1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * w1_ds2805 - w1 family 0d (DS28E05) driver
4 *
5 * Copyright (c) 2016 Andrew Worsley amworsley@gmail.com
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/moduleparam.h>
11 #include <linux/device.h>
12 #include <linux/types.h>
13 #include <linux/delay.h>
14
15 #include <linux/w1.h>
16
17 #define W1_EEPROM_DS2805 0x0D
18
19 #define W1_F0D_EEPROM_SIZE 128
20 #define W1_F0D_PAGE_BITS 3
21 #define W1_F0D_PAGE_SIZE (1<<W1_F0D_PAGE_BITS)
22 #define W1_F0D_PAGE_MASK 0x0F
23
24 #define W1_F0D_SCRATCH_BITS 1
25 #define W1_F0D_SCRATCH_SIZE (1<<W1_F0D_SCRATCH_BITS)
26 #define W1_F0D_SCRATCH_MASK (W1_F0D_SCRATCH_SIZE-1)
27
28 #define W1_F0D_READ_EEPROM 0xF0
29 #define W1_F0D_WRITE_EEPROM 0x55
30 #define W1_F0D_RELEASE 0xFF
31
32 #define W1_F0D_CS_OK 0xAA /* Chip Status Ok */
33
34 #define W1_F0D_TPROG_MS 16
35
36 #define W1_F0D_READ_RETRIES 10
37 #define W1_F0D_READ_MAXLEN W1_F0D_EEPROM_SIZE
38
39 /*
40 * Check the file size bounds and adjusts count as needed.
41 * This would not be needed if the file size didn't reset to 0 after a write.
42 */
w1_f0d_fix_count(loff_t off,size_t count,size_t size)43 static inline size_t w1_f0d_fix_count(loff_t off, size_t count, size_t size)
44 {
45 if (off > size)
46 return 0;
47
48 if ((off + count) > size)
49 return size - off;
50
51 return count;
52 }
53
54 /*
55 * Read a block from W1 ROM two times and compares the results.
56 * If they are equal they are returned, otherwise the read
57 * is repeated W1_F0D_READ_RETRIES times.
58 *
59 * count must not exceed W1_F0D_READ_MAXLEN.
60 */
w1_f0d_readblock(struct w1_slave * sl,int off,int count,char * buf)61 static int w1_f0d_readblock(struct w1_slave *sl, int off, int count, char *buf)
62 {
63 u8 wrbuf[3];
64 u8 cmp[W1_F0D_READ_MAXLEN];
65 int tries = W1_F0D_READ_RETRIES;
66
67 do {
68 wrbuf[0] = W1_F0D_READ_EEPROM;
69 wrbuf[1] = off & 0x7f;
70 wrbuf[2] = 0;
71
72 if (w1_reset_select_slave(sl))
73 return -1;
74
75 w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
76 w1_read_block(sl->master, buf, count);
77
78 if (w1_reset_select_slave(sl))
79 return -1;
80
81 w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
82 w1_read_block(sl->master, cmp, count);
83
84 if (!memcmp(cmp, buf, count))
85 return 0;
86 } while (--tries);
87
88 dev_err(&sl->dev, "proof reading failed %d times\n",
89 W1_F0D_READ_RETRIES);
90
91 return -1;
92 }
93
w1_f0d_read_bin(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)94 static ssize_t w1_f0d_read_bin(struct file *filp, struct kobject *kobj,
95 struct bin_attribute *bin_attr,
96 char *buf, loff_t off, size_t count)
97 {
98 struct w1_slave *sl = kobj_to_w1_slave(kobj);
99 int todo = count;
100
101 count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
102 if (count == 0)
103 return 0;
104
105 mutex_lock(&sl->master->mutex);
106
107 /* read directly from the EEPROM in chunks of W1_F0D_READ_MAXLEN */
108 while (todo > 0) {
109 int block_read;
110
111 if (todo >= W1_F0D_READ_MAXLEN)
112 block_read = W1_F0D_READ_MAXLEN;
113 else
114 block_read = todo;
115
116 if (w1_f0d_readblock(sl, off, block_read, buf) < 0) {
117 count = -EIO;
118 break;
119 }
120
121 todo -= W1_F0D_READ_MAXLEN;
122 buf += W1_F0D_READ_MAXLEN;
123 off += W1_F0D_READ_MAXLEN;
124 }
125
126 mutex_unlock(&sl->master->mutex);
127
128 return count;
129 }
130
131 /*
132 * Writes to the scratchpad and reads it back for verification.
133 * Then copies the scratchpad to EEPROM.
134 * The data must be aligned at W1_F0D_SCRATCH_SIZE bytes and
135 * must be W1_F0D_SCRATCH_SIZE bytes long.
136 * The master must be locked.
137 *
138 * @param sl The slave structure
139 * @param addr Address for the write
140 * @param len length must be <= (W1_F0D_PAGE_SIZE - (addr & W1_F0D_PAGE_MASK))
141 * @param data The data to write
142 * @return 0=Success -1=failure
143 */
w1_f0d_write(struct w1_slave * sl,int addr,int len,const u8 * data)144 static int w1_f0d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
145 {
146 int tries = W1_F0D_READ_RETRIES;
147 u8 wrbuf[3];
148 u8 rdbuf[W1_F0D_SCRATCH_SIZE];
149 u8 cs;
150
151 if ((addr & 1) || (len != 2)) {
152 dev_err(&sl->dev, "%s: bad addr/len - addr=%#x len=%d\n",
153 __func__, addr, len);
154 return -1;
155 }
156
157 retry:
158
159 /* Write the data to the scratchpad */
160 if (w1_reset_select_slave(sl))
161 return -1;
162
163 wrbuf[0] = W1_F0D_WRITE_EEPROM;
164 wrbuf[1] = addr & 0xff;
165 wrbuf[2] = 0xff; /* ?? from Example */
166
167 w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
168 w1_write_block(sl->master, data, len);
169
170 w1_read_block(sl->master, rdbuf, sizeof(rdbuf));
171 /* Compare what was read against the data written */
172 if ((rdbuf[0] != data[0]) || (rdbuf[1] != data[1])) {
173
174 if (--tries)
175 goto retry;
176
177 dev_err(&sl->dev,
178 "could not write to eeprom, scratchpad compare failed %d times\n",
179 W1_F0D_READ_RETRIES);
180 pr_info("%s: rdbuf = %#x %#x data = %#x %#x\n",
181 __func__, rdbuf[0], rdbuf[1], data[0], data[1]);
182
183 return -1;
184 }
185
186 /* Trigger write out to EEPROM */
187 w1_write_8(sl->master, W1_F0D_RELEASE);
188
189 /* Sleep for tprog ms to wait for the write to complete */
190 msleep(W1_F0D_TPROG_MS);
191
192 /* Check CS (Command Status) == 0xAA ? */
193 cs = w1_read_8(sl->master);
194 if (cs != W1_F0D_CS_OK) {
195 dev_err(&sl->dev, "save to eeprom failed = CS=%#x\n", cs);
196 return -1;
197 }
198
199 return 0;
200 }
201
w1_f0d_write_bin(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)202 static ssize_t w1_f0d_write_bin(struct file *filp, struct kobject *kobj,
203 struct bin_attribute *bin_attr,
204 char *buf, loff_t off, size_t count)
205 {
206 struct w1_slave *sl = kobj_to_w1_slave(kobj);
207 int addr, len;
208 int copy;
209
210 count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
211 if (count == 0)
212 return 0;
213
214 mutex_lock(&sl->master->mutex);
215
216 /* Can only write data in blocks of the size of the scratchpad */
217 addr = off;
218 len = count;
219 while (len > 0) {
220
221 /* if len too short or addr not aligned */
222 if (len < W1_F0D_SCRATCH_SIZE || addr & W1_F0D_SCRATCH_MASK) {
223 char tmp[W1_F0D_SCRATCH_SIZE];
224
225 /* read the block and update the parts to be written */
226 if (w1_f0d_readblock(sl, addr & ~W1_F0D_SCRATCH_MASK,
227 W1_F0D_SCRATCH_SIZE, tmp)) {
228 count = -EIO;
229 goto out_up;
230 }
231
232 /* copy at most to the boundary of the PAGE or len */
233 copy = W1_F0D_SCRATCH_SIZE -
234 (addr & W1_F0D_SCRATCH_MASK);
235
236 if (copy > len)
237 copy = len;
238
239 memcpy(&tmp[addr & W1_F0D_SCRATCH_MASK], buf, copy);
240 if (w1_f0d_write(sl, addr & ~W1_F0D_SCRATCH_MASK,
241 W1_F0D_SCRATCH_SIZE, tmp) < 0) {
242 count = -EIO;
243 goto out_up;
244 }
245 } else {
246
247 copy = W1_F0D_SCRATCH_SIZE;
248 if (w1_f0d_write(sl, addr, copy, buf) < 0) {
249 count = -EIO;
250 goto out_up;
251 }
252 }
253 buf += copy;
254 addr += copy;
255 len -= copy;
256 }
257
258 out_up:
259 mutex_unlock(&sl->master->mutex);
260
261 return count;
262 }
263
264 static struct bin_attribute w1_f0d_bin_attr = {
265 .attr = {
266 .name = "eeprom",
267 .mode = 0644,
268 },
269 .size = W1_F0D_EEPROM_SIZE,
270 .read = w1_f0d_read_bin,
271 .write = w1_f0d_write_bin,
272 };
273
w1_f0d_add_slave(struct w1_slave * sl)274 static int w1_f0d_add_slave(struct w1_slave *sl)
275 {
276 return sysfs_create_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
277 }
278
w1_f0d_remove_slave(struct w1_slave * sl)279 static void w1_f0d_remove_slave(struct w1_slave *sl)
280 {
281 sysfs_remove_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
282 }
283
284 static const struct w1_family_ops w1_f0d_fops = {
285 .add_slave = w1_f0d_add_slave,
286 .remove_slave = w1_f0d_remove_slave,
287 };
288
289 static struct w1_family w1_family_0d = {
290 .fid = W1_EEPROM_DS2805,
291 .fops = &w1_f0d_fops,
292 };
293
294 module_w1_family(w1_family_0d);
295
296 MODULE_LICENSE("GPL");
297 MODULE_AUTHOR("Andrew Worsley amworsley@gmail.com");
298 MODULE_DESCRIPTION("w1 family 0d driver for DS2805, 1kb EEPROM");
299