target/linux/mvebu/patches-4.9/414-phy-add-I2C-mdio-bus.patch

   1 From: Russell King <rmk+kernel@arm.linux.org.uk>
   2 Date: Fri, 25 Sep 2015 17:43:52 +0100
   3 Subject: [PATCH] phy: add I2C mdio bus
   4
   5 Add an I2C MDIO bus bridge library, to allow phylib to access PHYs which
   6 are connected to an I2C bus instead of the more conventional MDIO bus.
   7 Such PHYs can be found in SFP adapters and SFF modules.
   8
   9 Since PHYs appear at I2C bus address 0x40..0x5f, and 0x50/0x51 are
  10 reserved for SFP EEPROMs/diagnostics, we must not allow the MDIO bus
  11 to access these I2C addresses.
  12
  13 Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
  14 ---
  15  create mode 100644 drivers/net/phy/mdio-i2c.c
  16  create mode 100644 drivers/net/phy/mdio-i2c.h
  17
  18 --- a/drivers/net/phy/Kconfig
  19 +++ b/drivers/net/phy/Kconfig
  20 @@ -105,6 +105,16 @@ config MDIO_HISI_FEMAC
  21           This module provides a driver for the MDIO busses found in the
  22           Hisilicon SoC that have an Fast Ethernet MAC.
  23
  24 +config MDIO_I2C
  25 +       tristate
  26 +       depends on I2C
  27 +       help
  28 +         Support I2C based PHYs.  This provides a MDIO bus bridged
  29 +         to I2C to allow PHYs connected in I2C mode to be accessed
  30 +         using the existing infrastructure.
  31 +
  32 +         This is library mode.
  33 +
  34  config MDIO_MOXART
  35          tristate "MOXA ART MDIO interface support"
  36          depends on ARCH_MOXART
  37 --- a/drivers/net/phy/Makefile
  38 +++ b/drivers/net/phy/Makefile
  39 @@ -33,6 +33,7 @@ obj-$(CONFIG_MDIO_BUS_MUX_MMIOREG) += md
  40  obj-$(CONFIG_MDIO_CAVIUM)      += mdio-cavium.o
  41  obj-$(CONFIG_MDIO_GPIO)                += mdio-gpio.o
  42  obj-$(CONFIG_MDIO_HISI_FEMAC)  += mdio-hisi-femac.o
  43 +obj-$(CONFIG_MDIO_I2C)         += mdio-i2c.o
  44  obj-$(CONFIG_MDIO_MOXART)      += mdio-moxart.o
  45  obj-$(CONFIG_MDIO_OCTEON)      += mdio-octeon.o
  46  obj-$(CONFIG_MDIO_SUN4I)       += mdio-sun4i.o
  47 --- /dev/null
  48 +++ b/drivers/net/phy/mdio-i2c.c
  49 @@ -0,0 +1,109 @@
  50 +/*
  51 + * MDIO I2C bridge
  52 + *
  53 + * Copyright (C) 2015-2016 Russell King
  54 + *
  55 + * This program is free software; you can redistribute it and/or modify
  56 + * it under the terms of the GNU General Public License version 2 as
  57 + * published by the Free Software Foundation.
  58 + *
  59 + * Network PHYs can appear on I2C buses when they are part of SFP module.
  60 + * This driver exposes these PHYs to the networking PHY code, allowing
  61 + * our PHY drivers access to these PHYs, and so allowing configuration
  62 + * of their settings.
  63 + */
  64 +#include <linux/i2c.h>
  65 +#include <linux/phy.h>
  66 +
  67 +#include "mdio-i2c.h"
  68 +
  69 +/*
  70 + * I2C bus addresses 0x50 and 0x51 are normally an EEPROM, which is
  71 + * specified to be present in SFP modules.  These correspond with PHY
  72 + * addresses 16 and 17.  Disallow access to these "phy" addresses.
  73 + */
  74 +static bool i2c_mii_valid_phy_id(int phy_id)
  75 +{
  76 +       return phy_id != 0x10 && phy_id != 0x11;
  77 +}
  78 +
  79 +static unsigned int i2c_mii_phy_addr(int phy_id)
  80 +{
  81 +       return phy_id + 0x40;
  82 +}
  83 +
  84 +static int i2c_mii_read(struct mii_bus *bus, int phy_id, int reg)
  85 +{
  86 +       struct i2c_adapter *i2c = bus->priv;
  87 +       struct i2c_msg msgs[2];
  88 +       u8 data[2], dev_addr = reg;
  89 +       int bus_addr, ret;
  90 +
  91 +       if (!i2c_mii_valid_phy_id(phy_id))
  92 +               return 0xffff;
  93 +
  94 +       bus_addr = i2c_mii_phy_addr(phy_id);
  95 +       msgs[0].addr = bus_addr;
  96 +       msgs[0].flags = 0;
  97 +       msgs[0].len = 1;
  98 +       msgs[0].buf = &dev_addr;
  99 +       msgs[1].addr = bus_addr;
 100 +       msgs[1].flags = I2C_M_RD;
 101 +       msgs[1].len = sizeof(data);
 102 +       msgs[1].buf = data;
 103 +
 104 +       ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));
 105 +       if (ret != ARRAY_SIZE(msgs))
 106 +               return 0xffff;
 107 +
 108 +       return data[0] << 8 | data[1];
 109 +}
 110 +
 111 +static int i2c_mii_write(struct mii_bus *bus, int phy_id, int reg, u16 val)
 112 +{
 113 +       struct i2c_adapter *i2c = bus->priv;
 114 +       struct i2c_msg msg;
 115 +       int ret;
 116 +       u8 data[3];
 117 +
 118 +       if (!i2c_mii_valid_phy_id(phy_id))
 119 +               return 0;
 120 +
 121 +       data[0] = reg;
 122 +       data[1] = val >> 8;
 123 +       data[2] = val;
 124 +
 125 +       msg.addr = i2c_mii_phy_addr(phy_id);
 126 +       msg.flags = 0;
 127 +       msg.len = 3;
 128 +       msg.buf = data;
 129 +
 130 +       ret = i2c_transfer(i2c, &msg, 1);
 131 +
 132 +       return ret < 0 ? ret : 0;
 133 +}
 134 +
 135 +struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c)
 136 +{
 137 +       struct mii_bus *mii;
 138 +
 139 +       if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))
 140 +               return ERR_PTR(-EINVAL);
 141 +
 142 +       mii = mdiobus_alloc();
 143 +       if (!mii)
 144 +               return ERR_PTR(-ENOMEM);
 145 +
 146 +       snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));
 147 +       mii->parent = parent;
 148 +       mii->read = i2c_mii_read;
 149 +       mii->write = i2c_mii_write;
 150 +       mii->priv = i2c;
 151 +
 152 +       return mii;
 153 +}
 154 +EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
 155 +
 156 +MODULE_AUTHOR("Russell King");
 157 +MODULE_DESCRIPTION("MDIO I2C bridge library");
 158 +MODULE_LICENSE("GPL v2");
 159 --- /dev/null
 160 +++ b/drivers/net/phy/mdio-i2c.h
 161 @@ -0,0 +1,19 @@
 162 +/*
 163 + * MDIO I2C bridge
 164 + *
 165 + * Copyright (C) 2015 Russell King
 166 + *
 167 + * This program is free software; you can redistribute it and/or modify
 168 + * it under the terms of the GNU General Public License version 2 as
 169 + * published by the Free Software Foundation.
 170 + */
 171 +#ifndef MDIO_I2C_H
 172 +#define MDIO_I2C_H
 173 +
 174 +struct device;
 175 +struct i2c_adapter;
 176 +struct mii_bus;
 177 +
 178 +struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c);
 179 +
 180 +#endif