1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *	Implement 'Simple Boot Flag Specification 2.0'
  4 */
  5#include <linux/types.h>
  6#include <linux/kernel.h>
  7#include <linux/init.h>
  8#include <linux/string.h>
  9#include <linux/spinlock.h>
 10#include <linux/acpi.h>
 11#include <asm/io.h>
 12
 13#include <linux/mc146818rtc.h>
 14
 15#define SBF_RESERVED (0x78)
 16#define SBF_PNPOS    (1<<0)
 17#define SBF_BOOTING  (1<<1)
 18#define SBF_DIAG     (1<<2)
 19#define SBF_PARITY   (1<<7)
 20
 21int sbf_port __initdata = -1;	/* set via acpi_boot_init() */
 22
 23static int __init parity(u8 v)
 24{
 25	int x = 0;
 26	int i;
 27
 28	for (i = 0; i < 8; i++) {
 29		x ^= (v & 1);
 30		v >>= 1;
 31	}
 32
 33	return x;
 34}
 35
 36static void __init sbf_write(u8 v)
 37{
 38	unsigned long flags;
 39
 40	if (sbf_port != -1) {
 41		v &= ~SBF_PARITY;
 42		if (!parity(v))
 43			v |= SBF_PARITY;
 44
 45		printk(KERN_INFO "Simple Boot Flag at 0x%x set to 0x%x\n",
 46			sbf_port, v);
 47
 48		spin_lock_irqsave(&rtc_lock, flags);
 49		CMOS_WRITE(v, sbf_port);
 50		spin_unlock_irqrestore(&rtc_lock, flags);
 51	}
 52}
 53
 54static u8 __init sbf_read(void)
 55{
 56	unsigned long flags;
 57	u8 v;
 58
 59	if (sbf_port == -1)
 60		return 0;
 61
 62	spin_lock_irqsave(&rtc_lock, flags);
 63	v = CMOS_READ(sbf_port);
 64	spin_unlock_irqrestore(&rtc_lock, flags);
 65
 66	return v;
 67}
 68
 69static int __init sbf_value_valid(u8 v)
 70{
 71	if (v & SBF_RESERVED)		/* Reserved bits */
 72		return 0;
 73	if (!parity(v))
 74		return 0;
 75
 76	return 1;
 77}
 78
 79static int __init sbf_init(void)
 80{
 81	u8 v;
 82
 83	if (sbf_port == -1)
 84		return 0;
 85
 86	v = sbf_read();
 87	if (!sbf_value_valid(v)) {
 88		printk(KERN_WARNING "Simple Boot Flag value 0x%x read from "
 89			"CMOS RAM was invalid\n", v);
 90	}
 91
 92	v &= ~SBF_RESERVED;
 93	v &= ~SBF_BOOTING;
 94	v &= ~SBF_DIAG;
 95#if defined(CONFIG_ISAPNP)
 96	v |= SBF_PNPOS;
 97#endif
 98	sbf_write(v);
 99
100	return 0;
101}
102arch_initcall(sbf_init);

 
  1/*
  2 *	Implement 'Simple Boot Flag Specification 2.0'
  3 */
  4#include <linux/types.h>
  5#include <linux/kernel.h>
  6#include <linux/init.h>
  7#include <linux/string.h>
  8#include <linux/spinlock.h>
  9#include <linux/acpi.h>
 10#include <asm/io.h>
 11
 12#include <linux/mc146818rtc.h>
 13
 14#define SBF_RESERVED (0x78)
 15#define SBF_PNPOS    (1<<0)
 16#define SBF_BOOTING  (1<<1)
 17#define SBF_DIAG     (1<<2)
 18#define SBF_PARITY   (1<<7)
 19
 20int sbf_port __initdata = -1;	/* set via acpi_boot_init() */
 21
 22static int __init parity(u8 v)
 23{
 24	int x = 0;
 25	int i;
 26
 27	for (i = 0; i < 8; i++) {
 28		x ^= (v & 1);
 29		v >>= 1;
 30	}
 31
 32	return x;
 33}
 34
 35static void __init sbf_write(u8 v)
 36{
 37	unsigned long flags;
 38
 39	if (sbf_port != -1) {
 40		v &= ~SBF_PARITY;
 41		if (!parity(v))
 42			v |= SBF_PARITY;
 43
 44		printk(KERN_INFO "Simple Boot Flag at 0x%x set to 0x%x\n",
 45			sbf_port, v);
 46
 47		spin_lock_irqsave(&rtc_lock, flags);
 48		CMOS_WRITE(v, sbf_port);
 49		spin_unlock_irqrestore(&rtc_lock, flags);
 50	}
 51}
 52
 53static u8 __init sbf_read(void)
 54{
 55	unsigned long flags;
 56	u8 v;
 57
 58	if (sbf_port == -1)
 59		return 0;
 60
 61	spin_lock_irqsave(&rtc_lock, flags);
 62	v = CMOS_READ(sbf_port);
 63	spin_unlock_irqrestore(&rtc_lock, flags);
 64
 65	return v;
 66}
 67
 68static int __init sbf_value_valid(u8 v)
 69{
 70	if (v & SBF_RESERVED)		/* Reserved bits */
 71		return 0;
 72	if (!parity(v))
 73		return 0;
 74
 75	return 1;
 76}
 77
 78static int __init sbf_init(void)
 79{
 80	u8 v;
 81
 82	if (sbf_port == -1)
 83		return 0;
 84
 85	v = sbf_read();
 86	if (!sbf_value_valid(v)) {
 87		printk(KERN_WARNING "Simple Boot Flag value 0x%x read from "
 88			"CMOS RAM was invalid\n", v);
 89	}
 90
 91	v &= ~SBF_RESERVED;
 92	v &= ~SBF_BOOTING;
 93	v &= ~SBF_DIAG;
 94#if defined(CONFIG_ISAPNP)
 95	v |= SBF_PNPOS;
 96#endif
 97	sbf_write(v);
 98
 99	return 0;
100}
101module_init(sbf_init);