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