1/*
2 *	w1_ds28e04.c - w1 family 1C (DS28E04) driver
3 *
4 * Copyright (c) 2012 Markus Franke <franke.m@sebakmt.com>
5 *
6 * This source code is licensed under the GNU General Public License,
7 * Version 2. See the file COPYING for more details.
8 */
9
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/moduleparam.h>
13#include <linux/device.h>
14#include <linux/types.h>
15#include <linux/delay.h>
16#include <linux/slab.h>
17#include <linux/crc16.h>
18#include <linux/uaccess.h>
19
20#define CRC16_INIT		0
21#define CRC16_VALID		0xb001
22
23#include "../w1.h"
24#include "../w1_int.h"
25#include "../w1_family.h"
26
27MODULE_LICENSE("GPL");
28MODULE_AUTHOR("Markus Franke <franke.m@sebakmt.com>, <franm@hrz.tu-chemnitz.de>");
29MODULE_DESCRIPTION("w1 family 1C driver for DS28E04, 4kb EEPROM and PIO");
30MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS28E04));
31
32/* Allow the strong pullup to be disabled, but default to enabled.
33 * If it was disabled a parasite powered device might not get the required
34 * current to copy the data from the scratchpad to EEPROM.  If it is enabled
35 * parasite powered devices have a better chance of getting the current
36 * required.
37 */
38static int w1_strong_pullup = 1;
39module_param_named(strong_pullup, w1_strong_pullup, int, 0);
40
41/* enable/disable CRC checking on DS28E04-100 memory accesses */
42static char w1_enable_crccheck = 1;
43
44#define W1_EEPROM_SIZE		512
45#define W1_PAGE_COUNT		16
46#define W1_PAGE_SIZE		32
47#define W1_PAGE_BITS		5
48#define W1_PAGE_MASK		0x1F
49
50#define W1_F1C_READ_EEPROM	0xF0
51#define W1_F1C_WRITE_SCRATCH	0x0F
52#define W1_F1C_READ_SCRATCH	0xAA
53#define W1_F1C_COPY_SCRATCH	0x55
54#define W1_F1C_ACCESS_WRITE	0x5A
55
56#define W1_1C_REG_LOGIC_STATE	0x220
57
58struct w1_f1C_data {
59	u8	memory[W1_EEPROM_SIZE];
60	u32	validcrc;
61};
62
63/**
64 * Check the file size bounds and adjusts count as needed.
65 * This would not be needed if the file size didn't reset to 0 after a write.
66 */
67static inline size_t w1_f1C_fix_count(loff_t off, size_t count, size_t size)
68{
69	if (off > size)
70		return 0;
71
72	if ((off + count) > size)
73		return size - off;
74
75	return count;
76}
77
78static int w1_f1C_refresh_block(struct w1_slave *sl, struct w1_f1C_data *data,
79				int block)
80{
81	u8	wrbuf[3];
82	int	off = block * W1_PAGE_SIZE;
83
84	if (data->validcrc & (1 << block))
85		return 0;
86
87	if (w1_reset_select_slave(sl)) {
88		data->validcrc = 0;
89		return -EIO;
90	}
91
92	wrbuf[0] = W1_F1C_READ_EEPROM;
93	wrbuf[1] = off & 0xff;
94	wrbuf[2] = off >> 8;
95	w1_write_block(sl->master, wrbuf, 3);
96	w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);
97
98	/* cache the block if the CRC is valid */
99	if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
100		data->validcrc |= (1 << block);
101
102	return 0;
103}
104
105static int w1_f1C_read(struct w1_slave *sl, int addr, int len, char *data)
106{
107	u8 wrbuf[3];
108
109	/* read directly from the EEPROM */
110	if (w1_reset_select_slave(sl))
111		return -EIO;
112
113	wrbuf[0] = W1_F1C_READ_EEPROM;
114	wrbuf[1] = addr & 0xff;
115	wrbuf[2] = addr >> 8;
116
117	w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
118	return w1_read_block(sl->master, data, len);
119}
120
121static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
122			   struct bin_attribute *bin_attr, char *buf,
123			   loff_t off, size_t count)
124{
125	struct w1_slave *sl = kobj_to_w1_slave(kobj);
126	struct w1_f1C_data *data = sl->family_data;
127	int i, min_page, max_page;
128
129	count = w1_f1C_fix_count(off, count, W1_EEPROM_SIZE);
130	if (count == 0)
131		return 0;
132
133	mutex_lock(&sl->master->mutex);
134
135	if (w1_enable_crccheck) {
136		min_page = (off >> W1_PAGE_BITS);
137		max_page = (off + count - 1) >> W1_PAGE_BITS;
138		for (i = min_page; i <= max_page; i++) {
139			if (w1_f1C_refresh_block(sl, data, i)) {
140				count = -EIO;
141				goto out_up;
142			}
143		}
144		memcpy(buf, &data->memory[off], count);
145	} else {
146		count = w1_f1C_read(sl, off, count, buf);
147	}
148
149out_up:
150	mutex_unlock(&sl->master->mutex);
151
152	return count;
153}
154
155/**
156 * Writes to the scratchpad and reads it back for verification.
157 * Then copies the scratchpad to EEPROM.
158 * The data must be on one page.
159 * The master must be locked.
160 *
161 * @param sl	The slave structure
162 * @param addr	Address for the write
163 * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
164 * @param data	The data to write
165 * @return	0=Success -1=failure
166 */
167static int w1_f1C_write(struct w1_slave *sl, int addr, int len, const u8 *data)
168{
169	u8 wrbuf[4];
170	u8 rdbuf[W1_PAGE_SIZE + 3];
171	u8 es = (addr + len - 1) & 0x1f;
172	unsigned int tm = 10;
173	int i;
174	struct w1_f1C_data *f1C = sl->family_data;
175
176	/* Write the data to the scratchpad */
177	if (w1_reset_select_slave(sl))
178		return -1;
179
180	wrbuf[0] = W1_F1C_WRITE_SCRATCH;
181	wrbuf[1] = addr & 0xff;
182	wrbuf[2] = addr >> 8;
183
184	w1_write_block(sl->master, wrbuf, 3);
185	w1_write_block(sl->master, data, len);
186
187	/* Read the scratchpad and verify */
188	if (w1_reset_select_slave(sl))
189		return -1;
190
191	w1_write_8(sl->master, W1_F1C_READ_SCRATCH);
192	w1_read_block(sl->master, rdbuf, len + 3);
193
194	/* Compare what was read against the data written */
195	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
196	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
197		return -1;
198
199	/* Copy the scratchpad to EEPROM */
200	if (w1_reset_select_slave(sl))
201		return -1;
202
203	wrbuf[0] = W1_F1C_COPY_SCRATCH;
204	wrbuf[3] = es;
205
206	for (i = 0; i < sizeof(wrbuf); ++i) {
207		/* issue 10ms strong pullup (or delay) on the last byte
208		   for writing the data from the scratchpad to EEPROM */
209		if (w1_strong_pullup && i == sizeof(wrbuf)-1)
210			w1_next_pullup(sl->master, tm);
211
212		w1_write_8(sl->master, wrbuf[i]);
213	}
214
215	if (!w1_strong_pullup)
216		msleep(tm);
217
218	if (w1_enable_crccheck) {
219		/* invalidate cached data */
220		f1C->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
221	}
222
223	/* Reset the bus to wake up the EEPROM (this may not be needed) */
224	w1_reset_bus(sl->master);
225
226	return 0;
227}
228
229static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
230			    struct bin_attribute *bin_attr, char *buf,
231			    loff_t off, size_t count)
232
233{
234	struct w1_slave *sl = kobj_to_w1_slave(kobj);
235	int addr, len, idx;
236
237	count = w1_f1C_fix_count(off, count, W1_EEPROM_SIZE);
238	if (count == 0)
239		return 0;
240
241	if (w1_enable_crccheck) {
242		/* can only write full blocks in cached mode */
243		if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
244			dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
245				(int)off, count);
246			return -EINVAL;
247		}
248
249		/* make sure the block CRCs are valid */
250		for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
251			if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE)
252				!= CRC16_VALID) {
253				dev_err(&sl->dev, "bad CRC at offset %d\n",
254					(int)off);
255				return -EINVAL;
256			}
257		}
258	}
259
260	mutex_lock(&sl->master->mutex);
261
262	/* Can only write data to one page at a time */
263	idx = 0;
264	while (idx < count) {
265		addr = off + idx;
266		len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
267		if (len > (count - idx))
268			len = count - idx;
269
270		if (w1_f1C_write(sl, addr, len, &buf[idx]) < 0) {
271			count = -EIO;
272			goto out_up;
273		}
274		idx += len;
275	}
276
277out_up:
278	mutex_unlock(&sl->master->mutex);
279
280	return count;
281}
282
283static BIN_ATTR_RW(eeprom, W1_EEPROM_SIZE);
284
285static ssize_t pio_read(struct file *filp, struct kobject *kobj,
286			struct bin_attribute *bin_attr, char *buf, loff_t off,
287			size_t count)
288
289{
290	struct w1_slave *sl = kobj_to_w1_slave(kobj);
291	int ret;
292
293	/* check arguments */
294	if (off != 0 || count != 1 || buf == NULL)
295		return -EINVAL;
296
297	mutex_lock(&sl->master->mutex);
298	ret = w1_f1C_read(sl, W1_1C_REG_LOGIC_STATE, count, buf);
299	mutex_unlock(&sl->master->mutex);
300
301	return ret;
302}
303
304static ssize_t pio_write(struct file *filp, struct kobject *kobj,
305			 struct bin_attribute *bin_attr, char *buf, loff_t off,
306			 size_t count)
307
308{
309	struct w1_slave *sl = kobj_to_w1_slave(kobj);
310	u8 wrbuf[3];
311	u8 ack;
312
313	/* check arguments */
314	if (off != 0 || count != 1 || buf == NULL)
315		return -EINVAL;
316
317	mutex_lock(&sl->master->mutex);
318
319	/* Write the PIO data */
320	if (w1_reset_select_slave(sl)) {
321		mutex_unlock(&sl->master->mutex);
322		return -1;
323	}
324
325	/* set bit 7..2 to value '1' */
326	*buf = *buf | 0xFC;
327
328	wrbuf[0] = W1_F1C_ACCESS_WRITE;
329	wrbuf[1] = *buf;
330	wrbuf[2] = ~(*buf);
331	w1_write_block(sl->master, wrbuf, 3);
332
333	w1_read_block(sl->master, &ack, sizeof(ack));
334
335	mutex_unlock(&sl->master->mutex);
336
337	/* check for acknowledgement */
338	if (ack != 0xAA)
339		return -EIO;
340
341	return count;
342}
343
344static BIN_ATTR_RW(pio, 1);
345
346static ssize_t crccheck_show(struct device *dev, struct device_attribute *attr,
347			     char *buf)
348{
349	if (put_user(w1_enable_crccheck + 0x30, buf))
350		return -EFAULT;
351
352	return sizeof(w1_enable_crccheck);
353}
354
355static ssize_t crccheck_store(struct device *dev, struct device_attribute *attr,
356			      const char *buf, size_t count)
357{
358	char val;
359
360	if (count != 1 || !buf)
361		return -EINVAL;
362
363	if (get_user(val, buf))
364		return -EFAULT;
365
366	/* convert to decimal */
367	val = val - 0x30;
368	if (val != 0 && val != 1)
369		return -EINVAL;
370
371	/* set the new value */
372	w1_enable_crccheck = val;
373
374	return sizeof(w1_enable_crccheck);
375}
376
377static DEVICE_ATTR_RW(crccheck);
378
379static struct attribute *w1_f1C_attrs[] = {
380	&dev_attr_crccheck.attr,
381	NULL,
382};
383
384static struct bin_attribute *w1_f1C_bin_attrs[] = {
385	&bin_attr_eeprom,
386	&bin_attr_pio,
387	NULL,
388};
389
390static const struct attribute_group w1_f1C_group = {
391	.attrs		= w1_f1C_attrs,
392	.bin_attrs	= w1_f1C_bin_attrs,
393};
394
395static const struct attribute_group *w1_f1C_groups[] = {
396	&w1_f1C_group,
397	NULL,
398};
399
400static int w1_f1C_add_slave(struct w1_slave *sl)
401{
402	struct w1_f1C_data *data = NULL;
403
404	if (w1_enable_crccheck) {
405		data = kzalloc(sizeof(struct w1_f1C_data), GFP_KERNEL);
406		if (!data)
407			return -ENOMEM;
408		sl->family_data = data;
409	}
410
411	return 0;
412}
413
414static void w1_f1C_remove_slave(struct w1_slave *sl)
415{
416	kfree(sl->family_data);
417	sl->family_data = NULL;
418}
419
420static struct w1_family_ops w1_f1C_fops = {
421	.add_slave      = w1_f1C_add_slave,
422	.remove_slave   = w1_f1C_remove_slave,
423	.groups		= w1_f1C_groups,
424};
425
426static struct w1_family w1_family_1C = {
427	.fid = W1_FAMILY_DS28E04,
428	.fops = &w1_f1C_fops,
429};
430
431static int __init w1_f1C_init(void)
432{
433	return w1_register_family(&w1_family_1C);
434}
435
436static void __exit w1_f1C_fini(void)
437{
438	w1_unregister_family(&w1_family_1C);
439}
440
441module_init(w1_f1C_init);
442module_exit(w1_f1C_fini);
443