Linux DTS compatible MDIO bitbanging driver.
Both clause 22 and clause 45 MDIO supported and validated.
Heavily based on the Linux drivers (more or less the same code base).
Signed-off-by: Markus Gothe <markus.gothe(a)genexis.eu>
---
drivers/net/Kconfig | 6 +
drivers/net/Makefile | 1 +
drivers/net/mdio_gpio.c | 313 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 320 insertions(+)
create mode 100644 drivers/net/mdio_gpio.c
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 69ae7c0750..15019d8700 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -953,6 +953,12 @@ config FSL_ENETC
This driver supports the NXP ENETC Ethernet controller found on some
of the NXP SoCs.
+config MDIO_GPIO_BITBANG
+ bool "GPIO bitbanging MDIO driver"
+ depends on DM_MDIO && DM_GPIO
+ help
+ Driver for bitbanging MDIO
+
config MDIO_MUX_I2CREG
bool "MDIO MUX accessed as a register over I2C"
depends on DM_MDIO_MUX && DM_I2C
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 425dd721f9..ec178beb67 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_LITEETH) += liteeth.o
obj-$(CONFIG_MACB) += macb.o
obj-$(CONFIG_MCFFEC) += mcffec.o mcfmii.o
obj-$(CONFIG_MDIO_IPQ4019) += mdio-ipq4019.o
+obj-$(CONFIG_MDIO_GPIO_BITBANG) += mdio_gpio.o
obj-$(CONFIG_MDIO_MUX_I2CREG) += mdio_mux_i2creg.o
obj-$(CONFIG_MDIO_MUX_MESON_G12A) += mdio_mux_meson_g12a.o
obj-$(CONFIG_MDIO_MUX_MESON_GXL) += mdio_mux_meson_gxl.o
diff --git a/drivers/net/mdio_gpio.c b/drivers/net/mdio_gpio.c
new file mode 100644
index 0000000000..a2a41f9519
--- /dev/null
+++ b/drivers/net/mdio_gpio.c
@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GPIO based MDIO bitbang driver.
+ *
+ * Copyright 2024 Markus Gothe <markus.gothe(a)genexis.eu>
+ *
+ * This file is based on the Linux kernel drivers
drivers/net/phy/mdio-gpio.c
+ * and drivers/net/phy/mdio-bitbang.c which have the following copyrights:
+ *
+ * Copyright (c) 2008 CSE Semaphore Belgium.
+ * by Laurent Pinchart <laurentp(a)cse-semaphore.com>
+ *
+ * Copyright (C) 2008, Paulius Zaleckas <paulius.zaleckas(a)teltonika.lt>
+ *
+ * Author: Scott Wood <scottwood(a)freescale.com>
+ * Copyright (c) 2007 Freescale Semiconductor
+ *
+ * Copyright (c) 2003 Intracom S.A.
+ * by Pantelis Antoniou <panto(a)intracom.gr>
+ *
+ * 2005 (c) MontaVista Software, Inc.
+ * Vitaly Bordug <vbordug(a)ru.mvista.com>
+ */
+
+#include <dm.h>
+#include <log.h>
+#include <miiphy.h>
+#include <asm/gpio.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/mdio.h>
+
+#define MDIO_READ 2
+#define MDIO_WRITE 1
+
+#define MDIO_C45 BIT(15)
+#define MDIO_C45_ADDR (MDIO_C45 | 0)
+#define MDIO_C45_READ (MDIO_C45 | 3)
+#define MDIO_C45_WRITE (MDIO_C45 | 1)
+
+/* 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
+
+#define MDIO_GPIO_MDC 0
+#define MDIO_GPIO_MDIO 1
+#define MDIO_GPIO_MDO 2
+
+struct mdio_gpio_priv {
+ struct gpio_desc mdc, mdio, mdo;
+};
+
+static void mdio_dir(struct udevice *mdio_dev, int dir)
+{
+ struct mdio_gpio_priv *priv = dev_get_priv(mdio_dev);
+
+ if (dm_gpio_is_valid(&priv->mdo)) {
+ /* Separate output pin. Always set its value to high
+ * when changing direction. If direction is input,
+ * assume the pin serves as pull-up. If direction is
+ * output, the default value is high.
+ */
+ dm_gpio_set_value(&priv->mdo, 1);
+ return;
+ }
+
+ if (dir)
+ dm_gpio_set_dir_flags(&priv->mdio, GPIOD_IS_OUT |
GPIOD_IS_OUT_ACTIVE);
+ else
+ dm_gpio_set_dir_flags(&priv->mdio, GPIOD_IS_IN);
+}
+
+static int mdio_get(struct udevice *mdio_dev)
+{
+ struct mdio_gpio_priv *priv = dev_get_priv(mdio_dev);
+
+ return dm_gpio_get_value(&priv->mdio);
+}
+
+static void mdio_set(struct udevice *mdio_dev, int what)
+{
+ struct mdio_gpio_priv *priv = dev_get_priv(mdio_dev);
+
+ if (dm_gpio_is_valid(&priv->mdo))
+ dm_gpio_set_value(&priv->mdo, what);
+ else
+ dm_gpio_set_value(&priv->mdio, what);
+}
+
+static void mdc_set(struct udevice *mdio_dev, int what)
+{
+ struct mdio_gpio_priv *priv = dev_get_priv(mdio_dev);
+
+ dm_gpio_set_value(&priv->mdc, what);
+}
+
+/* MDIO must already be configured as output. */
+static void mdio_gpio_send_bit(struct udevice *mdio_dev, int val)
+{
+ mdio_set(mdio_dev, val);
+ ndelay(MDIO_DELAY);
+ mdc_set(mdio_dev, 1);
+ ndelay(MDIO_DELAY);
+ mdc_set(mdio_dev, 0);
+}
+
+/* MDIO must already be configured as input. */
+static int mdio_gpio_get_bit(struct udevice *mdio_dev)
+{
+ ndelay(MDIO_DELAY);
+ mdc_set(mdio_dev, 1);
+ ndelay(MDIO_READ_DELAY);
+ mdc_set(mdio_dev, 0);
+
+ return mdio_get(mdio_dev);
+}
+
+/* MDIO must already be configured as output. */
+static void mdio_gpio_send_num(struct udevice *mdio_dev, u16 val, int bits)
+{
+ int i;
+
+ for (i = bits - 1; i >= 0; i--)
+ mdio_gpio_send_bit(mdio_dev, (val >> i) & 1);
+}
+
+/* MDIO must already be configured as input. */
+static u16 mdio_gpio_get_num(struct udevice *mdio_dev, int bits)
+{
+ int i;
+ u16 ret = 0;
+
+ for (i = bits - 1; i >= 0; i--) {
+ ret <<= 1;
+ ret |= mdio_gpio_get_bit(mdio_dev);
+ }
+
+ return ret;
+}
+
+/* Utility to send the preamble, address, and
+ * register (common to read and write).
+ */
+static void mdio_gpio_cmd(struct udevice *mdio_dev, int op, u8 phy, u8 reg)
+{
+ int i;
+
+ mdio_dir(mdio_dev, 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_gpio_send_bit(mdio_dev, 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.
+ */
+ mdio_gpio_send_bit(mdio_dev, 0);
+ if (op & MDIO_C45)
+ mdio_gpio_send_bit(mdio_dev, 0);
+ else
+ mdio_gpio_send_bit(mdio_dev, 1);
+ mdio_gpio_send_bit(mdio_dev, (op >> 1) & 1);
+ mdio_gpio_send_bit(mdio_dev, (op >> 0) & 1);
+
+ mdio_gpio_send_num(mdio_dev, phy, 5);
+ mdio_gpio_send_num(mdio_dev, 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 mdio_gpio_cmd_addr(struct udevice *mdio_dev, int phy, u32
dev_addr, u32 reg)
+{
+ mdio_gpio_cmd(mdio_dev, MDIO_C45_ADDR, phy, dev_addr);
+
+ /* send the turnaround (10) */
+ mdio_gpio_send_bit(mdio_dev, 1);
+ mdio_gpio_send_bit(mdio_dev, 0);
+
+ mdio_gpio_send_num(mdio_dev, reg, 16);
+
+ mdio_dir(mdio_dev, 0);
+ mdio_gpio_get_bit(mdio_dev);
+
+ return dev_addr;
+}
+
+static int mdio_gpio_read(struct udevice *mdio_dev, int addr, int
devad, int reg)
+{
+ int ret, i;
+
+ if (devad != MDIO_DEVAD_NONE) {
+ reg = mdio_gpio_cmd_addr(mdio_dev, addr, devad, reg);
+ mdio_gpio_cmd(mdio_dev, MDIO_C45_READ, addr, reg);
+ } else {
+ mdio_gpio_cmd(mdio_dev, MDIO_READ, addr, reg);
+ }
+
+ mdio_dir(mdio_dev, 0);
+
+ /* check the turnaround bit: the PHY should be driving it to zero.
+ */
+ if (mdio_gpio_get_bit(mdio_dev) != 0) {
+ /* PHY didn't drive TA low -- flush any bits it
+ * may be trying to send.
+ */
+ for (i = 0; i < 32; i++)
+ mdio_gpio_get_bit(mdio_dev);
+
+ return 0xffff;
+ }
+
+ ret = mdio_gpio_get_num(mdio_dev, 16);
+ mdio_gpio_get_bit(mdio_dev);
+
+ return ret;
+}
+
+static int mdio_gpio_write(struct udevice *mdio_dev, int addr, int
devad, int reg, u16 val)
+{
+ if (devad != MDIO_DEVAD_NONE) {
+ reg = mdio_gpio_cmd_addr(mdio_dev, addr, devad, reg);
+ mdio_gpio_cmd(mdio_dev, MDIO_C45_WRITE, addr, reg);
+ } else {
+ mdio_gpio_cmd(mdio_dev, MDIO_WRITE, addr, reg);
+ }
+
+ /* send the turnaround (10) */
+ mdio_gpio_send_bit(mdio_dev, 1);
+ mdio_gpio_send_bit(mdio_dev, 0);
+
+ mdio_gpio_send_num(mdio_dev, val, 16);
+
+ mdio_dir(mdio_dev, 0);
+ mdio_gpio_get_bit(mdio_dev);
+
+ return 0;
+}
+
+static const struct mdio_ops mdio_gpio_ops = {
+ .read = mdio_gpio_read,
+ .write = mdio_gpio_write,
+ .reset = NULL,
+};
+
+/*
+ * Name the device, we use the device tree node name.
+ * This can be overwritten by MDIO class code if device-name property is
+ * present.
+ */
+static int mdio_gpio_bind(struct udevice *mdio_dev)
+{
+ if (ofnode_valid(dev_ofnode(mdio_dev)))
+ device_set_name(mdio_dev, ofnode_get_name(dev_ofnode(mdio_dev)));
+
+ return 0;
+}
+
+static int mdio_gpio_probe(struct udevice *mdio_dev)
+{
+ struct mdio_gpio_priv *priv = dev_get_priv(mdio_dev);
+ int ret = 0;
+
+ ret = gpio_request_by_name(mdio_dev, "gpios", MDIO_GPIO_MDC,
&priv->mdc, GPIOD_IS_OUT);
+ if (ret)
+ return ret;
+
+ ret = gpio_request_by_name(mdio_dev, "gpios", MDIO_GPIO_MDIO,
&priv->mdio, GPIOD_IS_IN);
+ if (ret)
+ return ret;
+
+ ret = gpio_request_by_name(mdio_dev, "gpios", MDIO_GPIO_MDO,
&priv->mdo, GPIOD_IS_OUT);
+ if (ret && ret != -ENOENT)
+ return ret;
+
+ return 0;
+}
+
+static const struct udevice_id mdio_gpio_ids[] = {
+ { .compatible = "virtual,mdio-gpio" },
+ { /* sentinel */ }
+};
+
+U_BOOT_DRIVER(gpio_mdio) = {
+ .name = "gpio_mdio",
+ .id = UCLASS_MDIO,
+ .of_match = mdio_gpio_ids,
+ .bind = mdio_gpio_bind,
+ .probe = mdio_gpio_probe,
+ .ops = &mdio_gpio_ops,
+ .plat_auto = sizeof(struct mdio_perdev_priv),
+ .priv_auto = sizeof(struct mdio_gpio_priv),
+};
--
2.46.1
