diff options
Diffstat (limited to 'drivers/net/phy/mdio-bitbang.c')
| -rw-r--r-- | drivers/net/phy/mdio-bitbang.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/drivers/net/phy/mdio-bitbang.c b/drivers/net/phy/mdio-bitbang.c new file mode 100644 index 00000000000..8cd243d92af --- /dev/null +++ b/drivers/net/phy/mdio-bitbang.c @@ -0,0 +1,187 @@ +/* + * 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> + * + * This file is licensed under the terms of the GNU General Public License + * version 2. This program is licensed "as is" without any warranty of any + * kind, whether express or implied. + */ + +#include <linux/module.h> +#include <linux/mdio-bitbang.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <linux/delay.h> + +#define MDIO_READ 1 +#define MDIO_WRITE 0 + +#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 read, 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 (10) */ + mdiobb_send_bit(ctrl, 0); + mdiobb_send_bit(ctrl, 1); + mdiobb_send_bit(ctrl, read); + mdiobb_send_bit(ctrl, !read); + + mdiobb_send_num(ctrl, phy, 5); + mdiobb_send_num(ctrl, reg, 5); +} + + +static int mdiobb_read(struct mii_bus *bus, int phy, int reg) +{ + struct mdiobb_ctrl *ctrl = bus->priv; + int ret, i; + + 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 (mdiobb_get_bit(ctrl) != 0) { + /* 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; + + 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 = kzalloc(sizeof(struct mii_bus), GFP_KERNEL); + if (!bus) + return NULL; + + __module_get(ctrl->ops->owner); + + bus->read = mdiobb_read; + bus->write = mdiobb_write; + bus->priv = ctrl; + + return bus; +} + +void free_mdio_bitbang(struct mii_bus *bus) +{ + struct mdiobb_ctrl *ctrl = bus->priv; + + module_put(ctrl->ops->owner); + kfree(bus); +} |