arch/sparc/kernel/devices.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* devices.c: Initial scan of the prom device tree for important
   3  *            Sparc device nodes which we need to find.
   4  *
   5  * This is based on the sparc64 version, but sun4m doesn't always use
   6  * the hardware MIDs, so be careful.
   7  *
   8  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/threads.h>
  13 #include <linux/string.h>
  14 #include <linux/init.h>
  15 #include <linux/errno.h>
  16
  17 #include <asm/page.h>
  18 #include <asm/oplib.h>
  19 #include <asm/prom.h>
  20 #include <asm/smp.h>
  21 #include <asm/cpudata.h>
  22 #include <asm/cpu_type.h>
  23 #include <asm/setup.h>
  24
  25 #include "kernel.h"
  26
  27 static char *cpu_mid_prop(void)
  28 {
  29         if (sparc_cpu_model == sun4d)
  30                 return "cpu-id";
  31         return "mid";
  32 }
  33
  34 static int check_cpu_node(phandle nd, int *cur_inst,
  35                 int (*compare)(phandle, int, void *), void *compare_arg,
  36                 phandle *prom_node, int *mid)
  37 {
  38         if (!compare(nd, *cur_inst, compare_arg)) {
  39                 if (prom_node)
  40                         *prom_node = nd;
  41                 if (mid) {
  42                         *mid = prom_getintdefault(nd, cpu_mid_prop(), 0);
  43                         if (sparc_cpu_model == sun4m)
  44                                 *mid &= 3;
  45                 }
  46                 return 0;
  47         }
  48
  49         (*cur_inst)++;
  50
  51         return -ENODEV;
  52 }
  53
  54 static int __cpu_find_by(int (*compare)(phandle, int, void *),
  55                 void *compare_arg, phandle *prom_node, int *mid)
  56 {
  57         struct device_node *dp;
  58         int cur_inst;
  59
  60         cur_inst = 0;
  61         for_each_node_by_type(dp, "cpu") {
  62                 int err = check_cpu_node(dp->phandle, &cur_inst,
  63                                          compare, compare_arg,
  64                                          prom_node, mid);
  65                 if (!err) {
  66                         of_node_put(dp);
  67                         return 0;
  68                 }
  69         }
  70
  71         return -ENODEV;
  72 }
  73
  74 static int cpu_instance_compare(phandle nd, int instance, void *_arg)
  75 {
  76         int desired_instance = (int) _arg;
  77
  78         if (instance == desired_instance)
  79                 return 0;
  80         return -ENODEV;
  81 }
  82
  83 int cpu_find_by_instance(int instance, phandle *prom_node, int *mid)
  84 {
  85         return __cpu_find_by(cpu_instance_compare, (void *)instance,
  86                              prom_node, mid);
  87 }
  88
  89 static int cpu_mid_compare(phandle nd, int instance, void *_arg)
  90 {
  91         int desired_mid = (int) _arg;
  92         int this_mid;
  93
  94         this_mid = prom_getintdefault(nd, cpu_mid_prop(), 0);
  95         if (this_mid == desired_mid
  96             || (sparc_cpu_model == sun4m && (this_mid & 3) == desired_mid))
  97                 return 0;
  98         return -ENODEV;
  99 }
 100
 101 int cpu_find_by_mid(int mid, phandle *prom_node)
 102 {
 103         return __cpu_find_by(cpu_mid_compare, (void *)mid,
 104                              prom_node, NULL);
 105 }
 106
 107 /* sun4m uses truncated mids since we base the cpuid on the ttable/irqset
 108  * address (0-3).  This gives us the true hardware mid, which might have
 109  * some other bits set.  On 4d hardware and software mids are the same.
 110  */
 111 int cpu_get_hwmid(phandle prom_node)
 112 {
 113         return prom_getintdefault(prom_node, cpu_mid_prop(), -ENODEV);
 114 }
 115
 116 void __init device_scan(void)
 117 {
 118         printk(KERN_NOTICE "Booting Linux...\n");
 119
 120 #ifndef CONFIG_SMP
 121         {
 122                 phandle cpu_node;
 123                 int err;
 124                 err = cpu_find_by_instance(0, &cpu_node, NULL);
 125                 if (err) {
 126                         /* Probably a sun4e, Sun is trying to trick us ;-) */
 127                         prom_printf("No cpu nodes, cannot continue\n");
 128                         prom_halt();
 129                 }
 130                 cpu_data(0).clock_tick = prom_getintdefault(cpu_node,
 131                                                             "clock-frequency",
 132                                                             0);
 133         }
 134 #endif /* !CONFIG_SMP */
 135
 136         auxio_probe();
 137         auxio_power_probe();
 138 }