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Linux kernel mirror (for testing)
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kernel
os
linux
Generic bitbanged MDIO library
Previously, bitbanged MDIO was only supported in individual
hardware-specific drivers. This code factors out the higher level
protocol implementation, reducing the hardware-specific portion to
functions setting direction, data, and clock.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
authored by
Scott Wood
and committed by
David S. Miller
e2ec4581
976de6a8
+239
+9
drivers/net/phy/Kconfig
+9
drivers/net/phy/Kconfig
···
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This control will have specified number allocated for each fixed
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PHY type enabled.
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config MDIO_BITBANG
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tristate "Support for bitbanged MDIO buses"
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help
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This module implements the MDIO bus protocol in software,
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for use by low level drivers that export the ability to
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drive the relevant pins.
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If in doubt, say N.
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endif # PHYLIB
+1
drivers/net/phy/Makefile
+1
drivers/net/phy/Makefile
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drivers/net/phy/mdio-bitbang.c
+187
drivers/net/phy/mdio-bitbang.c
···
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/*
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* Bitbanged MDIO support.
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*
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* Author: Scott Wood <scottwood@freescale.com>
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* Copyright (c) 2007 Freescale Semiconductor
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*
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* Based on CPM2 MDIO code which is:
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*
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* Copyright (c) 2003 Intracom S.A.
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* by Pantelis Antoniou <panto@intracom.gr>
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*
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* 2005 (c) MontaVista Software, Inc.
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* Vitaly Bordug <vbordug@ru.mvista.com>
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*
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* This file is licensed under the terms of the GNU General Public License
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* version 2. This program is licensed "as is" without any warranty of any
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* kind, whether express or implied.
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*/
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#include <linux/module.h>
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#include <linux/mdio-bitbang.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/delay.h>
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#define MDIO_READ 1
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#define MDIO_WRITE 0
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#define MDIO_SETUP_TIME 10
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#define MDIO_HOLD_TIME 10
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/* Minimum MDC period is 400 ns, plus some margin for error. MDIO_DELAY
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* is done twice per period.
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*/
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#define MDIO_DELAY 250
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/* The PHY may take up to 300 ns to produce data, plus some margin
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* for error.
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*/
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#define MDIO_READ_DELAY 350
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/* MDIO must already be configured as output. */
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static void mdiobb_send_bit(struct mdiobb_ctrl *ctrl, int val)
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{
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const struct mdiobb_ops *ops = ctrl->ops;
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ops->set_mdio_data(ctrl, val);
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ndelay(MDIO_DELAY);
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ops->set_mdc(ctrl, 1);
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ndelay(MDIO_DELAY);
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ops->set_mdc(ctrl, 0);
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}
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/* MDIO must already be configured as input. */
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static int mdiobb_get_bit(struct mdiobb_ctrl *ctrl)
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{
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const struct mdiobb_ops *ops = ctrl->ops;
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ndelay(MDIO_DELAY);
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ops->set_mdc(ctrl, 1);
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ndelay(MDIO_READ_DELAY);
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ops->set_mdc(ctrl, 0);
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return ops->get_mdio_data(ctrl);
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}
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/* MDIO must already be configured as output. */
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static void mdiobb_send_num(struct mdiobb_ctrl *ctrl, u16 val, int bits)
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{
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int i;
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for (i = bits - 1; i >= 0; i--)
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mdiobb_send_bit(ctrl, (val >> i) & 1);
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}
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/* MDIO must already be configured as input. */
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static u16 mdiobb_get_num(struct mdiobb_ctrl *ctrl, int bits)
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{
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int i;
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u16 ret = 0;
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for (i = bits - 1; i >= 0; i--) {
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ret <<= 1;
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ret |= mdiobb_get_bit(ctrl);
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}
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return ret;
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}
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/* Utility to send the preamble, address, and
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* register (common to read and write).
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*/
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static void mdiobb_cmd(struct mdiobb_ctrl *ctrl, int read, u8 phy, u8 reg)
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{
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const struct mdiobb_ops *ops = ctrl->ops;
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int i;
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ops->set_mdio_dir(ctrl, 1);
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/*
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* Send a 32 bit preamble ('1's) with an extra '1' bit for good
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* measure. The IEEE spec says this is a PHY optional
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* requirement. The AMD 79C874 requires one after power up and
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* one after a MII communications error. This means that we are
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* doing more preambles than we need, but it is safer and will be
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* much more robust.
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*/
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for (i = 0; i < 32; i++)
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mdiobb_send_bit(ctrl, 1);
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/* send the start bit (01) and the read opcode (10) or write (10) */
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mdiobb_send_bit(ctrl, 0);
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mdiobb_send_bit(ctrl, 1);
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mdiobb_send_bit(ctrl, read);
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mdiobb_send_bit(ctrl, !read);
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mdiobb_send_num(ctrl, phy, 5);
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mdiobb_send_num(ctrl, reg, 5);
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}
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static int mdiobb_read(struct mii_bus *bus, int phy, int reg)
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{
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struct mdiobb_ctrl *ctrl = bus->priv;
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int ret, i;
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mdiobb_cmd(ctrl, MDIO_READ, phy, reg);
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ctrl->ops->set_mdio_dir(ctrl, 0);
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/* check the turnaround bit: the PHY should be driving it to zero */
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if (mdiobb_get_bit(ctrl) != 0) {
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/* PHY didn't drive TA low -- flush any bits it
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* may be trying to send.
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*/
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for (i = 0; i < 32; i++)
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mdiobb_get_bit(ctrl);
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return 0xffff;
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}
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ret = mdiobb_get_num(ctrl, 16);
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mdiobb_get_bit(ctrl);
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return ret;
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}
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static int mdiobb_write(struct mii_bus *bus, int phy, int reg, u16 val)
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{
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struct mdiobb_ctrl *ctrl = bus->priv;
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mdiobb_cmd(ctrl, MDIO_WRITE, phy, reg);
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/* send the turnaround (10) */
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mdiobb_send_bit(ctrl, 1);
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mdiobb_send_bit(ctrl, 0);
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mdiobb_send_num(ctrl, val, 16);
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ctrl->ops->set_mdio_dir(ctrl, 0);
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mdiobb_get_bit(ctrl);
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return 0;
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}
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struct mii_bus *alloc_mdio_bitbang(struct mdiobb_ctrl *ctrl)
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{
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struct mii_bus *bus;
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bus = kzalloc(sizeof(struct mii_bus), GFP_KERNEL);
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if (!bus)
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return NULL;
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__module_get(ctrl->ops->owner);
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bus->read = mdiobb_read;
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bus->write = mdiobb_write;
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bus->priv = ctrl;
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return bus;
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}
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void free_mdio_bitbang(struct mii_bus *bus)
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{
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struct mdiobb_ctrl *ctrl = bus->priv;
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module_put(ctrl->ops->owner);
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kfree(bus);
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}
+42
include/linux/mdio-bitbang.h
+42
include/linux/mdio-bitbang.h
···
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#ifndef __LINUX_MDIO_BITBANG_H
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#define __LINUX_MDIO_BITBANG_H
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#include <linux/phy.h>
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#include <linux/module.h>
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struct mdiobb_ctrl;
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struct mdiobb_ops {
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struct module *owner;
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/* Set the Management Data Clock high if level is one,
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* low if level is zero.
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*/
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void (*set_mdc)(struct mdiobb_ctrl *ctrl, int level);
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/* Configure the Management Data I/O pin as an input if
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* "output" is zero, or an output if "output" is one.
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*/
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void (*set_mdio_dir)(struct mdiobb_ctrl *ctrl, int output);
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/* Set the Management Data I/O pin high if value is one,
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* low if "value" is zero. This may only be called
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* when the MDIO pin is configured as an output.
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*/
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void (*set_mdio_data)(struct mdiobb_ctrl *ctrl, int value);
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/* Retrieve the state Management Data I/O pin. */
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int (*get_mdio_data)(struct mdiobb_ctrl *ctrl);
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};
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struct mdiobb_ctrl {
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const struct mdiobb_ops *ops;
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};
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/* The returned bus is not yet registered with the phy layer. */
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struct mii_bus *alloc_mdio_bitbang(struct mdiobb_ctrl *ctrl);
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/* The bus must already have been unregistered. */
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void free_mdio_bitbang(struct mii_bus *bus);
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#endif