w1_ds2805.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * w1_ds2805 - w1 family 0d (DS28E05) driver
  4 *
  5 * Copyright (c) 2016 Andrew Worsley amworsley@gmail.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
 15#include <linux/w1.h>
 16
 17#define W1_EEPROM_DS2805       0x0D
 18
 19#define W1_F0D_EEPROM_SIZE		128
 20#define W1_F0D_PAGE_BITS		3
 21#define W1_F0D_PAGE_SIZE		(1<<W1_F0D_PAGE_BITS)
 22#define W1_F0D_PAGE_MASK		0x0F
 23
 24#define W1_F0D_SCRATCH_BITS  1
 25#define W1_F0D_SCRATCH_SIZE  (1<<W1_F0D_SCRATCH_BITS)
 26#define W1_F0D_SCRATCH_MASK  (W1_F0D_SCRATCH_SIZE-1)
 27
 28#define W1_F0D_READ_EEPROM	0xF0
 29#define W1_F0D_WRITE_EEPROM	0x55
 30#define W1_F0D_RELEASE		0xFF
 31
 32#define W1_F0D_CS_OK		0xAA /* Chip Status Ok */
 33
 34#define W1_F0D_TPROG_MS		16
 35
 36#define W1_F0D_READ_RETRIES		10
 37#define W1_F0D_READ_MAXLEN		W1_F0D_EEPROM_SIZE
 38
 39/*
 40 * Check the file size bounds and adjusts count as needed.
 41 * This would not be needed if the file size didn't reset to 0 after a write.
 42 */
 43static inline size_t w1_f0d_fix_count(loff_t off, size_t count, size_t size)
 44{
 45	if (off > size)
 46		return 0;
 47
 48	if ((off + count) > size)
 49		return size - off;
 50
 51	return count;
 52}
 53
 54/*
 55 * Read a block from W1 ROM two times and compares the results.
 56 * If they are equal they are returned, otherwise the read
 57 * is repeated W1_F0D_READ_RETRIES times.
 58 *
 59 * count must not exceed W1_F0D_READ_MAXLEN.
 60 */
 61static int w1_f0d_readblock(struct w1_slave *sl, int off, int count, char *buf)
 62{
 63	u8 wrbuf[3];
 64	u8 cmp[W1_F0D_READ_MAXLEN];
 65	int tries = W1_F0D_READ_RETRIES;
 66
 67	do {
 68		wrbuf[0] = W1_F0D_READ_EEPROM;
 69		wrbuf[1] = off & 0x7f;
 70		wrbuf[2] = 0;
 71
 72		if (w1_reset_select_slave(sl))
 73			return -1;
 74
 75		w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
 76		w1_read_block(sl->master, buf, count);
 77
 78		if (w1_reset_select_slave(sl))
 79			return -1;
 80
 81		w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
 82		w1_read_block(sl->master, cmp, count);
 83
 84		if (!memcmp(cmp, buf, count))
 85			return 0;
 86	} while (--tries);
 87
 88	dev_err(&sl->dev, "proof reading failed %d times\n",
 89			W1_F0D_READ_RETRIES);
 90
 91	return -1;
 92}
 93
 94static ssize_t w1_f0d_read_bin(struct file *filp, struct kobject *kobj,
 95			       const struct bin_attribute *bin_attr,
 96			       char *buf, loff_t off, size_t count)
 97{
 98	struct w1_slave *sl = kobj_to_w1_slave(kobj);
 99	int todo = count;
100
101	count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
102	if (count == 0)
103		return 0;
104
105	mutex_lock(&sl->master->mutex);
106
107	/* read directly from the EEPROM in chunks of W1_F0D_READ_MAXLEN */
108	while (todo > 0) {
109		int block_read;
110
111		if (todo >= W1_F0D_READ_MAXLEN)
112			block_read = W1_F0D_READ_MAXLEN;
113		else
114			block_read = todo;
115
116		if (w1_f0d_readblock(sl, off, block_read, buf) < 0) {
117			count = -EIO;
118			break;
119		}
120
121		todo -= W1_F0D_READ_MAXLEN;
122		buf += W1_F0D_READ_MAXLEN;
123		off += W1_F0D_READ_MAXLEN;
124	}
125
126	mutex_unlock(&sl->master->mutex);
127
128	return count;
129}
130
131/*
132 * Writes to the scratchpad and reads it back for verification.
133 * Then copies the scratchpad to EEPROM.
134 * The data must be aligned at W1_F0D_SCRATCH_SIZE bytes and
135 * must be W1_F0D_SCRATCH_SIZE bytes long.
136 * The master must be locked.
137 *
138 * @param sl	The slave structure
139 * @param addr	Address for the write
140 * @param len   length must be <= (W1_F0D_PAGE_SIZE - (addr & W1_F0D_PAGE_MASK))
141 * @param data	The data to write
142 * @return	0=Success -1=failure
143 */
144static int w1_f0d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
145{
146	int tries = W1_F0D_READ_RETRIES;
147	u8 wrbuf[3];
148	u8 rdbuf[W1_F0D_SCRATCH_SIZE];
149	u8 cs;
150
151	if ((addr & 1) || (len != 2)) {
152		dev_err(&sl->dev, "%s: bad addr/len -  addr=%#x len=%d\n",
153		    __func__, addr, len);
154		return -1;
155	}
156
157retry:
158
159	/* Write the data to the scratchpad */
160	if (w1_reset_select_slave(sl))
161		return -1;
162
163	wrbuf[0] = W1_F0D_WRITE_EEPROM;
164	wrbuf[1] = addr & 0xff;
165	wrbuf[2] = 0xff; /* ?? from Example */
166
167	w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
168	w1_write_block(sl->master, data, len);
169
170	w1_read_block(sl->master, rdbuf, sizeof(rdbuf));
171	/* Compare what was read against the data written */
172	if ((rdbuf[0] != data[0]) || (rdbuf[1] != data[1])) {
173
174		if (--tries)
175			goto retry;
176
177		dev_err(&sl->dev,
178			"could not write to eeprom, scratchpad compare failed %d times\n",
179			W1_F0D_READ_RETRIES);
180		pr_info("%s: rdbuf = %#x %#x data = %#x %#x\n",
181		    __func__, rdbuf[0], rdbuf[1], data[0], data[1]);
182
183		return -1;
184	}
185
186	/* Trigger write out to EEPROM */
187	w1_write_8(sl->master, W1_F0D_RELEASE);
188
189	/* Sleep for tprog ms to wait for the write to complete */
190	msleep(W1_F0D_TPROG_MS);
191
192	/* Check CS (Command Status) == 0xAA ? */
193	cs = w1_read_8(sl->master);
194	if (cs != W1_F0D_CS_OK) {
195		dev_err(&sl->dev, "save to eeprom failed = CS=%#x\n", cs);
196		return -1;
197	}
198
199	return 0;
200}
201
202static ssize_t w1_f0d_write_bin(struct file *filp, struct kobject *kobj,
203				const struct bin_attribute *bin_attr,
204				char *buf, loff_t off, size_t count)
205{
206	struct w1_slave *sl = kobj_to_w1_slave(kobj);
207	int addr, len;
208	int copy;
209
210	count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
211	if (count == 0)
212		return 0;
213
214	mutex_lock(&sl->master->mutex);
215
216	/* Can only write data in blocks of the size of the scratchpad */
217	addr = off;
218	len = count;
219	while (len > 0) {
220
221		/* if len too short or addr not aligned */
222		if (len < W1_F0D_SCRATCH_SIZE || addr & W1_F0D_SCRATCH_MASK) {
223			char tmp[W1_F0D_SCRATCH_SIZE];
224
225			/* read the block and update the parts to be written */
226			if (w1_f0d_readblock(sl, addr & ~W1_F0D_SCRATCH_MASK,
227					W1_F0D_SCRATCH_SIZE, tmp)) {
228				count = -EIO;
229				goto out_up;
230			}
231
232			/* copy at most to the boundary of the PAGE or len */
233			copy = W1_F0D_SCRATCH_SIZE -
234				(addr & W1_F0D_SCRATCH_MASK);
235
236			if (copy > len)
237				copy = len;
238
239			memcpy(&tmp[addr & W1_F0D_SCRATCH_MASK], buf, copy);
240			if (w1_f0d_write(sl, addr & ~W1_F0D_SCRATCH_MASK,
241					W1_F0D_SCRATCH_SIZE, tmp) < 0) {
242				count = -EIO;
243				goto out_up;
244			}
245		} else {
246
247			copy = W1_F0D_SCRATCH_SIZE;
248			if (w1_f0d_write(sl, addr, copy, buf) < 0) {
249				count = -EIO;
250				goto out_up;
251			}
252		}
253		buf += copy;
254		addr += copy;
255		len -= copy;
256	}
257
258out_up:
259	mutex_unlock(&sl->master->mutex);
260
261	return count;
262}
263
264static const struct bin_attribute w1_f0d_bin_attr = {
265	.attr = {
266		.name = "eeprom",
267		.mode = 0644,
268	},
269	.size = W1_F0D_EEPROM_SIZE,
270	.read = w1_f0d_read_bin,
271	.write = w1_f0d_write_bin,
272};
273
274static int w1_f0d_add_slave(struct w1_slave *sl)
275{
276	return sysfs_create_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
277}
278
279static void w1_f0d_remove_slave(struct w1_slave *sl)
280{
281	sysfs_remove_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
282}
283
284static const struct w1_family_ops w1_f0d_fops = {
285	.add_slave      = w1_f0d_add_slave,
286	.remove_slave   = w1_f0d_remove_slave,
287};
288
289static struct w1_family w1_family_0d = {
290	.fid = W1_EEPROM_DS2805,
291	.fops = &w1_f0d_fops,
292};
293
294module_w1_family(w1_family_0d);
295
296MODULE_LICENSE("GPL");
297MODULE_AUTHOR("Andrew Worsley amworsley@gmail.com");
298MODULE_DESCRIPTION("w1 family 0d driver for DS2805, 1kb EEPROM");