From 64a0fb4cc35ced6ac83e4177889501782b51891d Mon Sep 17 00:00:00 2001 From: Ioana Ciornei Date: Wed, 9 Dec 2020 13:31:58 +0200 Subject: [PATCH] net: memac_phy: add a timeout to MDIO operations 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 Reviewed-by: Madalin Bucur [Rebased] Signed-off-by: Priyanka Jain --- drivers/net/fm/memac_phy.c | 76 +++++++++++++++++++++++++++++++++++----------- 1 file changed, 58 insertions(+), 18 deletions(-) diff --git a/drivers/net/fm/memac_phy.c b/drivers/net/fm/memac_phy.c index 8bd32b0..72b500a 100644 --- a/drivers/net/fm/memac_phy.c +++ b/drivers/net/fm/memac_phy.c @@ -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 @@ -38,6 +40,42 @@ static u32 memac_in_32(u32 *reg) } /* + * 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(®s->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(®s->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 * done through the TSEC1 MIIM regs @@ -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(®s->mdio_stat, MDIO_STAT_ENC); - /* Wait till the bus is free */ - while ((memac_in_32(®s->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(®s->mdio_addr, regnum & 0xffff); - /* Wait till the bus is free */ - while ((memac_in_32(®s->mdio_stat)) & MDIO_STAT_BSY) - ; + err = memac_wait_until_free(regs); + if (err) + return err; /* Write the value to the register */ memac_out_32(®s->mdio_data, MDIO_DATA(value)); - /* Wait till the MDIO write is complete */ - while ((memac_in_32(®s->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(®s->mdio_stat, MDIO_STAT_ENC); - /* Wait till the bus is free */ - while ((memac_in_32(®s->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(®s->mdio_addr, regnum & 0xffff); - /* Wait till the bus is free */ - while ((memac_in_32(®s->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(®s->mdio_ctl, mdio_ctl); - /* Wait till the MDIO write is complete */ - while ((memac_in_32(®s->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(®s->mdio_stat) & MDIO_STAT_RD_ER) -- 2.7.4