1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * CMOS/NV-RAM driver for Atari. Adapted from drivers/char/nvram.c. 4 * Copyright (C) 1997 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de> 5 * idea by and with help from Richard Jelinek <rj@suse.de> 6 * Portions copyright (c) 2001,2002 Sun Microsystems (thockin@sun.com) 7 * Further contributions from Cesar Barros, Erik Gilling, Tim Hockin and 8 * Wim Van Sebroeck. 9 */ 10 11 #include <linux/errno.h> 12 #include <linux/init.h> 13 #include <linux/mc146818rtc.h> 14 #include <linux/module.h> 15 #include <linux/nvram.h> 16 #include <linux/proc_fs.h> 17 #include <linux/seq_file.h> 18 #include <linux/spinlock.h> 19 #include <linux/types.h> 20 #include <asm/atarihw.h> 21 #include <asm/atariints.h> 22 23 #define NVRAM_BYTES 50 24 25 /* It is worth noting that these functions all access bytes of general 26 * purpose memory in the NVRAM - that is to say, they all add the 27 * NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not 28 * know about the RTC cruft. 29 */ 30 31 /* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with 32 * rtc_lock held. Due to the index-port/data-port design of the RTC, we 33 * don't want two different things trying to get to it at once. (e.g. the 34 * periodic 11 min sync from kernel/time/ntp.c vs. this driver.) 35 */ 36 37 static unsigned char __nvram_read_byte(int i) 38 { 39 return CMOS_READ(NVRAM_FIRST_BYTE + i); 40 } 41 42 /* This races nicely with trying to read with checksum checking */ 43 static void __nvram_write_byte(unsigned char c, int i) 44 { 45 CMOS_WRITE(c, NVRAM_FIRST_BYTE + i); 46 } 47 48 /* On Ataris, the checksum is over all bytes except the checksum bytes 49 * themselves; these are at the very end. 50 */ 51 #define ATARI_CKS_RANGE_START 0 52 #define ATARI_CKS_RANGE_END 47 53 #define ATARI_CKS_LOC 48 54 55 static int __nvram_check_checksum(void) 56 { 57 int i; 58 unsigned char sum = 0; 59 60 for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i) 61 sum += __nvram_read_byte(i); 62 return (__nvram_read_byte(ATARI_CKS_LOC) == (~sum & 0xff)) && 63 (__nvram_read_byte(ATARI_CKS_LOC + 1) == (sum & 0xff)); 64 } 65 66 static void __nvram_set_checksum(void) 67 { 68 int i; 69 unsigned char sum = 0; 70 71 for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i) 72 sum += __nvram_read_byte(i); 73 __nvram_write_byte(~sum, ATARI_CKS_LOC); 74 __nvram_write_byte(sum, ATARI_CKS_LOC + 1); 75 } 76 77 long atari_nvram_set_checksum(void) 78 { 79 spin_lock_irq(&rtc_lock); 80 __nvram_set_checksum(); 81 spin_unlock_irq(&rtc_lock); 82 return 0; 83 } 84 85 long atari_nvram_initialize(void) 86 { 87 loff_t i; 88 89 spin_lock_irq(&rtc_lock); 90 for (i = 0; i < NVRAM_BYTES; ++i) 91 __nvram_write_byte(0, i); 92 __nvram_set_checksum(); 93 spin_unlock_irq(&rtc_lock); 94 return 0; 95 } 96 97 ssize_t atari_nvram_read(char *buf, size_t count, loff_t *ppos) 98 { 99 char *p = buf; 100 loff_t i; 101 102 spin_lock_irq(&rtc_lock); 103 if (!__nvram_check_checksum()) { 104 spin_unlock_irq(&rtc_lock); 105 return -EIO; 106 } 107 for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) 108 *p = __nvram_read_byte(i); 109 spin_unlock_irq(&rtc_lock); 110 111 *ppos = i; 112 return p - buf; 113 } 114 115 ssize_t atari_nvram_write(char *buf, size_t count, loff_t *ppos) 116 { 117 char *p = buf; 118 loff_t i; 119 120 spin_lock_irq(&rtc_lock); 121 if (!__nvram_check_checksum()) { 122 spin_unlock_irq(&rtc_lock); 123 return -EIO; 124 } 125 for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) 126 __nvram_write_byte(*p, i); 127 __nvram_set_checksum(); 128 spin_unlock_irq(&rtc_lock); 129 130 *ppos = i; 131 return p - buf; 132 } 133 134 ssize_t atari_nvram_get_size(void) 135 { 136 return NVRAM_BYTES; 137 } 138 139 #ifdef CONFIG_PROC_FS 140 static struct { 141 unsigned char val; 142 const char *name; 143 } boot_prefs[] = { 144 { 0x80, "TOS" }, 145 { 0x40, "ASV" }, 146 { 0x20, "NetBSD (?)" }, 147 { 0x10, "Linux" }, 148 { 0x00, "unspecified" }, 149 }; 150 151 static const char * const languages[] = { 152 "English (US)", 153 "German", 154 "French", 155 "English (UK)", 156 "Spanish", 157 "Italian", 158 "6 (undefined)", 159 "Swiss (French)", 160 "Swiss (German)", 161 }; 162 163 static const char * const dateformat[] = { 164 "MM%cDD%cYY", 165 "DD%cMM%cYY", 166 "YY%cMM%cDD", 167 "YY%cDD%cMM", 168 "4 (undefined)", 169 "5 (undefined)", 170 "6 (undefined)", 171 "7 (undefined)", 172 }; 173 174 static const char * const colors[] = { 175 "2", "4", "16", "256", "65536", "??", "??", "??" 176 }; 177 178 static void atari_nvram_proc_read(unsigned char *nvram, struct seq_file *seq, 179 void *offset) 180 { 181 int checksum; 182 int i; 183 unsigned int vmode; 184 185 spin_lock_irq(&rtc_lock); 186 checksum = __nvram_check_checksum(); 187 spin_unlock_irq(&rtc_lock); 188 189 seq_printf(seq, "Checksum status : %svalid\n", checksum ? "" : "not "); 190 191 seq_puts(seq, "Boot preference : "); 192 for (i = ARRAY_SIZE(boot_prefs) - 1; i >= 0; --i) 193 if (nvram[1] == boot_prefs[i].val) { 194 seq_printf(seq, "%s\n", boot_prefs[i].name); 195 break; 196 } 197 if (i < 0) 198 seq_printf(seq, "0x%02x (undefined)\n", nvram[1]); 199 200 seq_printf(seq, "SCSI arbitration : %s\n", 201 (nvram[16] & 0x80) ? "on" : "off"); 202 seq_puts(seq, "SCSI host ID : "); 203 if (nvram[16] & 0x80) 204 seq_printf(seq, "%d\n", nvram[16] & 7); 205 else 206 seq_puts(seq, "n/a\n"); 207 208 if (!MACH_IS_FALCON) 209 return; 210 211 seq_puts(seq, "OS language : "); 212 if (nvram[6] < ARRAY_SIZE(languages)) 213 seq_printf(seq, "%s\n", languages[nvram[6]]); 214 else 215 seq_printf(seq, "%u (undefined)\n", nvram[6]); 216 seq_puts(seq, "Keyboard language: "); 217 if (nvram[7] < ARRAY_SIZE(languages)) 218 seq_printf(seq, "%s\n", languages[nvram[7]]); 219 else 220 seq_printf(seq, "%u (undefined)\n", nvram[7]); 221 seq_puts(seq, "Date format : "); 222 seq_printf(seq, dateformat[nvram[8] & 7], 223 nvram[9] ? nvram[9] : '/', nvram[9] ? nvram[9] : '/'); 224 seq_printf(seq, ", %dh clock\n", nvram[8] & 16 ? 24 : 12); 225 seq_puts(seq, "Boot delay : "); 226 if (nvram[10] == 0) 227 seq_puts(seq, "default\n"); 228 else 229 seq_printf(seq, "%ds%s\n", nvram[10], 230 nvram[10] < 8 ? ", no memory test" : ""); 231 232 vmode = (nvram[14] << 8) | nvram[15]; 233 seq_printf(seq, 234 "Video mode : %s colors, %d columns, %s %s monitor\n", 235 colors[vmode & 7], vmode & 8 ? 80 : 40, 236 vmode & 16 ? "VGA" : "TV", vmode & 32 ? "PAL" : "NTSC"); 237 seq_printf(seq, 238 " %soverscan, compat. mode %s%s\n", 239 vmode & 64 ? "" : "no ", vmode & 128 ? "on" : "off", 240 vmode & 256 ? 241 (vmode & 16 ? ", line doubling" : ", half screen") : ""); 242 } 243 244 static int nvram_proc_read(struct seq_file *seq, void *offset) 245 { 246 unsigned char contents[NVRAM_BYTES]; 247 int i; 248 249 spin_lock_irq(&rtc_lock); 250 for (i = 0; i < NVRAM_BYTES; ++i) 251 contents[i] = __nvram_read_byte(i); 252 spin_unlock_irq(&rtc_lock); 253 254 atari_nvram_proc_read(contents, seq, offset); 255 256 return 0; 257 } 258 259 static int __init atari_nvram_init(void) 260 { 261 if (!(MACH_IS_ATARI && ATARIHW_PRESENT(TT_CLK))) 262 return -ENODEV; 263 264 if (!proc_create_single("driver/nvram", 0, NULL, nvram_proc_read)) { 265 pr_err("nvram: can't create /proc/driver/nvram\n"); 266 return -ENOMEM; 267 } 268 269 return 0; 270 } 271 device_initcall(atari_nvram_init); 272 #endif /* CONFIG_PROC_FS */ 273