w1_ds2431.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * w1_ds2431.c - w1 family 2d (DS2431) driver
  4 *
  5 * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>
  6 *
  7 * Heavily inspired by w1_DS2433 driver from Ben Gardner <bgardner@wabtec.com>
  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
 17#include <linux/w1.h>
 18
 19#define W1_EEPROM_DS2431	0x2D
 20
 21#define W1_F2D_EEPROM_SIZE		128
 22#define W1_F2D_PAGE_COUNT		4
 23#define W1_F2D_PAGE_BITS		5
 24#define W1_F2D_PAGE_SIZE		(1<<W1_F2D_PAGE_BITS)
 25#define W1_F2D_PAGE_MASK		0x1F
 26
 27#define W1_F2D_SCRATCH_BITS  3
 28#define W1_F2D_SCRATCH_SIZE  (1<<W1_F2D_SCRATCH_BITS)
 29#define W1_F2D_SCRATCH_MASK  (W1_F2D_SCRATCH_SIZE-1)
 30
 31#define W1_F2D_READ_EEPROM	0xF0
 32#define W1_F2D_WRITE_SCRATCH	0x0F
 33#define W1_F2D_READ_SCRATCH	0xAA
 34#define W1_F2D_COPY_SCRATCH	0x55
 35
 36
 37#define W1_F2D_TPROG_MS		11
 38
 39#define W1_F2D_READ_RETRIES		10
 40#define W1_F2D_READ_MAXLEN		8
 41
 42/*
 43 * Check the file size bounds and adjusts count as needed.
 44 * This would not be needed if the file size didn't reset to 0 after a write.
 45 */
 46static inline size_t w1_f2d_fix_count(loff_t off, size_t count, size_t size)
 47{
 48	if (off > size)
 49		return 0;
 50
 51	if ((off + count) > size)
 52		return size - off;
 53
 54	return count;
 55}
 56
 57/*
 58 * Read a block from W1 ROM two times and compares the results.
 59 * If they are equal they are returned, otherwise the read
 60 * is repeated W1_F2D_READ_RETRIES times.
 61 *
 62 * count must not exceed W1_F2D_READ_MAXLEN.
 63 */
 64static int w1_f2d_readblock(struct w1_slave *sl, int off, int count, char *buf)
 65{
 66	u8 wrbuf[3];
 67	u8 cmp[W1_F2D_READ_MAXLEN];
 68	int tries = W1_F2D_READ_RETRIES;
 69
 70	do {
 71		wrbuf[0] = W1_F2D_READ_EEPROM;
 72		wrbuf[1] = off & 0xff;
 73		wrbuf[2] = off >> 8;
 74
 75		if (w1_reset_select_slave(sl))
 76			return -1;
 77
 78		w1_write_block(sl->master, wrbuf, 3);
 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, 3);
 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_F2D_READ_RETRIES);
 93
 94	return -1;
 95}
 96
 97static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 98			   const 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_f2d_fix_count(off, count, W1_F2D_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_F2D_READ_MAXLEN */
111	while (todo > 0) {
112		int block_read;
113
114		if (todo >= W1_F2D_READ_MAXLEN)
115			block_read = W1_F2D_READ_MAXLEN;
116		else
117			block_read = todo;
118
119		if (w1_f2d_readblock(sl, off, block_read, buf) < 0)
120			count = -EIO;
121
122		todo -= W1_F2D_READ_MAXLEN;
123		buf += W1_F2D_READ_MAXLEN;
124		off += W1_F2D_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_F2D_SCRATCH_SIZE bytes and
136 * must be W1_F2D_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_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK))
142 * @param data	The data to write
143 * @return	0=Success -1=failure
144 */
145static int w1_f2d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
146{
147	int tries = W1_F2D_READ_RETRIES;
148	u8 wrbuf[4];
149	u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3];
150	u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE;
151
152retry:
153
154	/* Write the data to the scratchpad */
155	if (w1_reset_select_slave(sl))
156		return -1;
157
158	wrbuf[0] = W1_F2D_WRITE_SCRATCH;
159	wrbuf[1] = addr & 0xff;
160	wrbuf[2] = addr >> 8;
161
162	w1_write_block(sl->master, wrbuf, 3);
163	w1_write_block(sl->master, data, len);
164
165	/* Read the scratchpad and verify */
166	if (w1_reset_select_slave(sl))
167		return -1;
168
169	w1_write_8(sl->master, W1_F2D_READ_SCRATCH);
170	w1_read_block(sl->master, rdbuf, len + 3);
171
172	/* Compare what was read against the data written */
173	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
174	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0)) {
175
176		if (--tries)
177			goto retry;
178
179		dev_err(&sl->dev,
180			"could not write to eeprom, scratchpad compare failed %d times\n",
181			W1_F2D_READ_RETRIES);
182
183		return -1;
184	}
185
186	/* Copy the scratchpad to EEPROM */
187	if (w1_reset_select_slave(sl))
188		return -1;
189
190	wrbuf[0] = W1_F2D_COPY_SCRATCH;
191	wrbuf[3] = es;
192	w1_write_block(sl->master, wrbuf, 4);
193
194	/* Sleep for tprog ms to wait for the write to complete */
195	msleep(W1_F2D_TPROG_MS);
196
197	/* Reset the bus to wake up the EEPROM  */
198	w1_reset_bus(sl->master);
199
200	return 0;
201}
202
203static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
204			    const 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;
209	int copy;
210
211	count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
212	if (count == 0)
213		return 0;
214
215	mutex_lock(&sl->master->bus_mutex);
216
217	/* Can only write data in blocks of the size of the scratchpad */
218	addr = off;
219	len = count;
220	while (len > 0) {
221
222		/* if len too short or addr not aligned */
223		if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) {
224			char tmp[W1_F2D_SCRATCH_SIZE];
225
226			/* read the block and update the parts to be written */
227			if (w1_f2d_readblock(sl, addr & ~W1_F2D_SCRATCH_MASK,
228					W1_F2D_SCRATCH_SIZE, tmp)) {
229				count = -EIO;
230				goto out_up;
231			}
232
233			/* copy at most to the boundary of the PAGE or len */
234			copy = W1_F2D_SCRATCH_SIZE -
235				(addr & W1_F2D_SCRATCH_MASK);
236
237			if (copy > len)
238				copy = len;
239
240			memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy);
241			if (w1_f2d_write(sl, addr & ~W1_F2D_SCRATCH_MASK,
242					W1_F2D_SCRATCH_SIZE, tmp) < 0) {
243				count = -EIO;
244				goto out_up;
245			}
246		} else {
247
248			copy = W1_F2D_SCRATCH_SIZE;
249			if (w1_f2d_write(sl, addr, copy, buf) < 0) {
250				count = -EIO;
251				goto out_up;
252			}
253		}
254		buf += copy;
255		addr += copy;
256		len -= copy;
257	}
258
259out_up:
260	mutex_unlock(&sl->master->bus_mutex);
261
262	return count;
263}
264
265static const BIN_ATTR_RW(eeprom, W1_F2D_EEPROM_SIZE);
266
267static const struct bin_attribute *const w1_f2d_bin_attrs[] = {
268	&bin_attr_eeprom,
269	NULL,
270};
271
272static const struct attribute_group w1_f2d_group = {
273	.bin_attrs = w1_f2d_bin_attrs,
274};
275
276static const struct attribute_group *w1_f2d_groups[] = {
277	&w1_f2d_group,
278	NULL,
279};
280
281static const struct w1_family_ops w1_f2d_fops = {
282	.groups		= w1_f2d_groups,
283};
284
285static struct w1_family w1_family_2d = {
286	.fid = W1_EEPROM_DS2431,
287	.fops = &w1_f2d_fops,
288};
289module_w1_family(w1_family_2d);
290
291MODULE_AUTHOR("Bernhard Weirich <bernhard.weirich@riedel.net>");
292MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM");
293MODULE_LICENSE("GPL");
294MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2431));