diff options
Diffstat (limited to 'drivers/net/mdio/mdio-bitbang.c')
| -rw-r--r-- | drivers/net/mdio/mdio-bitbang.c | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/drivers/net/mdio/mdio-bitbang.c b/drivers/net/mdio/mdio-bitbang.c new file mode 100644 index 000000000000..5136275c8e73 --- /dev/null +++ b/drivers/net/mdio/mdio-bitbang.c @@ -0,0 +1,232 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Bitbanged MDIO support. + * + * Author: Scott Wood <scottwood@freescale.com> + * Copyright (c) 2007 Freescale Semiconductor + * + * Based on CPM2 MDIO code which is: + * + * Copyright (c) 2003 Intracom S.A. + * by Pantelis Antoniou <panto@intracom.gr> + * + * 2005 (c) MontaVista Software, Inc. + * Vitaly Bordug <vbordug@ru.mvista.com> + */ + +#include <linux/module.h> +#include <linux/mdio-bitbang.h> +#include <linux/types.h> +#include <linux/delay.h> + +#define MDIO_READ 2 +#define MDIO_WRITE 1 + +#define MDIO_C45 (1<<15) +#define MDIO_C45_ADDR (MDIO_C45 | 0) +#define MDIO_C45_READ (MDIO_C45 | 3) +#define MDIO_C45_WRITE (MDIO_C45 | 1) + +#define MDIO_SETUP_TIME 10 +#define MDIO_HOLD_TIME 10 + +/* Minimum MDC period is 400 ns, plus some margin for error. MDIO_DELAY + * is done twice per period. + */ +#define MDIO_DELAY 250 + +/* The PHY may take up to 300 ns to produce data, plus some margin + * for error. + */ +#define MDIO_READ_DELAY 350 + +/* MDIO must already be configured as output. */ +static void mdiobb_send_bit(struct mdiobb_ctrl *ctrl, int val) +{ + const struct mdiobb_ops *ops = ctrl->ops; + + ops->set_mdio_data(ctrl, val); + ndelay(MDIO_DELAY); + ops->set_mdc(ctrl, 1); + ndelay(MDIO_DELAY); + ops->set_mdc(ctrl, 0); +} + +/* MDIO must already be configured as input. */ +static int mdiobb_get_bit(struct mdiobb_ctrl *ctrl) +{ + const struct mdiobb_ops *ops = ctrl->ops; + + ndelay(MDIO_DELAY); + ops->set_mdc(ctrl, 1); + ndelay(MDIO_READ_DELAY); + ops->set_mdc(ctrl, 0); + + return ops->get_mdio_data(ctrl); +} + +/* MDIO must already be configured as output. */ +static void mdiobb_send_num(struct mdiobb_ctrl *ctrl, u16 val, int bits) +{ + int i; + + for (i = bits - 1; i >= 0; i--) + mdiobb_send_bit(ctrl, (val >> i) & 1); +} + +/* MDIO must already be configured as input. */ +static u16 mdiobb_get_num(struct mdiobb_ctrl *ctrl, int bits) +{ + int i; + u16 ret = 0; + + for (i = bits - 1; i >= 0; i--) { + ret <<= 1; + ret |= mdiobb_get_bit(ctrl); + } + + return ret; +} + +/* Utility to send the preamble, address, and + * register (common to read and write). + */ +static void mdiobb_cmd(struct mdiobb_ctrl *ctrl, int op, u8 phy, u8 reg) +{ + const struct mdiobb_ops *ops = ctrl->ops; + int i; + + ops->set_mdio_dir(ctrl, 1); + + /* + * Send a 32 bit preamble ('1's) with an extra '1' bit for good + * measure. The IEEE spec says this is a PHY optional + * requirement. The AMD 79C874 requires one after power up and + * one after a MII communications error. This means that we are + * doing more preambles than we need, but it is safer and will be + * much more robust. + */ + + for (i = 0; i < 32; i++) + mdiobb_send_bit(ctrl, 1); + + /* send the start bit (01) and the read opcode (10) or write (01). + Clause 45 operation uses 00 for the start and 11, 10 for + read/write */ + mdiobb_send_bit(ctrl, 0); + if (op & MDIO_C45) + mdiobb_send_bit(ctrl, 0); + else + mdiobb_send_bit(ctrl, 1); + mdiobb_send_bit(ctrl, (op >> 1) & 1); + mdiobb_send_bit(ctrl, (op >> 0) & 1); + + mdiobb_send_num(ctrl, phy, 5); + mdiobb_send_num(ctrl, reg, 5); +} + +/* In clause 45 mode all commands are prefixed by MDIO_ADDR to specify the + lower 16 bits of the 21 bit address. This transfer is done identically to a + MDIO_WRITE except for a different code. To enable clause 45 mode or + MII_ADDR_C45 into the address. Theoretically clause 45 and normal devices + can exist on the same bus. Normal devices should ignore the MDIO_ADDR + phase. */ +static int mdiobb_cmd_addr(struct mdiobb_ctrl *ctrl, int phy, u32 addr) +{ + unsigned int dev_addr = (addr >> 16) & 0x1F; + unsigned int reg = addr & 0xFFFF; + mdiobb_cmd(ctrl, MDIO_C45_ADDR, phy, dev_addr); + + /* send the turnaround (10) */ + mdiobb_send_bit(ctrl, 1); + mdiobb_send_bit(ctrl, 0); + + mdiobb_send_num(ctrl, reg, 16); + + ctrl->ops->set_mdio_dir(ctrl, 0); + mdiobb_get_bit(ctrl); + + return dev_addr; +} + +static int mdiobb_read(struct mii_bus *bus, int phy, int reg) +{ + struct mdiobb_ctrl *ctrl = bus->priv; + int ret, i; + + if (reg & MII_ADDR_C45) { + reg = mdiobb_cmd_addr(ctrl, phy, reg); + mdiobb_cmd(ctrl, MDIO_C45_READ, phy, reg); + } else + mdiobb_cmd(ctrl, MDIO_READ, phy, reg); + + ctrl->ops->set_mdio_dir(ctrl, 0); + + /* check the turnaround bit: the PHY should be driving it to zero, if this + * PHY is listed in phy_ignore_ta_mask as having broken TA, skip that + */ + if (mdiobb_get_bit(ctrl) != 0 && + !(bus->phy_ignore_ta_mask & (1 << phy))) { + /* PHY didn't drive TA low -- flush any bits it + * may be trying to send. + */ + for (i = 0; i < 32; i++) + mdiobb_get_bit(ctrl); + + return 0xffff; + } + + ret = mdiobb_get_num(ctrl, 16); + mdiobb_get_bit(ctrl); + return ret; +} + +static int mdiobb_write(struct mii_bus *bus, int phy, int reg, u16 val) +{ + struct mdiobb_ctrl *ctrl = bus->priv; + + if (reg & MII_ADDR_C45) { + reg = mdiobb_cmd_addr(ctrl, phy, reg); + mdiobb_cmd(ctrl, MDIO_C45_WRITE, phy, reg); + } else + mdiobb_cmd(ctrl, MDIO_WRITE, phy, reg); + + /* send the turnaround (10) */ + mdiobb_send_bit(ctrl, 1); + mdiobb_send_bit(ctrl, 0); + + mdiobb_send_num(ctrl, val, 16); + + ctrl->ops->set_mdio_dir(ctrl, 0); + mdiobb_get_bit(ctrl); + return 0; +} + +struct mii_bus *alloc_mdio_bitbang(struct mdiobb_ctrl *ctrl) +{ + struct mii_bus *bus; + + bus = mdiobus_alloc(); + if (!bus) + return NULL; + + __module_get(ctrl->ops->owner); + + bus->read = mdiobb_read; + bus->write = mdiobb_write; + bus->priv = ctrl; + + return bus; +} +EXPORT_SYMBOL(alloc_mdio_bitbang); + +void free_mdio_bitbang(struct mii_bus *bus) +{ + struct mdiobb_ctrl *ctrl = bus->priv; + + module_put(ctrl->ops->owner); + mdiobus_free(bus); +} +EXPORT_SYMBOL(free_mdio_bitbang); + +MODULE_LICENSE("GPL v2"); |