xref: /openbmc/linux/arch/s390/boot/als.c (revision 17e89e13)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *    Copyright IBM Corp. 2016
4  */
5 #include <linux/kernel.h>
6 #include <asm/processor.h>
7 #include <asm/facility.h>
8 #include <asm/lowcore.h>
9 #include <asm/sclp.h>
10 #include "boot.h"
11 
12 /*
13  * The code within this file will be called very early. It may _not_
14  * access anything within the bss section, since that is not cleared
15  * yet and may contain data (e.g. initrd) that must be saved by other
16  * code.
17  * For temporary objects the stack (16k) should be used.
18  */
19 
20 static unsigned long als[] = { FACILITIES_ALS };
21 
u16_to_hex(char * str,u16 val)22 static void u16_to_hex(char *str, u16 val)
23 {
24 	int i, num;
25 
26 	for (i = 1; i <= 4; i++) {
27 		num = (val >> (16 - 4 * i)) & 0xf;
28 		if (num >= 10)
29 			num += 7;
30 		*str++ = '0' + num;
31 	}
32 	*str = '\0';
33 }
34 
print_machine_type(void)35 static void print_machine_type(void)
36 {
37 	static char mach_str[80] = "Detected machine-type number: ";
38 	char type_str[5];
39 	struct cpuid id;
40 
41 	get_cpu_id(&id);
42 	u16_to_hex(type_str, id.machine);
43 	strcat(mach_str, type_str);
44 	strcat(mach_str, "\n");
45 	sclp_early_printk(mach_str);
46 }
47 
u16_to_decimal(char * str,u16 val)48 static void u16_to_decimal(char *str, u16 val)
49 {
50 	int div = 1;
51 
52 	while (div * 10 <= val)
53 		div *= 10;
54 	while (div) {
55 		*str++ = '0' + val / div;
56 		val %= div;
57 		div /= 10;
58 	}
59 	*str = '\0';
60 }
61 
print_missing_facilities(void)62 void print_missing_facilities(void)
63 {
64 	static char als_str[80] = "Missing facilities: ";
65 	unsigned long val;
66 	char val_str[6];
67 	int i, j, first;
68 
69 	first = 1;
70 	for (i = 0; i < ARRAY_SIZE(als); i++) {
71 		val = ~stfle_fac_list[i] & als[i];
72 		for (j = 0; j < BITS_PER_LONG; j++) {
73 			if (!(val & (1UL << (BITS_PER_LONG - 1 - j))))
74 				continue;
75 			if (!first)
76 				strcat(als_str, ",");
77 			/*
78 			 * Make sure we stay within one line. Consider that
79 			 * each facility bit adds up to five characters and
80 			 * z/VM adds a four character prefix.
81 			 */
82 			if (strlen(als_str) > 70) {
83 				strcat(als_str, "\n");
84 				sclp_early_printk(als_str);
85 				*als_str = '\0';
86 			}
87 			u16_to_decimal(val_str, i * BITS_PER_LONG + j);
88 			strcat(als_str, val_str);
89 			first = 0;
90 		}
91 	}
92 	strcat(als_str, "\n");
93 	sclp_early_printk(als_str);
94 }
95 
facility_mismatch(void)96 static void facility_mismatch(void)
97 {
98 	sclp_early_printk("The Linux kernel requires more recent processor hardware\n");
99 	print_machine_type();
100 	print_missing_facilities();
101 	sclp_early_printk("See Principles of Operations for facility bits\n");
102 	disabled_wait();
103 }
104 
verify_facilities(void)105 void verify_facilities(void)
106 {
107 	int i;
108 
109 	__stfle(stfle_fac_list, ARRAY_SIZE(stfle_fac_list));
110 	for (i = 0; i < ARRAY_SIZE(als); i++) {
111 		if ((stfle_fac_list[i] & als[i]) != als[i])
112 			facility_mismatch();
113 	}
114 }
115