LXR linux/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
  27static char *cpu_mid_prop(void)
  28{
  29        if (sparc_cpu_model == sun4d)
  30                return "cpu-id";
  31        return "mid";
  32}
  33
  34static 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
  54static 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
  74static 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
  83int 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
  89static 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
 101int 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 */
 111int cpu_get_hwmid(phandle prom_node)
 112{
 113        return prom_getintdefault(prom_node, cpu_mid_prop(), -ENODEV);
 114}
 115
 116void __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}
 139