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#ifdef CONFIG_W1_SLAVE_DS2433_CRC
17#include <linux/crc16.h>
18
19#define CRC16_INIT		0
20#define CRC16_VALID		0xb001
21
22#endif
23
24#include "../w1.h"
25#include "../w1_int.h"
26#include "../w1_family.h"
27
28MODULE_LICENSE("GPL");
29MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
30MODULE_DESCRIPTION("w1 family 23 driver for DS2433, 4kb EEPROM");
31
32#define W1_EEPROM_SIZE		512
33#define W1_PAGE_COUNT		16
34#define W1_PAGE_SIZE		32
35#define W1_PAGE_BITS		5
36#define W1_PAGE_MASK		0x1F
37
38#define W1_F23_TIME		300
39
40#define W1_F23_READ_EEPROM	0xF0
41#define W1_F23_WRITE_SCRATCH	0x0F
42#define W1_F23_READ_SCRATCH	0xAA
43#define W1_F23_COPY_SCRATCH	0x55
44
45struct w1_f23_data {
46	u8	memory[W1_EEPROM_SIZE];
47	u32	validcrc;
48};
49
50/**
51 * Check the file size bounds and adjusts count as needed.
52 * This would not be needed if the file size didn't reset to 0 after a write.
53 */
54static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size)
55{
56	if (off > size)
57		return 0;
58
59	if ((off + count) > size)
60		return (size - off);
61
62	return count;
63}
64
65#ifdef CONFIG_W1_SLAVE_DS2433_CRC
66static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
67				int block)
68{
69	u8	wrbuf[3];
70	int	off = block * W1_PAGE_SIZE;
71
72	if (data->validcrc & (1 << block))
73		return 0;
74
75	if (w1_reset_select_slave(sl)) {
76		data->validcrc = 0;
77		return -EIO;
78	}
79
80	wrbuf[0] = W1_F23_READ_EEPROM;
81	wrbuf[1] = off & 0xff;
82	wrbuf[2] = off >> 8;
83	w1_write_block(sl->master, wrbuf, 3);
84	w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);
85
86	/* cache the block if the CRC is valid */
87	if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
88		data->validcrc |= (1 << block);
89
90	return 0;
91}
92#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
93
94static ssize_t w1_f23_read_bin(struct kobject *kobj, char *buf, loff_t off,
95			       size_t count)
96{
97	struct w1_slave *sl = kobj_to_w1_slave(kobj);
98#ifdef CONFIG_W1_SLAVE_DS2433_CRC
99	struct w1_f23_data *data = sl->family_data;
100	int i, min_page, max_page;
101#else
102	u8 wrbuf[3];
103#endif
104
105	if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
106		return 0;
107
108	mutex_lock(&sl->master->mutex);
109
110#ifdef CONFIG_W1_SLAVE_DS2433_CRC
111
112	min_page = (off >> W1_PAGE_BITS);
113	max_page = (off + count - 1) >> W1_PAGE_BITS;
114	for (i = min_page; i <= max_page; i++) {
115		if (w1_f23_refresh_block(sl, data, i)) {
116			count = -EIO;
117			goto out_up;
118		}
119	}
120	memcpy(buf, &data->memory[off], count);
121
122#else 	/* CONFIG_W1_SLAVE_DS2433_CRC */
123
124	/* read directly from the EEPROM */
125	if (w1_reset_select_slave(sl)) {
126		count = -EIO;
127		goto out_up;
128	}
129
130	wrbuf[0] = W1_F23_READ_EEPROM;
131	wrbuf[1] = off & 0xff;
132	wrbuf[2] = off >> 8;
133	w1_write_block(sl->master, wrbuf, 3);
134	w1_read_block(sl->master, buf, count);
135
136#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
137
138out_up:
139	mutex_unlock(&sl->master->mutex);
140
141	return count;
142}
143
144/**
145 * Writes to the scratchpad and reads it back for verification.
146 * Then copies the scratchpad to EEPROM.
147 * The data must be on one page.
148 * The master must be locked.
149 *
150 * @param sl	The slave structure
151 * @param addr	Address for the write
152 * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
153 * @param data	The data to write
154 * @return	0=Success -1=failure
155 */
156static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
157{
158	u8 wrbuf[4];
159	u8 rdbuf[W1_PAGE_SIZE + 3];
160	u8 es = (addr + len - 1) & 0x1f;
161
162	/* Write the data to the scratchpad */
163	if (w1_reset_select_slave(sl))
164		return -1;
165
166	wrbuf[0] = W1_F23_WRITE_SCRATCH;
167	wrbuf[1] = addr & 0xff;
168	wrbuf[2] = addr >> 8;
169
170	w1_write_block(sl->master, wrbuf, 3);
171	w1_write_block(sl->master, data, len);
172
173	/* Read the scratchpad and verify */
174	if (w1_reset_select_slave(sl))
175		return -1;
176
177	w1_write_8(sl->master, W1_F23_READ_SCRATCH);
178	w1_read_block(sl->master, rdbuf, len + 3);
179
180	/* Compare what was read against the data written */
181	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
182	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
183		return -1;
184
185	/* Copy the scratchpad to EEPROM */
186	if (w1_reset_select_slave(sl))
187		return -1;
188
189	wrbuf[0] = W1_F23_COPY_SCRATCH;
190	wrbuf[3] = es;
191	w1_write_block(sl->master, wrbuf, 4);
192
193	/* Sleep for 5 ms to wait for the write to complete */
194	msleep(5);
195
196	/* Reset the bus to wake up the EEPROM (this may not be needed) */
197	w1_reset_bus(sl->master);
198
199	return 0;
200}
201
202static ssize_t w1_f23_write_bin(struct kobject *kobj, char *buf, loff_t off,
203				size_t count)
204{
205	struct w1_slave *sl = kobj_to_w1_slave(kobj);
206	int addr, len, idx;
207
208	if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
209		return 0;
210
211#ifdef CONFIG_W1_SLAVE_DS2433_CRC
212	/* can only write full blocks in cached mode */
213	if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
214		dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
215			(int)off, count);
216		return -EINVAL;
217	}
218
219	/* make sure the block CRCs are valid */
220	for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
221		if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {
222			dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);
223			return -EINVAL;
224		}
225	}
226#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
227
228	mutex_lock(&sl->master->mutex);
229
230	/* Can only write data to one page at a time */
231	idx = 0;
232	while (idx < count) {
233		addr = off + idx;
234		len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
235		if (len > (count - idx))
236			len = count - idx;
237
238		if (w1_f23_write(sl, addr, len, &buf[idx]) < 0) {
239			count = -EIO;
240			goto out_up;
241		}
242		idx += len;
243	}
244
245out_up:
246	mutex_unlock(&sl->master->mutex);
247
248	return count;
249}
250
251static struct bin_attribute w1_f23_bin_attr = {
252	.attr = {
253		.name = "eeprom",
254		.mode = S_IRUGO | S_IWUSR,
255		.owner = THIS_MODULE,
256	},
257	.size = W1_EEPROM_SIZE,
258	.read = w1_f23_read_bin,
259	.write = w1_f23_write_bin,
260};
261
262static int w1_f23_add_slave(struct w1_slave *sl)
263{
264	int err;
265#ifdef CONFIG_W1_SLAVE_DS2433_CRC
266	struct w1_f23_data *data;
267
268	data = kmalloc(sizeof(struct w1_f23_data), GFP_KERNEL);
269	if (!data)
270		return -ENOMEM;
271	memset(data, 0, sizeof(struct w1_f23_data));
272	sl->family_data = data;
273
274#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
275
276	err = sysfs_create_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);
277
278#ifdef CONFIG_W1_SLAVE_DS2433_CRC
279	if (err)
280		kfree(data);
281#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
282
283	return err;
284}
285
286static void w1_f23_remove_slave(struct w1_slave *sl)
287{
288#ifdef CONFIG_W1_SLAVE_DS2433_CRC
289	kfree(sl->family_data);
290	sl->family_data = NULL;
291#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
292	sysfs_remove_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);
293}
294
295static struct w1_family_ops w1_f23_fops = {
296	.add_slave      = w1_f23_add_slave,
297	.remove_slave   = w1_f23_remove_slave,
298};
299
300static struct w1_family w1_family_23 = {
301	.fid = W1_EEPROM_DS2433,
302	.fops = &w1_f23_fops,
303};
304
305static int __init w1_f23_init(void)
306{
307	return w1_register_family(&w1_family_23);
308}
309
310static void __exit w1_f23_fini(void)
311{
312	w1_unregister_family(&w1_family_23);
313}
314
315module_init(w1_f23_init);
316module_exit(w1_f23_fini);
317