1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *	w1_ds2433.c - w1 family 23 (DS2433) driver
4 *
5 * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.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#ifdef CONFIG_W1_SLAVE_DS2433_CRC
16#include <linux/crc16.h>
17
18#define CRC16_INIT		0
19#define CRC16_VALID		0xb001
20
21#endif
22
23#include <linux/w1.h>
24
25#define W1_EEPROM_DS2433	0x23
26
27#define W1_EEPROM_SIZE		512
28#define W1_PAGE_COUNT		16
29#define W1_PAGE_SIZE		32
30#define W1_PAGE_BITS		5
31#define W1_PAGE_MASK		0x1F
32
33#define W1_F23_TIME		300
34
35#define W1_F23_READ_EEPROM	0xF0
36#define W1_F23_WRITE_SCRATCH	0x0F
37#define W1_F23_READ_SCRATCH	0xAA
38#define W1_F23_COPY_SCRATCH	0x55
39
40struct w1_f23_data {
41	u8	memory[W1_EEPROM_SIZE];
42	u32	validcrc;
43};
44
45/**
46 * Check the file size bounds and adjusts count as needed.
47 * This would not be needed if the file size didn't reset to 0 after a write.
48 */
49static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size)
50{
51	if (off > size)
52		return 0;
53
54	if ((off + count) > size)
55		return (size - off);
56
57	return count;
58}
59
60#ifdef CONFIG_W1_SLAVE_DS2433_CRC
61static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
62				int block)
63{
64	u8	wrbuf[3];
65	int	off = block * W1_PAGE_SIZE;
66
67	if (data->validcrc & (1 << block))
68		return 0;
69
70	if (w1_reset_select_slave(sl)) {
71		data->validcrc = 0;
72		return -EIO;
73	}
74
75	wrbuf[0] = W1_F23_READ_EEPROM;
76	wrbuf[1] = off & 0xff;
77	wrbuf[2] = off >> 8;
78	w1_write_block(sl->master, wrbuf, 3);
79	w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);
80
81	/* cache the block if the CRC is valid */
82	if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
83		data->validcrc |= (1 << block);
84
85	return 0;
86}
87#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
88
89static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
90			   struct bin_attribute *bin_attr, char *buf,
91			   loff_t off, size_t count)
92{
93	struct w1_slave *sl = kobj_to_w1_slave(kobj);
94#ifdef CONFIG_W1_SLAVE_DS2433_CRC
95	struct w1_f23_data *data = sl->family_data;
96	int i, min_page, max_page;
97#else
98	u8 wrbuf[3];
99#endif
100
101	if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
102		return 0;
103
104	mutex_lock(&sl->master->bus_mutex);
105
106#ifdef CONFIG_W1_SLAVE_DS2433_CRC
107
108	min_page = (off >> W1_PAGE_BITS);
109	max_page = (off + count - 1) >> W1_PAGE_BITS;
110	for (i = min_page; i <= max_page; i++) {
111		if (w1_f23_refresh_block(sl, data, i)) {
112			count = -EIO;
113			goto out_up;
114		}
115	}
116	memcpy(buf, &data->memory[off], count);
117
118#else 	/* CONFIG_W1_SLAVE_DS2433_CRC */
119
120	/* read directly from the EEPROM */
121	if (w1_reset_select_slave(sl)) {
122		count = -EIO;
123		goto out_up;
124	}
125
126	wrbuf[0] = W1_F23_READ_EEPROM;
127	wrbuf[1] = off & 0xff;
128	wrbuf[2] = off >> 8;
129	w1_write_block(sl->master, wrbuf, 3);
130	w1_read_block(sl->master, buf, count);
131
132#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
133
134out_up:
135	mutex_unlock(&sl->master->bus_mutex);
136
137	return count;
138}
139
140/**
141 * Writes to the scratchpad and reads it back for verification.
142 * Then copies the scratchpad to EEPROM.
143 * The data must be on one page.
144 * The master must be locked.
145 *
146 * @param sl	The slave structure
147 * @param addr	Address for the write
148 * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
149 * @param data	The data to write
150 * @return	0=Success -1=failure
151 */
152static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
153{
154#ifdef CONFIG_W1_SLAVE_DS2433_CRC
155	struct w1_f23_data *f23 = sl->family_data;
156#endif
157	u8 wrbuf[4];
158	u8 rdbuf[W1_PAGE_SIZE + 3];
159	u8 es = (addr + len - 1) & 0x1f;
160
161	/* Write the data to the scratchpad */
162	if (w1_reset_select_slave(sl))
163		return -1;
164
165	wrbuf[0] = W1_F23_WRITE_SCRATCH;
166	wrbuf[1] = addr & 0xff;
167	wrbuf[2] = addr >> 8;
168
169	w1_write_block(sl->master, wrbuf, 3);
170	w1_write_block(sl->master, data, len);
171
172	/* Read the scratchpad and verify */
173	if (w1_reset_select_slave(sl))
174		return -1;
175
176	w1_write_8(sl->master, W1_F23_READ_SCRATCH);
177	w1_read_block(sl->master, rdbuf, len + 3);
178
179	/* Compare what was read against the data written */
180	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
181	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
182		return -1;
183
184	/* Copy the scratchpad to EEPROM */
185	if (w1_reset_select_slave(sl))
186		return -1;
187
188	wrbuf[0] = W1_F23_COPY_SCRATCH;
189	wrbuf[3] = es;
190	w1_write_block(sl->master, wrbuf, 4);
191
192	/* Sleep for 5 ms to wait for the write to complete */
193	msleep(5);
194
195	/* Reset the bus to wake up the EEPROM (this may not be needed) */
196	w1_reset_bus(sl->master);
197#ifdef CONFIG_W1_SLAVE_DS2433_CRC
198	f23->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
199#endif
200	return 0;
201}
202
203static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
204			    struct bin_attribute *bin_attr, char *buf,
205			    loff_t off, size_t count)
206{
207	struct w1_slave *sl = kobj_to_w1_slave(kobj);
208	int addr, len, idx;
209
210	if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
211		return 0;
212
213#ifdef CONFIG_W1_SLAVE_DS2433_CRC
214	/* can only write full blocks in cached mode */
215	if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
216		dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
217			(int)off, count);
218		return -EINVAL;
219	}
220
221	/* make sure the block CRCs are valid */
222	for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
223		if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {
224			dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);
225			return -EINVAL;
226		}
227	}
228#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
229
230	mutex_lock(&sl->master->bus_mutex);
231
232	/* Can only write data to one page at a time */
233	idx = 0;
234	while (idx < count) {
235		addr = off + idx;
236		len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
237		if (len > (count - idx))
238			len = count - idx;
239
240		if (w1_f23_write(sl, addr, len, &buf[idx]) < 0) {
241			count = -EIO;
242			goto out_up;
243		}
244		idx += len;
245	}
246
247out_up:
248	mutex_unlock(&sl->master->bus_mutex);
249
250	return count;
251}
252
253static BIN_ATTR_RW(eeprom, W1_EEPROM_SIZE);
254
255static struct bin_attribute *w1_f23_bin_attributes[] = {
256	&bin_attr_eeprom,
257	NULL,
258};
259
260static const struct attribute_group w1_f23_group = {
261	.bin_attrs = w1_f23_bin_attributes,
262};
263
264static const struct attribute_group *w1_f23_groups[] = {
265	&w1_f23_group,
266	NULL,
267};
268
269static int w1_f23_add_slave(struct w1_slave *sl)
270{
271#ifdef CONFIG_W1_SLAVE_DS2433_CRC
272	struct w1_f23_data *data;
273
274	data = kzalloc(sizeof(struct w1_f23_data), GFP_KERNEL);
275	if (!data)
276		return -ENOMEM;
277	sl->family_data = data;
278
279#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
280	return 0;
281}
282
283static void w1_f23_remove_slave(struct w1_slave *sl)
284{
285#ifdef CONFIG_W1_SLAVE_DS2433_CRC
286	kfree(sl->family_data);
287	sl->family_data = NULL;
288#endif	/* CONFIG_W1_SLAVE_DS2433_CRC */
289}
290
291static const struct w1_family_ops w1_f23_fops = {
292	.add_slave      = w1_f23_add_slave,
293	.remove_slave   = w1_f23_remove_slave,
294	.groups		= w1_f23_groups,
295};
296
297static struct w1_family w1_family_23 = {
298	.fid = W1_EEPROM_DS2433,
299	.fops = &w1_f23_fops,
300};
301module_w1_family(w1_family_23);
302
303MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
304MODULE_DESCRIPTION("w1 family 23 driver for DS2433, 4kb EEPROM");
305MODULE_LICENSE("GPL");
306MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2433));
307