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