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// SPDX-License-Identifier: GPL-2.0+
/*
* CMOS/NV-RAM driver for Atari. Adapted from drivers/char/nvram.c.
* Copyright (C) 1997 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>
* idea by and with help from Richard Jelinek <rj@suse.de>
* Portions copyright (c) 2001,2002 Sun Microsystems (thockin@sun.com)
* Further contributions from Cesar Barros, Erik Gilling, Tim Hockin and
* Wim Van Sebroeck.
*/
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/mc146818rtc.h>
#include <linux/module.h>
#include <linux/nvram.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <asm/atarihw.h>
#include <asm/atariints.h>
#define NVRAM_BYTES 50
/* It is worth noting that these functions all access bytes of general
* purpose memory in the NVRAM - that is to say, they all add the
* NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not
* know about the RTC cruft.
*/
/* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with
* rtc_lock held. Due to the index-port/data-port design of the RTC, we
* don't want two different things trying to get to it at once. (e.g. the
* periodic 11 min sync from kernel/time/ntp.c vs. this driver.)
*/
static unsigned char __nvram_read_byte(int i)
{
return CMOS_READ(NVRAM_FIRST_BYTE + i);
}
/* This races nicely with trying to read with checksum checking */
static void __nvram_write_byte(unsigned char c, int i)
{
CMOS_WRITE(c, NVRAM_FIRST_BYTE + i);
}
/* On Ataris, the checksum is over all bytes except the checksum bytes
* themselves; these are at the very end.
*/
#define ATARI_CKS_RANGE_START 0
#define ATARI_CKS_RANGE_END 47
#define ATARI_CKS_LOC 48
static int __nvram_check_checksum(void)
{
int i;
unsigned char sum = 0;
for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i)
sum += __nvram_read_byte(i);
return (__nvram_read_byte(ATARI_CKS_LOC) == (~sum & 0xff)) &&
(__nvram_read_byte(ATARI_CKS_LOC + 1) == (sum & 0xff));
}
static void __nvram_set_checksum(void)
{
int i;
unsigned char sum = 0;
for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i)
sum += __nvram_read_byte(i);
__nvram_write_byte(~sum, ATARI_CKS_LOC);
__nvram_write_byte(sum, ATARI_CKS_LOC + 1);
}
long atari_nvram_set_checksum(void)
{
spin_lock_irq(&rtc_lock);
__nvram_set_checksum();
spin_unlock_irq(&rtc_lock);
return 0;
}
long atari_nvram_initialize(void)
{
loff_t i;
spin_lock_irq(&rtc_lock);
for (i = 0; i < NVRAM_BYTES; ++i)
__nvram_write_byte(0, i);
__nvram_set_checksum();
spin_unlock_irq(&rtc_lock);
return 0;
}
ssize_t atari_nvram_read(char *buf, size_t count, loff_t *ppos)
{
char *p = buf;
loff_t i;
spin_lock_irq(&rtc_lock);
if (!__nvram_check_checksum()) {
spin_unlock_irq(&rtc_lock);
return -EIO;
}
for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p)
*p = __nvram_read_byte(i);
spin_unlock_irq(&rtc_lock);
*ppos = i;
return p - buf;
}
ssize_t atari_nvram_write(char *buf, size_t count, loff_t *ppos)
{
char *p = buf;
loff_t i;
spin_lock_irq(&rtc_lock);
if (!__nvram_check_checksum()) {
spin_unlock_irq(&rtc_lock);
return -EIO;
}
for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p)
__nvram_write_byte(*p, i);
__nvram_set_checksum();
spin_unlock_irq(&rtc_lock);
*ppos = i;
return p - buf;
}
ssize_t atari_nvram_get_size(void)
{
return NVRAM_BYTES;
}
#ifdef CONFIG_PROC_FS
static struct {
unsigned char val;
const char *name;
} boot_prefs[] = {
{ 0x80, "TOS" },
{ 0x40, "ASV" },
{ 0x20, "NetBSD (?)" },
{ 0x10, "Linux" },
{ 0x00, "unspecified" },
};
static const char * const languages[] = {
"English (US)",
"German",
"French",
"English (UK)",
"Spanish",
"Italian",
"6 (undefined)",
"Swiss (French)",
"Swiss (German)",
};
static const char * const dateformat[] = {
"MM%cDD%cYY",
"DD%cMM%cYY",
"YY%cMM%cDD",
"YY%cDD%cMM",
"4 (undefined)",
"5 (undefined)",
"6 (undefined)",
"7 (undefined)",
};
static const char * const colors[] = {
"2", "4", "16", "256", "65536", "??", "??", "??"
};
static void atari_nvram_proc_read(unsigned char *nvram, struct seq_file *seq,
void *offset)
{
int checksum;
int i;
unsigned int vmode;
spin_lock_irq(&rtc_lock);
checksum = __nvram_check_checksum();
spin_unlock_irq(&rtc_lock);
seq_printf(seq, "Checksum status : %svalid\n", checksum ? "" : "not ");
seq_puts(seq, "Boot preference : ");
for (i = ARRAY_SIZE(boot_prefs) - 1; i >= 0; --i)
if (nvram[1] == boot_prefs[i].val) {
seq_printf(seq, "%s\n", boot_prefs[i].name);
break;
}
if (i < 0)
seq_printf(seq, "0x%02x (undefined)\n", nvram[1]);
seq_printf(seq, "SCSI arbitration : %s\n",
(nvram[16] & 0x80) ? "on" : "off");
seq_puts(seq, "SCSI host ID : ");
if (nvram[16] & 0x80)
seq_printf(seq, "%d\n", nvram[16] & 7);
else
seq_puts(seq, "n/a\n");
if (!MACH_IS_FALCON)
return;
seq_puts(seq, "OS language : ");
if (nvram[6] < ARRAY_SIZE(languages))
seq_printf(seq, "%s\n", languages[nvram[6]]);
else
seq_printf(seq, "%u (undefined)\n", nvram[6]);
seq_puts(seq, "Keyboard language: ");
if (nvram[7] < ARRAY_SIZE(languages))
seq_printf(seq, "%s\n", languages[nvram[7]]);
else
seq_printf(seq, "%u (undefined)\n", nvram[7]);
seq_puts(seq, "Date format : ");
seq_printf(seq, dateformat[nvram[8] & 7],
nvram[9] ? nvram[9] : '/', nvram[9] ? nvram[9] : '/');
seq_printf(seq, ", %dh clock\n", nvram[8] & 16 ? 24 : 12);
seq_puts(seq, "Boot delay : ");
if (nvram[10] == 0)
seq_puts(seq, "default\n");
else
seq_printf(seq, "%ds%s\n", nvram[10],
nvram[10] < 8 ? ", no memory test" : "");
vmode = (nvram[14] << 8) | nvram[15];
seq_printf(seq,
"Video mode : %s colors, %d columns, %s %s monitor\n",
colors[vmode & 7], vmode & 8 ? 80 : 40,
vmode & 16 ? "VGA" : "TV", vmode & 32 ? "PAL" : "NTSC");
seq_printf(seq,
" %soverscan, compat. mode %s%s\n",
vmode & 64 ? "" : "no ", vmode & 128 ? "on" : "off",
vmode & 256 ?
(vmode & 16 ? ", line doubling" : ", half screen") : "");
}
static int nvram_proc_read(struct seq_file *seq, void *offset)
{
unsigned char contents[NVRAM_BYTES];
int i;
spin_lock_irq(&rtc_lock);
for (i = 0; i < NVRAM_BYTES; ++i)
contents[i] = __nvram_read_byte(i);
spin_unlock_irq(&rtc_lock);
atari_nvram_proc_read(contents, seq, offset);
return 0;
}
static int __init atari_nvram_init(void)
{
if (!(MACH_IS_ATARI && ATARIHW_PRESENT(TT_CLK)))
return -ENODEV;
if (!proc_create_single("driver/nvram", 0, NULL, nvram_proc_read)) {
pr_err("nvram: can't create /proc/driver/nvram\n");
return -ENOMEM;
}
return 0;
}
device_initcall(atari_nvram_init);
#endif /* CONFIG_PROC_FS */
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