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 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 /* last device or error, aborting here */ 88 if ((triplet_ret & 0x03) == 0x03) 89 last_device = true; 90 91 if ((triplet_ret & 0x03) != 0x03) { 92 if (desc_bit == last_zero || last_zero < 0) { 93 last_device = 1; 94 w1->search_id = 0; 95 } else { 96 w1->search_id = rn; 97 } 98 desc_bit = last_zero; 99 100 debug("%s: Detected new device 0x%llx (family 0x%x)\n", 101 bus->name, rn, (u8)(rn & 0xff)); 102 103 /* attempt to register as w1-eeprom device */ 104 w1_eeprom_register_new_device(rn); 105 } 106 } 107 108 return 0; 109 } 110 111 int w1_get_bus(int busnum, struct udevice **busp) 112 { 113 int ret, i = 0; 114 115 struct udevice *dev; 116 117 for (ret = uclass_first_device(UCLASS_W1, &dev); 118 dev && !ret; 119 ret = uclass_next_device(&dev), i++) { 120 if (i == busnum) { 121 *busp = dev; 122 return 0; 123 } 124 } 125 126 if (!ret) { 127 debug("Cannot find w1 bus %d\n", busnum); 128 ret = -ENODEV; 129 } 130 131 return ret; 132 } 133 134 u8 w1_get_device_family(struct udevice *dev) 135 { 136 struct w1_device *w1 = dev_get_parent_platdata(dev); 137 138 return w1->id & 0xff; 139 } 140 141 int w1_reset_select(struct udevice *dev) 142 { 143 struct w1_device *w1 = dev_get_parent_platdata(dev); 144 struct udevice *bus = dev_get_parent(dev); 145 const struct w1_ops *ops = device_get_ops(bus); 146 int i; 147 148 if (!ops->reset || !ops->write_byte) 149 return -ENOSYS; 150 151 ops->reset(bus); 152 153 ops->write_byte(bus, W1_MATCH_ROM); 154 155 for (i = 0; i < sizeof(w1->id); i++) 156 ops->write_byte(bus, (w1->id >> (i * 8)) & 0xff); 157 158 return 0; 159 } 160 161 int w1_read_byte(struct udevice *dev) 162 { 163 struct udevice *bus = dev_get_parent(dev); 164 const struct w1_ops *ops = device_get_ops(bus); 165 166 if (!ops->read_byte) 167 return -ENOSYS; 168 169 return ops->read_byte(bus); 170 } 171 172 int w1_read_buf(struct udevice *dev, u8 *buf, unsigned int count) 173 { 174 int i, ret; 175 176 for (i = 0; i < count; i++) { 177 ret = w1_read_byte(dev); 178 if (ret < 0) 179 return ret; 180 181 buf[i] = ret & 0xff; 182 } 183 184 return 0; 185 } 186 187 int w1_write_byte(struct udevice *dev, u8 byte) 188 { 189 struct udevice *bus = dev_get_parent(dev); 190 const struct w1_ops *ops = device_get_ops(bus); 191 192 if (!ops->write_byte) 193 return -ENOSYS; 194 195 ops->write_byte(bus, byte); 196 197 return 0; 198 } 199 200 static int w1_post_probe(struct udevice *bus) 201 { 202 w1_enumerate(bus); 203 204 return 0; 205 } 206 207 int w1_init(void) 208 { 209 struct udevice *bus; 210 struct uclass *uc; 211 int ret; 212 213 ret = uclass_get(UCLASS_W1, &uc); 214 if (ret) 215 return ret; 216 217 uclass_foreach_dev(bus, uc) { 218 ret = device_probe(bus); 219 if (ret == -ENODEV) { /* No such device. */ 220 printf("W1 controller not available.\n"); 221 continue; 222 } 223 224 if (ret) { /* Other error. */ 225 printf("W1 controller probe failed.\n"); 226 continue; 227 } 228 } 229 return 0; 230 } 231 232 UCLASS_DRIVER(w1) = { 233 .name = "w1", 234 .id = UCLASS_W1, 235 .flags = DM_UC_FLAG_SEQ_ALIAS, 236 .per_device_auto_alloc_size = sizeof(struct w1_bus), 237 .post_probe = w1_post_probe, 238 #if CONFIG_IS_ENABLED(OF_CONTROL) 239 .post_bind = dm_scan_fdt_dev, 240 #endif 241 .per_child_platdata_auto_alloc_size = sizeof(struct w1_device), 242 }; 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