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  * Functions related to starting/stopping cpus.
  92  */
  93
  94 /* Handler to start the current cpu. */
  95 static void smp_start_cpu_interrupt(void)
  96 {
  97         get_irq_regs()->pc = start_cpu_function_addr;
  98 }
  99
 100 /* Handler to stop the current cpu. */
 101 static void smp_stop_cpu_interrupt(void)
 102 {
 103         set_cpu_online(smp_processor_id(), 0);
 104         arch_local_irq_disable_all();
 105         for (;;)
 106                 asm("nap; nop");
 107 }
 108
 109 /* This function calls the 'stop' function on all other CPUs in the system. */
 110 void smp_send_stop(void)
 111 {
 112         stopping_cpus = 1;
 113         send_IPI_allbutself(MSG_TAG_STOP_CPU);
 114 }
 115
 116 /* On panic, just wait; we may get an smp_send_stop() later on. */
 117 void panic_smp_self_stop(void)
 118 {
 119         while (1)
 120                 asm("nap; nop");
 121 }
 122
 123 /*
 124  * Dispatch code called from hv_message_intr() for HV_MSG_TILE hv messages.
 125  */
 126 void evaluate_message(int tag)
 127 {
 128         switch (tag) {
 129         case MSG_TAG_START_CPU: /* Start up a cpu */
 130                 smp_start_cpu_interrupt();
 131                 break;
 132
 133         case MSG_TAG_STOP_CPU: /* Sent to shut down slave CPU's */
 134                 smp_stop_cpu_interrupt();
 135                 break;
 136
 137         case MSG_TAG_CALL_FUNCTION_MANY: /* Call function on cpumask */
 138                 generic_smp_call_function_interrupt();
 139                 break;
 140
 141         case MSG_TAG_CALL_FUNCTION_SINGLE: /* Call function on one other CPU */
 142                 generic_smp_call_function_single_interrupt();
 143                 break;
 144
 145         default:
 146                 panic("Unknown IPI message tag %d", tag);
 147                 break;
 148         }
 149 }
 150
 151
 152 /*
 153  * flush_icache_range() code uses smp_call_function().
 154  */
 155
 156 struct ipi_flush {
 157         unsigned long start;
 158         unsigned long end;
 159 };
 160
 161 static void ipi_flush_icache_range(void *info)
 162 {
 163         struct ipi_flush *flush = (struct ipi_flush *) info;
 164         __flush_icache_range(flush->start, flush->end);
 165 }
 166
 167 void flush_icache_range(unsigned long start, unsigned long end)
 168 {
 169         struct ipi_flush flush = { start, end };
 170         preempt_disable();
 171         on_each_cpu(ipi_flush_icache_range, &flush, 1);
 172         preempt_enable();
 173 }
 174
 175
 176 /* Called when smp_send_reschedule() triggers IRQ_RESCHEDULE. */
 177 static irqreturn_t handle_reschedule_ipi(int irq, void *token)
 178 {
 179         __get_cpu_var(irq_stat).irq_resched_count++;
 180         scheduler_ipi();
 181
 182         return IRQ_HANDLED;
 183 }
 184
 185 static struct irqaction resched_action = {
 186         .handler = handle_reschedule_ipi,
 187         .name = "resched",
 188         .dev_id = handle_reschedule_ipi /* unique token */,
 189 };
 190
 191 void __init ipi_init(void)
 192 {
 193 #if CHIP_HAS_IPI()
 194         int cpu;
 195         /* Map IPI trigger MMIO addresses. */
 196         for_each_possible_cpu(cpu) {
 197                 HV_Coord tile;
 198                 HV_PTE pte;
 199                 unsigned long offset;
 200
 201                 tile.x = cpu_x(cpu);
 202                 tile.y = cpu_y(cpu);
 203                 if (hv_get_ipi_pte(tile, KERNEL_PL, &pte) != 0)
 204                         panic("Failed to initialize IPI for cpu %d\n", cpu);
 205
 206                 offset = PFN_PHYS(pte_pfn(pte));
 207                 ipi_mappings[cpu] = ioremap_prot(offset, PAGE_SIZE, pte);
 208         }
 209 #endif
 210
 211         /* Bind handle_reschedule_ipi() to IRQ_RESCHEDULE. */
 212         tile_irq_activate(IRQ_RESCHEDULE, TILE_IRQ_PERCPU);
 213         BUG_ON(setup_irq(IRQ_RESCHEDULE, &resched_action));
 214 }
 215
 216 #if CHIP_HAS_IPI()
 217
 218 void smp_send_reschedule(int cpu)
 219 {
 220         WARN_ON(cpu_is_offline(cpu));
 221
 222         /*
 223          * We just want to do an MMIO store.  The traditional writeq()
 224          * functions aren't really correct here, since they're always
 225          * directed at the PCI shim.  For now, just do a raw store,
 226          * casting away the __iomem attribute.
 227          */
 228         ((unsigned long __force *)ipi_mappings[cpu])[IRQ_RESCHEDULE] = 0;
 229 }
 230
 231 #else
 232
 233 void smp_send_reschedule(int cpu)
 234 {
 235         HV_Coord coord;
 236
 237         WARN_ON(cpu_is_offline(cpu));
 238
 239         coord.y = cpu_y(cpu);
 240         coord.x = cpu_x(cpu);
 241         hv_trigger_ipi(coord, IRQ_RESCHEDULE);
 242 }
 243
 244 #endif /* CHIP_HAS_IPI() */