Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus
[linux-2.6] / drivers / w1 / slaves / w1_ds2431.c
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 "../w1.h"
20 #include "../w1_int.h"
21 #include "../w1_family.h"
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  */
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  */
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
99 static ssize_t w1_f2d_read_bin(struct kobject *kobj,
100                                struct bin_attribute *bin_attr,
101                                char *buf, 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->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->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  */
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
205 static ssize_t w1_f2d_write_bin(struct kobject *kobj,
206                                 struct bin_attribute *bin_attr,
207                                 char *buf, 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->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->mutex);
263
264         return count;
265 }
266
267 static struct bin_attribute w1_f2d_bin_attr = {
268         .attr = {
269                 .name = "eeprom",
270                 .mode = S_IRUGO | S_IWUSR,
271         },
272         .size = W1_F2D_EEPROM_SIZE,
273         .read = w1_f2d_read_bin,
274         .write = w1_f2d_write_bin,
275 };
276
277 static int w1_f2d_add_slave(struct w1_slave *sl)
278 {
279         return sysfs_create_bin_file(&sl->dev.kobj, &w1_f2d_bin_attr);
280 }
281
282 static void w1_f2d_remove_slave(struct w1_slave *sl)
283 {
284         sysfs_remove_bin_file(&sl->dev.kobj, &w1_f2d_bin_attr);
285 }
286
287 static struct w1_family_ops w1_f2d_fops = {
288         .add_slave      = w1_f2d_add_slave,
289         .remove_slave   = w1_f2d_remove_slave,
290 };
291
292 static struct w1_family w1_family_2d = {
293         .fid = W1_EEPROM_DS2431,
294         .fops = &w1_f2d_fops,
295 };
296
297 static int __init w1_f2d_init(void)
298 {
299         return w1_register_family(&w1_family_2d);
300 }
301
302 static void __exit w1_f2d_fini(void)
303 {
304         w1_unregister_family(&w1_family_2d);
305 }
306
307 module_init(w1_f2d_init);
308 module_exit(w1_f2d_fini);
309
310 MODULE_LICENSE("GPL");
311 MODULE_AUTHOR("Bernhard Weirich <bernhard.weirich@riedel.net>");
312 MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM");