1/*
2 * w1_ds2431.c - w1 family 2d (DS2431) driver
3 *
4 * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>
5 *
6 * Heavily inspired by w1_DS2433 driver from Ben Gardner <bgardner@wabtec.com>
7 *
8 * This source code is licensed under the GNU General Public License,
9 * Version 2. See the file COPYING for more details.
10 */
11
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/moduleparam.h>
15#include <linux/device.h>
16#include <linux/types.h>
17#include <linux/delay.h>
18
19#include "../w1.h"
20#include "../w1_int.h"
21#include "../w1_family.h"
22
23#define W1_F2D_EEPROM_SIZE		128
24#define W1_F2D_PAGE_COUNT		4
25#define W1_F2D_PAGE_BITS		5
26#define W1_F2D_PAGE_SIZE		(1<<W1_F2D_PAGE_BITS)
27#define W1_F2D_PAGE_MASK		0x1F
28
29#define W1_F2D_SCRATCH_BITS  3
30#define W1_F2D_SCRATCH_SIZE  (1<<W1_F2D_SCRATCH_BITS)
31#define W1_F2D_SCRATCH_MASK  (W1_F2D_SCRATCH_SIZE-1)
32
33#define W1_F2D_READ_EEPROM	0xF0
34#define W1_F2D_WRITE_SCRATCH	0x0F
35#define W1_F2D_READ_SCRATCH	0xAA
36#define W1_F2D_COPY_SCRATCH	0x55
37
38
39#define W1_F2D_TPROG_MS		11
40
41#define W1_F2D_READ_RETRIES		10
42#define W1_F2D_READ_MAXLEN		8
43
44/*
45 * Check the file size bounds and adjusts count as needed.
46 * This would not be needed if the file size didn't reset to 0 after a write.
47 */
48static inline size_t w1_f2d_fix_count(loff_t off, size_t count, size_t size)
49{
50	if (off > size)
51		return 0;
52
53	if ((off + count) > size)
54		return size - off;
55
56	return count;
57}
58
59/*
60 * Read a block from W1 ROM two times and compares the results.
61 * If they are equal they are returned, otherwise the read
62 * is repeated W1_F2D_READ_RETRIES times.
63 *
64 * count must not exceed W1_F2D_READ_MAXLEN.
65 */
66static int w1_f2d_readblock(struct w1_slave *sl, int off, int count, char *buf)
67{
68	u8 wrbuf[3];
69	u8 cmp[W1_F2D_READ_MAXLEN];
70	int tries = W1_F2D_READ_RETRIES;
71
72	do {
73		wrbuf[0] = W1_F2D_READ_EEPROM;
74		wrbuf[1] = off & 0xff;
75		wrbuf[2] = off >> 8;
76
77		if (w1_reset_select_slave(sl))
78			return -1;
79
80		w1_write_block(sl->master, wrbuf, 3);
81		w1_read_block(sl->master, buf, count);
82
83		if (w1_reset_select_slave(sl))
84			return -1;
85
86		w1_write_block(sl->master, wrbuf, 3);
87		w1_read_block(sl->master, cmp, count);
88
89		if (!memcmp(cmp, buf, count))
90			return 0;
91	} while (--tries);
92
93	dev_err(&sl->dev, "proof reading failed %d times\n",
94			W1_F2D_READ_RETRIES);
95
96	return -1;
97}
98
99static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
100			   struct bin_attribute *bin_attr, char *buf,
101			   loff_t off, size_t count)
102{
103	struct w1_slave *sl = kobj_to_w1_slave(kobj);
104	int todo = count;
105
106	count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
107	if (count == 0)
108		return 0;
109
110	mutex_lock(&sl->master->bus_mutex);
111
112	/* read directly from the EEPROM in chunks of W1_F2D_READ_MAXLEN */
113	while (todo > 0) {
114		int block_read;
115
116		if (todo >= W1_F2D_READ_MAXLEN)
117			block_read = W1_F2D_READ_MAXLEN;
118		else
119			block_read = todo;
120
121		if (w1_f2d_readblock(sl, off, block_read, buf) < 0)
122			count = -EIO;
123
124		todo -= W1_F2D_READ_MAXLEN;
125		buf += W1_F2D_READ_MAXLEN;
126		off += W1_F2D_READ_MAXLEN;
127	}
128
129	mutex_unlock(&sl->master->bus_mutex);
130
131	return count;
132}
133
134/*
135 * Writes to the scratchpad and reads it back for verification.
136 * Then copies the scratchpad to EEPROM.
137 * The data must be aligned at W1_F2D_SCRATCH_SIZE bytes and
138 * must be W1_F2D_SCRATCH_SIZE bytes long.
139 * The master must be locked.
140 *
141 * @param sl	The slave structure
142 * @param addr	Address for the write
143 * @param len   length must be <= (W1_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK))
144 * @param data	The data to write
145 * @return	0=Success -1=failure
146 */
147static int w1_f2d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
148{
149	int tries = W1_F2D_READ_RETRIES;
150	u8 wrbuf[4];
151	u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3];
152	u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE;
153
154retry:
155
156	/* Write the data to the scratchpad */
157	if (w1_reset_select_slave(sl))
158		return -1;
159
160	wrbuf[0] = W1_F2D_WRITE_SCRATCH;
161	wrbuf[1] = addr & 0xff;
162	wrbuf[2] = addr >> 8;
163
164	w1_write_block(sl->master, wrbuf, 3);
165	w1_write_block(sl->master, data, len);
166
167	/* Read the scratchpad and verify */
168	if (w1_reset_select_slave(sl))
169		return -1;
170
171	w1_write_8(sl->master, W1_F2D_READ_SCRATCH);
172	w1_read_block(sl->master, rdbuf, len + 3);
173
174	/* Compare what was read against the data written */
175	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
176	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0)) {
177
178		if (--tries)
179			goto retry;
180
181		dev_err(&sl->dev,
182			"could not write to eeprom, scratchpad compare failed %d times\n",
183			W1_F2D_READ_RETRIES);
184
185		return -1;
186	}
187
188	/* Copy the scratchpad to EEPROM */
189	if (w1_reset_select_slave(sl))
190		return -1;
191
192	wrbuf[0] = W1_F2D_COPY_SCRATCH;
193	wrbuf[3] = es;
194	w1_write_block(sl->master, wrbuf, 4);
195
196	/* Sleep for tprog ms to wait for the write to complete */
197	msleep(W1_F2D_TPROG_MS);
198
199	/* Reset the bus to wake up the EEPROM  */
200	w1_reset_bus(sl->master);
201
202	return 0;
203}
204
205static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
206			    struct bin_attribute *bin_attr, char *buf,
207			    loff_t off, size_t count)
208{
209	struct w1_slave *sl = kobj_to_w1_slave(kobj);
210	int addr, len;
211	int copy;
212
213	count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
214	if (count == 0)
215		return 0;
216
217	mutex_lock(&sl->master->bus_mutex);
218
219	/* Can only write data in blocks of the size of the scratchpad */
220	addr = off;
221	len = count;
222	while (len > 0) {
223
224		/* if len too short or addr not aligned */
225		if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) {
226			char tmp[W1_F2D_SCRATCH_SIZE];
227
228			/* read the block and update the parts to be written */
229			if (w1_f2d_readblock(sl, addr & ~W1_F2D_SCRATCH_MASK,
230					W1_F2D_SCRATCH_SIZE, tmp)) {
231				count = -EIO;
232				goto out_up;
233			}
234
235			/* copy at most to the boundary of the PAGE or len */
236			copy = W1_F2D_SCRATCH_SIZE -
237				(addr & W1_F2D_SCRATCH_MASK);
238
239			if (copy > len)
240				copy = len;
241
242			memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy);
243			if (w1_f2d_write(sl, addr & ~W1_F2D_SCRATCH_MASK,
244					W1_F2D_SCRATCH_SIZE, tmp) < 0) {
245				count = -EIO;
246				goto out_up;
247			}
248		} else {
249
250			copy = W1_F2D_SCRATCH_SIZE;
251			if (w1_f2d_write(sl, addr, copy, buf) < 0) {
252				count = -EIO;
253				goto out_up;
254			}
255		}
256		buf += copy;
257		addr += copy;
258		len -= copy;
259	}
260
261out_up:
262	mutex_unlock(&sl->master->bus_mutex);
263
264	return count;
265}
266
267static BIN_ATTR_RW(eeprom, W1_F2D_EEPROM_SIZE);
268
269static struct bin_attribute *w1_f2d_bin_attrs[] = {
270	&bin_attr_eeprom,
271	NULL,
272};
273
274static const struct attribute_group w1_f2d_group = {
275	.bin_attrs = w1_f2d_bin_attrs,
276};
277
278static const struct attribute_group *w1_f2d_groups[] = {
279	&w1_f2d_group,
280	NULL,
281};
282
283static struct w1_family_ops w1_f2d_fops = {
284	.groups		= w1_f2d_groups,
285};
286
287static struct w1_family w1_family_2d = {
288	.fid = W1_EEPROM_DS2431,
289	.fops = &w1_f2d_fops,
290};
291
292static int __init w1_f2d_init(void)
293{
294	return w1_register_family(&w1_family_2d);
295}
296
297static void __exit w1_f2d_fini(void)
298{
299	w1_unregister_family(&w1_family_2d);
300}
301
302module_init(w1_f2d_init);
303module_exit(w1_f2d_fini);
304
305MODULE_LICENSE("GPL");
306MODULE_AUTHOR("Bernhard Weirich <bernhard.weirich@riedel.net>");
307MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM");
308MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2431));
309