xref: /openbmc/linux/drivers/w1/slaves/w1_ds2805.c (revision 921e0f2f)
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