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/string_choices.h> 20 #include <linux/types.h> 21 22 #include <asm/atarihw.h> 23 #include <asm/atariints.h> 24 25 #define NVRAM_BYTES 50 26 27 /* It is worth noting that these functions all access bytes of general 28 * purpose memory in the NVRAM - that is to say, they all add the 29 * NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not 30 * know about the RTC cruft. 31 */ 32 33 /* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with 34 * rtc_lock held. Due to the index-port/data-port design of the RTC, we 35 * don't want two different things trying to get to it at once. (e.g. the 36 * periodic 11 min sync from kernel/time/ntp.c vs. this driver.) 37 */ 38 39 static unsigned char __nvram_read_byte(int i) 40 { 41 return CMOS_READ(NVRAM_FIRST_BYTE + i); 42 } 43 44 /* This races nicely with trying to read with checksum checking */ 45 static void __nvram_write_byte(unsigned char c, int i) 46 { 47 CMOS_WRITE(c, NVRAM_FIRST_BYTE + i); 48 } 49 50 /* On Ataris, the checksum is over all bytes except the checksum bytes 51 * themselves; these are at the very end. 52 */ 53 #define ATARI_CKS_RANGE_START 0 54 #define ATARI_CKS_RANGE_END 47 55 #define ATARI_CKS_LOC 48 56 57 static int __nvram_check_checksum(void) 58 { 59 int i; 60 unsigned char sum = 0; 61 62 for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i) 63 sum += __nvram_read_byte(i); 64 return (__nvram_read_byte(ATARI_CKS_LOC) == (~sum & 0xff)) && 65 (__nvram_read_byte(ATARI_CKS_LOC + 1) == (sum & 0xff)); 66 } 67 68 static void __nvram_set_checksum(void) 69 { 70 int i; 71 unsigned char sum = 0; 72 73 for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i) 74 sum += __nvram_read_byte(i); 75 __nvram_write_byte(~sum, ATARI_CKS_LOC); 76 __nvram_write_byte(sum, ATARI_CKS_LOC + 1); 77 } 78 79 long atari_nvram_set_checksum(void) 80 { 81 spin_lock_irq(&rtc_lock); 82 __nvram_set_checksum(); 83 spin_unlock_irq(&rtc_lock); 84 return 0; 85 } 86 87 long atari_nvram_initialize(void) 88 { 89 loff_t i; 90 91 spin_lock_irq(&rtc_lock); 92 for (i = 0; i < NVRAM_BYTES; ++i) 93 __nvram_write_byte(0, i); 94 __nvram_set_checksum(); 95 spin_unlock_irq(&rtc_lock); 96 return 0; 97 } 98 99 ssize_t atari_nvram_read(char *buf, size_t count, loff_t *ppos) 100 { 101 char *p = buf; 102 loff_t i; 103 104 spin_lock_irq(&rtc_lock); 105 if (!__nvram_check_checksum()) { 106 spin_unlock_irq(&rtc_lock); 107 return -EIO; 108 } 109 for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) 110 *p = __nvram_read_byte(i); 111 spin_unlock_irq(&rtc_lock); 112 113 *ppos = i; 114 return p - buf; 115 } 116 117 ssize_t atari_nvram_write(char *buf, size_t count, loff_t *ppos) 118 { 119 char *p = buf; 120 loff_t i; 121 122 spin_lock_irq(&rtc_lock); 123 if (!__nvram_check_checksum()) { 124 spin_unlock_irq(&rtc_lock); 125 return -EIO; 126 } 127 for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) 128 __nvram_write_byte(*p, i); 129 __nvram_set_checksum(); 130 spin_unlock_irq(&rtc_lock); 131 132 *ppos = i; 133 return p - buf; 134 } 135 136 ssize_t atari_nvram_get_size(void) 137 { 138 return NVRAM_BYTES; 139 } 140 141 #ifdef CONFIG_PROC_FS 142 static struct { 143 unsigned char val; 144 const char *name; 145 } boot_prefs[] = { 146 { 0x80, "TOS" }, 147 { 0x40, "ASV" }, 148 { 0x20, "NetBSD (?)" }, 149 { 0x10, "Linux" }, 150 { 0x00, "unspecified" }, 151 }; 152 153 static const char * const languages[] = { 154 "English (US)", 155 "German", 156 "French", 157 "English (UK)", 158 "Spanish", 159 "Italian", 160 "6 (undefined)", 161 "Swiss (French)", 162 "Swiss (German)", 163 }; 164 165 static const char * const dateformat[] = { 166 "MM%cDD%cYY", 167 "DD%cMM%cYY", 168 "YY%cMM%cDD", 169 "YY%cDD%cMM", 170 "4 (undefined)", 171 "5 (undefined)", 172 "6 (undefined)", 173 "7 (undefined)", 174 }; 175 176 static const char * const colors[] = { 177 "2", "4", "16", "256", "65536", "??", "??", "??" 178 }; 179 180 static void atari_nvram_proc_read(unsigned char *nvram, struct seq_file *seq, 181 void *offset) 182 { 183 int checksum; 184 int i; 185 unsigned int vmode; 186 187 spin_lock_irq(&rtc_lock); 188 checksum = __nvram_check_checksum(); 189 spin_unlock_irq(&rtc_lock); 190 191 seq_printf(seq, "Checksum status : %svalid\n", checksum ? "" : "not "); 192 193 seq_puts(seq, "Boot preference : "); 194 for (i = ARRAY_SIZE(boot_prefs) - 1; i >= 0; --i) 195 if (nvram[1] == boot_prefs[i].val) { 196 seq_printf(seq, "%s\n", boot_prefs[i].name); 197 break; 198 } 199 if (i < 0) 200 seq_printf(seq, "0x%02x (undefined)\n", nvram[1]); 201 202 seq_printf(seq, "SCSI arbitration : %s\n", 203 str_on_off(nvram[16] & 0x80)); 204 seq_puts(seq, "SCSI host ID : "); 205 if (nvram[16] & 0x80) 206 seq_printf(seq, "%d\n", nvram[16] & 7); 207 else 208 seq_puts(seq, "n/a\n"); 209 210 if (!MACH_IS_FALCON) 211 return; 212 213 seq_puts(seq, "OS language : "); 214 if (nvram[6] < ARRAY_SIZE(languages)) 215 seq_printf(seq, "%s\n", languages[nvram[6]]); 216 else 217 seq_printf(seq, "%u (undefined)\n", nvram[6]); 218 seq_puts(seq, "Keyboard language: "); 219 if (nvram[7] < ARRAY_SIZE(languages)) 220 seq_printf(seq, "%s\n", languages[nvram[7]]); 221 else 222 seq_printf(seq, "%u (undefined)\n", nvram[7]); 223 seq_puts(seq, "Date format : "); 224 seq_printf(seq, dateformat[nvram[8] & 7], 225 nvram[9] ? nvram[9] : '/', nvram[9] ? nvram[9] : '/'); 226 seq_printf(seq, ", %dh clock\n", nvram[8] & 16 ? 24 : 12); 227 seq_puts(seq, "Boot delay : "); 228 if (nvram[10] == 0) 229 seq_puts(seq, "default\n"); 230 else 231 seq_printf(seq, "%ds%s\n", nvram[10], 232 nvram[10] < 8 ? ", no memory test" : ""); 233 234 vmode = (nvram[14] << 8) | nvram[15]; 235 seq_printf(seq, 236 "Video mode : %s colors, %d columns, %s %s monitor\n", 237 colors[vmode & 7], vmode & 8 ? 80 : 40, 238 vmode & 16 ? "VGA" : "TV", vmode & 32 ? "PAL" : "NTSC"); 239 seq_printf(seq, 240 " %soverscan, compat. mode %s%s\n", 241 vmode & 64 ? "" : "no ", str_on_off(vmode & 128), 242 vmode & 256 ? 243 (vmode & 16 ? ", line doubling" : ", half screen") : ""); 244 } 245 246 static int nvram_proc_read(struct seq_file *seq, void *offset) 247 { 248 unsigned char contents[NVRAM_BYTES]; 249 int i; 250 251 spin_lock_irq(&rtc_lock); 252 for (i = 0; i < NVRAM_BYTES; ++i) 253 contents[i] = __nvram_read_byte(i); 254 spin_unlock_irq(&rtc_lock); 255 256 atari_nvram_proc_read(contents, seq, offset); 257 258 return 0; 259 } 260 261 static int __init atari_nvram_init(void) 262 { 263 if (!(MACH_IS_ATARI && ATARIHW_PRESENT(TT_CLK))) 264 return -ENODEV; 265 266 if (!proc_create_single("driver/nvram", 0, NULL, nvram_proc_read)) { 267 pr_err("nvram: can't create /proc/driver/nvram\n"); 268 return -ENOMEM; 269 } 270 271 return 0; 272 } 273 device_initcall(atari_nvram_init); 274 #endif /* CONFIG_PROC_FS */ 275