Add support for an MDIO bus multiplexer controlled by a regmap
device, like an FPGA.
Tested on a NXP LX2160AQDS board which uses the "QIXIS" FPGA
attached to the i2c bus.
Signed-off-by: Pankaj Bansal <pankaj.ban...@nxp.com>
---
drivers/net/phy/Makefile | 2 +-
drivers/net/phy/mdio-mux-regmap.c | 170 ++++++++++++++++++++++++++++
include/linux/mdio-mux.h | 20 ++++
3 files changed, 191 insertions(+), 1 deletion(-)
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index f41b14115fde..16145973a42f 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -25,7 +25,7 @@ obj-$(CONFIG_PHYLIB) += libphy.o
obj-$(CONFIG_MDIO_BCM_IPROC) += mdio-bcm-iproc.o
obj-$(CONFIG_MDIO_BCM_UNIMAC) += mdio-bcm-unimac.o
obj-$(CONFIG_MDIO_BITBANG) += mdio-bitbang.o
-obj-$(CONFIG_MDIO_BUS_MUX) += mdio-mux.o
+obj-$(CONFIG_MDIO_BUS_MUX) += mdio-mux.o mdio-mux-regmap.o
obj-$(CONFIG_MDIO_BUS_MUX_BCM_IPROC) += mdio-mux-bcm-iproc.o
obj-$(CONFIG_MDIO_BUS_MUX_GPIO) += mdio-mux-gpio.o
obj-$(CONFIG_MDIO_BUS_MUX_MMIOREG) += mdio-mux-mmioreg.o
diff --git a/drivers/net/phy/mdio-mux-regmap.c
b/drivers/net/phy/mdio-mux-regmap.c
new file mode 100644
index 000000000000..ca63a44da25f
--- /dev/null
+++ b/drivers/net/phy/mdio-mux-regmap.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/* Simple regmap based MDIO MUX driver
+ *
+ * Copyright 2018 NXP
+ *
+ * Based on mdio-mux-mmioreg.c by Timur Tabi
+ *
+ * Author:
+ * Pankaj Bansal <pankaj.ban...@nxp.com>
+ */
+
+#include <linux/platform_device.h>
+#include <linux/device.h>
+#include <linux/of_mdio.h>
+#include <linux/module.h>
+#include <linux/phy.h>
+#include <linux/mdio-mux.h>
+#include <linux/regmap.h>
+
+struct mdio_mux_regmap_state {
+ void *mux_handle;
+ struct device *dev;
+ struct regmap *regmap;
+ u32 mux_reg;
+ u32 mask;
+};
+
+/* MDIO multiplexing switch function
+ *
+ * This function is called by the mdio-mux layer when it thinks the mdio bus
+ * multiplexer needs to switch.
+ *
+ * 'current_child' is the current value of the mux register (masked via
+ * s->mask).
+ *
+ * 'desired_child' is the value of the 'reg' property of the target child MDIO
+ * node.
+ *
+ * The first time this function is called, current_child == -1.
+ *
+ * If current_child == desired_child, then the mux is already set to the
+ * correct bus.
+ */
+static int mdio_mux_regmap_switch_fn(int current_child, int desired_child,
+ void *data)
+{
+ struct mdio_mux_regmap_state *s = data;
+ bool change;
+ int ret;
+
+ ret = regmap_update_bits_check(s->regmap,
+ s->mux_reg,
+ s->mask,
+ desired_child,
+ &change);
+
+ if (ret)
+ return ret;
+ if (change)
+ dev_dbg(s->dev, "%s %d -> %d\n", __func__, current_child,
+ desired_child);
+ return ret;
+}
+
+/**
+ * mdio_mux_regmap_init - control MDIO bus muxing using regmap constructs.
+ * @dev: device with which regmap construct is associated.
+ * @mux_node: mdio bus mux node that contains parent mdio bus phandle.
+ * This node also contains sub nodes, where each subnode denotes
+ * a child mdio bus. All the child mdio buses are muxed, i.e. at a
+ * time only one of the child mdio buses can be used.
+ * @data: to store the address of data allocated by this function
+ */
+int mdio_mux_regmap_init(struct device *dev,
+ struct device_node *mux_node,
+ void **data)
+{
+ struct device_node *child;
+ struct mdio_mux_regmap_state *s;
+ int ret;
+ u32 val;
+
+ dev_dbg(dev, "probing node %pOF\n", mux_node);
+
+ s = devm_kzalloc(dev, sizeof(*s), GFP_KERNEL);
+ if (!s)
+ return -ENOMEM;
+
+ s->regmap = dev_get_regmap(dev, NULL);
+ if (IS_ERR(s->regmap)) {
+ dev_err(dev, "Failed to get parent regmap\n");
+ return PTR_ERR(s->regmap);
+ }
+
+ ret = of_property_read_u32(mux_node, "reg", &s->mux_reg);
+ if (ret) {
+ dev_err(dev, "missing or invalid reg property\n");
+ return -ENODEV;
+ }
+
+ /* Test Register read write */
+ ret = regmap_read(s->regmap, s->mux_reg, &val);
+ if (ret) {
+ dev_err(dev, "error while reading reg\n");
+ return ret;
+ }
+
+ ret = regmap_write(s->regmap, s->mux_reg, val);
+ if (ret) {
+ dev_err(dev, "error while writing reg\n");
+ return ret;
+ }
+
+ ret = of_property_read_u32(mux_node, "mux-mask", &s->mask);
+ if (ret) {
+ dev_err(dev, "missing or invalid mux-mask property\n");
+ return -ENODEV;
+ }
+
+ /* Verify that the 'reg' property of each child MDIO bus does not
+ * set any bits outside of the 'mask'.
+ */
+ for_each_available_child_of_node(mux_node, child) {
+ ret = of_property_read_u32(child, "reg", &val);
+ if (ret) {
+ dev_err(dev, "mdio-mux child node %pOF is missing a
'reg' property\n", child);
+ of_node_put(child);
+ return -ENODEV;
+ }
+ if (val & ~s->mask) {
+ dev_err(dev, "mdio-mux child node %pOF has a 'reg'
value with unmasked bits\n", child);
+ of_node_put(child);
+ return -ENODEV;
+ }
+ }
+
+ ret = mdio_mux_init(dev, mux_node, mdio_mux_regmap_switch_fn,
+ &s->mux_handle, s, NULL);
+ if (ret) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(dev, "failed to register mdio-mux bus %pOF\n",
mux_node);
+ return ret;
+ }
+
+ *data = s;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(mdio_mux_regmap_init);
+
+/**
+ * mdio_mux_regmap_uninit - relinquish the control of MDIO bus muxing using
+ * regmap constructs.
+ * @data: address of data allocated by mdio_mux_regmap_init
+ */
+int mdio_mux_regmap_uninit(void *data)
+{
+ struct mdio_mux_regmap_state *s = data;
+
+ mdio_mux_uninit(s->mux_handle);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(mdio_mux_regmap_uninit);
+
+MODULE_AUTHOR("Pankaj Bansal <pankaj.ban...@nxp.com>");
+MODULE_DESCRIPTION("regmap based MDIO MUX driver");
+MODULE_LICENSE("GPL v2");
+
diff --git a/include/linux/mdio-mux.h b/include/linux/mdio-mux.h
index a5d58f221939..231cfa3ba429 100644
--- a/include/linux/mdio-mux.h
+++ b/include/linux/mdio-mux.h
@@ -29,4 +29,24 @@ int mdio_mux_init(struct device *dev,
void mdio_mux_uninit(void *mux_handle);
+/**
+ * mdio_mux_regmap_init - control MDIO bus muxing using regmap constructs.
+ * @dev: device with which regmap construct is associated.
+ * @mux_node: mdio bus mux node that contains parent mdio bus phandle.
+ * This node also contains sub nodes, where each subnode denotes
+ * a child mdio bus. All the child mdio buses are muxed, i.e. at a
+ * time only one of the child mdio buses can be used.
+ * @data: to store the address of data allocated by this function
+ */
+int mdio_mux_regmap_init(struct device *dev,
+ struct device_node *mux_node,
+ void **data);
+
+/**
+ * mdio_mux_regmap_uninit - relinquish the control of MDIO bus muxing using
+ * regmap constructs.
+ * @data: address of data allocated by mdio_mux_regmap_init
+ */
+int mdio_mux_regmap_uninit(void *data);
+
#endif /* __LINUX_MDIO_MUX_H */
--
2.17.1
