1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 2015-2016 Russell King
6 * Copyright (C) 2021 Marek Behun
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
13 #include <linux/i2c.h>
14 #include <linux/mdio/mdio-i2c.h>
15 #include <linux/phy.h>
16 #include <linux/sfp.h>
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.
23 static bool i2c_mii_valid_phy_id(int phy_id)
25 return phy_id != 0x10 && phy_id != 0x11;
28 static unsigned int i2c_mii_phy_addr(int phy_id)
33 static int i2c_mii_read_default_c45(struct mii_bus *bus, int phy_id, int devad,
36 struct i2c_adapter *i2c = bus->priv;
37 struct i2c_msg msgs[2];
38 u8 addr[3], data[2], *p;
41 if (!i2c_mii_valid_phy_id(phy_id))
51 bus_addr = i2c_mii_phy_addr(phy_id);
52 msgs[0].addr = bus_addr;
54 msgs[0].len = p - addr;
56 msgs[1].addr = bus_addr;
57 msgs[1].flags = I2C_M_RD;
58 msgs[1].len = sizeof(data);
61 ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));
62 if (ret != ARRAY_SIZE(msgs))
65 return data[0] << 8 | data[1];
68 static int i2c_mii_write_default_c45(struct mii_bus *bus, int phy_id,
69 int devad, int reg, u16 val)
71 struct i2c_adapter *i2c = bus->priv;
76 if (!i2c_mii_valid_phy_id(phy_id))
88 msg.addr = i2c_mii_phy_addr(phy_id);
93 ret = i2c_transfer(i2c, &msg, 1);
95 return ret < 0 ? ret : 0;
98 static int i2c_mii_read_default_c22(struct mii_bus *bus, int phy_id, int reg)
100 return i2c_mii_read_default_c45(bus, phy_id, -1, reg);
103 static int i2c_mii_write_default_c22(struct mii_bus *bus, int phy_id, int reg,
106 return i2c_mii_write_default_c45(bus, phy_id, -1, reg, val);
109 /* RollBall SFPs do not access internal PHY via I2C address 0x56, but
110 * instead via address 0x51, when SFP page is set to 0x03 and password to
113 * address size contents description
114 * ------- ---- -------- -----------
115 * 0x80 1 CMD 0x01/0x02/0x04 for write/read/done
116 * 0x81 1 DEV Clause 45 device
117 * 0x82 2 REG Clause 45 register
118 * 0x84 2 VAL Register value
120 #define ROLLBALL_PHY_I2C_ADDR 0x51
122 #define ROLLBALL_PASSWORD (SFP_VSL + 3)
124 #define ROLLBALL_CMD_ADDR 0x80
125 #define ROLLBALL_DATA_ADDR 0x81
127 #define ROLLBALL_CMD_WRITE 0x01
128 #define ROLLBALL_CMD_READ 0x02
129 #define ROLLBALL_CMD_DONE 0x04
131 #define SFP_PAGE_ROLLBALL_MDIO 3
133 static int __i2c_transfer_err(struct i2c_adapter *i2c, struct i2c_msg *msgs,
138 ret = __i2c_transfer(i2c, msgs, num);
147 static int __i2c_rollball_get_page(struct i2c_adapter *i2c, int bus_addr,
150 struct i2c_msg msgs[2];
153 msgs[0].addr = bus_addr;
158 msgs[1].addr = bus_addr;
159 msgs[1].flags = I2C_M_RD;
163 return __i2c_transfer_err(i2c, msgs, 2);
166 static int __i2c_rollball_set_page(struct i2c_adapter *i2c, int bus_addr,
180 return __i2c_transfer_err(i2c, &msg, 1);
183 /* In order to not interfere with other SFP code (which possibly may manipulate
184 * SFP_PAGE), for every transfer we do this:
186 * 2. save content of SFP_PAGE
187 * 3. set SFP_PAGE to 3
189 * 5. restore original SFP_PAGE
191 * Note that one might think that steps 2 to 5 could be theoretically done all
192 * in one call to i2c_transfer (by constructing msgs array in such a way), but
193 * unfortunately tests show that this does not work :-( Changed SFP_PAGE does
194 * not take into account until i2c_transfer() is done.
196 static int i2c_transfer_rollball(struct i2c_adapter *i2c,
197 struct i2c_msg *msgs, int num)
199 int ret, main_err = 0;
202 i2c_lock_bus(i2c, I2C_LOCK_SEGMENT);
204 /* save original page */
205 ret = __i2c_rollball_get_page(i2c, msgs->addr, &saved_page);
209 /* change to RollBall MDIO page */
210 ret = __i2c_rollball_set_page(i2c, msgs->addr, SFP_PAGE_ROLLBALL_MDIO);
214 /* do the transfer; we try to restore original page if this fails */
215 ret = __i2c_transfer_err(i2c, msgs, num);
219 /* restore original page */
220 ret = __i2c_rollball_set_page(i2c, msgs->addr, saved_page);
223 i2c_unlock_bus(i2c, I2C_LOCK_SEGMENT);
225 return main_err ? : ret;
228 static int i2c_rollball_mii_poll(struct mii_bus *bus, int bus_addr, u8 *buf,
231 struct i2c_adapter *i2c = bus->priv;
232 struct i2c_msg msgs[2];
233 u8 cmd_addr, tmp, *res;
236 cmd_addr = ROLLBALL_CMD_ADDR;
238 res = buf ? buf : &tmp;
241 msgs[0].addr = bus_addr;
244 msgs[0].buf = &cmd_addr;
246 msgs[1].addr = bus_addr;
247 msgs[1].flags = I2C_M_RD;
251 /* By experiment it takes up to 70 ms to access a register for these
252 * SFPs. Sleep 20ms between iterations and try 10 times.
258 ret = i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
262 if (*res == ROLLBALL_CMD_DONE)
266 dev_dbg(&bus->dev, "poll timed out\n");
271 static int i2c_rollball_mii_cmd(struct mii_bus *bus, int bus_addr, u8 cmd,
272 u8 *data, size_t len)
274 struct i2c_adapter *i2c = bus->priv;
275 struct i2c_msg msgs[2];
278 cmdbuf[0] = ROLLBALL_CMD_ADDR;
281 msgs[0].addr = bus_addr;
286 msgs[1].addr = bus_addr;
288 msgs[1].len = sizeof(cmdbuf);
289 msgs[1].buf = cmdbuf;
291 return i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
294 static int i2c_mii_read_rollball(struct mii_bus *bus, int phy_id, int reg)
300 if (!(reg & MII_ADDR_C45))
303 bus_addr = i2c_mii_phy_addr(phy_id);
304 if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
307 buf[0] = ROLLBALL_DATA_ADDR;
308 buf[1] = (reg >> 16) & 0x1f;
309 buf[2] = (reg >> 8) & 0xff;
312 ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_READ, buf,
317 ret = i2c_rollball_mii_poll(bus, bus_addr, res, sizeof(res));
318 if (ret == -ETIMEDOUT)
323 val = res[4] << 8 | res[5];
328 static int i2c_mii_write_rollball(struct mii_bus *bus, int phy_id, int reg,
334 if (!(reg & MII_ADDR_C45))
337 bus_addr = i2c_mii_phy_addr(phy_id);
338 if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
341 buf[0] = ROLLBALL_DATA_ADDR;
342 buf[1] = (reg >> 16) & 0x1f;
343 buf[2] = (reg >> 8) & 0xff;
348 ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_WRITE, buf,
353 ret = i2c_rollball_mii_poll(bus, bus_addr, NULL, 0);
360 static int i2c_mii_init_rollball(struct i2c_adapter *i2c)
366 pw[0] = ROLLBALL_PASSWORD;
372 msg.addr = ROLLBALL_PHY_I2C_ADDR;
374 msg.len = sizeof(pw);
377 ret = i2c_transfer(i2c, &msg, 1);
386 struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,
387 enum mdio_i2c_proto protocol)
392 if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))
393 return ERR_PTR(-EINVAL);
395 mii = mdiobus_alloc();
397 return ERR_PTR(-ENOMEM);
399 snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));
400 mii->parent = parent;
404 case MDIO_I2C_ROLLBALL:
405 ret = i2c_mii_init_rollball(i2c);
408 "Cannot initialize RollBall MDIO I2C protocol: %d\n",
414 mii->read = i2c_mii_read_rollball;
415 mii->write = i2c_mii_write_rollball;
418 mii->read = i2c_mii_read_default_c22;
419 mii->write = i2c_mii_write_default_c22;
420 mii->read_c45 = i2c_mii_read_default_c45;
421 mii->write_c45 = i2c_mii_write_default_c45;
427 EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
429 MODULE_AUTHOR("Russell King");
430 MODULE_DESCRIPTION("MDIO I2C bridge library");
431 MODULE_LICENSE("GPL v2");