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net: memac_phy: add a timeout to MDIO operations

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We have encountered circumstances when a board design does not include
pull-up resistors on the external MDIO buses which are not used. This
leads to the MDIO data line not being pulled-up, thus the MDIO controller
will always see the line as busy.

Without a timeout in the MDIO bus driver, the execution is stuck in an
infinite loop when any access is initiated on that external bus.

Add a timeout in the driver so that we are protected in this
circumstance. This is similar to what is being done in the Linux
xgmac_mdio driver.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Madalin Bucur <madalin.bucur@oss.nxp.com>
[Rebased]
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>
This commit is contained in:
Ioana Ciornei 2020-12-09 13:31:58 +02:00 committed by Priyanka Jain
parent 46fdf763b8
commit 64a0fb4cc3
1 changed files with 58 additions and 18 deletions
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76
drivers/net/fm/memac_phy.c
View file

@ -28,6 +28,8 @@ struct fm_mdio_priv {
};
#endif
#define MAX_NUM_RETRIES 1000
static u32 memac_in_32(u32 *reg)
{
#ifdef CONFIG_SYS_MEMAC_LITTLE_ENDIAN
@ -37,6 +39,42 @@ static u32 memac_in_32(u32 *reg)
#endif
}
/*
* Wait until the MDIO bus is free
*/
static int memac_wait_until_free(struct memac_mdio_controller *regs)
{
unsigned int timeout = MAX_NUM_RETRIES;
while ((memac_in_32(&regs->mdio_stat) & MDIO_STAT_BSY) && timeout--)
;
if (!timeout) {
printf("timeout waiting for MDIO bus to be free\n");
return -ETIMEDOUT;
}
return 0;
}
/*
* Wait till the MDIO read or write operation is complete
*/
static int memac_wait_until_done(struct memac_mdio_controller *regs)
{
unsigned int timeout = MAX_NUM_RETRIES;
while ((memac_in_32(&regs->mdio_data) & MDIO_DATA_BSY) && timeout--)
;
if (!timeout) {
printf("timeout waiting for MDIO operation to complete\n");
return -ETIMEDOUT;
}
return 0;
}
/*
* Write value to the PHY for this device to the register at regnum, waiting
* until the write is done before it returns. All PHY configuration has to be
@ -48,6 +86,7 @@ int memac_mdio_write(struct mii_dev *bus, int port_addr, int dev_addr,
struct memac_mdio_controller *regs;
u32 mdio_ctl;
u32 c45 = 1; /* Default to 10G interface */
int err;
#ifndef CONFIG_DM_ETH
regs = bus->priv;
@ -69,9 +108,9 @@ int memac_mdio_write(struct mii_dev *bus, int port_addr, int dev_addr,
} else
memac_setbits_32(&regs->mdio_stat, MDIO_STAT_ENC);
/* Wait till the bus is free */
while ((memac_in_32(&regs->mdio_stat)) & MDIO_STAT_BSY)
;
err = memac_wait_until_free(regs);
if (err)
return err;
/* Set the port and dev addr */
mdio_ctl = MDIO_CTL_PORT_ADDR(port_addr) | MDIO_CTL_DEV_ADDR(dev_addr);
@ -81,16 +120,16 @@ int memac_mdio_write(struct mii_dev *bus, int port_addr, int dev_addr,
if (c45)
memac_out_32(&regs->mdio_addr, regnum & 0xffff);
/* Wait till the bus is free */
while ((memac_in_32(&regs->mdio_stat)) & MDIO_STAT_BSY)
;
err = memac_wait_until_free(regs);
if (err)
return err;
/* Write the value to the register */
memac_out_32(&regs->mdio_data, MDIO_DATA(value));
/* Wait till the MDIO write is complete */
while ((memac_in_32(&regs->mdio_data)) & MDIO_DATA_BSY)
;
err = memac_wait_until_done(regs);
if (err)
return err;
return 0;
}
@ -106,6 +145,7 @@ int memac_mdio_read(struct mii_dev *bus, int port_addr, int dev_addr,
struct memac_mdio_controller *regs;
u32 mdio_ctl;
u32 c45 = 1;
int err;
#ifndef CONFIG_DM_ETH
regs = bus->priv;
@ -129,9 +169,9 @@ int memac_mdio_read(struct mii_dev *bus, int port_addr, int dev_addr,
} else
memac_setbits_32(&regs->mdio_stat, MDIO_STAT_ENC);
/* Wait till the bus is free */
while ((memac_in_32(&regs->mdio_stat)) & MDIO_STAT_BSY)
;
err = memac_wait_until_free(regs);
if (err)
return err;
/* Set the Port and Device Addrs */
mdio_ctl = MDIO_CTL_PORT_ADDR(port_addr) | MDIO_CTL_DEV_ADDR(dev_addr);
@ -141,17 +181,17 @@ int memac_mdio_read(struct mii_dev *bus, int port_addr, int dev_addr,
if (c45)
memac_out_32(&regs->mdio_addr, regnum & 0xffff);
/* Wait till the bus is free */
while ((memac_in_32(&regs->mdio_stat)) & MDIO_STAT_BSY)
;
err = memac_wait_until_free(regs);
if (err)
return err;
/* Initiate the read */
mdio_ctl |= MDIO_CTL_READ;
memac_out_32(&regs->mdio_ctl, mdio_ctl);
/* Wait till the MDIO write is complete */
while ((memac_in_32(&regs->mdio_data)) & MDIO_DATA_BSY)
;
err = memac_wait_until_done(regs);
if (err)
return err;
/* Return all Fs if nothing was there */
if (memac_in_32(&regs->mdio_stat) & MDIO_STAT_RD_ER)