1 /*
2 * w1_ds2431.c - w1 family 2d (DS2431) driver
3 *
4 * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>
5 *
6 * Heavily inspired by w1_DS2433 driver from Ben Gardner <bgardner@wabtec.com>
7 *
8 * This source code is licensed under the GNU General Public License,
9 * Version 2. See the file COPYING for more details.
10 */
11
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/moduleparam.h>
15 #include <linux/device.h>
16 #include <linux/types.h>
17 #include <linux/delay.h>
18
19 #include <linux/w1.h>
20
21 #define W1_EEPROM_DS2431 0x2D
22
23 #define W1_F2D_EEPROM_SIZE 128
24 #define W1_F2D_PAGE_COUNT 4
25 #define W1_F2D_PAGE_BITS 5
26 #define W1_F2D_PAGE_SIZE (1<<W1_F2D_PAGE_BITS)
27 #define W1_F2D_PAGE_MASK 0x1F
28
29 #define W1_F2D_SCRATCH_BITS 3
30 #define W1_F2D_SCRATCH_SIZE (1<<W1_F2D_SCRATCH_BITS)
31 #define W1_F2D_SCRATCH_MASK (W1_F2D_SCRATCH_SIZE-1)
32
33 #define W1_F2D_READ_EEPROM 0xF0
34 #define W1_F2D_WRITE_SCRATCH 0x0F
35 #define W1_F2D_READ_SCRATCH 0xAA
36 #define W1_F2D_COPY_SCRATCH 0x55
37
38
39 #define W1_F2D_TPROG_MS 11
40
41 #define W1_F2D_READ_RETRIES 10
42 #define W1_F2D_READ_MAXLEN 8
43
44 /*
45 * Check the file size bounds and adjusts count as needed.
46 * This would not be needed if the file size didn't reset to 0 after a write.
47 */
w1_f2d_fix_count(loff_t off,size_t count,size_t size)48 static inline size_t w1_f2d_fix_count(loff_t off, size_t count, size_t size)
49 {
50 if (off > size)
51 return 0;
52
53 if ((off + count) > size)
54 return size - off;
55
56 return count;
57 }
58
59 /*
60 * Read a block from W1 ROM two times and compares the results.
61 * If they are equal they are returned, otherwise the read
62 * is repeated W1_F2D_READ_RETRIES times.
63 *
64 * count must not exceed W1_F2D_READ_MAXLEN.
65 */
w1_f2d_readblock(struct w1_slave * sl,int off,int count,char * buf)66 static int w1_f2d_readblock(struct w1_slave *sl, int off, int count, char *buf)
67 {
68 u8 wrbuf[3];
69 u8 cmp[W1_F2D_READ_MAXLEN];
70 int tries = W1_F2D_READ_RETRIES;
71
72 do {
73 wrbuf[0] = W1_F2D_READ_EEPROM;
74 wrbuf[1] = off & 0xff;
75 wrbuf[2] = off >> 8;
76
77 if (w1_reset_select_slave(sl))
78 return -1;
79
80 w1_write_block(sl->master, wrbuf, 3);
81 w1_read_block(sl->master, buf, count);
82
83 if (w1_reset_select_slave(sl))
84 return -1;
85
86 w1_write_block(sl->master, wrbuf, 3);
87 w1_read_block(sl->master, cmp, count);
88
89 if (!memcmp(cmp, buf, count))
90 return 0;
91 } while (--tries);
92
93 dev_err(&sl->dev, "proof reading failed %d times\n",
94 W1_F2D_READ_RETRIES);
95
96 return -1;
97 }
98
eeprom_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)99 static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
100 struct bin_attribute *bin_attr, char *buf,
101 loff_t off, size_t count)
102 {
103 struct w1_slave *sl = kobj_to_w1_slave(kobj);
104 int todo = count;
105
106 count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
107 if (count == 0)
108 return 0;
109
110 mutex_lock(&sl->master->bus_mutex);
111
112 /* read directly from the EEPROM in chunks of W1_F2D_READ_MAXLEN */
113 while (todo > 0) {
114 int block_read;
115
116 if (todo >= W1_F2D_READ_MAXLEN)
117 block_read = W1_F2D_READ_MAXLEN;
118 else
119 block_read = todo;
120
121 if (w1_f2d_readblock(sl, off, block_read, buf) < 0)
122 count = -EIO;
123
124 todo -= W1_F2D_READ_MAXLEN;
125 buf += W1_F2D_READ_MAXLEN;
126 off += W1_F2D_READ_MAXLEN;
127 }
128
129 mutex_unlock(&sl->master->bus_mutex);
130
131 return count;
132 }
133
134 /*
135 * Writes to the scratchpad and reads it back for verification.
136 * Then copies the scratchpad to EEPROM.
137 * The data must be aligned at W1_F2D_SCRATCH_SIZE bytes and
138 * must be W1_F2D_SCRATCH_SIZE bytes long.
139 * The master must be locked.
140 *
141 * @param sl The slave structure
142 * @param addr Address for the write
143 * @param len length must be <= (W1_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK))
144 * @param data The data to write
145 * @return 0=Success -1=failure
146 */
w1_f2d_write(struct w1_slave * sl,int addr,int len,const u8 * data)147 static int w1_f2d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
148 {
149 int tries = W1_F2D_READ_RETRIES;
150 u8 wrbuf[4];
151 u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3];
152 u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE;
153
154 retry:
155
156 /* Write the data to the scratchpad */
157 if (w1_reset_select_slave(sl))
158 return -1;
159
160 wrbuf[0] = W1_F2D_WRITE_SCRATCH;
161 wrbuf[1] = addr & 0xff;
162 wrbuf[2] = addr >> 8;
163
164 w1_write_block(sl->master, wrbuf, 3);
165 w1_write_block(sl->master, data, len);
166
167 /* Read the scratchpad and verify */
168 if (w1_reset_select_slave(sl))
169 return -1;
170
171 w1_write_8(sl->master, W1_F2D_READ_SCRATCH);
172 w1_read_block(sl->master, rdbuf, len + 3);
173
174 /* Compare what was read against the data written */
175 if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
176 (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0)) {
177
178 if (--tries)
179 goto retry;
180
181 dev_err(&sl->dev,
182 "could not write to eeprom, scratchpad compare failed %d times\n",
183 W1_F2D_READ_RETRIES);
184
185 return -1;
186 }
187
188 /* Copy the scratchpad to EEPROM */
189 if (w1_reset_select_slave(sl))
190 return -1;
191
192 wrbuf[0] = W1_F2D_COPY_SCRATCH;
193 wrbuf[3] = es;
194 w1_write_block(sl->master, wrbuf, 4);
195
196 /* Sleep for tprog ms to wait for the write to complete */
197 msleep(W1_F2D_TPROG_MS);
198
199 /* Reset the bus to wake up the EEPROM */
200 w1_reset_bus(sl->master);
201
202 return 0;
203 }
204
eeprom_write(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)205 static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
206 struct bin_attribute *bin_attr, char *buf,
207 loff_t off, size_t count)
208 {
209 struct w1_slave *sl = kobj_to_w1_slave(kobj);
210 int addr, len;
211 int copy;
212
213 count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
214 if (count == 0)
215 return 0;
216
217 mutex_lock(&sl->master->bus_mutex);
218
219 /* Can only write data in blocks of the size of the scratchpad */
220 addr = off;
221 len = count;
222 while (len > 0) {
223
224 /* if len too short or addr not aligned */
225 if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) {
226 char tmp[W1_F2D_SCRATCH_SIZE];
227
228 /* read the block and update the parts to be written */
229 if (w1_f2d_readblock(sl, addr & ~W1_F2D_SCRATCH_MASK,
230 W1_F2D_SCRATCH_SIZE, tmp)) {
231 count = -EIO;
232 goto out_up;
233 }
234
235 /* copy at most to the boundary of the PAGE or len */
236 copy = W1_F2D_SCRATCH_SIZE -
237 (addr & W1_F2D_SCRATCH_MASK);
238
239 if (copy > len)
240 copy = len;
241
242 memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy);
243 if (w1_f2d_write(sl, addr & ~W1_F2D_SCRATCH_MASK,
244 W1_F2D_SCRATCH_SIZE, tmp) < 0) {
245 count = -EIO;
246 goto out_up;
247 }
248 } else {
249
250 copy = W1_F2D_SCRATCH_SIZE;
251 if (w1_f2d_write(sl, addr, copy, buf) < 0) {
252 count = -EIO;
253 goto out_up;
254 }
255 }
256 buf += copy;
257 addr += copy;
258 len -= copy;
259 }
260
261 out_up:
262 mutex_unlock(&sl->master->bus_mutex);
263
264 return count;
265 }
266
267 static BIN_ATTR_RW(eeprom, W1_F2D_EEPROM_SIZE);
268
269 static struct bin_attribute *w1_f2d_bin_attrs[] = {
270 &bin_attr_eeprom,
271 NULL,
272 };
273
274 static const struct attribute_group w1_f2d_group = {
275 .bin_attrs = w1_f2d_bin_attrs,
276 };
277
278 static const struct attribute_group *w1_f2d_groups[] = {
279 &w1_f2d_group,
280 NULL,
281 };
282
283 static struct w1_family_ops w1_f2d_fops = {
284 .groups = w1_f2d_groups,
285 };
286
287 static struct w1_family w1_family_2d = {
288 .fid = W1_EEPROM_DS2431,
289 .fops = &w1_f2d_fops,
290 };
291 module_w1_family(w1_family_2d);
292
293 MODULE_AUTHOR("Bernhard Weirich <bernhard.weirich@riedel.net>");
294 MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM");
295 MODULE_LICENSE("GPL");
296 MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2431));
297
