[PATCH v3 1/8] Generic bitbanged MDIO library
Scott Wood
scottwood at freescale.com
Wed Aug 29 06:11:27 EST 2007
Previously, bitbanged MDIO was only supported in individual
hardware-specific drivers. This code factors out the higher level
protocol implementation, reducing the hardware-specific portion to
functions setting direction, data, and clock.
Signed-off-by: Scott Wood <scottwood at freescale.com>
---
drivers/net/phy/Kconfig | 9 ++
drivers/net/phy/Makefile | 1 +
drivers/net/phy/mdio-bitbang.c | 187 ++++++++++++++++++++++++++++++++++++++++
include/linux/mdio-bitbang.h | 42 +++++++++
4 files changed, 239 insertions(+), 0 deletions(-)
create mode 100644 drivers/net/phy/mdio-bitbang.c
create mode 100644 include/linux/mdio-bitbang.h
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index dd09011..72a98dd 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -76,4 +76,13 @@ config FIXED_MII_100_FDX
bool "Emulation for 100M Fdx fixed PHY behavior"
depends on FIXED_PHY
+config MDIO_BITBANG
+ tristate "Support for bitbanged MDIO buses"
+ help
+ This module implements the MDIO bus protocol in software,
+ for use by low level drivers that export the ability to
+ drive the relevant pins.
+
+ If in doubt, say N.
+
endif # PHYLIB
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 8885650..3d6cc7b 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_VITESSE_PHY) += vitesse.o
obj-$(CONFIG_BROADCOM_PHY) += broadcom.o
obj-$(CONFIG_ICPLUS_PHY) += icplus.o
obj-$(CONFIG_FIXED_PHY) += fixed.o
+obj-$(CONFIG_MDIO_BITBANG) += mdio-bitbang.o
diff --git a/drivers/net/phy/mdio-bitbang.c b/drivers/net/phy/mdio-bitbang.c
new file mode 100644
index 0000000..9bfc9ce
--- /dev/null
+++ b/drivers/net/phy/mdio-bitbang.c
@@ -0,0 +1,187 @@
+/*
+ * Bitbanged MDIO support.
+ *
+ * Author: Scott Wood <scottwood at freescale.com>
+ * Copyright (c) 2007 Freescale Semiconductor
+ *
+ * Based on CPM2 MDIO code which is:
+ *
+ * Copyright (c) 2003 Intracom S.A.
+ * by Pantelis Antoniou <panto at intracom.gr>
+ *
+ * 2005 (c) MontaVista Software, Inc.
+ * Vitaly Bordug <vbordug at 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 */
+#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 mdio_bitbang_send_bit(struct mdio_bitbang_ctrl *ctrl, int val)
+{
+ const struct mdio_bitbang_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 mdio_bitbang_get_bit(struct mdio_bitbang_ctrl *ctrl)
+{
+ const struct mdio_bitbang_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 mdio_bitbang_send_num(struct mdio_bitbang_ctrl *ctrl,
+ u16 val, int bits)
+{
+ int i;
+
+ for (i = bits - 1; i >= 0; i--)
+ mdio_bitbang_send_bit(ctrl, (val >> i) & 1);
+}
+
+/* MDIO must already be configured as input. */
+static u16 mdio_bitbang_get_num(struct mdio_bitbang_ctrl *ctrl, int bits)
+{
+ int i;
+ u16 ret = 0;
+
+ for (i = bits - 1; i >= 0; i--) {
+ ret <<= 1;
+ ret |= mdio_bitbang_get_bit(ctrl);
+ }
+
+ return ret;
+}
+
+/* Utility to send the preamble, address, and
+ * register (common to read and write).
+ */
+static void mdio_bitbang_cmd(struct mdio_bitbang_ctrl *ctrl,
+ int read, u8 phy, u8 reg)
+{
+ const struct mdio_bitbang_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++)
+ mdio_bitbang_send_bit(ctrl, 1);
+
+ /* send the start bit (01) and the read opcode (10) or write (10) */
+ mdio_bitbang_send_bit(ctrl, 0);
+ mdio_bitbang_send_bit(ctrl, 1);
+ mdio_bitbang_send_bit(ctrl, read);
+ mdio_bitbang_send_bit(ctrl, !read);
+
+ mdio_bitbang_send_num(ctrl, phy, 5);
+ mdio_bitbang_send_num(ctrl, reg, 5);
+}
+
+
+static int mdio_bitbang_read(struct mii_bus *bus, int phy, int reg)
+{
+ struct mdio_bitbang_ctrl *ctrl = bus->priv;
+ int ret, i;
+
+ mdio_bitbang_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 (mdio_bitbang_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++)
+ mdio_bitbang_get_bit(ctrl);
+
+ return 0xffff;
+ }
+
+ ret = mdio_bitbang_get_num(ctrl, 16);
+ mdio_bitbang_get_bit(ctrl);
+ return ret;
+}
+
+static int mdio_bitbang_write(struct mii_bus *bus, int phy, int reg, u16 val)
+{
+ struct mdio_bitbang_ctrl *ctrl = bus->priv;
+
+ mdio_bitbang_cmd(ctrl, MDIO_WRITE, phy, reg);
+
+ /* send the turnaround (10) */
+ mdio_bitbang_send_bit(ctrl, 1);
+ mdio_bitbang_send_bit(ctrl, 0);
+
+ mdio_bitbang_send_num(ctrl, val, 16);
+
+ ctrl->ops->set_mdio_dir(ctrl, 0);
+ mdio_bitbang_get_bit(ctrl);
+ return 0;
+}
+
+struct mii_bus *alloc_mdio_bitbang(struct mdio_bitbang_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 = mdio_bitbang_read;
+ bus->write = mdio_bitbang_write;
+ bus->priv = ctrl;
+
+ return bus;
+}
+
+void free_mdio_bitbang(struct mii_bus *bus)
+{
+ struct mdio_bitbang_ctrl *ctrl = bus->priv;
+
+ module_put(ctrl->ops->owner);
+ kfree(bus);
+}
diff --git a/include/linux/mdio-bitbang.h b/include/linux/mdio-bitbang.h
new file mode 100644
index 0000000..63a11dd
--- /dev/null
+++ b/include/linux/mdio-bitbang.h
@@ -0,0 +1,42 @@
+#ifndef __LINUX_MDIO_BITBANG_H
+#define __LINUX_MDIO_BITBANG_H
+
+#include <linux/phy.h>
+#include <linux/module.h>
+
+struct mdio_bitbang_ctrl;
+
+struct mdio_bitbang_ops {
+ struct module *owner;
+
+ /* Set the Management Data Clock high if level is one,
+ * low if level is zero.
+ */
+ void (*set_mdc)(struct mdio_bitbang_ctrl *ctrl, int level);
+
+ /* Configure the Management Data I/O pin as an input if
+ * "output" is zero, or an output if "output" is one.
+ */
+ void (*set_mdio_dir)(struct mdio_bitbang_ctrl *ctrl, int output);
+
+ /* Set the Management Data I/O pin high if value is one,
+ * low if "value" is zero. This may only be called
+ * when the MDIO pin is configured as an output.
+ */
+ void (*set_mdio_data)(struct mdio_bitbang_ctrl *ctrl, int value);
+
+ /* Retrieve the state Management Data I/O pin. */
+ int (*get_mdio_data)(struct mdio_bitbang_ctrl *ctrl);
+};
+
+struct mdio_bitbang_ctrl {
+ const struct mdio_bitbang_ops *ops;
+};
+
+/* The returned bus is not yet registered with the phy layer. */
+struct mii_bus *alloc_mdio_bitbang(struct mdio_bitbang_ctrl *ctrl);
+
+/* The bus must already have been unregistered. */
+void free_mdio_bitbang(struct mii_bus *bus);
+
+#endif
--
1.5.0.3
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