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 */
31static int w1_strong_pullup = 1;
32module_param_named(strong_pullup, w1_strong_pullup, int, 0);
33
34/* enable/disable CRC checking on DS28E04-100 memory accesses */
35static 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
51struct 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 */
60static 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
71static 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
98static 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
114static 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
142out_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 */
161static 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
225static 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
273out_up:
274	mutex_unlock(&sl->master->mutex);
275
276	return count;
277}
278
279static BIN_ATTR_RW(eeprom, W1_EEPROM_SIZE);
280
281static 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
300static 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
340static BIN_ATTR_RW(pio, 1);
341
342static 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
348static 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
359static DEVICE_ATTR_RW(crccheck);
360
361static struct attribute *w1_f1C_attrs[] = {
362	&dev_attr_crccheck.attr,
363	NULL,
364};
365
366static struct bin_attribute *w1_f1C_bin_attrs[] = {
367	&bin_attr_eeprom,
368	&bin_attr_pio,
369	NULL,
370};
371
372static const struct attribute_group w1_f1C_group = {
373	.attrs		= w1_f1C_attrs,
374	.bin_attrs	= w1_f1C_bin_attrs,
375};
376
377static const struct attribute_group *w1_f1C_groups[] = {
378	&w1_f1C_group,
379	NULL,
380};
381
382static 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
396static void w1_f1C_remove_slave(struct w1_slave *sl)
397{
398	kfree(sl->family_data);
399	sl->family_data = NULL;
400}
401
402static 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
408static struct w1_family w1_family_1C = {
409	.fid = W1_FAMILY_DS28E04,
410	.fops = &w1_f1C_fops,
411};
412module_w1_family(w1_family_1C);
413
414MODULE_AUTHOR("Markus Franke <franke.m@sebakmt.com>, <franm@hrz.tu-chemnitz.de>");
415MODULE_DESCRIPTION("w1 family 1C driver for DS28E04, 4kb EEPROM and PIO");
416MODULE_LICENSE("GPL");
417MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS28E04));
418