LXR linux/drivers/net/phy/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/phy.h>
  14
  15#include "mdio-i2c.h"
  16
  17/*
  18 * I2C bus addresses 0x50 and 0x51 are normally an EEPROM, which is
  19 * specified to be present in SFP modules.  These correspond with PHY
  20 * addresses 16 and 17.  Disallow access to these "phy" addresses.
  21 */
  22static bool i2c_mii_valid_phy_id(int phy_id)
  23{
  24        return phy_id != 0x10 && phy_id != 0x11;
  25}
  26
  27static unsigned int i2c_mii_phy_addr(int phy_id)
  28{
  29        return phy_id + 0x40;
  30}
  31
  32static int i2c_mii_read(struct mii_bus *bus, int phy_id, int reg)
  33{
  34        struct i2c_adapter *i2c = bus->priv;
  35        struct i2c_msg msgs[2];
  36        u8 addr[3], data[2], *p;
  37        int bus_addr, ret;
  38
  39        if (!i2c_mii_valid_phy_id(phy_id))
  40                return 0xffff;
  41
  42        p = addr;
  43        if (reg & MII_ADDR_C45) {
  44                *p++ = 0x20 | ((reg >> 16) & 31);
  45                *p++ = reg >> 8;
  46        }
  47        *p++ = reg;
  48
  49        bus_addr = i2c_mii_phy_addr(phy_id);
  50        msgs[0].addr = bus_addr;
  51        msgs[0].flags = 0;
  52        msgs[0].len = p - addr;
  53        msgs[0].buf = addr;
  54        msgs[1].addr = bus_addr;
  55        msgs[1].flags = I2C_M_RD;
  56        msgs[1].len = sizeof(data);
  57        msgs[1].buf = data;
  58
  59        ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));
  60        if (ret != ARRAY_SIZE(msgs))
  61                return 0xffff;
  62
  63        return data[0] << 8 | data[1];
  64}
  65
  66static int i2c_mii_write(struct mii_bus *bus, int phy_id, int reg, u16 val)
  67{
  68        struct i2c_adapter *i2c = bus->priv;
  69        struct i2c_msg msg;
  70        int ret;
  71        u8 data[5], *p;
  72
  73        if (!i2c_mii_valid_phy_id(phy_id))
  74                return 0;
  75
  76        p = data;
  77        if (reg & MII_ADDR_C45) {
  78                *p++ = (reg >> 16) & 31;
  79                *p++ = reg >> 8;
  80        }
  81        *p++ = reg;
  82        *p++ = val >> 8;
  83        *p++ = val;
  84
  85        msg.addr = i2c_mii_phy_addr(phy_id);
  86        msg.flags = 0;
  87        msg.len = p - data;
  88        msg.buf = data;
  89
  90        ret = i2c_transfer(i2c, &msg, 1);
  91
  92        return ret < 0 ? ret : 0;
  93}
  94
  95struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c)
  96{
  97        struct mii_bus *mii;
  98
  99        if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))
 100                return ERR_PTR(-EINVAL);
 101
 102        mii = mdiobus_alloc();
 103        if (!mii)
 104                return ERR_PTR(-ENOMEM);
 105
 106        snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));
 107        mii->parent = parent;
 108        mii->read = i2c_mii_read;
 109        mii->write = i2c_mii_write;
 110        mii->priv = i2c;
 111
 112        return mii;
 113}
 114EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
 115
 116MODULE_AUTHOR("Russell King");
 117MODULE_DESCRIPTION("MDIO I2C bridge library");
 118MODULE_LICENSE("GPL v2");
 119