| Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * MDIO I2C bridge |
| 4 | * |
| 5 | * Copyright (C) 2015-2016 Russell King |
| 6 | * |
| 7 | * Network PHYs can appear on I2C buses when they are part of SFP module. |
| 8 | * This driver exposes these PHYs to the networking PHY code, allowing |
| 9 | * our PHY drivers access to these PHYs, and so allowing configuration |
| 10 | * of their settings. |
| 11 | */ |
| 12 | #include <linux/i2c.h> |
| 13 | #include <linux/mdio/mdio-i2c.h> |
| 14 | #include <linux/phy.h> |
| 15 | |
| 16 | /* |
| 17 | * I2C bus addresses 0x50 and 0x51 are normally an EEPROM, which is |
| 18 | * specified to be present in SFP modules. These correspond with PHY |
| 19 | * addresses 16 and 17. Disallow access to these "phy" addresses. |
| 20 | */ |
| 21 | static bool i2c_mii_valid_phy_id(int phy_id) |
| 22 | { |
| 23 | return phy_id != 0x10 && phy_id != 0x11; |
| 24 | } |
| 25 | |
| 26 | static unsigned int i2c_mii_phy_addr(int phy_id) |
| 27 | { |
| 28 | return phy_id + 0x40; |
| 29 | } |
| 30 | |
| 31 | static int i2c_mii_read(struct mii_bus *bus, int phy_id, int reg) |
| 32 | { |
| 33 | struct i2c_adapter *i2c = bus->priv; |
| 34 | struct i2c_msg msgs[2]; |
| 35 | u8 addr[3], data[2], *p; |
| 36 | int bus_addr, ret; |
| 37 | |
| 38 | if (!i2c_mii_valid_phy_id(phy_id)) |
| 39 | return 0xffff; |
| 40 | |
| 41 | p = addr; |
| 42 | if (reg & MII_ADDR_C45) { |
| 43 | *p++ = 0x20 | ((reg >> 16) & 31); |
| 44 | *p++ = reg >> 8; |
| 45 | } |
| 46 | *p++ = reg; |
| 47 | |
| 48 | bus_addr = i2c_mii_phy_addr(phy_id); |
| 49 | msgs[0].addr = bus_addr; |
| 50 | msgs[0].flags = 0; |
| 51 | msgs[0].len = p - addr; |
| 52 | msgs[0].buf = addr; |
| 53 | msgs[1].addr = bus_addr; |
| 54 | msgs[1].flags = I2C_M_RD; |
| 55 | msgs[1].len = sizeof(data); |
| 56 | msgs[1].buf = data; |
| 57 | |
| 58 | ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs)); |
| 59 | if (ret != ARRAY_SIZE(msgs)) |
| 60 | return 0xffff; |
| 61 | |
| 62 | return data[0] << 8 | data[1]; |
| 63 | } |
| 64 | |
| 65 | static int i2c_mii_write(struct mii_bus *bus, int phy_id, int reg, u16 val) |
| 66 | { |
| 67 | struct i2c_adapter *i2c = bus->priv; |
| 68 | struct i2c_msg msg; |
| 69 | int ret; |
| 70 | u8 data[5], *p; |
| 71 | |
| 72 | if (!i2c_mii_valid_phy_id(phy_id)) |
| 73 | return 0; |
| 74 | |
| 75 | p = data; |
| 76 | if (reg & MII_ADDR_C45) { |
| 77 | *p++ = (reg >> 16) & 31; |
| 78 | *p++ = reg >> 8; |
| 79 | } |
| 80 | *p++ = reg; |
| 81 | *p++ = val >> 8; |
| 82 | *p++ = val; |
| 83 | |
| 84 | msg.addr = i2c_mii_phy_addr(phy_id); |
| 85 | msg.flags = 0; |
| 86 | msg.len = p - data; |
| 87 | msg.buf = data; |
| 88 | |
| 89 | ret = i2c_transfer(i2c, &msg, 1); |
| 90 | |
| 91 | return ret < 0 ? ret : 0; |
| 92 | } |
| 93 | |
| 94 | struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c) |
| 95 | { |
| 96 | struct mii_bus *mii; |
| 97 | |
| 98 | if (!i2c_check_functionality(i2c, I2C_FUNC_I2C)) |
| 99 | return ERR_PTR(-EINVAL); |
| 100 | |
| 101 | mii = mdiobus_alloc(); |
| 102 | if (!mii) |
| 103 | return ERR_PTR(-ENOMEM); |
| 104 | |
| 105 | snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent)); |
| 106 | mii->parent = parent; |
| 107 | mii->read = i2c_mii_read; |
| 108 | mii->write = i2c_mii_write; |
| 109 | mii->priv = i2c; |
| 110 | |
| 111 | return mii; |
| 112 | } |
| 113 | EXPORT_SYMBOL_GPL(mdio_i2c_alloc); |
| 114 | |
| 115 | MODULE_AUTHOR("Russell King"); |
| 116 | MODULE_DESCRIPTION("MDIO I2C bridge library"); |
| 117 | MODULE_LICENSE("GPL v2"); |