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 * Writes to the scratchpad and reads it back for verification.
150 * Then copies the scratchpad to EEPROM.
151 * The data must be on one page.
152 * The master must be locked.
153 *
154 * @param sl	The slave structure
155 * @param addr	Address for the write
156 * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
157 * @param data	The data to write
158 * @return	0=Success -1=failure
159 */
160static int w1_f1C_write(struct w1_slave *sl, int addr, int len, const u8 *data)
161{
162	u8 wrbuf[4];
163	u8 rdbuf[W1_PAGE_SIZE + 3];
164	u8 es = (addr + len - 1) & 0x1f;
165	unsigned int tm = 10;
166	int i;
167	struct w1_f1C_data *f1C = sl->family_data;
168
169	/* Write the data to the scratchpad */
170	if (w1_reset_select_slave(sl))
171		return -1;
172
173	wrbuf[0] = W1_F1C_WRITE_SCRATCH;
174	wrbuf[1] = addr & 0xff;
175	wrbuf[2] = addr >> 8;
176
177	w1_write_block(sl->master, wrbuf, 3);
178	w1_write_block(sl->master, data, len);
179
180	/* Read the scratchpad and verify */
181	if (w1_reset_select_slave(sl))
182		return -1;
183
184	w1_write_8(sl->master, W1_F1C_READ_SCRATCH);
185	w1_read_block(sl->master, rdbuf, len + 3);
186
187	/* Compare what was read against the data written */
188	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
189	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
190		return -1;
191
192	/* Copy the scratchpad to EEPROM */
193	if (w1_reset_select_slave(sl))
194		return -1;
195
196	wrbuf[0] = W1_F1C_COPY_SCRATCH;
197	wrbuf[3] = es;
198
199	for (i = 0; i < sizeof(wrbuf); ++i) {
200		/* issue 10ms strong pullup (or delay) on the last byte
201		   for writing the data from the scratchpad to EEPROM */
202		if (w1_strong_pullup && i == sizeof(wrbuf)-1)
203			w1_next_pullup(sl->master, tm);
204
205		w1_write_8(sl->master, wrbuf[i]);
206	}
207
208	if (!w1_strong_pullup)
209		msleep(tm);
210
211	if (w1_enable_crccheck) {
212		/* invalidate cached data */
213		f1C->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
214	}
215
216	/* Reset the bus to wake up the EEPROM (this may not be needed) */
217	w1_reset_bus(sl->master);
218
219	return 0;
220}
221
222static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
223			    struct bin_attribute *bin_attr, char *buf,
224			    loff_t off, size_t count)
225
226{
227	struct w1_slave *sl = kobj_to_w1_slave(kobj);
228	int addr, len, idx;
229
230	count = w1_f1C_fix_count(off, count, W1_EEPROM_SIZE);
231	if (count == 0)
232		return 0;
233
234	if (w1_enable_crccheck) {
235		/* can only write full blocks in cached mode */
236		if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
237			dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
238				(int)off, count);
239			return -EINVAL;
240		}
241
242		/* make sure the block CRCs are valid */
243		for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
244			if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE)
245				!= CRC16_VALID) {
246				dev_err(&sl->dev, "bad CRC at offset %d\n",
247					(int)off);
248				return -EINVAL;
249			}
250		}
251	}
252
253	mutex_lock(&sl->master->mutex);
254
255	/* Can only write data to one page at a time */
256	idx = 0;
257	while (idx < count) {
258		addr = off + idx;
259		len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
260		if (len > (count - idx))
261			len = count - idx;
262
263		if (w1_f1C_write(sl, addr, len, &buf[idx]) < 0) {
264			count = -EIO;
265			goto out_up;
266		}
267		idx += len;
268	}
269
270out_up:
271	mutex_unlock(&sl->master->mutex);
272
273	return count;
274}
275
276static BIN_ATTR_RW(eeprom, W1_EEPROM_SIZE);
277
278static ssize_t pio_read(struct file *filp, struct kobject *kobj,
279			struct bin_attribute *bin_attr, char *buf, loff_t off,
280			size_t count)
281
282{
283	struct w1_slave *sl = kobj_to_w1_slave(kobj);
284	int ret;
285
286	/* check arguments */
287	if (off != 0 || count != 1 || buf == NULL)
288		return -EINVAL;
289
290	mutex_lock(&sl->master->mutex);
291	ret = w1_f1C_read(sl, W1_1C_REG_LOGIC_STATE, count, buf);
292	mutex_unlock(&sl->master->mutex);
293
294	return ret;
295}
296
297static ssize_t pio_write(struct file *filp, struct kobject *kobj,
298			 struct bin_attribute *bin_attr, char *buf, loff_t off,
299			 size_t count)
300
301{
302	struct w1_slave *sl = kobj_to_w1_slave(kobj);
303	u8 wrbuf[3];
304	u8 ack;
305
306	/* check arguments */
307	if (off != 0 || count != 1 || buf == NULL)
308		return -EINVAL;
309
310	mutex_lock(&sl->master->mutex);
311
312	/* Write the PIO data */
313	if (w1_reset_select_slave(sl)) {
314		mutex_unlock(&sl->master->mutex);
315		return -1;
316	}
317
318	/* set bit 7..2 to value '1' */
319	*buf = *buf | 0xFC;
320
321	wrbuf[0] = W1_F1C_ACCESS_WRITE;
322	wrbuf[1] = *buf;
323	wrbuf[2] = ~(*buf);
324	w1_write_block(sl->master, wrbuf, 3);
325
326	w1_read_block(sl->master, &ack, sizeof(ack));
327
328	mutex_unlock(&sl->master->mutex);
329
330	/* check for acknowledgement */
331	if (ack != 0xAA)
332		return -EIO;
333
334	return count;
335}
336
337static BIN_ATTR_RW(pio, 1);
338
339static ssize_t crccheck_show(struct device *dev, struct device_attribute *attr,
340			     char *buf)
341{
342	return sysfs_emit(buf, "%d\n", w1_enable_crccheck);
343}
344
345static ssize_t crccheck_store(struct device *dev, struct device_attribute *attr,
346			      const char *buf, size_t count)
347{
348	int err = kstrtobool(buf, &w1_enable_crccheck);
349
350	if (err)
351		return err;
352
353	return count;
354}
355
356static DEVICE_ATTR_RW(crccheck);
357
358static struct attribute *w1_f1C_attrs[] = {
359	&dev_attr_crccheck.attr,
360	NULL,
361};
362
363static struct bin_attribute *w1_f1C_bin_attrs[] = {
364	&bin_attr_eeprom,
365	&bin_attr_pio,
366	NULL,
367};
368
369static const struct attribute_group w1_f1C_group = {
370	.attrs		= w1_f1C_attrs,
371	.bin_attrs	= w1_f1C_bin_attrs,
372};
373
374static const struct attribute_group *w1_f1C_groups[] = {
375	&w1_f1C_group,
376	NULL,
377};
378
379static int w1_f1C_add_slave(struct w1_slave *sl)
380{
381	struct w1_f1C_data *data = NULL;
382
383	if (w1_enable_crccheck) {
384		data = kzalloc(sizeof(struct w1_f1C_data), GFP_KERNEL);
385		if (!data)
386			return -ENOMEM;
387		sl->family_data = data;
388	}
389
390	return 0;
391}
392
393static void w1_f1C_remove_slave(struct w1_slave *sl)
394{
395	kfree(sl->family_data);
396	sl->family_data = NULL;
397}
398
399static const struct w1_family_ops w1_f1C_fops = {
400	.add_slave      = w1_f1C_add_slave,
401	.remove_slave   = w1_f1C_remove_slave,
402	.groups		= w1_f1C_groups,
403};
404
405static struct w1_family w1_family_1C = {
406	.fid = W1_FAMILY_DS28E04,
407	.fops = &w1_f1C_fops,
408};
409module_w1_family(w1_family_1C);
410
411MODULE_AUTHOR("Markus Franke <franke.m@sebakmt.com>, <franm@hrz.tu-chemnitz.de>");
412MODULE_DESCRIPTION("w1 family 1C driver for DS28E04, 4kb EEPROM and PIO");
413MODULE_LICENSE("GPL");
414MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS28E04));
415