1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 *
4 * Copyright (c) 2015 Free Electrons
5 * Copyright (c) 2015 NextThing Co.
6 * Copyright (c) 2018 Microchip Technology, Inc.
7 *
8 * Maxime Ripard <maxime.ripard@free-electrons.com>
9 * Eugen Hristev <eugen.hristev@microchip.com>
10 *
11 */
12
13 #include <common.h>
14 #include <dm.h>
15 #include <w1.h>
16 #include <w1-eeprom.h>
17
18 #include <dm/device-internal.h>
19
20 #define W1_MATCH_ROM 0x55
21 #define W1_SKIP_ROM 0xcc
22 #define W1_SEARCH 0xf0
23
24 struct w1_bus {
25 u64 search_id;
26 };
27
w1_enumerate(struct udevice * bus)28 static int w1_enumerate(struct udevice *bus)
29 {
30 const struct w1_ops *ops = device_get_ops(bus);
31 struct w1_bus *w1 = dev_get_uclass_priv(bus);
32 u64 last_rn, rn = w1->search_id, tmp64;
33 bool last_device = false;
34 int search_bit, desc_bit = 64;
35 int last_zero = -1;
36 u8 triplet_ret = 0;
37 int i;
38
39 if (!ops->reset || !ops->write_byte || !ops->triplet)
40 return -ENOSYS;
41
42 while (!last_device) {
43 last_rn = rn;
44 rn = 0;
45
46 /*
47 * Reset bus and all 1-wire device state machines
48 * so they can respond to our requests.
49 *
50 * Return 0 - device(s) present, 1 - no devices present.
51 */
52 if (ops->reset(bus)) {
53 debug("%s: No devices present on the wire.\n",
54 __func__);
55 break;
56 }
57
58 /* Start the search */
59 ops->write_byte(bus, W1_SEARCH);
60 for (i = 0; i < 64; ++i) {
61 /* Determine the direction/search bit */
62 if (i == desc_bit)
63 /* took the 0 path last time, so take the 1 path */
64 search_bit = 1;
65 else if (i > desc_bit)
66 /* take the 0 path on the next branch */
67 search_bit = 0;
68 else
69 search_bit = ((last_rn >> i) & 0x1);
70
71 /* Read two bits and write one bit */
72 triplet_ret = ops->triplet(bus, search_bit);
73
74 /* quit if no device responded */
75 if ((triplet_ret & 0x03) == 0x03)
76 break;
77
78 /* If both directions were valid, and we took the 0 path... */
79 if (triplet_ret == 0)
80 last_zero = i;
81
82 /* extract the direction taken & update the device number */
83 tmp64 = (triplet_ret >> 2);
84 rn |= (tmp64 << i);
85 }
86
87 if ((triplet_ret & 0x03) != 0x03) {
88 if (desc_bit == last_zero || last_zero < 0) {
89 last_device = 1;
90 w1->search_id = 0;
91 } else {
92 w1->search_id = rn;
93 }
94 desc_bit = last_zero;
95
96 debug("%s: Detected new device 0x%llx (family 0x%x)\n",
97 bus->name, rn, (u8)(rn & 0xff));
98
99 /* attempt to register as w1-eeprom device */
100 w1_eeprom_register_new_device(rn);
101 }
102 }
103
104 return 0;
105 }
106
w1_get_bus(int busnum,struct udevice ** busp)107 int w1_get_bus(int busnum, struct udevice **busp)
108 {
109 int ret, i = 0;
110
111 struct udevice *dev;
112
113 for (ret = uclass_first_device(UCLASS_W1, &dev);
114 dev && !ret;
115 ret = uclass_next_device(&dev), i++) {
116 if (i == busnum) {
117 *busp = dev;
118 return 0;
119 }
120 }
121
122 if (!ret) {
123 debug("Cannot find w1 bus %d\n", busnum);
124 ret = -ENODEV;
125 }
126
127 return ret;
128 }
129
w1_get_device_family(struct udevice * dev)130 u8 w1_get_device_family(struct udevice *dev)
131 {
132 struct w1_device *w1 = dev_get_parent_platdata(dev);
133
134 return w1->id & 0xff;
135 }
136
w1_reset_select(struct udevice * dev)137 int w1_reset_select(struct udevice *dev)
138 {
139 struct w1_device *w1 = dev_get_parent_platdata(dev);
140 struct udevice *bus = dev_get_parent(dev);
141 const struct w1_ops *ops = device_get_ops(bus);
142 int i;
143
144 if (!ops->reset || !ops->write_byte)
145 return -ENOSYS;
146
147 ops->reset(bus);
148
149 ops->write_byte(bus, W1_MATCH_ROM);
150
151 for (i = 0; i < sizeof(w1->id); i++)
152 ops->write_byte(bus, (w1->id >> (i * 8)) & 0xff);
153
154 return 0;
155 }
156
w1_read_byte(struct udevice * dev)157 int w1_read_byte(struct udevice *dev)
158 {
159 struct udevice *bus = dev_get_parent(dev);
160 const struct w1_ops *ops = device_get_ops(bus);
161
162 if (!ops->read_byte)
163 return -ENOSYS;
164
165 return ops->read_byte(bus);
166 }
167
w1_read_buf(struct udevice * dev,u8 * buf,unsigned int count)168 int w1_read_buf(struct udevice *dev, u8 *buf, unsigned int count)
169 {
170 int i, ret;
171
172 for (i = 0; i < count; i++) {
173 ret = w1_read_byte(dev);
174 if (ret < 0)
175 return ret;
176
177 buf[i] = ret & 0xff;
178 }
179
180 return 0;
181 }
182
w1_write_byte(struct udevice * dev,u8 byte)183 int w1_write_byte(struct udevice *dev, u8 byte)
184 {
185 struct udevice *bus = dev_get_parent(dev);
186 const struct w1_ops *ops = device_get_ops(bus);
187
188 if (!ops->write_byte)
189 return -ENOSYS;
190
191 ops->write_byte(bus, byte);
192
193 return 0;
194 }
195
w1_post_probe(struct udevice * bus)196 static int w1_post_probe(struct udevice *bus)
197 {
198 w1_enumerate(bus);
199
200 return 0;
201 }
202
w1_init(void)203 int w1_init(void)
204 {
205 struct udevice *bus;
206 struct uclass *uc;
207 int ret;
208
209 ret = uclass_get(UCLASS_W1, &uc);
210 if (ret)
211 return ret;
212
213 uclass_foreach_dev(bus, uc) {
214 ret = device_probe(bus);
215 if (ret == -ENODEV) { /* No such device. */
216 printf("W1 controller not available.\n");
217 continue;
218 }
219
220 if (ret) { /* Other error. */
221 printf("W1 controller probe failed.\n");
222 continue;
223 }
224 }
225 return 0;
226 }
227
228 UCLASS_DRIVER(w1) = {
229 .name = "w1",
230 .id = UCLASS_W1,
231 .flags = DM_UC_FLAG_SEQ_ALIAS,
232 .per_device_auto_alloc_size = sizeof(struct w1_bus),
233 .post_probe = w1_post_probe,
234 #if CONFIG_IS_ENABLED(OF_CONTROL)
235 .post_bind = dm_scan_fdt_dev,
236 #endif
237 .per_child_platdata_auto_alloc_size = sizeof(struct w1_device),
238 };
239