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
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