[net-next RFC PATCH v5 04/10] net: pcs: implement Firmware node support for PCS driver

Christian Marangi
2026-05-05T18:27:34Z

Implement the foundation of Firmware node support for PCS driver.

To support this, implement a simple Provider API where a PCS driver can
expose multiple PCS with an xlate .get function.

PCS driver will have to call fwnode_pcs_add_provider() and pass the
firmware node pointer and a xlate function to return the correct PCS for
the passed #pcs-cells.

This will register the PCS in a global list of providers so that
consumer can access it.

The consumer will then use fwnode_pcs_get() to get the actual PCS by
passing the firmware node pointer and the index for #pcs-cells.

For a simple implementation where #pcs-cells is 0 and the PCS driver
expose a single PCS, the xlate function fwnode_pcs_simple_get() is
provided.

For an advanced implementation a custom xlate function is required.

One removal the PCS driver should first delete itself from the provider
list using fwnode_pcs_del_provider() and then call phylink_release_pcs()
on every PCS the driver provides.

A generic function fwnode_phylink_pcs_parse() is provided for MAC driver
that will declare PCS in DT (or ACPI).
This function will parse "pcs-handle" property and fill the passed array
with the parsed PCS in available_pcs up to the passed num_pcs value.
It's also possible to pass NULL as array to only parse the PCS and
update the num_pcs value with the count of scanned PCS.

Co-developed-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
drivers/net/pcs/Kconfig | 6 +
drivers/net/pcs/Makefile | 1 +
drivers/net/pcs/pcs.c | 201 +++++++++++++++++++++++++++++++
include/linux/pcs/pcs-provider.h | 41 +++++++
include/linux/pcs/pcs.h | 56 +++++++++
5 files changed, 305 insertions(+)
create mode 100644 drivers/net/pcs/pcs.c
create mode 100644 include/linux/pcs/pcs-provider.h
create mode 100644 include/linux/pcs/pcs.h

diff --git a/drivers/net/pcs/Kconfig b/drivers/net/pcs/Kconfig
index e417fd66f660..874de743b22c 100644
--- a/drivers/net/pcs/Kconfig
+++ b/drivers/net/pcs/Kconfig
@@ -5,6 +5,12 @@

menu "PCS device drivers"

+config FWNODE_PCS
+ tristate
+ depends on (ACPI || OF)
+ help
+ Firmware node PCS accessors
+
config PCS_XPCS
tristate "Synopsys DesignWare Ethernet XPCS"
select PHYLINK
diff --git a/drivers/net/pcs/Makefile b/drivers/net/pcs/Makefile
index 4f7920618b90..3005cdd89ab7 100644
--- a/drivers/net/pcs/Makefile
+++ b/drivers/net/pcs/Makefile
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
# Makefile for Linux PCS drivers

+obj-$(CONFIG_FWNODE_PCS) += pcs.o
pcs_xpcs-$(CONFIG_PCS_XPCS) := pcs-xpcs.o pcs-xpcs-plat.o \
pcs-xpcs-nxp.o pcs-xpcs-wx.o

diff --git a/drivers/net/pcs/pcs.c b/drivers/net/pcs/pcs.c
new file mode 100644
index 000000000000..72f56f55d198
--- /dev/null
+++ b/drivers/net/pcs/pcs.c
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/mutex.h>
+#include <linux/property.h>
+#include <linux/phylink.h>
+#include <linux/pcs/pcs.h>
+#include <linux/pcs/pcs-provider.h>
+
+MODULE_DESCRIPTION("PCS library");
+MODULE_AUTHOR("Christian Marangi <ansuelsmth@gmail.com>");
+MODULE_LICENSE("GPL");
+
+struct fwnode_pcs_provider {
+ struct list_head link;
+
+ struct fwnode_handle *fwnode;
+ struct phylink_pcs *(*get)(struct fwnode_reference_args *pcsspec,
+ void *data);
+
+ void *data;
+};
+
+static LIST_HEAD(fwnode_pcs_providers);
+static DEFINE_MUTEX(fwnode_pcs_mutex);
+
+struct phylink_pcs *fwnode_pcs_simple_get(struct fwnode_reference_args *pcsspec,
+ void *data)
+{
+ return data;
+}
+EXPORT_SYMBOL_GPL(fwnode_pcs_simple_get);
+
+int fwnode_pcs_add_provider(struct fwnode_handle *fwnode,
+ struct phylink_pcs *(*get)(struct fwnode_reference_args *pcsspec,
+ void *data),
+ void *data)
+{
+ struct fwnode_pcs_provider *pp;
+
+ if (!fwnode)
+ return 0;
+
+ pp = kzalloc_obj(*pp);
+ if (!pp)
+ return -ENOMEM;
+
+ pp->fwnode = fwnode_handle_get(fwnode);
+ pp->data = data;
+ pp->get = get;
+
+ mutex_lock(&fwnode_pcs_mutex);
+ list_add(&pp->link, &fwnode_pcs_providers);
+ mutex_unlock(&fwnode_pcs_mutex);
+ pr_debug("Added pcs provider from %pfwf\n", fwnode);
+
+ fwnode_dev_initialized(fwnode, true);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(fwnode_pcs_add_provider);
+
+void fwnode_pcs_del_provider(struct fwnode_handle *fwnode)
+{
+ struct fwnode_pcs_provider *pp;
+
+ if (!fwnode)
+ return;
+
+ mutex_lock(&fwnode_pcs_mutex);
+ list_for_each_entry(pp, &fwnode_pcs_providers, link) {
+ if (pp->fwnode == fwnode) {
+ list_del(&pp->link);
+ fwnode_dev_initialized(pp->fwnode, false);
+ fwnode_handle_put(pp->fwnode);
+ kfree(pp);
+ break;
+ }
+ }
+ mutex_unlock(&fwnode_pcs_mutex);
+}
+EXPORT_SYMBOL_GPL(fwnode_pcs_del_provider);
+
+static int fwnode_parse_pcsspec(const struct fwnode_handle *fwnode, int index,
+ const char *name,
+ struct fwnode_reference_args *out_args)
+{
+ int ret;
+
+ if (!fwnode)
+ return -ENOENT;
+
+ if (name)
+ index = fwnode_property_match_string(fwnode, "pcs-names",
+ name);
+
+ ret = fwnode_property_get_reference_args(fwnode, "pcs-handle",
+ "#pcs-cells",
+ -1, index, out_args);
+ if (ret || (name && index < 0))
+ return ret;
+
+ return 0;
+}
+
+static struct phylink_pcs *
+fwnode_pcs_get_from_pcsspec(struct fwnode_reference_args *pcsspec)
+{
+ struct fwnode_pcs_provider *provider;
+ struct phylink_pcs *pcs = ERR_PTR(-ENODEV);
+
+ if (!pcsspec)
+ return ERR_PTR(-EINVAL);
+
+ mutex_lock(&fwnode_pcs_mutex);
+ list_for_each_entry(provider, &fwnode_pcs_providers, link) {
+ if (provider->fwnode == pcsspec->fwnode) {
+ pcs = provider->get(pcsspec, provider->data);
+ if (!IS_ERR(pcs))
+ break;
+ }
+ }
+ mutex_unlock(&fwnode_pcs_mutex);
+
+ return pcs;
+}
+
+static struct phylink_pcs *__fwnode_pcs_get(struct fwnode_handle *fwnode,
+ int index, const char *con_id)
+{
+ struct fwnode_reference_args pcsspec;
+ struct phylink_pcs *pcs;
+ int ret;
+
+ ret = fwnode_parse_pcsspec(fwnode, index, con_id, &pcsspec);
+ if (ret)
+ return ERR_PTR(ret);
+
+ pcs = fwnode_pcs_get_from_pcsspec(&pcsspec);
+ fwnode_handle_put(pcsspec.fwnode);
+
+ return pcs;
+}
+
+struct phylink_pcs *fwnode_pcs_get(struct fwnode_handle *fwnode, int index)
+{
+ return __fwnode_pcs_get(fwnode, index, NULL);
+}
+EXPORT_SYMBOL_GPL(fwnode_pcs_get);
+
+static int fwnode_phylink_pcs_count(struct fwnode_handle *fwnode,
+ unsigned int *num_pcs)
+{
+ struct fwnode_reference_args out_args;
+ int index = 0;
+ int ret;
+
+ while (true) {
+ ret = fwnode_property_get_reference_args(fwnode, "pcs-handle",
+ "#pcs-cells",
+ -1, index, &out_args);
+ /* We expect to reach an -ENOENT error while counting */
+ if (ret)
+ break;
+
+ fwnode_handle_put(out_args.fwnode);
+ index++;
+ }
+
+ /* Update num_pcs with parsed PCS */
+ *num_pcs = index;
+
+ /* Return error if we didn't found any PCS */
+ return index > 0 ? 0 : -ENOENT;
+}
+
+int fwnode_phylink_pcs_parse(struct fwnode_handle *fwnode,
+ struct phylink_pcs **available_pcs,
+ unsigned int *num_pcs)
+{
+ int i;
+
+ if (!fwnode_property_present(fwnode, "pcs-handle"))
+ return -ENODEV;
+
+ /* With available_pcs NULL, only count the PCS */
+ if (!available_pcs)
+ return fwnode_phylink_pcs_count(fwnode, num_pcs);
+
+ for (i = 0; i < *num_pcs; i++) {
+ struct phylink_pcs *pcs;
+
+ pcs = fwnode_pcs_get(fwnode, i);
+ if (IS_ERR(pcs))
+ return PTR_ERR(pcs);
+
+ available_pcs[i] = pcs;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(fwnode_phylink_pcs_parse);
diff --git a/include/linux/pcs/pcs-provider.h b/include/linux/pcs/pcs-provider.h
new file mode 100644
index 000000000000..ae51c108147e
--- /dev/null
+++ b/include/linux/pcs/pcs-provider.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __LINUX_PCS_PROVIDER_H
+#define __LINUX_PCS_PROVIDER_H
+
+/**
+ * fwnode_pcs_simple_get - Simple xlate function to retrieve PCS
+ * @pcsspec: reference arguments
+ * @data: Context data (assumed assigned to the single PCS)
+ *
+ * Returns: the PCS pointed by data.
+ */
+struct phylink_pcs *fwnode_pcs_simple_get(struct fwnode_reference_args *pcsspec,
+ void *data);
+
+/**
+ * fwnode_pcs_add_provider - Registers a new PCS provider
+ * @fwnode: Firmware node
+ * @get: xlate function to retrieve the PCS
+ * @data: Context data
+ *
+ * Register and add a new PCS to the global providers list
+ * for the firmware node. A function to get the PCS from
+ * firmware node with the use fwnode reference arguments.
+ * To the get function is also passed the interface type
+ * requested for the PHY. PCS driver will use the passed
+ * interface to understand if the PCS can support it or not.
+ *
+ * Returns: 0 on success or -ENOMEM on allocation failure.
+ */
+int fwnode_pcs_add_provider(struct fwnode_handle *fwnode,
+ struct phylink_pcs *(*get)(struct fwnode_reference_args *pcsspec,
+ void *data),
+ void *data);
+
+/**
+ * fwnode_pcs_del_provider - Removes a PCS provider
+ * @fwnode: Firmware node
+ */
+void fwnode_pcs_del_provider(struct fwnode_handle *fwnode);
+
+#endif /* __LINUX_PCS_PROVIDER_H */
diff --git a/include/linux/pcs/pcs.h b/include/linux/pcs/pcs.h
new file mode 100644
index 000000000000..33244e3a442b
--- /dev/null
+++ b/include/linux/pcs/pcs.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __LINUX_PCS_H
+#define __LINUX_PCS_H
+
+#include <linux/phylink.h>
+
+#if IS_ENABLED(CONFIG_FWNODE_PCS)
+/**
+ * fwnode_pcs_get - Retrieves a PCS from a firmware node
+ * @fwnode: firmware node
+ * @index: index fwnode PCS handle in firmware node
+ *
+ * Get a PCS from the firmware node at index.
+ *
+ * Returns: a pointer to the phylink_pcs or a negative
+ * error pointer. Can return -EPROBE_DEFER if the PCS is not
+ * present in global providers list (either due to driver
+ * still needs to be probed or it failed to probe/removed)
+ */
+struct phylink_pcs *fwnode_pcs_get(struct fwnode_handle *fwnode,
+ int index);
+
+/**
+ * fwnode_phylink_pcs_parse - generic PCS parse for fwnode PCS provider
+ * @fwnode: firmware node
+ * @available_pcs: pointer to preallocated array of PCS
+ * @num_pcs: where to store count of parsed PCS
+ *
+ * Generic helper function to fill available_pcs array with PCS parsed
+ * from a "pcs-handle" fwnode property defined in firmware node up to
+ * passed num_pcs.
+ *
+ * If available_pcs is NULL, num_pcs is updated with the count of the
+ * parsed PCS.
+ *
+ * Returns: 0 or a negative error.
+ */
+int fwnode_phylink_pcs_parse(struct fwnode_handle *fwnode,
+ struct phylink_pcs **available_pcs,
+ unsigned int *num_pcs);
+#else
+static inline struct phylink_pcs *fwnode_pcs_get(struct fwnode_handle *fwnode,
+ int index)
+{
+ return ERR_PTR(-ENOENT);
+}
+
+static inline int fwnode_phylink_pcs_parse(struct fwnode_handle *fwnode,
+ struct phylink_pcs **available_pcs,
+ unsigned int *num_pcs)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+
+#endif /* __LINUX_PCS_H */
--
2.53.0