arch/riscv/kernel/cpu_ops_sbi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * HSM extension and cpu_ops implementation.
   4  *
   5  * Copyright (c) 2020 Western Digital Corporation or its affiliates.
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/mm.h>
  10 #include <linux/sched/task_stack.h>
  11 #include <asm/cpu_ops.h>
  12 #include <asm/cpu_ops_sbi.h>
  13 #include <asm/sbi.h>
  14 #include <asm/smp.h>
  15
  16 extern char secondary_start_sbi[];
  17 const struct cpu_operations cpu_ops_sbi;
  18
  19 /*
  20  * Ordered booting via HSM brings one cpu at a time. However, cpu hotplug can
  21  * be invoked from multiple threads in parallel. Define a per cpu data
  22  * to handle that.
  23  */
  24 static DEFINE_PER_CPU(struct sbi_hart_boot_data, boot_data);
  25
  26 static int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,
  27                               unsigned long priv)
  28 {
  29         struct sbiret ret;
  30
  31         ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_START,
  32                         hartid, saddr, priv, 0, 0, 0);
  33         if (ret.error)
  34                 return sbi_err_map_linux_errno(ret.error);
  35         else
  36                 return 0;
  37 }
  38
  39 #ifdef CONFIG_HOTPLUG_CPU
  40 static int sbi_hsm_hart_stop(void)
  41 {
  42         struct sbiret ret;
  43
  44         ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STOP, 0, 0, 0, 0, 0, 0);
  45
  46         if (ret.error)
  47                 return sbi_err_map_linux_errno(ret.error);
  48         else
  49                 return 0;
  50 }
  51
  52 static int sbi_hsm_hart_get_status(unsigned long hartid)
  53 {
  54         struct sbiret ret;
  55
  56         ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STATUS,
  57                         hartid, 0, 0, 0, 0, 0);
  58         if (ret.error)
  59                 return sbi_err_map_linux_errno(ret.error);
  60         else
  61                 return ret.value;
  62 }
  63 #endif
  64
  65 static int sbi_cpu_start(unsigned int cpuid, struct task_struct *tidle)
  66 {
  67         unsigned long boot_addr = __pa_symbol(secondary_start_sbi);
  68         unsigned long hartid = cpuid_to_hartid_map(cpuid);
  69         unsigned long hsm_data;
  70         struct sbi_hart_boot_data *bdata = &per_cpu(boot_data, cpuid);
  71
  72         /* Make sure tidle is updated */
  73         smp_mb();
  74         bdata->task_ptr = tidle;
  75         bdata->stack_ptr = task_pt_regs(tidle);
  76         /* Make sure boot data is updated */
  77         smp_mb();
  78         hsm_data = __pa(bdata);
  79         return sbi_hsm_hart_start(hartid, boot_addr, hsm_data);
  80 }
  81
  82 #ifdef CONFIG_HOTPLUG_CPU
  83 static void sbi_cpu_stop(void)
  84 {
  85         int ret;
  86
  87         ret = sbi_hsm_hart_stop();
  88         pr_crit("Unable to stop the cpu %u (%d)\n", smp_processor_id(), ret);
  89 }
  90
  91 static int sbi_cpu_is_stopped(unsigned int cpuid)
  92 {
  93         int rc;
  94         unsigned long hartid = cpuid_to_hartid_map(cpuid);
  95
  96         rc = sbi_hsm_hart_get_status(hartid);
  97
  98         if (rc == SBI_HSM_STATE_STOPPED)
  99                 return 0;
 100         return rc;
 101 }
 102 #endif
 103
 104 const struct cpu_operations cpu_ops_sbi = {
 105         .cpu_start      = sbi_cpu_start,
 106 #ifdef CONFIG_HOTPLUG_CPU
 107         .cpu_stop       = sbi_cpu_stop,
 108         .cpu_is_stopped = sbi_cpu_is_stopped,
 109 #endif
 110 };