root/arch/hexagon/kernel/smp.c

DEFINITIONS

1. __handle_ipi
2. smp_vm_unmask_irq
3. handle_ipi
4. send_ipi
5. smp_prepare_boot_cpu
6. start_secondary
7. __cpu_up
8. smp_cpus_done
9. smp_prepare_cpus
10. smp_send_reschedule
11. smp_send_stop
12. arch_send_call_function_single_ipi
13. arch_send_call_function_ipi_mask
14. setup_profiling_timer
15. smp_start_cpus

   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 static struct irqaction ipi_intdesc = {
 118         .handler = handle_ipi,
 119         .flags = IRQF_TRIGGER_RISING,
 120         .name = "ipi_handler"
 121 };
 122 
 123 void __init smp_prepare_boot_cpu(void)
 124 {
 125 }
 126 
 127 /*
 128  * interrupts should already be disabled from the VM
 129  * SP should already be correct; need to set THREADINFO_REG
 130  * to point to current thread info
 131  */
 132 
 133 void start_secondary(void)
 134 {
 135         unsigned int cpu;
 136         unsigned long thread_ptr;
 137 
 138         /*  Calculate thread_info pointer from stack pointer  */
 139         __asm__ __volatile__(
 140                 "%0 = SP;\n"
 141                 : "=r" (thread_ptr)
 142         );
 143 
 144         thread_ptr = thread_ptr & ~(THREAD_SIZE-1);
 145 
 146         __asm__ __volatile__(
 147                 QUOTED_THREADINFO_REG " = %0;\n"
 148                 :
 149                 : "r" (thread_ptr)
 150         );
 151 
 152         /*  Set the memory struct  */
 153         mmgrab(&init_mm);
 154         current->active_mm = &init_mm;
 155 
 156         cpu = smp_processor_id();
 157 
 158         setup_irq(BASE_IPI_IRQ + cpu, &ipi_intdesc);
 159 
 160         /*  Register the clock_event dummy  */
 161         setup_percpu_clockdev();
 162 
 163         printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
 164 
 165         notify_cpu_starting(cpu);
 166 
 167         set_cpu_online(cpu, true);
 168 
 169         local_irq_enable();
 170 
 171         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 172 }
 173 
 174 
 175 /*
 176  * called once for each present cpu
 177  * apparently starts up the CPU and then
 178  * maintains control until "cpu_online(cpu)" is set.
 179  */
 180 
 181 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 182 {
 183         struct thread_info *thread = (struct thread_info *)idle->stack;
 184         void *stack_start;
 185 
 186         thread->cpu = cpu;
 187 
 188         /*  Boot to the head.  */
 189         stack_start =  ((void *) thread) + THREAD_SIZE;
 190         __vmstart(start_secondary, stack_start);
 191 
 192         while (!cpu_online(cpu))
 193                 barrier();
 194 
 195         return 0;
 196 }
 197 
 198 void __init smp_cpus_done(unsigned int max_cpus)
 199 {
 200 }
 201 
 202 void __init smp_prepare_cpus(unsigned int max_cpus)
 203 {
 204         int i;
 205 
 206         /*
 207          * should eventually have some sort of machine
 208          * descriptor that has this stuff
 209          */
 210 
 211         /*  Right now, let's just fake it. */
 212         for (i = 0; i < max_cpus; i++)
 213                 set_cpu_present(i, true);
 214 
 215         /*  Also need to register the interrupts for IPI  */
 216         if (max_cpus > 1)
 217                 setup_irq(BASE_IPI_IRQ, &ipi_intdesc);
 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 }