Commit 453d00de authored by Russell King's avatar Russell King Committed by David S. Miller
Browse files

net: phy: add I2C mdio bus 



Add an I2C MDIO bus bridge library, to allow phylib to access PHYs which
are connected to an I2C bus instead of the more conventional MDIO bus.
Such PHYs can be found in SFP adapters and SFF modules.

Since PHYs appear at I2C bus address 0x40..0x5f, and 0x50/0x51 are
reserved for SFP EEPROMs/diagnostics, we must not allow the MDIO bus
to access these I2C addresses.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5e5758d9

drivers/net/phy/Kconfig

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@@ -106,6 +106,16 @@ config MDIO_HISI_FEMAC 
	  This module provides a driver for the MDIO busses found in the

	  Hisilicon SoC that have an Fast Ethernet MAC.



config MDIO_I2C

	tristate

	depends on I2C

	help

	  Support I2C based PHYs.  This provides a MDIO bus bridged

	  to I2C to allow PHYs connected in I2C mode to be accessed

	  using the existing infrastructure.



	  This is library mode.



config MDIO_MOXART

        tristate "MOXA ART MDIO interface support"

        depends on ARCH_MOXART

drivers/net/phy/Makefile

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@@ -30,6 +30,7 @@ obj-$(CONFIG_MDIO_BUS_MUX_MMIOREG) += mdio-mux-mmioreg.o 
obj-$(CONFIG_MDIO_CAVIUM)	+= mdio-cavium.o

obj-$(CONFIG_MDIO_GPIO)		+= mdio-gpio.o

obj-$(CONFIG_MDIO_HISI_FEMAC)	+= mdio-hisi-femac.o

obj-$(CONFIG_MDIO_I2C)		+= mdio-i2c.o

obj-$(CONFIG_MDIO_MOXART)	+= mdio-moxart.o

obj-$(CONFIG_MDIO_OCTEON)	+= mdio-octeon.o

obj-$(CONFIG_MDIO_SUN4I)	+= mdio-sun4i.o

drivers/net/phy/mdio-i2c.c

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/*

 * MDIO I2C bridge

 *

 * Copyright (C) 2015-2016 Russell King

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * Network PHYs can appear on I2C buses when they are part of SFP module.

 * This driver exposes these PHYs to the networking PHY code, allowing

 * our PHY drivers access to these PHYs, and so allowing configuration

 * of their settings.

 */

#include <linux/i2c.h>

#include <linux/phy.h>



#include "mdio-i2c.h"



/*

 * I2C bus addresses 0x50 and 0x51 are normally an EEPROM, which is

 * specified to be present in SFP modules.  These correspond with PHY

 * addresses 16 and 17.  Disallow access to these "phy" addresses.

 */

static bool i2c_mii_valid_phy_id(int phy_id)

{

	return phy_id != 0x10 && phy_id != 0x11;

}



static unsigned int i2c_mii_phy_addr(int phy_id)

{

	return phy_id + 0x40;

}



static int i2c_mii_read(struct mii_bus *bus, int phy_id, int reg)

{

	struct i2c_adapter *i2c = bus->priv;

	struct i2c_msg msgs[2];

	u8 data[2], dev_addr = reg;

	int bus_addr, ret;



	if (!i2c_mii_valid_phy_id(phy_id))

		return 0xffff;



	bus_addr = i2c_mii_phy_addr(phy_id);

	msgs[0].addr = bus_addr;

	msgs[0].flags = 0;

	msgs[0].len = 1;

	msgs[0].buf = &dev_addr;

	msgs[1].addr = bus_addr;

	msgs[1].flags = I2C_M_RD;

	msgs[1].len = sizeof(data);

	msgs[1].buf = data;



	ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));

	if (ret != ARRAY_SIZE(msgs))

		return 0xffff;



	return data[0] << 8 | data[1];

}



static int i2c_mii_write(struct mii_bus *bus, int phy_id, int reg, u16 val)

{

	struct i2c_adapter *i2c = bus->priv;

	struct i2c_msg msg;

	int ret;

	u8 data[3];



	if (!i2c_mii_valid_phy_id(phy_id))

		return 0;



	data[0] = reg;

	data[1] = val >> 8;

	data[2] = val;



	msg.addr = i2c_mii_phy_addr(phy_id);

	msg.flags = 0;

	msg.len = 3;

	msg.buf = data;



	ret = i2c_transfer(i2c, &msg, 1);



	return ret < 0 ? ret : 0;

}



struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c)

{

	struct mii_bus *mii;



	if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))

		return ERR_PTR(-EINVAL);



	mii = mdiobus_alloc();

	if (!mii)

		return ERR_PTR(-ENOMEM);



	snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));

	mii->parent = parent;

	mii->read = i2c_mii_read;

	mii->write = i2c_mii_write;

	mii->priv = i2c;



	return mii;

}

EXPORT_SYMBOL_GPL(mdio_i2c_alloc);



MODULE_AUTHOR("Russell King");

MODULE_DESCRIPTION("MDIO I2C bridge library");

MODULE_LICENSE("GPL v2");

drivers/net/phy/mdio-i2c.h

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/*

 * MDIO I2C bridge

 *

 * Copyright (C) 2015 Russell King

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */

#ifndef MDIO_I2C_H

#define MDIO_I2C_H



struct device;

struct i2c_adapter;

struct mii_bus;



struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c);



#endif

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