LXR linux/drivers/net/mdio/mdio-i2c.c

   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 */
  21static bool i2c_mii_valid_phy_id(int phy_id)
  22{
  23        return phy_id != 0x10 && phy_id != 0x11;
  24}
  25
  26static unsigned int i2c_mii_phy_addr(int phy_id)
  27{
  28        return phy_id + 0x40;
  29}
  30
  31static 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
  65static 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
  94struct 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}
 113EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
 114
 115MODULE_AUTHOR("Russell King");
 116MODULE_DESCRIPTION("MDIO I2C bridge library");
 117MODULE_LICENSE("GPL v2");
 118