arch/riscv/kernel/cpu.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Regents of the University of California
   4  */
   5
   6 #include <linux/init.h>
   7 #include <linux/seq_file.h>
   8 #include <linux/of.h>
   9 #include <asm/smp.h>
  10
  11 /*
  12  * Returns the hart ID of the given device tree node, or -ENODEV if the node
  13  * isn't an enabled and valid RISC-V hart node.
  14  */
  15 int riscv_of_processor_hartid(struct device_node *node)
  16 {
  17         const char *isa;
  18         u32 hart;
  19
  20         if (!of_device_is_compatible(node, "riscv")) {
  21                 pr_warn("Found incompatible CPU\n");
  22                 return -ENODEV;
  23         }
  24
  25         if (of_property_read_u32(node, "reg", &hart)) {
  26                 pr_warn("Found CPU without hart ID\n");
  27                 return -ENODEV;
  28         }
  29
  30         if (!of_device_is_available(node)) {
  31                 pr_info("CPU with hartid=%d is not available\n", hart);
  32                 return -ENODEV;
  33         }
  34
  35         if (of_property_read_string(node, "riscv,isa", &isa)) {
  36                 pr_warn("CPU with hartid=%d has no \"riscv,isa\" property\n", hart);
  37                 return -ENODEV;
  38         }
  39         if (isa[0] != 'r' || isa[1] != 'v') {
  40                 pr_warn("CPU with hartid=%d has an invalid ISA of \"%s\"\n", hart, isa);
  41                 return -ENODEV;
  42         }
  43
  44         return hart;
  45 }
  46
  47 #ifdef CONFIG_PROC_FS
  48
  49 static void print_isa(struct seq_file *f, const char *orig_isa)
  50 {
  51         static const char *ext = "mafdcsu";
  52         const char *isa = orig_isa;
  53         const char *e;
  54
  55         /*
  56          * Linux doesn't support rv32e or rv128i, and we only support booting
  57          * kernels on harts with the same ISA that the kernel is compiled for.
  58          */
  59 #if defined(CONFIG_32BIT)
  60         if (strncmp(isa, "rv32i", 5) != 0)
  61                 return;
  62 #elif defined(CONFIG_64BIT)
  63         if (strncmp(isa, "rv64i", 5) != 0)
  64                 return;
  65 #endif
  66
  67         /* Print the base ISA, as we already know it's legal. */
  68         seq_puts(f, "isa\t\t: ");
  69         seq_write(f, isa, 5);
  70         isa += 5;
  71
  72         /*
  73          * Check the rest of the ISA string for valid extensions, printing those
  74          * we find.  RISC-V ISA strings define an order, so we only print the
  75          * extension bits when they're in order. Hide the supervisor (S)
  76          * extension from userspace as it's not accessible from there.
  77          */
  78         for (e = ext; *e != '\0'; ++e) {
  79                 if (isa[0] == e[0]) {
  80                         if (isa[0] != 's')
  81                                 seq_write(f, isa, 1);
  82
  83                         isa++;
  84                 }
  85         }
  86         seq_puts(f, "\n");
  87
  88         /*
  89          * If we were given an unsupported ISA in the device tree then print
  90          * a bit of info describing what went wrong.
  91          */
  92         if (isa[0] != '\0')
  93                 pr_info("unsupported ISA \"%s\" in device tree\n", orig_isa);
  94 }
  95
  96 static void print_mmu(struct seq_file *f, const char *mmu_type)
  97 {
  98 #if defined(CONFIG_32BIT)
  99         if (strcmp(mmu_type, "riscv,sv32") != 0)
 100                 return;
 101 #elif defined(CONFIG_64BIT)
 102         if (strcmp(mmu_type, "riscv,sv39") != 0 &&
 103             strcmp(mmu_type, "riscv,sv48") != 0)
 104                 return;
 105 #endif
 106
 107         seq_printf(f, "mmu\t\t: %s\n", mmu_type+6);
 108 }
 109
 110 static void *c_start(struct seq_file *m, loff_t *pos)
 111 {
 112         *pos = cpumask_next(*pos - 1, cpu_online_mask);
 113         if ((*pos) < nr_cpu_ids)
 114                 return (void *)(uintptr_t)(1 + *pos);
 115         return NULL;
 116 }
 117
 118 static void *c_next(struct seq_file *m, void *v, loff_t *pos)
 119 {
 120         (*pos)++;
 121         return c_start(m, pos);
 122 }
 123
 124 static void c_stop(struct seq_file *m, void *v)
 125 {
 126 }
 127
 128 static int c_show(struct seq_file *m, void *v)
 129 {
 130         unsigned long cpu_id = (unsigned long)v - 1;
 131         struct device_node *node = of_get_cpu_node(cpu_id, NULL);
 132         const char *compat, *isa, *mmu;
 133
 134         seq_printf(m, "processor\t: %lu\n", cpu_id);
 135         seq_printf(m, "hart\t\t: %lu\n", cpuid_to_hartid_map(cpu_id));
 136         if (!of_property_read_string(node, "riscv,isa", &isa))
 137                 print_isa(m, isa);
 138         if (!of_property_read_string(node, "mmu-type", &mmu))
 139                 print_mmu(m, mmu);
 140         if (!of_property_read_string(node, "compatible", &compat)
 141             && strcmp(compat, "riscv"))
 142                 seq_printf(m, "uarch\t\t: %s\n", compat);
 143         seq_puts(m, "\n");
 144         of_node_put(node);
 145
 146         return 0;
 147 }
 148
 149 const struct seq_operations cpuinfo_op = {
 150         .start  = c_start,
 151         .next   = c_next,
 152         .stop   = c_stop,
 153         .show   = c_show
 154 };
 155
 156 #endif /* CONFIG_PROC_FS */