1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * w1_ds2430.c - w1 family 14 (DS2430) driver
4 **
5 * Copyright (c) 2019 Angelo Dureghello <angelo.dureghello@timesys.com>
6 *
7 * Cloned and modified from ds2431
8 * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>
9 *
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_DS2430 0x14
22
23 #define W1_F14_EEPROM_SIZE 32
24 #define W1_F14_PAGE_COUNT 1
25 #define W1_F14_PAGE_BITS 5
26 #define W1_F14_PAGE_SIZE (1 << W1_F14_PAGE_BITS)
27 #define W1_F14_PAGE_MASK 0x1F
28
29 #define W1_F14_SCRATCH_BITS 5
30 #define W1_F14_SCRATCH_SIZE (1 << W1_F14_SCRATCH_BITS)
31 #define W1_F14_SCRATCH_MASK (W1_F14_SCRATCH_SIZE-1)
32
33 #define W1_F14_READ_EEPROM 0xF0
34 #define W1_F14_WRITE_SCRATCH 0x0F
35 #define W1_F14_READ_SCRATCH 0xAA
36 #define W1_F14_COPY_SCRATCH 0x55
37 #define W1_F14_VALIDATION_KEY 0xa5
38
39 #define W1_F14_TPROG_MS 11
40 #define W1_F14_READ_RETRIES 10
41 #define W1_F14_READ_MAXLEN W1_F14_SCRATCH_SIZE
42
43 /*
44 * Check the file size bounds and adjusts count as needed.
45 * This would not be needed if the file size didn't reset to 0 after a write.
46 */
w1_f14_fix_count(loff_t off,size_t count,size_t size)47 static inline size_t w1_f14_fix_count(loff_t off, size_t count, size_t size)
48 {
49 if (off > size)
50 return 0;
51
52 if ((off + count) > size)
53 return size - off;
54
55 return count;
56 }
57
58 /*
59 * Read a block from W1 ROM two times and compares the results.
60 * If they are equal they are returned, otherwise the read
61 * is repeated W1_F14_READ_RETRIES times.
62 *
63 * count must not exceed W1_F14_READ_MAXLEN.
64 */
w1_f14_readblock(struct w1_slave * sl,int off,int count,char * buf)65 static int w1_f14_readblock(struct w1_slave *sl, int off, int count, char *buf)
66 {
67 u8 wrbuf[2];
68 u8 cmp[W1_F14_READ_MAXLEN];
69 int tries = W1_F14_READ_RETRIES;
70
71 do {
72 wrbuf[0] = W1_F14_READ_EEPROM;
73 wrbuf[1] = off & 0xff;
74
75 if (w1_reset_select_slave(sl))
76 return -1;
77
78 w1_write_block(sl->master, wrbuf, 2);
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, 2);
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_F14_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_f14_fix_count(off, count, W1_F14_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_F14_READ_MAXLEN */
111 while (todo > 0) {
112 int block_read;
113
114 if (todo >= W1_F14_READ_MAXLEN)
115 block_read = W1_F14_READ_MAXLEN;
116 else
117 block_read = todo;
118
119 if (w1_f14_readblock(sl, off, block_read, buf) < 0)
120 count = -EIO;
121
122 todo -= W1_F14_READ_MAXLEN;
123 buf += W1_F14_READ_MAXLEN;
124 off += W1_F14_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_F14_SCRATCH_SIZE bytes and
136 * must be W1_F14_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_F14_PAGE_SIZE - (addr & W1_F14_PAGE_MASK))
142 * @param data The data to write
143 * @return 0=Success -1=failure
144 */
w1_f14_write(struct w1_slave * sl,int addr,int len,const u8 * data)145 static int w1_f14_write(struct w1_slave *sl, int addr, int len, const u8 *data)
146 {
147 int tries = W1_F14_READ_RETRIES;
148 u8 wrbuf[2];
149 u8 rdbuf[W1_F14_SCRATCH_SIZE + 3];
150
151 retry:
152
153 /* Write the data to the scratchpad */
154 if (w1_reset_select_slave(sl))
155 return -1;
156
157 wrbuf[0] = W1_F14_WRITE_SCRATCH;
158 wrbuf[1] = addr & 0xff;
159
160 w1_write_block(sl->master, wrbuf, 2);
161 w1_write_block(sl->master, data, len);
162
163 /* Read the scratchpad and verify */
164 if (w1_reset_select_slave(sl))
165 return -1;
166
167 w1_write_8(sl->master, W1_F14_READ_SCRATCH);
168 w1_read_block(sl->master, rdbuf, len + 2);
169
170 /*
171 * Compare what was read against the data written
172 * Note: on read scratchpad, device returns 2 bulk 0xff bytes,
173 * to be discarded.
174 */
175 if ((memcmp(data, &rdbuf[2], len) != 0)) {
176
177 if (--tries)
178 goto retry;
179
180 dev_err(&sl->dev,
181 "could not write to eeprom, scratchpad compare failed %d times\n",
182 W1_F14_READ_RETRIES);
183
184 return -1;
185 }
186
187 /* Copy the scratchpad to EEPROM */
188 if (w1_reset_select_slave(sl))
189 return -1;
190
191 wrbuf[0] = W1_F14_COPY_SCRATCH;
192 wrbuf[1] = W1_F14_VALIDATION_KEY;
193 w1_write_block(sl->master, wrbuf, 2);
194
195 /* Sleep for tprog ms to wait for the write to complete */
196 msleep(W1_F14_TPROG_MS);
197
198 /* Reset the bus to wake up the EEPROM */
199 w1_reset_bus(sl->master);
200
201 return 0;
202 }
203
eeprom_write(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)204 static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
205 struct bin_attribute *bin_attr, char *buf,
206 loff_t off, size_t count)
207 {
208 struct w1_slave *sl = kobj_to_w1_slave(kobj);
209 int addr, len;
210 int copy;
211
212 count = w1_f14_fix_count(off, count, W1_F14_EEPROM_SIZE);
213 if (count == 0)
214 return 0;
215
216 mutex_lock(&sl->master->bus_mutex);
217
218 /* Can only write data in blocks of the size of the scratchpad */
219 addr = off;
220 len = count;
221 while (len > 0) {
222
223 /* if len too short or addr not aligned */
224 if (len < W1_F14_SCRATCH_SIZE || addr & W1_F14_SCRATCH_MASK) {
225 char tmp[W1_F14_SCRATCH_SIZE];
226
227 /* read the block and update the parts to be written */
228 if (w1_f14_readblock(sl, addr & ~W1_F14_SCRATCH_MASK,
229 W1_F14_SCRATCH_SIZE, tmp)) {
230 count = -EIO;
231 goto out_up;
232 }
233
234 /* copy at most to the boundary of the PAGE or len */
235 copy = W1_F14_SCRATCH_SIZE -
236 (addr & W1_F14_SCRATCH_MASK);
237
238 if (copy > len)
239 copy = len;
240
241 memcpy(&tmp[addr & W1_F14_SCRATCH_MASK], buf, copy);
242 if (w1_f14_write(sl, addr & ~W1_F14_SCRATCH_MASK,
243 W1_F14_SCRATCH_SIZE, tmp) < 0) {
244 count = -EIO;
245 goto out_up;
246 }
247 } else {
248
249 copy = W1_F14_SCRATCH_SIZE;
250 if (w1_f14_write(sl, addr, copy, buf) < 0) {
251 count = -EIO;
252 goto out_up;
253 }
254 }
255 buf += copy;
256 addr += copy;
257 len -= copy;
258 }
259
260 out_up:
261 mutex_unlock(&sl->master->bus_mutex);
262
263 return count;
264 }
265
266 static BIN_ATTR_RW(eeprom, W1_F14_EEPROM_SIZE);
267
268 static struct bin_attribute *w1_f14_bin_attrs[] = {
269 &bin_attr_eeprom,
270 NULL,
271 };
272
273 static const struct attribute_group w1_f14_group = {
274 .bin_attrs = w1_f14_bin_attrs,
275 };
276
277 static const struct attribute_group *w1_f14_groups[] = {
278 &w1_f14_group,
279 NULL,
280 };
281
282 static const struct w1_family_ops w1_f14_fops = {
283 .groups = w1_f14_groups,
284 };
285
286 static struct w1_family w1_family_14 = {
287 .fid = W1_EEPROM_DS2430,
288 .fops = &w1_f14_fops,
289 };
290 module_w1_family(w1_family_14);
291
292 MODULE_AUTHOR("Angelo Dureghello <angelo.dureghello@timesys.com>");
293 MODULE_DESCRIPTION("w1 family 14 driver for DS2430, 256b EEPROM");
294 MODULE_LICENSE("GPL");
295 MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2430));
296