1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * w1_ds2431.c - w1 family 2d (DS2431) driver
4 *
5 * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>
6 *
7 * Heavily inspired by w1_DS2433 driver from Ben Gardner <bgardner@wabtec.com>
8 */
9
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/moduleparam.h>
13 #include <linux/device.h>
14 #include <linux/types.h>
15 #include <linux/delay.h>
16
17 #include <linux/w1.h>
18
19 #define W1_EEPROM_DS2431 0x2D
20
21 #define W1_F2D_EEPROM_SIZE 128
22 #define W1_F2D_PAGE_COUNT 4
23 #define W1_F2D_PAGE_BITS 5
24 #define W1_F2D_PAGE_SIZE (1<<W1_F2D_PAGE_BITS)
25 #define W1_F2D_PAGE_MASK 0x1F
26
27 #define W1_F2D_SCRATCH_BITS 3
28 #define W1_F2D_SCRATCH_SIZE (1<<W1_F2D_SCRATCH_BITS)
29 #define W1_F2D_SCRATCH_MASK (W1_F2D_SCRATCH_SIZE-1)
30
31 #define W1_F2D_READ_EEPROM 0xF0
32 #define W1_F2D_WRITE_SCRATCH 0x0F
33 #define W1_F2D_READ_SCRATCH 0xAA
34 #define W1_F2D_COPY_SCRATCH 0x55
35
36
37 #define W1_F2D_TPROG_MS 11
38
39 #define W1_F2D_READ_RETRIES 10
40 #define W1_F2D_READ_MAXLEN 8
41
42 /*
43 * Check the file size bounds and adjusts count as needed.
44 * This would not be needed if the file size didn't reset to 0 after a write.
45 */
w1_f2d_fix_count(loff_t off,size_t count,size_t size)46 static inline size_t w1_f2d_fix_count(loff_t off, size_t count, size_t size)
47 {
48 if (off > size)
49 return 0;
50
51 if ((off + count) > size)
52 return size - off;
53
54 return count;
55 }
56
57 /*
58 * Read a block from W1 ROM two times and compares the results.
59 * If they are equal they are returned, otherwise the read
60 * is repeated W1_F2D_READ_RETRIES times.
61 *
62 * count must not exceed W1_F2D_READ_MAXLEN.
63 */
w1_f2d_readblock(struct w1_slave * sl,int off,int count,char * buf)64 static int w1_f2d_readblock(struct w1_slave *sl, int off, int count, char *buf)
65 {
66 u8 wrbuf[3];
67 u8 cmp[W1_F2D_READ_MAXLEN];
68 int tries = W1_F2D_READ_RETRIES;
69
70 do {
71 wrbuf[0] = W1_F2D_READ_EEPROM;
72 wrbuf[1] = off & 0xff;
73 wrbuf[2] = off >> 8;
74
75 if (w1_reset_select_slave(sl))
76 return -1;
77
78 w1_write_block(sl->master, wrbuf, 3);
79 w1_read_block(sl->master, buf, count);
80
81 if (w1_reset_select_slave(sl))
82 return -1;
83
84 w1_write_block(sl->master, wrbuf, 3);
85 w1_read_block(sl->master, cmp, count);
86
87 if (!memcmp(cmp, buf, count))
88 return 0;
89 } while (--tries);
90
91 dev_err(&sl->dev, "proof reading failed %d times\n",
92 W1_F2D_READ_RETRIES);
93
94 return -1;
95 }
96
eeprom_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)97 static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
98 struct bin_attribute *bin_attr, char *buf,
99 loff_t off, size_t count)
100 {
101 struct w1_slave *sl = kobj_to_w1_slave(kobj);
102 int todo = count;
103
104 count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
105 if (count == 0)
106 return 0;
107
108 mutex_lock(&sl->master->bus_mutex);
109
110 /* read directly from the EEPROM in chunks of W1_F2D_READ_MAXLEN */
111 while (todo > 0) {
112 int block_read;
113
114 if (todo >= W1_F2D_READ_MAXLEN)
115 block_read = W1_F2D_READ_MAXLEN;
116 else
117 block_read = todo;
118
119 if (w1_f2d_readblock(sl, off, block_read, buf) < 0)
120 count = -EIO;
121
122 todo -= W1_F2D_READ_MAXLEN;
123 buf += W1_F2D_READ_MAXLEN;
124 off += W1_F2D_READ_MAXLEN;
125 }
126
127 mutex_unlock(&sl->master->bus_mutex);
128
129 return count;
130 }
131
132 /*
133 * Writes to the scratchpad and reads it back for verification.
134 * Then copies the scratchpad to EEPROM.
135 * The data must be aligned at W1_F2D_SCRATCH_SIZE bytes and
136 * must be W1_F2D_SCRATCH_SIZE bytes long.
137 * The master must be locked.
138 *
139 * @param sl The slave structure
140 * @param addr Address for the write
141 * @param len length must be <= (W1_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK))
142 * @param data The data to write
143 * @return 0=Success -1=failure
144 */
w1_f2d_write(struct w1_slave * sl,int addr,int len,const u8 * data)145 static int w1_f2d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
146 {
147 int tries = W1_F2D_READ_RETRIES;
148 u8 wrbuf[4];
149 u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3];
150 u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE;
151
152 retry:
153
154 /* Write the data to the scratchpad */
155 if (w1_reset_select_slave(sl))
156 return -1;
157
158 wrbuf[0] = W1_F2D_WRITE_SCRATCH;
159 wrbuf[1] = addr & 0xff;
160 wrbuf[2] = addr >> 8;
161
162 w1_write_block(sl->master, wrbuf, 3);
163 w1_write_block(sl->master, data, len);
164
165 /* Read the scratchpad and verify */
166 if (w1_reset_select_slave(sl))
167 return -1;
168
169 w1_write_8(sl->master, W1_F2D_READ_SCRATCH);
170 w1_read_block(sl->master, rdbuf, len + 3);
171
172 /* Compare what was read against the data written */
173 if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
174 (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0)) {
175
176 if (--tries)
177 goto retry;
178
179 dev_err(&sl->dev,
180 "could not write to eeprom, scratchpad compare failed %d times\n",
181 W1_F2D_READ_RETRIES);
182
183 return -1;
184 }
185
186 /* Copy the scratchpad to EEPROM */
187 if (w1_reset_select_slave(sl))
188 return -1;
189
190 wrbuf[0] = W1_F2D_COPY_SCRATCH;
191 wrbuf[3] = es;
192 w1_write_block(sl->master, wrbuf, 4);
193
194 /* Sleep for tprog ms to wait for the write to complete */
195 msleep(W1_F2D_TPROG_MS);
196
197 /* Reset the bus to wake up the EEPROM */
198 w1_reset_bus(sl->master);
199
200 return 0;
201 }
202
eeprom_write(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)203 static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
204 struct bin_attribute *bin_attr, char *buf,
205 loff_t off, size_t count)
206 {
207 struct w1_slave *sl = kobj_to_w1_slave(kobj);
208 int addr, len;
209 int copy;
210
211 count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
212 if (count == 0)
213 return 0;
214
215 mutex_lock(&sl->master->bus_mutex);
216
217 /* Can only write data in blocks of the size of the scratchpad */
218 addr = off;
219 len = count;
220 while (len > 0) {
221
222 /* if len too short or addr not aligned */
223 if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) {
224 char tmp[W1_F2D_SCRATCH_SIZE];
225
226 /* read the block and update the parts to be written */
227 if (w1_f2d_readblock(sl, addr & ~W1_F2D_SCRATCH_MASK,
228 W1_F2D_SCRATCH_SIZE, tmp)) {
229 count = -EIO;
230 goto out_up;
231 }
232
233 /* copy at most to the boundary of the PAGE or len */
234 copy = W1_F2D_SCRATCH_SIZE -
235 (addr & W1_F2D_SCRATCH_MASK);
236
237 if (copy > len)
238 copy = len;
239
240 memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy);
241 if (w1_f2d_write(sl, addr & ~W1_F2D_SCRATCH_MASK,
242 W1_F2D_SCRATCH_SIZE, tmp) < 0) {
243 count = -EIO;
244 goto out_up;
245 }
246 } else {
247
248 copy = W1_F2D_SCRATCH_SIZE;
249 if (w1_f2d_write(sl, addr, copy, buf) < 0) {
250 count = -EIO;
251 goto out_up;
252 }
253 }
254 buf += copy;
255 addr += copy;
256 len -= copy;
257 }
258
259 out_up:
260 mutex_unlock(&sl->master->bus_mutex);
261
262 return count;
263 }
264
265 static BIN_ATTR_RW(eeprom, W1_F2D_EEPROM_SIZE);
266
267 static struct bin_attribute *w1_f2d_bin_attrs[] = {
268 &bin_attr_eeprom,
269 NULL,
270 };
271
272 static const struct attribute_group w1_f2d_group = {
273 .bin_attrs = w1_f2d_bin_attrs,
274 };
275
276 static const struct attribute_group *w1_f2d_groups[] = {
277 &w1_f2d_group,
278 NULL,
279 };
280
281 static const struct w1_family_ops w1_f2d_fops = {
282 .groups = w1_f2d_groups,
283 };
284
285 static struct w1_family w1_family_2d = {
286 .fid = W1_EEPROM_DS2431,
287 .fops = &w1_f2d_fops,
288 };
289 module_w1_family(w1_family_2d);
290
291 MODULE_AUTHOR("Bernhard Weirich <bernhard.weirich@riedel.net>");
292 MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM");
293 MODULE_LICENSE("GPL");
294 MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2431));
295