1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * w1_ds2430.c - w1 family 14 (DS2430) driver
4 **
5 * Copyright (c) 2019 Angelo Dureghello <angelo.dureghello@timesys.com>
6 *
7 * Cloned and modified from ds2431
8 * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>
9 *
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 <linux/w1.h>
20
21#define W1_EEPROM_DS2430	0x14
22
23#define W1_F14_EEPROM_SIZE	32
24#define W1_F14_PAGE_COUNT	1
25#define W1_F14_PAGE_BITS	5
26#define W1_F14_PAGE_SIZE	(1 << W1_F14_PAGE_BITS)
27#define W1_F14_PAGE_MASK	0x1F
28
29#define W1_F14_SCRATCH_BITS	5
30#define W1_F14_SCRATCH_SIZE	(1 << W1_F14_SCRATCH_BITS)
31#define W1_F14_SCRATCH_MASK	(W1_F14_SCRATCH_SIZE-1)
32
33#define W1_F14_READ_EEPROM	0xF0
34#define W1_F14_WRITE_SCRATCH	0x0F
35#define W1_F14_READ_SCRATCH	0xAA
36#define W1_F14_COPY_SCRATCH	0x55
37#define W1_F14_VALIDATION_KEY	0xa5
38
39#define W1_F14_TPROG_MS		11
40#define W1_F14_READ_RETRIES	10
41#define W1_F14_READ_MAXLEN	W1_F14_SCRATCH_SIZE
42
43/*
44 * Check the file size bounds and adjusts count as needed.
45 * This would not be needed if the file size didn't reset to 0 after a write.
46 */
47static inline size_t w1_f14_fix_count(loff_t off, size_t count, size_t size)
48{
49	if (off > size)
50		return 0;
51
52	if ((off + count) > size)
53		return size - off;
54
55	return count;
56}
57
58/*
59 * Read a block from W1 ROM two times and compares the results.
60 * If they are equal they are returned, otherwise the read
61 * is repeated W1_F14_READ_RETRIES times.
62 *
63 * count must not exceed W1_F14_READ_MAXLEN.
64 */
65static int w1_f14_readblock(struct w1_slave *sl, int off, int count, char *buf)
66{
67	u8 wrbuf[2];
68	u8 cmp[W1_F14_READ_MAXLEN];
69	int tries = W1_F14_READ_RETRIES;
70
71	do {
72		wrbuf[0] = W1_F14_READ_EEPROM;
73		wrbuf[1] = off & 0xff;
74
75		if (w1_reset_select_slave(sl))
76			return -1;
77
78		w1_write_block(sl->master, wrbuf, 2);
79		w1_read_block(sl->master, buf, count);
80
81		if (w1_reset_select_slave(sl))
82			return -1;
83
84		w1_write_block(sl->master, wrbuf, 2);
85		w1_read_block(sl->master, cmp, count);
86
87		if (!memcmp(cmp, buf, count))
88			return 0;
89	} while (--tries);
90
91	dev_err(&sl->dev, "proof reading failed %d times\n",
92			W1_F14_READ_RETRIES);
93
94	return -1;
95}
96
97static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
98			   struct bin_attribute *bin_attr, char *buf,
99			   loff_t off, size_t count)
100{
101	struct w1_slave *sl = kobj_to_w1_slave(kobj);
102	int todo = count;
103
104	count = w1_f14_fix_count(off, count, W1_F14_EEPROM_SIZE);
105	if (count == 0)
106		return 0;
107
108	mutex_lock(&sl->master->bus_mutex);
109
110	/* read directly from the EEPROM in chunks of W1_F14_READ_MAXLEN */
111	while (todo > 0) {
112		int block_read;
113
114		if (todo >= W1_F14_READ_MAXLEN)
115			block_read = W1_F14_READ_MAXLEN;
116		else
117			block_read = todo;
118
119		if (w1_f14_readblock(sl, off, block_read, buf) < 0)
120			count = -EIO;
121
122		todo -= W1_F14_READ_MAXLEN;
123		buf += W1_F14_READ_MAXLEN;
124		off += W1_F14_READ_MAXLEN;
125	}
126
127	mutex_unlock(&sl->master->bus_mutex);
128
129	return count;
130}
131
132/*
133 * Writes to the scratchpad and reads it back for verification.
134 * Then copies the scratchpad to EEPROM.
135 * The data must be aligned at W1_F14_SCRATCH_SIZE bytes and
136 * must be W1_F14_SCRATCH_SIZE bytes long.
137 * The master must be locked.
138 *
139 * @param sl	The slave structure
140 * @param addr	Address for the write
141 * @param len   length must be <= (W1_F14_PAGE_SIZE - (addr & W1_F14_PAGE_MASK))
142 * @param data	The data to write
143 * @return	0=Success -1=failure
144 */
145static int w1_f14_write(struct w1_slave *sl, int addr, int len, const u8 *data)
146{
147	int tries = W1_F14_READ_RETRIES;
148	u8 wrbuf[2];
149	u8 rdbuf[W1_F14_SCRATCH_SIZE + 3];
150
151retry:
152
153	/* Write the data to the scratchpad */
154	if (w1_reset_select_slave(sl))
155		return -1;
156
157	wrbuf[0] = W1_F14_WRITE_SCRATCH;
158	wrbuf[1] = addr & 0xff;
159
160	w1_write_block(sl->master, wrbuf, 2);
161	w1_write_block(sl->master, data, len);
162
163	/* Read the scratchpad and verify */
164	if (w1_reset_select_slave(sl))
165		return -1;
166
167	w1_write_8(sl->master, W1_F14_READ_SCRATCH);
168	w1_read_block(sl->master, rdbuf, len + 2);
169
170	/*
171	 * Compare what was read against the data written
172	 * Note: on read scratchpad, device returns 2 bulk 0xff bytes,
173	 * to be discarded.
174	 */
175	if ((memcmp(data, &rdbuf[2], len) != 0)) {
176
177		if (--tries)
178			goto retry;
179
180		dev_err(&sl->dev,
181			"could not write to eeprom, scratchpad compare failed %d times\n",
182			W1_F14_READ_RETRIES);
183
184		return -1;
185	}
186
187	/* Copy the scratchpad to EEPROM */
188	if (w1_reset_select_slave(sl))
189		return -1;
190
191	wrbuf[0] = W1_F14_COPY_SCRATCH;
192	wrbuf[1] = W1_F14_VALIDATION_KEY;
193	w1_write_block(sl->master, wrbuf, 2);
194
195	/* Sleep for tprog ms to wait for the write to complete */
196	msleep(W1_F14_TPROG_MS);
197
198	/* Reset the bus to wake up the EEPROM  */
199	w1_reset_bus(sl->master);
200
201	return 0;
202}
203
204static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
205			    struct bin_attribute *bin_attr, char *buf,
206			    loff_t off, size_t count)
207{
208	struct w1_slave *sl = kobj_to_w1_slave(kobj);
209	int addr, len;
210	int copy;
211
212	count = w1_f14_fix_count(off, count, W1_F14_EEPROM_SIZE);
213	if (count == 0)
214		return 0;
215
216	mutex_lock(&sl->master->bus_mutex);
217
218	/* Can only write data in blocks of the size of the scratchpad */
219	addr = off;
220	len = count;
221	while (len > 0) {
222
223		/* if len too short or addr not aligned */
224		if (len < W1_F14_SCRATCH_SIZE || addr & W1_F14_SCRATCH_MASK) {
225			char tmp[W1_F14_SCRATCH_SIZE];
226
227			/* read the block and update the parts to be written */
228			if (w1_f14_readblock(sl, addr & ~W1_F14_SCRATCH_MASK,
229					W1_F14_SCRATCH_SIZE, tmp)) {
230				count = -EIO;
231				goto out_up;
232			}
233
234			/* copy at most to the boundary of the PAGE or len */
235			copy = W1_F14_SCRATCH_SIZE -
236				(addr & W1_F14_SCRATCH_MASK);
237
238			if (copy > len)
239				copy = len;
240
241			memcpy(&tmp[addr & W1_F14_SCRATCH_MASK], buf, copy);
242			if (w1_f14_write(sl, addr & ~W1_F14_SCRATCH_MASK,
243					W1_F14_SCRATCH_SIZE, tmp) < 0) {
244				count = -EIO;
245				goto out_up;
246			}
247		} else {
248
249			copy = W1_F14_SCRATCH_SIZE;
250			if (w1_f14_write(sl, addr, copy, buf) < 0) {
251				count = -EIO;
252				goto out_up;
253			}
254		}
255		buf += copy;
256		addr += copy;
257		len -= copy;
258	}
259
260out_up:
261	mutex_unlock(&sl->master->bus_mutex);
262
263	return count;
264}
265
266static BIN_ATTR_RW(eeprom, W1_F14_EEPROM_SIZE);
267
268static struct bin_attribute *w1_f14_bin_attrs[] = {
269	&bin_attr_eeprom,
270	NULL,
271};
272
273static const struct attribute_group w1_f14_group = {
274	.bin_attrs = w1_f14_bin_attrs,
275};
276
277static const struct attribute_group *w1_f14_groups[] = {
278	&w1_f14_group,
279	NULL,
280};
281
282static const struct w1_family_ops w1_f14_fops = {
283	.groups	= w1_f14_groups,
284};
285
286static struct w1_family w1_family_14 = {
287	.fid = W1_EEPROM_DS2430,
288	.fops = &w1_f14_fops,
289};
290module_w1_family(w1_family_14);
291
292MODULE_AUTHOR("Angelo Dureghello <angelo.dureghello@timesys.com>");
293MODULE_DESCRIPTION("w1 family 14 driver for DS2430, 256b EEPROM");
294MODULE_LICENSE("GPL");
295MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2430));
296