xref: /openbmc/linux/drivers/w1/slaves/w1_ds28e04.c (revision ad9c36be)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *	w1_ds28e04.c - w1 family 1C (DS28E04) driver
4  *
5  * Copyright (c) 2012 Markus Franke <franke.m@sebakmt.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 #include <linux/slab.h>
15 #include <linux/crc16.h>
16 #include <linux/uaccess.h>
17 
18 #define CRC16_INIT		0
19 #define CRC16_VALID		0xb001
20 
21 #include <linux/w1.h>
22 
23 #define W1_FAMILY_DS28E04	0x1C
24 
25 /* Allow the strong pullup to be disabled, but default to enabled.
26  * If it was disabled a parasite powered device might not get the required
27  * current to copy the data from the scratchpad to EEPROM.  If it is enabled
28  * parasite powered devices have a better chance of getting the current
29  * required.
30  */
31 static int w1_strong_pullup = 1;
32 module_param_named(strong_pullup, w1_strong_pullup, int, 0);
33 
34 /* enable/disable CRC checking on DS28E04-100 memory accesses */
35 static bool w1_enable_crccheck = true;
36 
37 #define W1_EEPROM_SIZE		512
38 #define W1_PAGE_COUNT		16
39 #define W1_PAGE_SIZE		32
40 #define W1_PAGE_BITS		5
41 #define W1_PAGE_MASK		0x1F
42 
43 #define W1_F1C_READ_EEPROM	0xF0
44 #define W1_F1C_WRITE_SCRATCH	0x0F
45 #define W1_F1C_READ_SCRATCH	0xAA
46 #define W1_F1C_COPY_SCRATCH	0x55
47 #define W1_F1C_ACCESS_WRITE	0x5A
48 
49 #define W1_1C_REG_LOGIC_STATE	0x220
50 
51 struct w1_f1C_data {
52 	u8	memory[W1_EEPROM_SIZE];
53 	u32	validcrc;
54 };
55 
56 /*
57  * Check the file size bounds and adjusts count as needed.
58  * This would not be needed if the file size didn't reset to 0 after a write.
59  */
w1_f1C_fix_count(loff_t off,size_t count,size_t size)60 static inline size_t w1_f1C_fix_count(loff_t off, size_t count, size_t size)
61 {
62 	if (off > size)
63 		return 0;
64 
65 	if ((off + count) > size)
66 		return size - off;
67 
68 	return count;
69 }
70 
w1_f1C_refresh_block(struct w1_slave * sl,struct w1_f1C_data * data,int block)71 static int w1_f1C_refresh_block(struct w1_slave *sl, struct w1_f1C_data *data,
72 				int block)
73 {
74 	u8	wrbuf[3];
75 	int	off = block * W1_PAGE_SIZE;
76 
77 	if (data->validcrc & (1 << block))
78 		return 0;
79 
80 	if (w1_reset_select_slave(sl)) {
81 		data->validcrc = 0;
82 		return -EIO;
83 	}
84 
85 	wrbuf[0] = W1_F1C_READ_EEPROM;
86 	wrbuf[1] = off & 0xff;
87 	wrbuf[2] = off >> 8;
88 	w1_write_block(sl->master, wrbuf, 3);
89 	w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);
90 
91 	/* cache the block if the CRC is valid */
92 	if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
93 		data->validcrc |= (1 << block);
94 
95 	return 0;
96 }
97 
w1_f1C_read(struct w1_slave * sl,int addr,int len,char * data)98 static int w1_f1C_read(struct w1_slave *sl, int addr, int len, char *data)
99 {
100 	u8 wrbuf[3];
101 
102 	/* read directly from the EEPROM */
103 	if (w1_reset_select_slave(sl))
104 		return -EIO;
105 
106 	wrbuf[0] = W1_F1C_READ_EEPROM;
107 	wrbuf[1] = addr & 0xff;
108 	wrbuf[2] = addr >> 8;
109 
110 	w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
111 	return w1_read_block(sl->master, data, len);
112 }
113 
eeprom_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)114 static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
115 			   struct bin_attribute *bin_attr, char *buf,
116 			   loff_t off, size_t count)
117 {
118 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
119 	struct w1_f1C_data *data = sl->family_data;
120 	int i, min_page, max_page;
121 
122 	count = w1_f1C_fix_count(off, count, W1_EEPROM_SIZE);
123 	if (count == 0)
124 		return 0;
125 
126 	mutex_lock(&sl->master->mutex);
127 
128 	if (w1_enable_crccheck) {
129 		min_page = (off >> W1_PAGE_BITS);
130 		max_page = (off + count - 1) >> W1_PAGE_BITS;
131 		for (i = min_page; i <= max_page; i++) {
132 			if (w1_f1C_refresh_block(sl, data, i)) {
133 				count = -EIO;
134 				goto out_up;
135 			}
136 		}
137 		memcpy(buf, &data->memory[off], count);
138 	} else {
139 		count = w1_f1C_read(sl, off, count, buf);
140 	}
141 
142 out_up:
143 	mutex_unlock(&sl->master->mutex);
144 
145 	return count;
146 }
147 
148 /**
149  * w1_f1C_write() - Writes to the scratchpad and reads it back for verification.
150  * @sl:		The slave structure
151  * @addr:	Address for the write
152  * @len:	length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
153  * @data:	The data to write
154  *
155  * Then copies the scratchpad to EEPROM.
156  * The data must be on one page.
157  * The master must be locked.
158  *
159  * Return:	0=Success, -1=failure
160  */
w1_f1C_write(struct w1_slave * sl,int addr,int len,const u8 * data)161 static int w1_f1C_write(struct w1_slave *sl, int addr, int len, const u8 *data)
162 {
163 	u8 wrbuf[4];
164 	u8 rdbuf[W1_PAGE_SIZE + 3];
165 	u8 es = (addr + len - 1) & 0x1f;
166 	unsigned int tm = 10;
167 	int i;
168 	struct w1_f1C_data *f1C = sl->family_data;
169 
170 	/* Write the data to the scratchpad */
171 	if (w1_reset_select_slave(sl))
172 		return -1;
173 
174 	wrbuf[0] = W1_F1C_WRITE_SCRATCH;
175 	wrbuf[1] = addr & 0xff;
176 	wrbuf[2] = addr >> 8;
177 
178 	w1_write_block(sl->master, wrbuf, 3);
179 	w1_write_block(sl->master, data, len);
180 
181 	/* Read the scratchpad and verify */
182 	if (w1_reset_select_slave(sl))
183 		return -1;
184 
185 	w1_write_8(sl->master, W1_F1C_READ_SCRATCH);
186 	w1_read_block(sl->master, rdbuf, len + 3);
187 
188 	/* Compare what was read against the data written */
189 	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
190 	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
191 		return -1;
192 
193 	/* Copy the scratchpad to EEPROM */
194 	if (w1_reset_select_slave(sl))
195 		return -1;
196 
197 	wrbuf[0] = W1_F1C_COPY_SCRATCH;
198 	wrbuf[3] = es;
199 
200 	for (i = 0; i < sizeof(wrbuf); ++i) {
201 		/*
202 		 * issue 10ms strong pullup (or delay) on the last byte
203 		 * for writing the data from the scratchpad to EEPROM
204 		 */
205 		if (w1_strong_pullup && i == sizeof(wrbuf)-1)
206 			w1_next_pullup(sl->master, tm);
207 
208 		w1_write_8(sl->master, wrbuf[i]);
209 	}
210 
211 	if (!w1_strong_pullup)
212 		msleep(tm);
213 
214 	if (w1_enable_crccheck) {
215 		/* invalidate cached data */
216 		f1C->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
217 	}
218 
219 	/* Reset the bus to wake up the EEPROM (this may not be needed) */
220 	w1_reset_bus(sl->master);
221 
222 	return 0;
223 }
224 
eeprom_write(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)225 static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
226 			    struct bin_attribute *bin_attr, char *buf,
227 			    loff_t off, size_t count)
228 
229 {
230 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
231 	int addr, len, idx;
232 
233 	count = w1_f1C_fix_count(off, count, W1_EEPROM_SIZE);
234 	if (count == 0)
235 		return 0;
236 
237 	if (w1_enable_crccheck) {
238 		/* can only write full blocks in cached mode */
239 		if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
240 			dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
241 				(int)off, count);
242 			return -EINVAL;
243 		}
244 
245 		/* make sure the block CRCs are valid */
246 		for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
247 			if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE)
248 				!= CRC16_VALID) {
249 				dev_err(&sl->dev, "bad CRC at offset %d\n",
250 					(int)off);
251 				return -EINVAL;
252 			}
253 		}
254 	}
255 
256 	mutex_lock(&sl->master->mutex);
257 
258 	/* Can only write data to one page at a time */
259 	idx = 0;
260 	while (idx < count) {
261 		addr = off + idx;
262 		len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
263 		if (len > (count - idx))
264 			len = count - idx;
265 
266 		if (w1_f1C_write(sl, addr, len, &buf[idx]) < 0) {
267 			count = -EIO;
268 			goto out_up;
269 		}
270 		idx += len;
271 	}
272 
273 out_up:
274 	mutex_unlock(&sl->master->mutex);
275 
276 	return count;
277 }
278 
279 static BIN_ATTR_RW(eeprom, W1_EEPROM_SIZE);
280 
pio_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)281 static ssize_t pio_read(struct file *filp, struct kobject *kobj,
282 			struct bin_attribute *bin_attr, char *buf, loff_t off,
283 			size_t count)
284 
285 {
286 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
287 	int ret;
288 
289 	/* check arguments */
290 	if (off != 0 || count != 1 || buf == NULL)
291 		return -EINVAL;
292 
293 	mutex_lock(&sl->master->mutex);
294 	ret = w1_f1C_read(sl, W1_1C_REG_LOGIC_STATE, count, buf);
295 	mutex_unlock(&sl->master->mutex);
296 
297 	return ret;
298 }
299 
pio_write(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)300 static ssize_t pio_write(struct file *filp, struct kobject *kobj,
301 			 struct bin_attribute *bin_attr, char *buf, loff_t off,
302 			 size_t count)
303 
304 {
305 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
306 	u8 wrbuf[3];
307 	u8 ack;
308 
309 	/* check arguments */
310 	if (off != 0 || count != 1 || buf == NULL)
311 		return -EINVAL;
312 
313 	mutex_lock(&sl->master->mutex);
314 
315 	/* Write the PIO data */
316 	if (w1_reset_select_slave(sl)) {
317 		mutex_unlock(&sl->master->mutex);
318 		return -1;
319 	}
320 
321 	/* set bit 7..2 to value '1' */
322 	*buf = *buf | 0xFC;
323 
324 	wrbuf[0] = W1_F1C_ACCESS_WRITE;
325 	wrbuf[1] = *buf;
326 	wrbuf[2] = ~(*buf);
327 	w1_write_block(sl->master, wrbuf, 3);
328 
329 	w1_read_block(sl->master, &ack, sizeof(ack));
330 
331 	mutex_unlock(&sl->master->mutex);
332 
333 	/* check for acknowledgement */
334 	if (ack != 0xAA)
335 		return -EIO;
336 
337 	return count;
338 }
339 
340 static BIN_ATTR_RW(pio, 1);
341 
crccheck_show(struct device * dev,struct device_attribute * attr,char * buf)342 static ssize_t crccheck_show(struct device *dev, struct device_attribute *attr,
343 			     char *buf)
344 {
345 	return sysfs_emit(buf, "%d\n", w1_enable_crccheck);
346 }
347 
crccheck_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)348 static ssize_t crccheck_store(struct device *dev, struct device_attribute *attr,
349 			      const char *buf, size_t count)
350 {
351 	int err = kstrtobool(buf, &w1_enable_crccheck);
352 
353 	if (err)
354 		return err;
355 
356 	return count;
357 }
358 
359 static DEVICE_ATTR_RW(crccheck);
360 
361 static struct attribute *w1_f1C_attrs[] = {
362 	&dev_attr_crccheck.attr,
363 	NULL,
364 };
365 
366 static struct bin_attribute *w1_f1C_bin_attrs[] = {
367 	&bin_attr_eeprom,
368 	&bin_attr_pio,
369 	NULL,
370 };
371 
372 static const struct attribute_group w1_f1C_group = {
373 	.attrs		= w1_f1C_attrs,
374 	.bin_attrs	= w1_f1C_bin_attrs,
375 };
376 
377 static const struct attribute_group *w1_f1C_groups[] = {
378 	&w1_f1C_group,
379 	NULL,
380 };
381 
w1_f1C_add_slave(struct w1_slave * sl)382 static int w1_f1C_add_slave(struct w1_slave *sl)
383 {
384 	struct w1_f1C_data *data = NULL;
385 
386 	if (w1_enable_crccheck) {
387 		data = kzalloc(sizeof(struct w1_f1C_data), GFP_KERNEL);
388 		if (!data)
389 			return -ENOMEM;
390 		sl->family_data = data;
391 	}
392 
393 	return 0;
394 }
395 
w1_f1C_remove_slave(struct w1_slave * sl)396 static void w1_f1C_remove_slave(struct w1_slave *sl)
397 {
398 	kfree(sl->family_data);
399 	sl->family_data = NULL;
400 }
401 
402 static const struct w1_family_ops w1_f1C_fops = {
403 	.add_slave      = w1_f1C_add_slave,
404 	.remove_slave   = w1_f1C_remove_slave,
405 	.groups		= w1_f1C_groups,
406 };
407 
408 static struct w1_family w1_family_1C = {
409 	.fid = W1_FAMILY_DS28E04,
410 	.fops = &w1_f1C_fops,
411 };
412 module_w1_family(w1_family_1C);
413 
414 MODULE_AUTHOR("Markus Franke <franke.m@sebakmt.com>, <franm@hrz.tu-chemnitz.de>");
415 MODULE_DESCRIPTION("w1 family 1C driver for DS28E04, 4kb EEPROM and PIO");
416 MODULE_LICENSE("GPL");
417 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS28E04));
418