[U-Boot] [PATCH v2 1/2] drivers: net: driver for MDIO muxes controlled over I2C

[Alex Marginean]

This driver is used for MDIO muxes driven over I2C.  This is currently
used on Freescale LS1028A QDS board, on which the physical MDIO MUX is
controlled by an on-board FPGA which in turn is configured through I2C.

Signed-off-by: Alex Marginean <alexm.osslist at gmail.com>
Acked-by: Joe Hershberger <joe.hershberger at ni.com>
---

Changes in v2:
	- renamed APIs, config options to mdio_mux_i2creg (instead of i2c_reg)

 drivers/net/Kconfig           |   8 +++
 drivers/net/Makefile          |   1 +
 drivers/net/mdio_mux_i2creg.c | 108 ++++++++++++++++++++++++++++++++++
 3 files changed, 117 insertions(+)
 create mode 100644 drivers/net/mdio_mux_i2creg.c

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 4d85fb1716..883b849b78 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -595,4 +595,12 @@ config FSL_ENETC
 	  This driver supports the NXP ENETC Ethernet controller found on some
 	  of the NXP SoCs.
 
+config MDIO_MUX_I2CREG
+	bool "MDIO MUX accessed as a register over I2C"
+	depends on DM_MDIO_MUX && DM_I2C
+	help
+	  This driver is used for MDIO muxes driven by writing to a register of
+	  an I2C chip.  The board it was developed for uses a mux controlled by
+	  on-board FPGA which in turn is accessed as a chip over I2C.
+
 endif # NETDEVICES
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 97119cec7c..6122bcdb81 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -80,3 +80,4 @@ obj-$(CONFIG_HIGMACV300_ETH) += higmacv300.o
 obj-$(CONFIG_MDIO_SANDBOX) += mdio_sandbox.o
 obj-$(CONFIG_FSL_ENETC) += fsl_enetc.o fsl_enetc_mdio.o
 obj-$(CONFIG_MDIO_MUX_SANDBOX) += mdio_mux_sandbox.o
+obj-$(CONFIG_MDIO_MUX_I2CREG) += mdio_mux_i2creg.o
diff --git a/drivers/net/mdio_mux_i2creg.c b/drivers/net/mdio_mux_i2creg.c
new file mode 100644
index 0000000000..3e82898f46
--- /dev/null
+++ b/drivers/net/mdio_mux_i2creg.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2019
+ * Alex Marginean, NXP
+ */
+
+#include <dm.h>
+#include <errno.h>
+#include <miiphy.h>
+#include <i2c.h>
+
+/*
+ * This driver is used for MDIO muxes driven by writing to a register of an I2C
+ * chip.  The board it was developed for uses a mux controlled by on-board FPGA
+ * which in turn is accessed as a chip over I2C.
+ */
+
+struct mdio_mux_i2creg_priv {
+	struct udevice *chip;
+	int reg;
+	int mask;
+};
+
+static int mdio_mux_i2creg_select(struct udevice *mux, int cur, int sel)
+{
+	struct mdio_mux_i2creg_priv *priv = dev_get_priv(mux);
+	u8 val, val_old;
+
+	/* if last selection didn't change we're good to go */
+	if (cur == sel)
+		return 0;
+
+	val_old = dm_i2c_reg_read(priv->chip, priv->reg);
+	val = (val_old & ~priv->mask) | (sel & priv->mask);
+	debug("%s: chip %s, reg %x, val %x => %x\n", __func__, priv->chip->name,
+	      priv->reg, val_old, val);
+	dm_i2c_reg_write(priv->chip, priv->reg, val);
+
+	return 0;
+}
+
+static const struct mdio_mux_ops mdio_mux_i2creg_ops = {
+	.select = mdio_mux_i2creg_select,
+};
+
+static int mdio_mux_i2creg_probe(struct udevice *dev)
+{
+	struct mdio_mux_i2creg_priv *priv = dev_get_priv(dev);
+	ofnode chip_node, bus_node;
+	struct udevice *i2c_bus;
+	u32 reg_mask[2];
+	u32 chip_addr;
+	int err;
+
+	/* read the register addr/mask pair */
+	err = dev_read_u32_array(dev, "mux-reg-masks", reg_mask, 2);
+	if (err) {
+		debug("%s: error reading mux-reg-masks property\n", __func__);
+		return err;
+	}
+
+	/* parent should be an I2C chip, grandparent should be an I2C bus */
+	chip_node = ofnode_get_parent(dev->node);
+	bus_node = ofnode_get_parent(chip_node);
+
+	err = uclass_get_device_by_ofnode(UCLASS_I2C, bus_node, &i2c_bus);
+	if (err) {
+		debug("%s: can't find I2C bus for node %s\n", __func__,
+		      ofnode_get_name(bus_node));
+		return err;
+	}
+
+	err = ofnode_read_u32(chip_node, "reg", &chip_addr);
+	if (err) {
+		debug("%s: can't read chip address in %s\n", __func__,
+		      ofnode_get_name(chip_node));
+		return err;
+	}
+
+	err = i2c_get_chip(i2c_bus, (uint)chip_addr, 1, &priv->chip);
+	if (err) {
+		debug("%s: can't find i2c chip device for addr %x\n", __func__,
+		      chip_addr);
+		return err;
+	}
+
+	priv->reg = (int)reg_mask[0];
+	priv->mask = (int)reg_mask[1];
+
+	debug("%s: chip %s, reg %x, mask %x\n", __func__, priv->chip->name,
+	      priv->reg, priv->mask);
+
+	return 0;
+}
+
+static const struct udevice_id mdio_mux_i2creg_ids[] = {
+	{ .compatible = "mdio-mux-i2creg" },
+	{ }
+};
+
+U_BOOT_DRIVER(mdio_mux_i2creg) = {
+	.name		= "mdio_mux_i2creg",
+	.id		= UCLASS_MDIO_MUX,
+	.of_match	= mdio_mux_i2creg_ids,
+	.probe		= mdio_mux_i2creg_probe,
+	.ops		= &mdio_mux_i2creg_ops,
+	.priv_auto_alloc_size = sizeof(struct mdio_mux_i2creg_priv),
+};
-- 
2.17.1