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 !ret; 119 uclass_next_device(&dev), i++) { 120 if (ret) { 121 debug("Cannot find w1 bus %d\n", busnum); 122 return ret; 123 } 124 if (i == busnum) { 125 *busp = dev; 126 return 0; 127 } 128 } 129 return ret; 130 } 131 132 u8 w1_get_device_family(struct udevice *dev) 133 { 134 struct w1_device *w1 = dev_get_parent_platdata(dev); 135 136 return w1->id & 0xff; 137 } 138 139 int w1_reset_select(struct udevice *dev) 140 { 141 struct w1_device *w1 = dev_get_parent_platdata(dev); 142 struct udevice *bus = dev_get_parent(dev); 143 const struct w1_ops *ops = device_get_ops(bus); 144 int i; 145 146 if (!ops->reset || !ops->write_byte) 147 return -ENOSYS; 148 149 ops->reset(bus); 150 151 ops->write_byte(bus, W1_MATCH_ROM); 152 153 for (i = 0; i < sizeof(w1->id); i++) 154 ops->write_byte(bus, (w1->id >> (i * 8)) & 0xff); 155 156 return 0; 157 } 158 159 int w1_read_byte(struct udevice *dev) 160 { 161 struct udevice *bus = dev_get_parent(dev); 162 const struct w1_ops *ops = device_get_ops(bus); 163 164 if (!ops->read_byte) 165 return -ENOSYS; 166 167 return ops->read_byte(bus); 168 } 169 170 int w1_read_buf(struct udevice *dev, u8 *buf, unsigned int count) 171 { 172 int i, ret; 173 174 for (i = 0; i < count; i++) { 175 ret = w1_read_byte(dev); 176 if (ret < 0) 177 return ret; 178 179 buf[i] = ret & 0xff; 180 } 181 182 return 0; 183 } 184 185 int w1_write_byte(struct udevice *dev, u8 byte) 186 { 187 struct udevice *bus = dev_get_parent(dev); 188 const struct w1_ops *ops = device_get_ops(bus); 189 190 if (!ops->write_byte) 191 return -ENOSYS; 192 193 ops->write_byte(bus, byte); 194 195 return 0; 196 } 197 198 static int w1_post_probe(struct udevice *bus) 199 { 200 w1_enumerate(bus); 201 202 return 0; 203 } 204 205 int w1_init(void) 206 { 207 struct udevice *bus; 208 struct uclass *uc; 209 int ret; 210 211 ret = uclass_get(UCLASS_W1, &uc); 212 if (ret) 213 return ret; 214 215 uclass_foreach_dev(bus, uc) { 216 ret = device_probe(bus); 217 if (ret == -ENODEV) { /* No such device. */ 218 printf("W1 controller not available.\n"); 219 continue; 220 } 221 222 if (ret) { /* Other error. */ 223 printf("W1 controller probe failed.\n"); 224 continue; 225 } 226 } 227 return 0; 228 } 229 230 UCLASS_DRIVER(w1) = { 231 .name = "w1", 232 .id = UCLASS_W1, 233 .flags = DM_UC_FLAG_SEQ_ALIAS, 234 .per_device_auto_alloc_size = sizeof(struct w1_bus), 235 .post_probe = w1_post_probe, 236 #if CONFIG_IS_ENABLED(OF_CONTROL) 237 .post_bind = dm_scan_fdt_dev, 238 #endif 239 .per_child_platdata_auto_alloc_size = sizeof(struct w1_device), 240 }; 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