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 void send_IPI_single(int cpu, int tag)
  40 {
  41         HV_Recipient recip = {
  42                 .y = cpu / smp_width,
  43                 .x = cpu % smp_width,
  44                 .state = HV_TO_BE_SENT
  45         };
  46         int rc = hv_send_message(&recip, 1, (HV_VirtAddr)&tag, sizeof(tag));
  47         BUG_ON(rc <= 0);
  48 }
  49
  50 void send_IPI_many(const struct cpumask *mask, int tag)
  51 {
  52         HV_Recipient recip[NR_CPUS];
  53         int cpu, sent;
  54         int nrecip = 0;
  55         int my_cpu = smp_processor_id();
  56         for_each_cpu(cpu, mask) {
  57                 HV_Recipient *r;
  58                 BUG_ON(cpu == my_cpu);
  59                 r = &recip[nrecip++];
  60                 r->y = cpu / smp_width;
  61                 r->x = cpu % smp_width;
  62                 r->state = HV_TO_BE_SENT;
  63         }
  64         sent = 0;
  65         while (sent < nrecip) {
  66                 int rc = hv_send_message(recip, nrecip,
  67                                          (HV_VirtAddr)&tag, sizeof(tag));
  68                 if (rc <= 0) {
  69                         if (!stopping_cpus)  /* avoid recursive panic */
  70                                 panic("hv_send_message returned %d", rc);
  71                         break;
  72                 }
  73                 sent += rc;
  74         }
  75 }
  76
  77 void send_IPI_allbutself(int tag)
  78 {
  79         struct cpumask mask;
  80         cpumask_copy(&mask, cpu_online_mask);
  81         cpumask_clear_cpu(smp_processor_id(), &mask);
  82         send_IPI_many(&mask, tag);
  83 }
  84
  85
  86 /*
  87  * Provide smp_call_function_mask, but also run function locally
  88  * if specified in the mask.
  89  */
  90 void on_each_cpu_mask(const struct cpumask *mask, void (*func)(void *),
  91                       void *info, bool wait)
  92 {
  93         int cpu = get_cpu();
  94         smp_call_function_many(mask, func, info, wait);
  95         if (cpumask_test_cpu(cpu, mask)) {
  96                 local_irq_disable();
  97                 func(info);
  98                 local_irq_enable();
  99         }
 100         put_cpu();
 101 }
 102
 103
 104 /*
 105  * Functions related to starting/stopping cpus.
 106  */
 107
 108 /* Handler to start the current cpu. */
 109 static void smp_start_cpu_interrupt(void)
 110 {
 111         get_irq_regs()->pc = start_cpu_function_addr;
 112 }
 113
 114 /* Handler to stop the current cpu. */
 115 static void smp_stop_cpu_interrupt(void)
 116 {
 117         set_cpu_online(smp_processor_id(), 0);
 118         arch_local_irq_disable_all();
 119         for (;;)
 120                 asm("nap");
 121 }
 122
 123 /* This function calls the 'stop' function on all other CPUs in the system. */
 124 void smp_send_stop(void)
 125 {
 126         stopping_cpus = 1;
 127         send_IPI_allbutself(MSG_TAG_STOP_CPU);
 128 }
 129
 130
 131 /*
 132  * Dispatch code called from hv_message_intr() for HV_MSG_TILE hv messages.
 133  */
 134 void evaluate_message(int tag)
 135 {
 136         switch (tag) {
 137         case MSG_TAG_START_CPU: /* Start up a cpu */
 138                 smp_start_cpu_interrupt();
 139                 break;
 140
 141         case MSG_TAG_STOP_CPU: /* Sent to shut down slave CPU's */
 142                 smp_stop_cpu_interrupt();
 143                 break;
 144
 145         case MSG_TAG_CALL_FUNCTION_MANY: /* Call function on cpumask */
 146                 generic_smp_call_function_interrupt();
 147                 break;
 148
 149         case MSG_TAG_CALL_FUNCTION_SINGLE: /* Call function on one other CPU */
 150                 generic_smp_call_function_single_interrupt();
 151                 break;
 152
 153         default:
 154                 panic("Unknown IPI message tag %d", tag);
 155                 break;
 156         }
 157 }
 158
 159
 160 /*
 161  * flush_icache_range() code uses smp_call_function().
 162  */
 163
 164 struct ipi_flush {
 165         unsigned long start;
 166         unsigned long end;
 167 };
 168
 169 static void ipi_flush_icache_range(void *info)
 170 {
 171         struct ipi_flush *flush = (struct ipi_flush *) info;
 172         __flush_icache_range(flush->start, flush->end);
 173 }
 174
 175 void flush_icache_range(unsigned long start, unsigned long end)
 176 {
 177         struct ipi_flush flush = { start, end };
 178         preempt_disable();
 179         on_each_cpu(ipi_flush_icache_range, &flush, 1);
 180         preempt_enable();
 181 }
 182
 183
 184 /* Called when smp_send_reschedule() triggers IRQ_RESCHEDULE. */
 185 static irqreturn_t handle_reschedule_ipi(int irq, void *token)
 186 {
 187         /*
 188          * Nothing to do here; when we return from interrupt, the
 189          * rescheduling will occur there. But do bump the interrupt
 190          * profiler count in the meantime.
 191          */
 192         __get_cpu_var(irq_stat).irq_resched_count++;
 193
 194         return IRQ_HANDLED;
 195 }
 196
 197 static struct irqaction resched_action = {
 198         .handler = handle_reschedule_ipi,
 199         .name = "resched",
 200         .dev_id = handle_reschedule_ipi /* unique token */,
 201 };
 202
 203 void __init ipi_init(void)
 204 {
 205 #if CHIP_HAS_IPI()
 206         int cpu;
 207         /* Map IPI trigger MMIO addresses. */
 208         for_each_possible_cpu(cpu) {
 209                 HV_Coord tile;
 210                 HV_PTE pte;
 211                 unsigned long offset;
 212
 213                 tile.x = cpu_x(cpu);
 214                 tile.y = cpu_y(cpu);
 215                 if (hv_get_ipi_pte(tile, KERNEL_PL, &pte) != 0)
 216                         panic("Failed to initialize IPI for cpu %d\n", cpu);
 217
 218                 offset = hv_pte_get_pfn(pte) << PAGE_SHIFT;
 219                 ipi_mappings[cpu] = ioremap_prot(offset, PAGE_SIZE, pte);
 220         }
 221 #endif
 222
 223         /* Bind handle_reschedule_ipi() to IRQ_RESCHEDULE. */
 224         tile_irq_activate(IRQ_RESCHEDULE, TILE_IRQ_PERCPU);
 225         BUG_ON(setup_irq(IRQ_RESCHEDULE, &resched_action));
 226 }
 227
 228 #if CHIP_HAS_IPI()
 229
 230 void smp_send_reschedule(int cpu)
 231 {
 232         WARN_ON(cpu_is_offline(cpu));
 233
 234         /*
 235          * We just want to do an MMIO store.  The traditional writeq()
 236          * functions aren't really correct here, since they're always
 237          * directed at the PCI shim.  For now, just do a raw store,
 238          * casting away the __iomem attribute.
 239          */
 240         ((unsigned long __force *)ipi_mappings[cpu])[IRQ_RESCHEDULE] = 0;
 241 }
 242
 243 #else
 244
 245 void smp_send_reschedule(int cpu)
 246 {
 247         HV_Coord coord;
 248
 249         WARN_ON(cpu_is_offline(cpu));
 250
 251         coord.y = cpu_y(cpu);
 252         coord.x = cpu_x(cpu);
 253         hv_trigger_ipi(coord, IRQ_RESCHEDULE);
 254 }
 255
 256 #endif /* CHIP_HAS_IPI() */