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 */
23static bool i2c_mii_valid_phy_id(int phy_id)
24{
25 return phy_id != 0x10 && phy_id != 0x11;
26}
27
28static unsigned int i2c_mii_phy_addr(int phy_id)
29{
30 return phy_id + 0x40;
31}
32
33static 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(adap: i2c, msgs, ARRAY_SIZE(msgs));
62 if (ret != ARRAY_SIZE(msgs))
63 return 0xffff;
64
65 return data[0] << 8 | data[1];
66}
67
68static 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(adap: i2c, msgs: &msg, num: 1);
94
95 return ret < 0 ? ret : 0;
96}
97
98static 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, devad: -1, reg);
101}
102
103static 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, devad: -1, reg, val);
107}
108
109static 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 i2c_lock_bus(adapter: i2c, I2C_LOCK_SEGMENT);
120
121 ret = __i2c_smbus_xfer(adapter: i2c, addr: i2c_mii_phy_addr(phy_id), flags: 0,
122 I2C_SMBUS_READ, command: reg,
123 I2C_SMBUS_BYTE_DATA, data: &smbus_data);
124 if (ret < 0)
125 goto unlock;
126
127 val = (smbus_data.byte & 0xff) << 8;
128
129 ret = __i2c_smbus_xfer(adapter: i2c, addr: i2c_mii_phy_addr(phy_id), flags: 0,
130 I2C_SMBUS_READ, command: reg,
131 I2C_SMBUS_BYTE_DATA, data: &smbus_data);
132
133unlock:
134 i2c_unlock_bus(adapter: i2c, I2C_LOCK_SEGMENT);
135
136 if (ret < 0)
137 return ret;
138
139 val |= smbus_data.byte & 0xff;
140
141 return val;
142}
143
144static int smbus_byte_mii_write_default_c22(struct mii_bus *bus, int phy_id,
145 int reg, u16 val)
146{
147 struct i2c_adapter *i2c = bus->priv;
148 union i2c_smbus_data smbus_data;
149 int ret;
150
151 if (!i2c_mii_valid_phy_id(phy_id))
152 return 0;
153
154 smbus_data.byte = (val & 0xff00) >> 8;
155
156 i2c_lock_bus(adapter: i2c, I2C_LOCK_SEGMENT);
157
158 ret = __i2c_smbus_xfer(adapter: i2c, addr: i2c_mii_phy_addr(phy_id), flags: 0,
159 I2C_SMBUS_WRITE, command: reg,
160 I2C_SMBUS_BYTE_DATA, data: &smbus_data);
161 if (ret < 0)
162 goto unlock;
163
164 smbus_data.byte = val & 0xff;
165
166 ret = __i2c_smbus_xfer(adapter: i2c, addr: i2c_mii_phy_addr(phy_id), flags: 0,
167 I2C_SMBUS_WRITE, command: reg,
168 I2C_SMBUS_BYTE_DATA, data: &smbus_data);
169
170unlock:
171 i2c_unlock_bus(adapter: i2c, I2C_LOCK_SEGMENT);
172
173 return ret < 0 ? ret : 0;
174}
175
176/* RollBall SFPs do not access internal PHY via I2C address 0x56, but
177 * instead via address 0x51, when SFP page is set to 0x03 and password to
178 * 0xffffffff.
179 *
180 * address size contents description
181 * ------- ---- -------- -----------
182 * 0x80 1 CMD 0x01/0x02/0x04 for write/read/done
183 * 0x81 1 DEV Clause 45 device
184 * 0x82 2 REG Clause 45 register
185 * 0x84 2 VAL Register value
186 */
187#define ROLLBALL_PHY_I2C_ADDR 0x51
188
189#define ROLLBALL_PASSWORD (SFP_VSL + 3)
190
191#define ROLLBALL_CMD_ADDR 0x80
192#define ROLLBALL_DATA_ADDR 0x81
193
194#define ROLLBALL_CMD_WRITE 0x01
195#define ROLLBALL_CMD_READ 0x02
196#define ROLLBALL_CMD_DONE 0x04
197
198#define SFP_PAGE_ROLLBALL_MDIO 3
199
200static int __i2c_transfer_err(struct i2c_adapter *i2c, struct i2c_msg *msgs,
201 int num)
202{
203 int ret;
204
205 ret = __i2c_transfer(adap: i2c, msgs, num);
206 if (ret < 0)
207 return ret;
208 else if (ret != num)
209 return -EIO;
210 else
211 return 0;
212}
213
214static int __i2c_rollball_get_page(struct i2c_adapter *i2c, int bus_addr,
215 u8 *page)
216{
217 struct i2c_msg msgs[2];
218 u8 addr = SFP_PAGE;
219
220 msgs[0].addr = bus_addr;
221 msgs[0].flags = 0;
222 msgs[0].len = 1;
223 msgs[0].buf = &addr;
224
225 msgs[1].addr = bus_addr;
226 msgs[1].flags = I2C_M_RD;
227 msgs[1].len = 1;
228 msgs[1].buf = page;
229
230 return __i2c_transfer_err(i2c, msgs, num: 2);
231}
232
233static int __i2c_rollball_set_page(struct i2c_adapter *i2c, int bus_addr,
234 u8 page)
235{
236 struct i2c_msg msg;
237 u8 buf[2];
238
239 buf[0] = SFP_PAGE;
240 buf[1] = page;
241
242 msg.addr = bus_addr;
243 msg.flags = 0;
244 msg.len = 2;
245 msg.buf = buf;
246
247 return __i2c_transfer_err(i2c, msgs: &msg, num: 1);
248}
249
250/* In order to not interfere with other SFP code (which possibly may manipulate
251 * SFP_PAGE), for every transfer we do this:
252 * 1. lock the bus
253 * 2. save content of SFP_PAGE
254 * 3. set SFP_PAGE to 3
255 * 4. do the transfer
256 * 5. restore original SFP_PAGE
257 * 6. unlock the bus
258 * Note that one might think that steps 2 to 5 could be theoretically done all
259 * in one call to i2c_transfer (by constructing msgs array in such a way), but
260 * unfortunately tests show that this does not work :-( Changed SFP_PAGE does
261 * not take into account until i2c_transfer() is done.
262 */
263static int i2c_transfer_rollball(struct i2c_adapter *i2c,
264 struct i2c_msg *msgs, int num)
265{
266 int ret, main_err = 0;
267 u8 saved_page;
268
269 i2c_lock_bus(adapter: i2c, I2C_LOCK_SEGMENT);
270
271 /* save original page */
272 ret = __i2c_rollball_get_page(i2c, bus_addr: msgs->addr, page: &saved_page);
273 if (ret)
274 goto unlock;
275
276 /* change to RollBall MDIO page */
277 ret = __i2c_rollball_set_page(i2c, bus_addr: msgs->addr, SFP_PAGE_ROLLBALL_MDIO);
278 if (ret)
279 goto unlock;
280
281 /* do the transfer; we try to restore original page if this fails */
282 ret = __i2c_transfer_err(i2c, msgs, num);
283 if (ret)
284 main_err = ret;
285
286 /* restore original page */
287 ret = __i2c_rollball_set_page(i2c, bus_addr: msgs->addr, page: saved_page);
288
289unlock:
290 i2c_unlock_bus(adapter: i2c, I2C_LOCK_SEGMENT);
291
292 return main_err ? : ret;
293}
294
295static int i2c_rollball_mii_poll(struct mii_bus *bus, int bus_addr, u8 *buf,
296 size_t len)
297{
298 struct i2c_adapter *i2c = bus->priv;
299 struct i2c_msg msgs[2];
300 u8 cmd_addr, tmp, *res;
301 int i, ret;
302
303 cmd_addr = ROLLBALL_CMD_ADDR;
304
305 res = buf ? buf : &tmp;
306 len = buf ? len : 1;
307
308 msgs[0].addr = bus_addr;
309 msgs[0].flags = 0;
310 msgs[0].len = 1;
311 msgs[0].buf = &cmd_addr;
312
313 msgs[1].addr = bus_addr;
314 msgs[1].flags = I2C_M_RD;
315 msgs[1].len = len;
316 msgs[1].buf = res;
317
318 /* By experiment it takes up to 70 ms to access a register for these
319 * SFPs. Sleep 20ms between iterations and try 10 times.
320 */
321 i = 10;
322 do {
323 msleep(msecs: 20);
324
325 ret = i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
326 if (ret)
327 return ret;
328
329 if (*res == ROLLBALL_CMD_DONE)
330 return 0;
331 } while (i-- > 0);
332
333 dev_dbg(&bus->dev, "poll timed out\n");
334
335 return -ETIMEDOUT;
336}
337
338static int i2c_rollball_mii_cmd(struct mii_bus *bus, int bus_addr, u8 cmd,
339 u8 *data, size_t len)
340{
341 struct i2c_adapter *i2c = bus->priv;
342 struct i2c_msg msgs[2];
343 u8 cmdbuf[2];
344
345 cmdbuf[0] = ROLLBALL_CMD_ADDR;
346 cmdbuf[1] = cmd;
347
348 msgs[0].addr = bus_addr;
349 msgs[0].flags = 0;
350 msgs[0].len = len;
351 msgs[0].buf = data;
352
353 msgs[1].addr = bus_addr;
354 msgs[1].flags = 0;
355 msgs[1].len = sizeof(cmdbuf);
356 msgs[1].buf = cmdbuf;
357
358 return i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
359}
360
361static int i2c_mii_read_rollball(struct mii_bus *bus, int phy_id, int devad,
362 int reg)
363{
364 u8 buf[4], res[6];
365 int bus_addr, ret;
366 u16 val;
367
368 bus_addr = i2c_mii_phy_addr(phy_id);
369 if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
370 return 0xffff;
371
372 buf[0] = ROLLBALL_DATA_ADDR;
373 buf[1] = devad;
374 buf[2] = (reg >> 8) & 0xff;
375 buf[3] = reg & 0xff;
376
377 ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_READ, data: buf,
378 len: sizeof(buf));
379 if (ret < 0)
380 return ret;
381
382 ret = i2c_rollball_mii_poll(bus, bus_addr, buf: res, len: sizeof(res));
383 if (ret == -ETIMEDOUT)
384 return 0xffff;
385 else if (ret < 0)
386 return ret;
387
388 val = res[4] << 8 | res[5];
389
390 return val;
391}
392
393static int i2c_mii_write_rollball(struct mii_bus *bus, int phy_id, int devad,
394 int reg, u16 val)
395{
396 int bus_addr, ret;
397 u8 buf[6];
398
399 bus_addr = i2c_mii_phy_addr(phy_id);
400 if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
401 return 0;
402
403 buf[0] = ROLLBALL_DATA_ADDR;
404 buf[1] = devad;
405 buf[2] = (reg >> 8) & 0xff;
406 buf[3] = reg & 0xff;
407 buf[4] = val >> 8;
408 buf[5] = val & 0xff;
409
410 ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_WRITE, data: buf,
411 len: sizeof(buf));
412 if (ret < 0)
413 return ret;
414
415 ret = i2c_rollball_mii_poll(bus, bus_addr, NULL, len: 0);
416 if (ret < 0)
417 return ret;
418
419 return 0;
420}
421
422static int i2c_mii_init_rollball(struct i2c_adapter *i2c)
423{
424 struct i2c_msg msg;
425 u8 pw[5];
426 int ret;
427
428 pw[0] = ROLLBALL_PASSWORD;
429 pw[1] = 0xff;
430 pw[2] = 0xff;
431 pw[3] = 0xff;
432 pw[4] = 0xff;
433
434 msg.addr = ROLLBALL_PHY_I2C_ADDR;
435 msg.flags = 0;
436 msg.len = sizeof(pw);
437 msg.buf = pw;
438
439 ret = i2c_transfer(adap: i2c, msgs: &msg, num: 1);
440 if (ret < 0)
441 return ret;
442 else if (ret != 1)
443 return -EIO;
444 else
445 return 0;
446}
447
448static bool mdio_i2c_check_functionality(struct i2c_adapter *i2c,
449 enum mdio_i2c_proto protocol)
450{
451 if (i2c_check_functionality(adap: i2c, I2C_FUNC_I2C))
452 return true;
453
454 if (i2c_check_functionality(adap: i2c, I2C_FUNC_SMBUS_BYTE_DATA) &&
455 protocol == MDIO_I2C_MARVELL_C22)
456 return true;
457
458 return false;
459}
460
461struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,
462 enum mdio_i2c_proto protocol)
463{
464 struct mii_bus *mii;
465 int ret;
466
467 if (!mdio_i2c_check_functionality(i2c, protocol))
468 return ERR_PTR(error: -EINVAL);
469
470 mii = mdiobus_alloc();
471 if (!mii)
472 return ERR_PTR(error: -ENOMEM);
473
474 snprintf(buf: mii->id, MII_BUS_ID_SIZE, fmt: "i2c:%s", dev_name(dev: parent));
475 mii->parent = parent;
476 mii->priv = i2c;
477
478 /* Only use SMBus if we have no other choice */
479 if (i2c_check_functionality(adap: i2c, I2C_FUNC_SMBUS_BYTE_DATA) &&
480 !i2c_check_functionality(adap: i2c, I2C_FUNC_I2C)) {
481 mii->read = smbus_byte_mii_read_default_c22;
482 mii->write = smbus_byte_mii_write_default_c22;
483 return mii;
484 }
485
486 switch (protocol) {
487 case MDIO_I2C_ROLLBALL:
488 ret = i2c_mii_init_rollball(i2c);
489 if (ret < 0) {
490 dev_err(parent,
491 "Cannot initialize RollBall MDIO I2C protocol: %d\n",
492 ret);
493 mdiobus_free(bus: mii);
494 return ERR_PTR(error: ret);
495 }
496
497 mii->read_c45 = i2c_mii_read_rollball;
498 mii->write_c45 = i2c_mii_write_rollball;
499 break;
500 default:
501 mii->read = i2c_mii_read_default_c22;
502 mii->write = i2c_mii_write_default_c22;
503 mii->read_c45 = i2c_mii_read_default_c45;
504 mii->write_c45 = i2c_mii_write_default_c45;
505 break;
506 }
507
508 return mii;
509}
510EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
511
512MODULE_AUTHOR("Russell King");
513MODULE_DESCRIPTION("MDIO I2C bridge library");
514MODULE_LICENSE("GPL v2");
515

source code of linux/drivers/net/mdio/mdio-i2c.c