kernel-ark/drivers/net/gianfar_mii.c
Trent Piepho c132419e56 gianfar: Fix race in TBI/SerDes configuration
The init_phy() function attaches to the PHY, then configures the
SerDes<->TBI link (in SGMII mode).  The TBI is on the MDIO bus with the PHY
(sort of) and is accessed via the gianfar's MDIO registers, using the
functions gfar_local_mdio_read/write(), which don't do any locking.

The previously attached PHY will start a work-queue on a timer, and
probably an irq handler as well, which will talk to the PHY and thus use
the MDIO bus.  This uses phy_read/write(), which have locking, but not
against the gfar_local_mdio versions.

The result is that PHY code will try to use the MDIO bus at the same time
as the SerDes setup code, corrupting the transfers.

Setting up the SerDes before attaching to the PHY will insure that there is
no race between the SerDes code and *our* PHY, but doesn't fix everything.
Typically the PHYs for all gianfar devices are on the same MDIO bus, which
is associated with the first gianfar device.  This means that the first
gianfar's SerDes code could corrupt the MDIO transfers for a different
gianfar's PHY.

The lock used by phy_read/write() is contained in the mii_bus structure,
which is pointed to by the PHY.  This is difficult to access from the
gianfar drivers, as there is no link between a gianfar device and the
mii_bus which shares the same MDIO registers.  As far as the device layer
and drivers are concerned they are two unrelated devices (which happen to
share registers).

Generally all gianfar devices' PHYs will be on the bus associated with the
first gianfar.  But this might not be the case, so simply locking the
gianfar's PHY's mii bus might not lock the mii bus that the SerDes setup
code is going to use.

We solve this by having the code that creates the gianfar platform device
look in the device tree for an mdio device that shares the gianfar's
registers.  If one is found the ID of its platform device is saved in the
gianfar's platform data.

A new function in the gianfar mii code, gfar_get_miibus(), can use the bus
ID to search through the platform devices for a gianfar_mdio device with
the right ID.  The platform device's driver data is the mii_bus structure,
which the SerDes setup code can use to lock the current bus.

Signed-off-by: Trent Piepho <tpiepho@freescale.com>
CC: Andy Fleming <afleming@freescale.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
2008-10-31 00:59:46 -04:00

302 lines
7.7 KiB
C

/*
* drivers/net/gianfar_mii.c
*
* Gianfar Ethernet Driver -- MIIM bus implementation
* Provides Bus interface for MIIM regs
*
* Author: Andy Fleming
* Maintainer: Kumar Gala
*
* Copyright (c) 2002-2004 Freescale Semiconductor, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
*/
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/crc32.h>
#include <linux/mii.h>
#include <linux/phy.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include "gianfar.h"
#include "gianfar_mii.h"
/*
* Write value to the PHY at mii_id at register regnum,
* on the bus attached to the local interface, which may be different from the
* generic mdio bus (tied to a single interface), waiting until the write is
* done before returning. This is helpful in programming interfaces like
* the TBI which control interfaces like onchip SERDES and are always tied to
* the local mdio pins, which may not be the same as system mdio bus, used for
* controlling the external PHYs, for example.
*/
int gfar_local_mdio_write(struct gfar_mii __iomem *regs, int mii_id,
int regnum, u16 value)
{
/* Set the PHY address and the register address we want to write */
gfar_write(&regs->miimadd, (mii_id << 8) | regnum);
/* Write out the value we want */
gfar_write(&regs->miimcon, value);
/* Wait for the transaction to finish */
while (gfar_read(&regs->miimind) & MIIMIND_BUSY)
cpu_relax();
return 0;
}
/*
* Read the bus for PHY at addr mii_id, register regnum, and
* return the value. Clears miimcom first. All PHY operation
* done on the bus attached to the local interface,
* which may be different from the generic mdio bus
* This is helpful in programming interfaces like
* the TBI which, inturn, control interfaces like onchip SERDES
* and are always tied to the local mdio pins, which may not be the
* same as system mdio bus, used for controlling the external PHYs, for eg.
*/
int gfar_local_mdio_read(struct gfar_mii __iomem *regs, int mii_id, int regnum)
{
u16 value;
/* Set the PHY address and the register address we want to read */
gfar_write(&regs->miimadd, (mii_id << 8) | regnum);
/* Clear miimcom, and then initiate a read */
gfar_write(&regs->miimcom, 0);
gfar_write(&regs->miimcom, MII_READ_COMMAND);
/* Wait for the transaction to finish */
while (gfar_read(&regs->miimind) & (MIIMIND_NOTVALID | MIIMIND_BUSY))
cpu_relax();
/* Grab the value of the register from miimstat */
value = gfar_read(&regs->miimstat);
return value;
}
/* Write value to the PHY at mii_id at register regnum,
* on the bus, waiting until the write is done before returning.
* All PHY configuration is done through the TSEC1 MIIM regs */
int gfar_mdio_write(struct mii_bus *bus, int mii_id, int regnum, u16 value)
{
struct gfar_mii __iomem *regs = (void __iomem *)bus->priv;
/* Write to the local MII regs */
return(gfar_local_mdio_write(regs, mii_id, regnum, value));
}
/* Read the bus for PHY at addr mii_id, register regnum, and
* return the value. Clears miimcom first. All PHY
* configuration has to be done through the TSEC1 MIIM regs */
int gfar_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
{
struct gfar_mii __iomem *regs = (void __iomem *)bus->priv;
/* Read the local MII regs */
return(gfar_local_mdio_read(regs, mii_id, regnum));
}
/* Reset the MIIM registers, and wait for the bus to free */
static int gfar_mdio_reset(struct mii_bus *bus)
{
struct gfar_mii __iomem *regs = (void __iomem *)bus->priv;
unsigned int timeout = PHY_INIT_TIMEOUT;
mutex_lock(&bus->mdio_lock);
/* Reset the management interface */
gfar_write(&regs->miimcfg, MIIMCFG_RESET);
/* Setup the MII Mgmt clock speed */
gfar_write(&regs->miimcfg, MIIMCFG_INIT_VALUE);
/* Wait until the bus is free */
while ((gfar_read(&regs->miimind) & MIIMIND_BUSY) &&
--timeout)
cpu_relax();
mutex_unlock(&bus->mdio_lock);
if(timeout == 0) {
printk(KERN_ERR "%s: The MII Bus is stuck!\n",
bus->name);
return -EBUSY;
}
return 0;
}
static int gfar_mdio_probe(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct gianfar_mdio_data *pdata;
struct gfar_mii __iomem *regs;
struct gfar __iomem *enet_regs;
struct mii_bus *new_bus;
struct resource *r;
int i, err = 0;
if (NULL == dev)
return -EINVAL;
new_bus = mdiobus_alloc();
if (NULL == new_bus)
return -ENOMEM;
new_bus->name = "Gianfar MII Bus",
new_bus->read = &gfar_mdio_read,
new_bus->write = &gfar_mdio_write,
new_bus->reset = &gfar_mdio_reset,
snprintf(new_bus->id, MII_BUS_ID_SIZE, "%x", pdev->id);
pdata = (struct gianfar_mdio_data *)pdev->dev.platform_data;
if (NULL == pdata) {
printk(KERN_ERR "gfar mdio %d: Missing platform data!\n", pdev->id);
return -ENODEV;
}
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
/* Set the PHY base address */
regs = ioremap(r->start, sizeof (struct gfar_mii));
if (NULL == regs) {
err = -ENOMEM;
goto reg_map_fail;
}
new_bus->priv = (void __force *)regs;
new_bus->irq = pdata->irq;
new_bus->parent = dev;
dev_set_drvdata(dev, new_bus);
/*
* This is mildly evil, but so is our hardware for doing this.
* Also, we have to cast back to struct gfar_mii because of
* definition weirdness done in gianfar.h.
*/
enet_regs = (struct gfar __iomem *)
((char *)regs - offsetof(struct gfar, gfar_mii_regs));
/* Scan the bus, looking for an empty spot for TBIPA */
gfar_write(&enet_regs->tbipa, 0);
for (i = PHY_MAX_ADDR; i > 0; i--) {
u32 phy_id;
err = get_phy_id(new_bus, i, &phy_id);
if (err)
goto bus_register_fail;
if (phy_id == 0xffffffff)
break;
}
/* The bus is full. We don't support using 31 PHYs, sorry */
if (i == 0) {
err = -EBUSY;
goto bus_register_fail;
}
gfar_write(&enet_regs->tbipa, i);
err = mdiobus_register(new_bus);
if (0 != err) {
printk (KERN_ERR "%s: Cannot register as MDIO bus\n",
new_bus->name);
goto bus_register_fail;
}
return 0;
bus_register_fail:
iounmap(regs);
reg_map_fail:
mdiobus_free(new_bus);
return err;
}
static int gfar_mdio_remove(struct device *dev)
{
struct mii_bus *bus = dev_get_drvdata(dev);
mdiobus_unregister(bus);
dev_set_drvdata(dev, NULL);
iounmap((void __iomem *)bus->priv);
bus->priv = NULL;
mdiobus_free(bus);
return 0;
}
static struct device_driver gianfar_mdio_driver = {
.name = "fsl-gianfar_mdio",
.bus = &platform_bus_type,
.probe = gfar_mdio_probe,
.remove = gfar_mdio_remove,
};
static int match_mdio_bus(struct device *dev, void *data)
{
const struct gfar_private *priv = data;
const struct platform_device *pdev = to_platform_device(dev);
return !strcmp(pdev->name, gianfar_mdio_driver.name) &&
pdev->id == priv->einfo->mdio_bus;
}
/* Given a gfar_priv structure, find the mii_bus controlled by this device (not
* necessarily the same as the bus the gfar's PHY is on), if one exists.
* Normally only the first gianfar controls a mii_bus. */
struct mii_bus *gfar_get_miibus(const struct gfar_private *priv)
{
/*const*/ struct device *d;
d = bus_find_device(gianfar_mdio_driver.bus, NULL, (void *)priv,
match_mdio_bus);
return d ? dev_get_drvdata(d) : NULL;
}
int __init gfar_mdio_init(void)
{
return driver_register(&gianfar_mdio_driver);
}
void gfar_mdio_exit(void)
{
driver_unregister(&gianfar_mdio_driver);
}