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1// SPDX-License-Identifier: GPL-2.02/*3 * MDIO I2C bridge4 *5 * Copyright (C) 2015-2016 Russell King6 * Copyright (C) 2021 Marek Behun7 *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, allowing10 * our PHY drivers access to these PHYs, and so allowing configuration11 * 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 is20 * specified to be present in SFP modules. These correspond with PHY21 * 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(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(i2c, &msg, 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, -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, -1, reg, val);107}108 109/* RollBall SFPs do not access internal PHY via I2C address 0x56, but110 * instead via address 0x51, when SFP page is set to 0x03 and password to111 * 0xffffffff.112 *113 * address size contents description114 * ------- ---- -------- -----------115 * 0x80 1 CMD 0x01/0x02/0x04 for write/read/done116 * 0x81 1 DEV Clause 45 device117 * 0x82 2 REG Clause 45 register118 * 0x84 2 VAL Register value119 */120#define ROLLBALL_PHY_I2C_ADDR 0x51121 122#define ROLLBALL_PASSWORD (SFP_VSL + 3)123 124#define ROLLBALL_CMD_ADDR 0x80125#define ROLLBALL_DATA_ADDR 0x81126 127#define ROLLBALL_CMD_WRITE 0x01128#define ROLLBALL_CMD_READ 0x02129#define ROLLBALL_CMD_DONE 0x04130 131#define SFP_PAGE_ROLLBALL_MDIO 3132 133static int __i2c_transfer_err(struct i2c_adapter *i2c, struct i2c_msg *msgs,134 int num)135{136 int ret;137 138 ret = __i2c_transfer(i2c, msgs, num);139 if (ret < 0)140 return ret;141 else if (ret != num)142 return -EIO;143 else144 return 0;145}146 147static int __i2c_rollball_get_page(struct i2c_adapter *i2c, int bus_addr,148 u8 *page)149{150 struct i2c_msg msgs[2];151 u8 addr = SFP_PAGE;152 153 msgs[0].addr = bus_addr;154 msgs[0].flags = 0;155 msgs[0].len = 1;156 msgs[0].buf = &addr;157 158 msgs[1].addr = bus_addr;159 msgs[1].flags = I2C_M_RD;160 msgs[1].len = 1;161 msgs[1].buf = page;162 163 return __i2c_transfer_err(i2c, msgs, 2);164}165 166static int __i2c_rollball_set_page(struct i2c_adapter *i2c, int bus_addr,167 u8 page)168{169 struct i2c_msg msg;170 u8 buf[2];171 172 buf[0] = SFP_PAGE;173 buf[1] = page;174 175 msg.addr = bus_addr;176 msg.flags = 0;177 msg.len = 2;178 msg.buf = buf;179 180 return __i2c_transfer_err(i2c, &msg, 1);181}182 183/* In order to not interfere with other SFP code (which possibly may manipulate184 * SFP_PAGE), for every transfer we do this:185 * 1. lock the bus186 * 2. save content of SFP_PAGE187 * 3. set SFP_PAGE to 3188 * 4. do the transfer189 * 5. restore original SFP_PAGE190 * 6. unlock the bus191 * Note that one might think that steps 2 to 5 could be theoretically done all192 * in one call to i2c_transfer (by constructing msgs array in such a way), but193 * unfortunately tests show that this does not work :-( Changed SFP_PAGE does194 * not take into account until i2c_transfer() is done.195 */196static int i2c_transfer_rollball(struct i2c_adapter *i2c,197 struct i2c_msg *msgs, int num)198{199 int ret, main_err = 0;200 u8 saved_page;201 202 i2c_lock_bus(i2c, I2C_LOCK_SEGMENT);203 204 /* save original page */205 ret = __i2c_rollball_get_page(i2c, msgs->addr, &saved_page);206 if (ret)207 goto unlock;208 209 /* change to RollBall MDIO page */210 ret = __i2c_rollball_set_page(i2c, msgs->addr, SFP_PAGE_ROLLBALL_MDIO);211 if (ret)212 goto unlock;213 214 /* do the transfer; we try to restore original page if this fails */215 ret = __i2c_transfer_err(i2c, msgs, num);216 if (ret)217 main_err = ret;218 219 /* restore original page */220 ret = __i2c_rollball_set_page(i2c, msgs->addr, saved_page);221 222unlock:223 i2c_unlock_bus(i2c, I2C_LOCK_SEGMENT);224 225 return main_err ? : ret;226}227 228static int i2c_rollball_mii_poll(struct mii_bus *bus, int bus_addr, u8 *buf,229 size_t len)230{231 struct i2c_adapter *i2c = bus->priv;232 struct i2c_msg msgs[2];233 u8 cmd_addr, tmp, *res;234 int i, ret;235 236 cmd_addr = ROLLBALL_CMD_ADDR;237 238 res = buf ? buf : &tmp;239 len = buf ? len : 1;240 241 msgs[0].addr = bus_addr;242 msgs[0].flags = 0;243 msgs[0].len = 1;244 msgs[0].buf = &cmd_addr;245 246 msgs[1].addr = bus_addr;247 msgs[1].flags = I2C_M_RD;248 msgs[1].len = len;249 msgs[1].buf = res;250 251 /* By experiment it takes up to 70 ms to access a register for these252 * SFPs. Sleep 20ms between iterations and try 10 times.253 */254 i = 10;255 do {256 msleep(20);257 258 ret = i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));259 if (ret)260 return ret;261 262 if (*res == ROLLBALL_CMD_DONE)263 return 0;264 } while (i-- > 0);265 266 dev_dbg(&bus->dev, "poll timed out\n");267 268 return -ETIMEDOUT;269}270 271static int i2c_rollball_mii_cmd(struct mii_bus *bus, int bus_addr, u8 cmd,272 u8 *data, size_t len)273{274 struct i2c_adapter *i2c = bus->priv;275 struct i2c_msg msgs[2];276 u8 cmdbuf[2];277 278 cmdbuf[0] = ROLLBALL_CMD_ADDR;279 cmdbuf[1] = cmd;280 281 msgs[0].addr = bus_addr;282 msgs[0].flags = 0;283 msgs[0].len = len;284 msgs[0].buf = data;285 286 msgs[1].addr = bus_addr;287 msgs[1].flags = 0;288 msgs[1].len = sizeof(cmdbuf);289 msgs[1].buf = cmdbuf;290 291 return i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));292}293 294static int i2c_mii_read_rollball(struct mii_bus *bus, int phy_id, int devad,295 int reg)296{297 u8 buf[4], res[6];298 int bus_addr, ret;299 u16 val;300 301 bus_addr = i2c_mii_phy_addr(phy_id);302 if (bus_addr != ROLLBALL_PHY_I2C_ADDR)303 return 0xffff;304 305 buf[0] = ROLLBALL_DATA_ADDR;306 buf[1] = devad;307 buf[2] = (reg >> 8) & 0xff;308 buf[3] = reg & 0xff;309 310 ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_READ, buf,311 sizeof(buf));312 if (ret < 0)313 return ret;314 315 ret = i2c_rollball_mii_poll(bus, bus_addr, res, sizeof(res));316 if (ret == -ETIMEDOUT)317 return 0xffff;318 else if (ret < 0)319 return ret;320 321 val = res[4] << 8 | res[5];322 323 return val;324}325 326static int i2c_mii_write_rollball(struct mii_bus *bus, int phy_id, int devad,327 int reg, u16 val)328{329 int bus_addr, ret;330 u8 buf[6];331 332 bus_addr = i2c_mii_phy_addr(phy_id);333 if (bus_addr != ROLLBALL_PHY_I2C_ADDR)334 return 0;335 336 buf[0] = ROLLBALL_DATA_ADDR;337 buf[1] = devad;338 buf[2] = (reg >> 8) & 0xff;339 buf[3] = reg & 0xff;340 buf[4] = val >> 8;341 buf[5] = val & 0xff;342 343 ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_WRITE, buf,344 sizeof(buf));345 if (ret < 0)346 return ret;347 348 ret = i2c_rollball_mii_poll(bus, bus_addr, NULL, 0);349 if (ret < 0)350 return ret;351 352 return 0;353}354 355static int i2c_mii_init_rollball(struct i2c_adapter *i2c)356{357 struct i2c_msg msg;358 u8 pw[5];359 int ret;360 361 pw[0] = ROLLBALL_PASSWORD;362 pw[1] = 0xff;363 pw[2] = 0xff;364 pw[3] = 0xff;365 pw[4] = 0xff;366 367 msg.addr = ROLLBALL_PHY_I2C_ADDR;368 msg.flags = 0;369 msg.len = sizeof(pw);370 msg.buf = pw;371 372 ret = i2c_transfer(i2c, &msg, 1);373 if (ret < 0)374 return ret;375 else if (ret != 1)376 return -EIO;377 else378 return 0;379}380 381struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,382 enum mdio_i2c_proto protocol)383{384 struct mii_bus *mii;385 int ret;386 387 if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))388 return ERR_PTR(-EINVAL);389 390 mii = mdiobus_alloc();391 if (!mii)392 return ERR_PTR(-ENOMEM);393 394 snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));395 mii->parent = parent;396 mii->priv = i2c;397 398 switch (protocol) {399 case MDIO_I2C_ROLLBALL:400 ret = i2c_mii_init_rollball(i2c);401 if (ret < 0) {402 dev_err(parent,403 "Cannot initialize RollBall MDIO I2C protocol: %d\n",404 ret);405 mdiobus_free(mii);406 return ERR_PTR(ret);407 }408 409 mii->read_c45 = i2c_mii_read_rollball;410 mii->write_c45 = i2c_mii_write_rollball;411 break;412 default:413 mii->read = i2c_mii_read_default_c22;414 mii->write = i2c_mii_write_default_c22;415 mii->read_c45 = i2c_mii_read_default_c45;416 mii->write_c45 = i2c_mii_write_default_c45;417 break;418 }419 420 return mii;421}422EXPORT_SYMBOL_GPL(mdio_i2c_alloc);423 424MODULE_AUTHOR("Russell King");425MODULE_DESCRIPTION("MDIO I2C bridge library");426MODULE_LICENSE("GPL v2");427