1/*
2 *	w1_ds2433.c - w1 family 23 (DS2433) driver
3 *
4 * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.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#ifdef CONFIG_W1_SLAVE_DS2433_CRC
18#include <linux/crc16.h>
19
20#define CRC16_INIT		0
21#define CRC16_VALID		0xb001
22
23#endif
24
25#include "../w1.h"
26#include "../w1_int.h"
27#include "../w1_family.h"
28
29MODULE_LICENSE("GPL");
30MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
31MODULE_DESCRIPTION("w1 family 23 driver for DS2433, 4kb EEPROM");
32MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2433));
33
34#define W1_EEPROM_SIZE		512
35#define W1_PAGE_COUNT		16
36#define W1_PAGE_SIZE		32
37#define W1_PAGE_BITS		5
38#define W1_PAGE_MASK		0x1F
39
40#define W1_F23_TIME		300
41
42#define W1_F23_READ_EEPROM	0xF0
43#define W1_F23_WRITE_SCRATCH	0x0F
44#define W1_F23_READ_SCRATCH	0xAA
45#define W1_F23_COPY_SCRATCH	0x55
46
47struct w1_f23_data {
48	u8	memory[W1_EEPROM_SIZE];
49	u32	validcrc;
50};
51
52/**
53 * Check the file size bounds and adjusts count as needed.
54 * This would not be needed if the file size didn't reset to 0 after a write.
55 */
56static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size)
57{
58	if (off > size)
59		return 0;
60
61	if ((off + count) > size)
62		return (size - off);
63
64	return count;
65}
66
67#ifdef CONFIG_W1_SLAVE_DS2433_CRC
68static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
69				int block)
70{
71	u8	wrbuf[3];
72	int	off = block * W1_PAGE_SIZE;
73
74	if (data->validcrc & (1 << block))
75		return 0;
76
77	if (w1_reset_select_slave(sl)) {
78		data->validcrc = 0;
79		return -EIO;
80	}
81
82	wrbuf[0] = W1_F23_READ_EEPROM;
83	wrbuf[1] = off & 0xff;
84	wrbuf[2] = off >> 8;
85	w1_write_block(sl->master, wrbuf, 3);
86	w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);
87
88	/* cache the block if the CRC is valid */
89	if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
90		data->validcrc |= (1 << block);
91
92	return 0;
93}
94#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
95
96static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
97			   struct bin_attribute *bin_attr, char *buf,
98			   loff_t off, size_t count)
99{
100	struct w1_slave *sl = kobj_to_w1_slave(kobj);
101#ifdef CONFIG_W1_SLAVE_DS2433_CRC
102	struct w1_f23_data *data = sl->family_data;
103	int i, min_page, max_page;
104#else
105	u8 wrbuf[3];
106#endif
107
108	if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
109		return 0;
110
111	mutex_lock(&sl->master->bus_mutex);
112
113#ifdef CONFIG_W1_SLAVE_DS2433_CRC
114
115	min_page = (off >> W1_PAGE_BITS);
116	max_page = (off + count - 1) >> W1_PAGE_BITS;
117	for (i = min_page; i <= max_page; i++) {
118		if (w1_f23_refresh_block(sl, data, i)) {
119			count = -EIO;
120			goto out_up;
121		}
122	}
123	memcpy(buf, &data->memory[off], count);
124
125#else 	/* CONFIG_W1_SLAVE_DS2433_CRC */
126
127	/* read directly from the EEPROM */
128	if (w1_reset_select_slave(sl)) {
129		count = -EIO;
130		goto out_up;
131	}
132
133	wrbuf[0] = W1_F23_READ_EEPROM;
134	wrbuf[1] = off & 0xff;
135	wrbuf[2] = off >> 8;
136	w1_write_block(sl->master, wrbuf, 3);
137	w1_read_block(sl->master, buf, count);
138
139#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
140
141out_up:
142	mutex_unlock(&sl->master->bus_mutex);
143
144	return count;
145}
146
147/**
148 * Writes to the scratchpad and reads it back for verification.
149 * Then copies the scratchpad to EEPROM.
150 * The data must be on one page.
151 * The master must be locked.
152 *
153 * @param sl	The slave structure
154 * @param addr	Address for the write
155 * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
156 * @param data	The data to write
157 * @return	0=Success -1=failure
158 */
159static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
160{
161#ifdef CONFIG_W1_SLAVE_DS2433_CRC
162	struct w1_f23_data *f23 = sl->family_data;
163#endif
164	u8 wrbuf[4];
165	u8 rdbuf[W1_PAGE_SIZE + 3];
166	u8 es = (addr + len - 1) & 0x1f;
167
168	/* Write the data to the scratchpad */
169	if (w1_reset_select_slave(sl))
170		return -1;
171
172	wrbuf[0] = W1_F23_WRITE_SCRATCH;
173	wrbuf[1] = addr & 0xff;
174	wrbuf[2] = addr >> 8;
175
176	w1_write_block(sl->master, wrbuf, 3);
177	w1_write_block(sl->master, data, len);
178
179	/* Read the scratchpad and verify */
180	if (w1_reset_select_slave(sl))
181		return -1;
182
183	w1_write_8(sl->master, W1_F23_READ_SCRATCH);
184	w1_read_block(sl->master, rdbuf, len + 3);
185
186	/* Compare what was read against the data written */
187	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
188	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
189		return -1;
190
191	/* Copy the scratchpad to EEPROM */
192	if (w1_reset_select_slave(sl))
193		return -1;
194
195	wrbuf[0] = W1_F23_COPY_SCRATCH;
196	wrbuf[3] = es;
197	w1_write_block(sl->master, wrbuf, 4);
198
199	/* Sleep for 5 ms to wait for the write to complete */
200	msleep(5);
201
202	/* Reset the bus to wake up the EEPROM (this may not be needed) */
203	w1_reset_bus(sl->master);
204#ifdef CONFIG_W1_SLAVE_DS2433_CRC
205	f23->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
206#endif
207	return 0;
208}
209
210static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
211			    struct bin_attribute *bin_attr, char *buf,
212			    loff_t off, size_t count)
213{
214	struct w1_slave *sl = kobj_to_w1_slave(kobj);
215	int addr, len, idx;
216
217	if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
218		return 0;
219
220#ifdef CONFIG_W1_SLAVE_DS2433_CRC
221	/* can only write full blocks in cached mode */
222	if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
223		dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
224			(int)off, count);
225		return -EINVAL;
226	}
227
228	/* make sure the block CRCs are valid */
229	for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
230		if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {
231			dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);
232			return -EINVAL;
233		}
234	}
235#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
236
237	mutex_lock(&sl->master->bus_mutex);
238
239	/* Can only write data to one page at a time */
240	idx = 0;
241	while (idx < count) {
242		addr = off + idx;
243		len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
244		if (len > (count - idx))
245			len = count - idx;
246
247		if (w1_f23_write(sl, addr, len, &buf[idx]) < 0) {
248			count = -EIO;
249			goto out_up;
250		}
251		idx += len;
252	}
253
254out_up:
255	mutex_unlock(&sl->master->bus_mutex);
256
257	return count;
258}
259
260static BIN_ATTR_RW(eeprom, W1_EEPROM_SIZE);
261
262static struct bin_attribute *w1_f23_bin_attributes[] = {
263	&bin_attr_eeprom,
264	NULL,
265};
266
267static const struct attribute_group w1_f23_group = {
268	.bin_attrs = w1_f23_bin_attributes,
269};
270
271static const struct attribute_group *w1_f23_groups[] = {
272	&w1_f23_group,
273	NULL,
274};
275
276static int w1_f23_add_slave(struct w1_slave *sl)
277{
278#ifdef CONFIG_W1_SLAVE_DS2433_CRC
279	struct w1_f23_data *data;
280
281	data = kzalloc(sizeof(struct w1_f23_data), GFP_KERNEL);
282	if (!data)
283		return -ENOMEM;
284	sl->family_data = data;
285
286#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
287	return 0;
288}
289
290static void w1_f23_remove_slave(struct w1_slave *sl)
291{
292#ifdef CONFIG_W1_SLAVE_DS2433_CRC
293	kfree(sl->family_data);
294	sl->family_data = NULL;
295#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
296}
297
298static struct w1_family_ops w1_f23_fops = {
299	.add_slave      = w1_f23_add_slave,
300	.remove_slave   = w1_f23_remove_slave,
301	.groups		= w1_f23_groups,
302};
303
304static struct w1_family w1_family_23 = {
305	.fid = W1_EEPROM_DS2433,
306	.fops = &w1_f23_fops,
307};
308
309static int __init w1_f23_init(void)
310{
311	return w1_register_family(&w1_family_23);
312}
313
314static void __exit w1_f23_fini(void)
315{
316	w1_unregister_family(&w1_family_23);
317}
318
319module_init(w1_f23_init);
320module_exit(w1_f23_fini);
321