIPS CPS SMP unable to proceed without a CM\n");
 455                 return -ENODEV;
 456         }
 457
 458         /* check we have a GIC - we need one for IPIs */
 459         if (!(read_gcr_gic_status() & CM_GCR_GIC_STATUS_EX_MSK)) {
 460                 pr_warn("MIPS CPS SMP unable to proceed without a GIC\n");
 461                 return -ENODEV;
 462         }
 463
 464         register_smp_ops(&cps_smp_ops);
 465         return 0;
 466 }