1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * MDIO I2C bridge
4 *
5 * Copyright (C) 2015-2016 Russell King
6 * Copyright (C) 2021 Marek Behun
7 *
8 * Network PHYs can appear on I2C buses when they are part of SFP module.
9 * This driver exposes these PHYs to the networking PHY code, allowing
10 * our PHY drivers access to these PHYs, and so allowing configuration
11 * of their settings.
12 */
13 #include <linux/i2c.h>
14 #include <linux/mdio/mdio-i2c.h>
15 #include <linux/phy.h>
16 #include <linux/sfp.h>
17
18 /*
19 * I2C bus addresses 0x50 and 0x51 are normally an EEPROM, which is
20 * specified to be present in SFP modules. These correspond with PHY
21 * addresses 16 and 17. Disallow access to these "phy" addresses.
22 */
i2c_mii_valid_phy_id(int phy_id)23 static bool i2c_mii_valid_phy_id(int phy_id)
24 {
25 return phy_id != 0x10 && phy_id != 0x11;
26 }
27
i2c_mii_phy_addr(int phy_id)28 static unsigned int i2c_mii_phy_addr(int phy_id)
29 {
30 return phy_id + 0x40;
31 }
32
i2c_mii_read_default_c45(struct mii_bus * bus,int phy_id,int devad,int reg)33 static int i2c_mii_read_default_c45(struct mii_bus *bus, int phy_id, int devad,
34 int reg)
35 {
36 struct i2c_adapter *i2c = bus->priv;
37 struct i2c_msg msgs[2];
38 u8 addr[3], data[2], *p;
39 int bus_addr, ret;
40
41 if (!i2c_mii_valid_phy_id(phy_id))
42 return 0xffff;
43
44 p = addr;
45 if (devad >= 0) {
46 *p++ = 0x20 | devad;
47 *p++ = reg >> 8;
48 }
49 *p++ = reg;
50
51 bus_addr = i2c_mii_phy_addr(phy_id);
52 msgs[0].addr = bus_addr;
53 msgs[0].flags = 0;
54 msgs[0].len = p - addr;
55 msgs[0].buf = addr;
56 msgs[1].addr = bus_addr;
57 msgs[1].flags = I2C_M_RD;
58 msgs[1].len = sizeof(data);
59 msgs[1].buf = data;
60
61 ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));
62 if (ret != ARRAY_SIZE(msgs))
63 return 0xffff;
64
65 return data[0] << 8 | data[1];
66 }
67
i2c_mii_write_default_c45(struct mii_bus * bus,int phy_id,int devad,int reg,u16 val)68 static int i2c_mii_write_default_c45(struct mii_bus *bus, int phy_id,
69 int devad, int reg, u16 val)
70 {
71 struct i2c_adapter *i2c = bus->priv;
72 struct i2c_msg msg;
73 int ret;
74 u8 data[5], *p;
75
76 if (!i2c_mii_valid_phy_id(phy_id))
77 return 0;
78
79 p = data;
80 if (devad >= 0) {
81 *p++ = devad;
82 *p++ = reg >> 8;
83 }
84 *p++ = reg;
85 *p++ = val >> 8;
86 *p++ = val;
87
88 msg.addr = i2c_mii_phy_addr(phy_id);
89 msg.flags = 0;
90 msg.len = p - data;
91 msg.buf = data;
92
93 ret = i2c_transfer(i2c, &msg, 1);
94
95 return ret < 0 ? ret : 0;
96 }
97
i2c_mii_read_default_c22(struct mii_bus * bus,int phy_id,int reg)98 static int i2c_mii_read_default_c22(struct mii_bus *bus, int phy_id, int reg)
99 {
100 return i2c_mii_read_default_c45(bus, phy_id, -1, reg);
101 }
102
i2c_mii_write_default_c22(struct mii_bus * bus,int phy_id,int reg,u16 val)103 static int i2c_mii_write_default_c22(struct mii_bus *bus, int phy_id, int reg,
104 u16 val)
105 {
106 return i2c_mii_write_default_c45(bus, phy_id, -1, reg, val);
107 }
108
smbus_byte_mii_read_default_c22(struct mii_bus * bus,int phy_id,int reg)109 static int smbus_byte_mii_read_default_c22(struct mii_bus *bus, int phy_id,
110 int reg)
111 {
112 struct i2c_adapter *i2c = bus->priv;
113 union i2c_smbus_data smbus_data;
114 int val = 0, ret;
115
116 if (!i2c_mii_valid_phy_id(phy_id))
117 return 0;
118
119 ret = i2c_smbus_xfer(i2c, i2c_mii_phy_addr(phy_id), 0,
120 I2C_SMBUS_READ, reg,
121 I2C_SMBUS_BYTE_DATA, &smbus_data);
122 if (ret < 0)
123 return ret;
124
125 val = (smbus_data.byte & 0xff) << 8;
126
127 ret = i2c_smbus_xfer(i2c, i2c_mii_phy_addr(phy_id), 0,
128 I2C_SMBUS_READ, reg,
129 I2C_SMBUS_BYTE_DATA, &smbus_data);
130 if (ret < 0)
131 return ret;
132
133 val |= smbus_data.byte & 0xff;
134
135 return val;
136 }
137
smbus_byte_mii_write_default_c22(struct mii_bus * bus,int phy_id,int reg,u16 val)138 static int smbus_byte_mii_write_default_c22(struct mii_bus *bus, int phy_id,
139 int reg, u16 val)
140 {
141 struct i2c_adapter *i2c = bus->priv;
142 union i2c_smbus_data smbus_data;
143 int ret;
144
145 if (!i2c_mii_valid_phy_id(phy_id))
146 return 0;
147
148 smbus_data.byte = (val & 0xff00) >> 8;
149
150 ret = i2c_smbus_xfer(i2c, i2c_mii_phy_addr(phy_id), 0,
151 I2C_SMBUS_WRITE, reg,
152 I2C_SMBUS_BYTE_DATA, &smbus_data);
153 if (ret < 0)
154 return ret;
155
156 smbus_data.byte = val & 0xff;
157
158 ret = i2c_smbus_xfer(i2c, i2c_mii_phy_addr(phy_id), 0,
159 I2C_SMBUS_WRITE, reg,
160 I2C_SMBUS_BYTE_DATA, &smbus_data);
161
162 return ret < 0 ? ret : 0;
163 }
164
165 /* RollBall SFPs do not access internal PHY via I2C address 0x56, but
166 * instead via address 0x51, when SFP page is set to 0x03 and password to
167 * 0xffffffff.
168 *
169 * address size contents description
170 * ------- ---- -------- -----------
171 * 0x80 1 CMD 0x01/0x02/0x04 for write/read/done
172 * 0x81 1 DEV Clause 45 device
173 * 0x82 2 REG Clause 45 register
174 * 0x84 2 VAL Register value
175 */
176 #define ROLLBALL_PHY_I2C_ADDR 0x51
177
178 #define ROLLBALL_PASSWORD (SFP_VSL + 3)
179
180 #define ROLLBALL_CMD_ADDR 0x80
181 #define ROLLBALL_DATA_ADDR 0x81
182
183 #define ROLLBALL_CMD_WRITE 0x01
184 #define ROLLBALL_CMD_READ 0x02
185 #define ROLLBALL_CMD_DONE 0x04
186
187 #define SFP_PAGE_ROLLBALL_MDIO 3
188
__i2c_transfer_err(struct i2c_adapter * i2c,struct i2c_msg * msgs,int num)189 static int __i2c_transfer_err(struct i2c_adapter *i2c, struct i2c_msg *msgs,
190 int num)
191 {
192 int ret;
193
194 ret = __i2c_transfer(i2c, msgs, num);
195 if (ret < 0)
196 return ret;
197 else if (ret != num)
198 return -EIO;
199 else
200 return 0;
201 }
202
__i2c_rollball_get_page(struct i2c_adapter * i2c,int bus_addr,u8 * page)203 static int __i2c_rollball_get_page(struct i2c_adapter *i2c, int bus_addr,
204 u8 *page)
205 {
206 struct i2c_msg msgs[2];
207 u8 addr = SFP_PAGE;
208
209 msgs[0].addr = bus_addr;
210 msgs[0].flags = 0;
211 msgs[0].len = 1;
212 msgs[0].buf = &addr;
213
214 msgs[1].addr = bus_addr;
215 msgs[1].flags = I2C_M_RD;
216 msgs[1].len = 1;
217 msgs[1].buf = page;
218
219 return __i2c_transfer_err(i2c, msgs, 2);
220 }
221
__i2c_rollball_set_page(struct i2c_adapter * i2c,int bus_addr,u8 page)222 static int __i2c_rollball_set_page(struct i2c_adapter *i2c, int bus_addr,
223 u8 page)
224 {
225 struct i2c_msg msg;
226 u8 buf[2];
227
228 buf[0] = SFP_PAGE;
229 buf[1] = page;
230
231 msg.addr = bus_addr;
232 msg.flags = 0;
233 msg.len = 2;
234 msg.buf = buf;
235
236 return __i2c_transfer_err(i2c, &msg, 1);
237 }
238
239 /* In order to not interfere with other SFP code (which possibly may manipulate
240 * SFP_PAGE), for every transfer we do this:
241 * 1. lock the bus
242 * 2. save content of SFP_PAGE
243 * 3. set SFP_PAGE to 3
244 * 4. do the transfer
245 * 5. restore original SFP_PAGE
246 * 6. unlock the bus
247 * Note that one might think that steps 2 to 5 could be theoretically done all
248 * in one call to i2c_transfer (by constructing msgs array in such a way), but
249 * unfortunately tests show that this does not work :-( Changed SFP_PAGE does
250 * not take into account until i2c_transfer() is done.
251 */
i2c_transfer_rollball(struct i2c_adapter * i2c,struct i2c_msg * msgs,int num)252 static int i2c_transfer_rollball(struct i2c_adapter *i2c,
253 struct i2c_msg *msgs, int num)
254 {
255 int ret, main_err = 0;
256 u8 saved_page;
257
258 i2c_lock_bus(i2c, I2C_LOCK_SEGMENT);
259
260 /* save original page */
261 ret = __i2c_rollball_get_page(i2c, msgs->addr, &saved_page);
262 if (ret)
263 goto unlock;
264
265 /* change to RollBall MDIO page */
266 ret = __i2c_rollball_set_page(i2c, msgs->addr, SFP_PAGE_ROLLBALL_MDIO);
267 if (ret)
268 goto unlock;
269
270 /* do the transfer; we try to restore original page if this fails */
271 ret = __i2c_transfer_err(i2c, msgs, num);
272 if (ret)
273 main_err = ret;
274
275 /* restore original page */
276 ret = __i2c_rollball_set_page(i2c, msgs->addr, saved_page);
277
278 unlock:
279 i2c_unlock_bus(i2c, I2C_LOCK_SEGMENT);
280
281 return main_err ? : ret;
282 }
283
i2c_rollball_mii_poll(struct mii_bus * bus,int bus_addr,u8 * buf,size_t len)284 static int i2c_rollball_mii_poll(struct mii_bus *bus, int bus_addr, u8 *buf,
285 size_t len)
286 {
287 struct i2c_adapter *i2c = bus->priv;
288 struct i2c_msg msgs[2];
289 u8 cmd_addr, tmp, *res;
290 int i, ret;
291
292 cmd_addr = ROLLBALL_CMD_ADDR;
293
294 res = buf ? buf : &tmp;
295 len = buf ? len : 1;
296
297 msgs[0].addr = bus_addr;
298 msgs[0].flags = 0;
299 msgs[0].len = 1;
300 msgs[0].buf = &cmd_addr;
301
302 msgs[1].addr = bus_addr;
303 msgs[1].flags = I2C_M_RD;
304 msgs[1].len = len;
305 msgs[1].buf = res;
306
307 /* By experiment it takes up to 70 ms to access a register for these
308 * SFPs. Sleep 20ms between iterations and try 10 times.
309 */
310 i = 10;
311 do {
312 msleep(20);
313
314 ret = i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
315 if (ret)
316 return ret;
317
318 if (*res == ROLLBALL_CMD_DONE)
319 return 0;
320 } while (i-- > 0);
321
322 dev_dbg(&bus->dev, "poll timed out\n");
323
324 return -ETIMEDOUT;
325 }
326
i2c_rollball_mii_cmd(struct mii_bus * bus,int bus_addr,u8 cmd,u8 * data,size_t len)327 static int i2c_rollball_mii_cmd(struct mii_bus *bus, int bus_addr, u8 cmd,
328 u8 *data, size_t len)
329 {
330 struct i2c_adapter *i2c = bus->priv;
331 struct i2c_msg msgs[2];
332 u8 cmdbuf[2];
333
334 cmdbuf[0] = ROLLBALL_CMD_ADDR;
335 cmdbuf[1] = cmd;
336
337 msgs[0].addr = bus_addr;
338 msgs[0].flags = 0;
339 msgs[0].len = len;
340 msgs[0].buf = data;
341
342 msgs[1].addr = bus_addr;
343 msgs[1].flags = 0;
344 msgs[1].len = sizeof(cmdbuf);
345 msgs[1].buf = cmdbuf;
346
347 return i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
348 }
349
i2c_mii_read_rollball(struct mii_bus * bus,int phy_id,int devad,int reg)350 static int i2c_mii_read_rollball(struct mii_bus *bus, int phy_id, int devad,
351 int reg)
352 {
353 u8 buf[4], res[6];
354 int bus_addr, ret;
355 u16 val;
356
357 bus_addr = i2c_mii_phy_addr(phy_id);
358 if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
359 return 0xffff;
360
361 buf[0] = ROLLBALL_DATA_ADDR;
362 buf[1] = devad;
363 buf[2] = (reg >> 8) & 0xff;
364 buf[3] = reg & 0xff;
365
366 ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_READ, buf,
367 sizeof(buf));
368 if (ret < 0)
369 return ret;
370
371 ret = i2c_rollball_mii_poll(bus, bus_addr, res, sizeof(res));
372 if (ret == -ETIMEDOUT)
373 return 0xffff;
374 else if (ret < 0)
375 return ret;
376
377 val = res[4] << 8 | res[5];
378
379 return val;
380 }
381
i2c_mii_write_rollball(struct mii_bus * bus,int phy_id,int devad,int reg,u16 val)382 static int i2c_mii_write_rollball(struct mii_bus *bus, int phy_id, int devad,
383 int reg, u16 val)
384 {
385 int bus_addr, ret;
386 u8 buf[6];
387
388 bus_addr = i2c_mii_phy_addr(phy_id);
389 if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
390 return 0;
391
392 buf[0] = ROLLBALL_DATA_ADDR;
393 buf[1] = devad;
394 buf[2] = (reg >> 8) & 0xff;
395 buf[3] = reg & 0xff;
396 buf[4] = val >> 8;
397 buf[5] = val & 0xff;
398
399 ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_WRITE, buf,
400 sizeof(buf));
401 if (ret < 0)
402 return ret;
403
404 ret = i2c_rollball_mii_poll(bus, bus_addr, NULL, 0);
405 if (ret < 0)
406 return ret;
407
408 return 0;
409 }
410
i2c_mii_init_rollball(struct i2c_adapter * i2c)411 static int i2c_mii_init_rollball(struct i2c_adapter *i2c)
412 {
413 struct i2c_msg msg;
414 u8 pw[5];
415 int ret;
416
417 pw[0] = ROLLBALL_PASSWORD;
418 pw[1] = 0xff;
419 pw[2] = 0xff;
420 pw[3] = 0xff;
421 pw[4] = 0xff;
422
423 msg.addr = ROLLBALL_PHY_I2C_ADDR;
424 msg.flags = 0;
425 msg.len = sizeof(pw);
426 msg.buf = pw;
427
428 ret = i2c_transfer(i2c, &msg, 1);
429 if (ret < 0)
430 return ret;
431 else if (ret != 1)
432 return -EIO;
433 else
434 return 0;
435 }
436
mdio_i2c_check_functionality(struct i2c_adapter * i2c,enum mdio_i2c_proto protocol)437 static bool mdio_i2c_check_functionality(struct i2c_adapter *i2c,
438 enum mdio_i2c_proto protocol)
439 {
440 if (i2c_check_functionality(i2c, I2C_FUNC_I2C))
441 return true;
442
443 if (i2c_check_functionality(i2c, I2C_FUNC_SMBUS_BYTE_DATA) &&
444 protocol == MDIO_I2C_MARVELL_C22)
445 return true;
446
447 return false;
448 }
449
mdio_i2c_alloc(struct device * parent,struct i2c_adapter * i2c,enum mdio_i2c_proto protocol)450 struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,
451 enum mdio_i2c_proto protocol)
452 {
453 struct mii_bus *mii;
454 int ret;
455
456 if (!mdio_i2c_check_functionality(i2c, protocol))
457 return ERR_PTR(-EINVAL);
458
459 mii = mdiobus_alloc();
460 if (!mii)
461 return ERR_PTR(-ENOMEM);
462
463 snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));
464 mii->parent = parent;
465 mii->priv = i2c;
466
467 /* Only use SMBus if we have no other choice */
468 if (i2c_check_functionality(i2c, I2C_FUNC_SMBUS_BYTE_DATA) &&
469 !i2c_check_functionality(i2c, I2C_FUNC_I2C)) {
470 mii->read = smbus_byte_mii_read_default_c22;
471 mii->write = smbus_byte_mii_write_default_c22;
472 return mii;
473 }
474
475 switch (protocol) {
476 case MDIO_I2C_ROLLBALL:
477 ret = i2c_mii_init_rollball(i2c);
478 if (ret < 0) {
479 dev_err(parent,
480 "Cannot initialize RollBall MDIO I2C protocol: %d\n",
481 ret);
482 mdiobus_free(mii);
483 return ERR_PTR(ret);
484 }
485
486 mii->read_c45 = i2c_mii_read_rollball;
487 mii->write_c45 = i2c_mii_write_rollball;
488 break;
489 default:
490 mii->read = i2c_mii_read_default_c22;
491 mii->write = i2c_mii_write_default_c22;
492 mii->read_c45 = i2c_mii_read_default_c45;
493 mii->write_c45 = i2c_mii_write_default_c45;
494 break;
495 }
496
497 return mii;
498 }
499 EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
500
501 MODULE_AUTHOR("Russell King");
502 MODULE_DESCRIPTION("MDIO I2C bridge library");
503 MODULE_LICENSE("GPL v2");
504