arch/tile/kernel/smp.c

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  *
  14  * TILE SMP support routines.
  15  */
  16
  17 #include <linux/smp.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/io.h>
  20 #include <linux/irq.h>
  21 #include <linux/module.h>
  22 #include <asm/cacheflush.h>
  23
  24 HV_Topology smp_topology __write_once;
  25 EXPORT_SYMBOL(smp_topology);
  26
  27 #if CHIP_HAS_IPI()
  28 static unsigned long __iomem *ipi_mappings[NR_CPUS];
  29 #endif
  30
  31
  32 /*
  33  * Top-level send_IPI*() functions to send messages to other cpus.
  34  */
  35
  36 /* Set by smp_send_stop() to avoid recursive panics. */
  37 static int stopping_cpus;
  38
  39 static void __send_IPI_many(HV_Recipient *recip, int nrecip, int tag)
  40 {
  41         int sent = 0;
  42         while (sent < nrecip) {
  43                 int rc = hv_send_message(recip, nrecip,
  44                                          (HV_VirtAddr)&tag, sizeof(tag));
  45                 if (rc < 0) {
  46                         if (!stopping_cpus)  /* avoid recursive panic */
  47                                 panic("hv_send_message returned %d", rc);
  48                         break;
  49                 }
  50                 WARN_ONCE(rc == 0, "hv_send_message() returned zero\n");
  51                 sent += rc;
  52         }
  53 }
  54
  55 void send_IPI_single(int cpu, int tag)
  56 {
  57         HV_Recipient recip = {
  58                 .y = cpu / smp_width,
  59                 .x = cpu % smp_width,
  60                 .state = HV_TO_BE_SENT
  61         };
  62         __send_IPI_many(&recip, 1, tag);
  63 }
  64
  65 void send_IPI_many(const struct cpumask *mask, int tag)
  66 {
  67         HV_Recipient recip[NR_CPUS];
  68         int cpu;
  69         int nrecip = 0;
  70         int my_cpu = smp_processor_id();
  71         for_each_cpu(cpu, mask) {
  72                 HV_Recipient *r;
  73                 BUG_ON(cpu == my_cpu);
  74                 r = &recip[nrecip++];
  75                 r->y = cpu / smp_width;
  76                 r->x = cpu % smp_width;
  77                 r->state = HV_TO_BE_SENT;
  78         }
  79         __send_IPI_many(recip, nrecip, tag);
  80 }
  81
  82 void send_IPI_allbutself(int tag)
  83 {
  84         struct cpumask mask;
  85         cpumask_copy(&mask, cpu_online_mask);
  86         cpumask_clear_cpu(smp_processor_id(), &mask);
  87         send_IPI_many(&mask, tag);
  88 }
  89
  90
  91 /*
  92  * Provide smp_call_function_mask, but also run function locally
  93  * if specified in the mask.
  94  */
  95 void on_each_cpu_mask(const struct cpumask *mask, void (*func)(void *),
  96                       void *info, bool wait)
  97 {
  98         int cpu = get_cpu();
  99         smp_call_function_many(mask, func, info, wait);
 100         if (cpumask_test_cpu(cpu, mask)) {
 101                 local_irq_disable();
 102                 func(info);
 103                 local_irq_enable();
 104         }
 105         put_cpu();
 106 }
 107
 108
 109 /*
 110  * Functions related to starting/stopping cpus.
 111  */
 112
 113 /* Handler to start the current cpu. */
 114 static void smp_start_cpu_interrupt(void)
 115 {
 116         get_irq_regs()->pc = start_cpu_function_addr;
 117 }
 118
 119 /* Handler to stop the current cpu. */
 120 static void smp_stop_cpu_interrupt(void)
 121 {
 122         set_cpu_online(smp_processor_id(), 0);
 123         arch_local_irq_disable_all();
 124         for (;;)
 125                 asm("nap");
 126 }
 127
 128 /* This function calls the 'stop' function on all other CPUs in the system. */
 129 void smp_send_stop(void)
 130 {
 131         stopping_cpus = 1;
 132         send_IPI_allbutself(MSG_TAG_STOP_CPU);
 133 }
 134
 135
 136 /*
 137  * Dispatch code called from hv_message_intr() for HV_MSG_TILE hv messages.
 138  */
 139 void evaluate_message(int tag)
 140 {
 141         switch (tag) {
 142         case MSG_TAG_START_CPU: /* Start up a cpu */
 143                 smp_start_cpu_interrupt();
 144                 break;
 145
 146         case MSG_TAG_STOP_CPU: /* Sent to shut down slave CPU's */
 147                 smp_stop_cpu_interrupt();
 148                 break;
 149
 150         case MSG_TAG_CALL_FUNCTION_MANY: /* Call function on cpumask */
 151                 generic_smp_call_function_interrupt();
 152                 break;
 153
 154         case MSG_TAG_CALL_FUNCTION_SINGLE: /* Call function on one other CPU */
 155                 generic_smp_call_function_single_interrupt();
 156                 break;
 157
 158         default:
 159                 panic("Unknown IPI message tag %d", tag);
 160                 break;
 161         }
 162 }
 163
 164
 165 /*
 166  * flush_icache_range() code uses smp_call_function().
 167  */
 168
 169 struct ipi_flush {
 170         unsigned long start;
 171         unsigned long end;
 172 };
 173
 174 static void ipi_flush_icache_range(void *info)
 175 {
 176         struct ipi_flush *flush = (struct ipi_flush *) info;
 177         __flush_icache_range(flush->start, flush->end);
 178 }
 179
 180 void flush_icache_range(unsigned long start, unsigned long end)
 181 {
 182         struct ipi_flush flush = { start, end };
 183         preempt_disable();
 184         on_each_cpu(ipi_flush_icache_range, &flush, 1);
 185         preempt_enable();
 186 }
 187
 188
 189 /* Called when smp_send_reschedule() triggers IRQ_RESCHEDULE. */
 190 static irqreturn_t handle_reschedule_ipi(int irq, void *token)
 191 {
 192         __get_cpu_var(irq_stat).irq_resched_count++;
 193         scheduler_ipi();
 194
 195         return IRQ_HANDLED;
 196 }
 197
 198 static struct irqaction resched_action = {
 199         .handler = handle_reschedule_ipi,
 200         .name = "resched",
 201         .dev_id = handle_reschedule_ipi /* unique token */,
 202 };
 203
 204 void __init ipi_init(void)
 205 {
 206 #if CHIP_HAS_IPI()
 207         int cpu;
 208         /* Map IPI trigger MMIO addresses. */
 209         for_each_possible_cpu(cpu) {
 210                 HV_Coord tile;
 211                 HV_PTE pte;
 212                 unsigned long offset;
 213
 214                 tile.x = cpu_x(cpu);
 215                 tile.y = cpu_y(cpu);
 216                 if (hv_get_ipi_pte(tile, KERNEL_PL, &pte) != 0)
 217                         panic("Failed to initialize IPI for cpu %d\n", cpu);
 218
 219                 offset = hv_pte_get_pfn(pte) << PAGE_SHIFT;
 220                 ipi_mappings[cpu] = ioremap_prot(offset, PAGE_SIZE, pte);
 221         }
 222 #endif
 223
 224         /* Bind handle_reschedule_ipi() to IRQ_RESCHEDULE. */
 225         tile_irq_activate(IRQ_RESCHEDULE, TILE_IRQ_PERCPU);
 226         BUG_ON(setup_irq(IRQ_RESCHEDULE, &resched_action));
 227 }
 228
 229 #if CHIP_HAS_IPI()
 230
 231 void smp_send_reschedule(int cpu)
 232 {
 233         WARN_ON(cpu_is_offline(cpu));
 234
 235         /*
 236          * We just want to do an MMIO store.  The traditional writeq()
 237          * functions aren't really correct here, since they're always
 238          * directed at the PCI shim.  For now, just do a raw store,
 239          * casting away the __iomem attribute.
 240          */
 241         ((unsigned long __force *)ipi_mappings[cpu])[IRQ_RESCHEDULE] = 0;
 242 }
 243
 244 #else
 245
 246 void smp_send_reschedule(int cpu)
 247 {
 248         HV_Coord coord;
 249
 250         WARN_ON(cpu_is_offline(cpu));
 251
 252         coord.y = cpu_y(cpu);
 253         coord.x = cpu_x(cpu);
 254         hv_trigger_ipi(coord, IRQ_RESCHEDULE);
 255 }
 256
 257 #endif /* CHIP_HAS_IPI() */