arch/hexagon/kernel/smp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * SMP support for Hexagon
   4  *
   5  * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
   6  */
   7
   8 #include <linux/err.h>
   9 #include <linux/errno.h>
  10 #include <linux/kernel.h>
  11 #include <linux/init.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/module.h>
  14 #include <linux/percpu.h>
  15 #include <linux/sched/mm.h>
  16 #include <linux/smp.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/cpu.h>
  19 #include <linux/mm_types.h>
  20
  21 #include <asm/time.h>    /*  timer_interrupt  */
  22 #include <asm/hexagon_vm.h>
  23
  24 #define BASE_IPI_IRQ 26
  25
  26 /*
  27  * cpu_possible_mask needs to be filled out prior to setup_per_cpu_areas
  28  * (which is prior to any of our smp_prepare_cpu crap), in order to set
  29  * up the...  per_cpu areas.
  30  */
  31
  32 struct ipi_data {
  33         unsigned long bits;
  34 };
  35
  36 static DEFINE_PER_CPU(struct ipi_data, ipi_data);
  37
  38 static inline void __handle_ipi(unsigned long *ops, struct ipi_data *ipi,
  39                                 int cpu)
  40 {
  41         unsigned long msg = 0;
  42         do {
  43                 msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
  44
  45                 switch (msg) {
  46
  47                 case IPI_TIMER:
  48                         ipi_timer();
  49                         break;
  50
  51                 case IPI_CALL_FUNC:
  52                         generic_smp_call_function_interrupt();
  53                         break;
  54
  55                 case IPI_CPU_STOP:
  56                         /*
  57                          * call vmstop()
  58                          */
  59                         __vmstop();
  60                         break;
  61
  62                 case IPI_RESCHEDULE:
  63                         scheduler_ipi();
  64                         break;
  65                 }
  66         } while (msg < BITS_PER_LONG);
  67 }
  68
  69 /*  Used for IPI call from other CPU's to unmask int  */
  70 void smp_vm_unmask_irq(void *info)
  71 {
  72         __vmintop_locen((long) info);
  73 }
  74
  75
  76 /*
  77  * This is based on Alpha's IPI stuff.
  78  * Supposed to take (int, void*) as args now.
  79  * Specifically, first arg is irq, second is the irq_desc.
  80  */
  81
  82 irqreturn_t handle_ipi(int irq, void *desc)
  83 {
  84         int cpu = smp_processor_id();
  85         struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
  86         unsigned long ops;
  87
  88         while ((ops = xchg(&ipi->bits, 0)) != 0)
  89                 __handle_ipi(&ops, ipi, cpu);
  90         return IRQ_HANDLED;
  91 }
  92
  93 void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
  94 {
  95         unsigned long flags;
  96         unsigned long cpu;
  97         unsigned long retval;
  98
  99         local_irq_save(flags);
 100
 101         for_each_cpu(cpu, cpumask) {
 102                 struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 103
 104                 set_bit(msg, &ipi->bits);
 105                 /*  Possible barrier here  */
 106                 retval = __vmintop_post(BASE_IPI_IRQ+cpu);
 107
 108                 if (retval != 0) {
 109                         printk(KERN_ERR "interrupt %ld not configured?\n",
 110                                 BASE_IPI_IRQ+cpu);
 111                 }
 112         }
 113
 114         local_irq_restore(flags);
 115 }
 116
 117 void __init smp_prepare_boot_cpu(void)
 118 {
 119 }
 120
 121 /*
 122  * interrupts should already be disabled from the VM
 123  * SP should already be correct; need to set THREADINFO_REG
 124  * to point to current thread info
 125  */
 126
 127 void start_secondary(void)
 128 {
 129         unsigned long thread_ptr;
 130         unsigned int cpu, irq;
 131
 132         /*  Calculate thread_info pointer from stack pointer  */
 133         __asm__ __volatile__(
 134                 "%0 = SP;\n"
 135                 : "=r" (thread_ptr)
 136         );
 137
 138         thread_ptr = thread_ptr & ~(THREAD_SIZE-1);
 139
 140         __asm__ __volatile__(
 141                 QUOTED_THREADINFO_REG " = %0;\n"
 142                 :
 143                 : "r" (thread_ptr)
 144         );
 145
 146         /*  Set the memory struct  */
 147         mmgrab(&init_mm);
 148         current->active_mm = &init_mm;
 149
 150         cpu = smp_processor_id();
 151
 152         irq = BASE_IPI_IRQ + cpu;
 153         if (request_irq(irq, handle_ipi, IRQF_TRIGGER_RISING, "ipi_handler",
 154                         NULL))
 155                 pr_err("Failed to request irq %u (ipi_handler)\n", irq);
 156
 157         /*  Register the clock_event dummy  */
 158         setup_percpu_clockdev();
 159
 160         printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
 161
 162         notify_cpu_starting(cpu);
 163
 164         set_cpu_online(cpu, true);
 165
 166         local_irq_enable();
 167
 168         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 169 }
 170
 171
 172 /*
 173  * called once for each present cpu
 174  * apparently starts up the CPU and then
 175  * maintains control until "cpu_online(cpu)" is set.
 176  */
 177
 178 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 179 {
 180         struct thread_info *thread = (struct thread_info *)idle->stack;
 181         void *stack_start;
 182
 183         thread->cpu = cpu;
 184
 185         /*  Boot to the head.  */
 186         stack_start =  ((void *) thread) + THREAD_SIZE;
 187         __vmstart(start_secondary, stack_start);
 188
 189         while (!cpu_online(cpu))
 190                 barrier();
 191
 192         return 0;
 193 }
 194
 195 void __init smp_cpus_done(unsigned int max_cpus)
 196 {
 197 }
 198
 199 void __init smp_prepare_cpus(unsigned int max_cpus)
 200 {
 201         int i, irq = BASE_IPI_IRQ;
 202
 203         /*
 204          * should eventually have some sort of machine
 205          * descriptor that has this stuff
 206          */
 207
 208         /*  Right now, let's just fake it. */
 209         for (i = 0; i < max_cpus; i++)
 210                 set_cpu_present(i, true);
 211
 212         /*  Also need to register the interrupts for IPI  */
 213         if (max_cpus > 1) {
 214                 if (request_irq(irq, handle_ipi, IRQF_TRIGGER_RISING,
 215                                 "ipi_handler", NULL))
 216                         pr_err("Failed to request irq %d (ipi_handler)\n", irq);
 217         }
 218 }
 219
 220 void smp_send_reschedule(int cpu)
 221 {
 222         send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
 223 }
 224
 225 void smp_send_stop(void)
 226 {
 227         struct cpumask targets;
 228         cpumask_copy(&targets, cpu_online_mask);
 229         cpumask_clear_cpu(smp_processor_id(), &targets);
 230         send_ipi(&targets, IPI_CPU_STOP);
 231 }
 232
 233 void arch_send_call_function_single_ipi(int cpu)
 234 {
 235         send_ipi(cpumask_of(cpu), IPI_CALL_FUNC);
 236 }
 237
 238 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 239 {
 240         send_ipi(mask, IPI_CALL_FUNC);
 241 }
 242
 243 int setup_profiling_timer(unsigned int multiplier)
 244 {
 245         return -EINVAL;
 246 }
 247
 248 void smp_start_cpus(void)
 249 {
 250         int i;
 251
 252         for (i = 0; i < NR_CPUS; i++)
 253                 set_cpu_possible(i, true);
 254 }