[PATCH v5 01/14] net: ionic: Create an auxiliary device for rdma driver

[Abhijit Gangurde <abhijit.gangurde@amd.com>]

To support RDMA capable ethernet device, create an auxiliary device in
the ionic Ethernet driver. The RDMA device is modeled as an auxiliary
device to the Ethernet device.

Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
---
v4->v5
  - Updated documentation
  - Fixed error path in aux device creation

 .../ethernet/pensando/ionic.rst               | 10 +++
 drivers/net/ethernet/pensando/Kconfig         |  1 +
 drivers/net/ethernet/pensando/ionic/Makefile  |  2 +-
 .../net/ethernet/pensando/ionic/ionic_api.h   | 21 +++++
 .../net/ethernet/pensando/ionic/ionic_aux.c   | 80 +++++++++++++++++++
 .../net/ethernet/pensando/ionic/ionic_aux.h   | 10 +++
 .../ethernet/pensando/ionic/ionic_bus_pci.c   |  5 ++
 .../net/ethernet/pensando/ionic/ionic_lif.c   |  7 ++
 .../net/ethernet/pensando/ionic/ionic_lif.h   |  3 +
 9 files changed, 138 insertions(+), 1 deletion(-)
 create mode 100644 drivers/net/ethernet/pensando/ionic/ionic_api.h
 create mode 100644 drivers/net/ethernet/pensando/ionic/ionic_aux.c
 create mode 100644 drivers/net/ethernet/pensando/ionic/ionic_aux.h

diff --git a/Documentation/networking/device_drivers/ethernet/pensando/ionic.rst b/Documentation/networking/device_drivers/ethernet/pensando/ionic.rst
index 05fe2b11bb18..d0005a7f04c7 100644
--- a/Documentation/networking/device_drivers/ethernet/pensando/ionic.rst
+++ b/Documentation/networking/device_drivers/ethernet/pensando/ionic.rst
@@ -13,6 +13,7 @@ Contents
 - Identifying the Adapter
 - Enabling the driver
 - Configuring the driver
+- RDMA Support via Auxiliary Device
 - Statistics
 - Support
 
@@ -105,6 +106,15 @@ XDP
 Support for XDP includes the basics, plus Jumbo frames, Redirect and
 ndo_xmit.  There is no current support for zero-copy sockets or HW offload.
 
+RDMA Support via Auxiliary Device
+=================================
+
+The ionic driver supports RDMA (Remote Direct Memory Access) functionality
+through the Linux auxiliary device framework when advertised by the firmware.
+RDMA capability is detected during device initialization, and if supported,
+the ethernet driver will create an auxiliary device that allows the rdma
+driver to bind and provide InfiniBand/RoCE functionality.
+
 Statistics
 ==========
 
diff --git a/drivers/net/ethernet/pensando/Kconfig b/drivers/net/ethernet/pensando/Kconfig
index 01fe76786f77..c99758adf3ad 100644
--- a/drivers/net/ethernet/pensando/Kconfig
+++ b/drivers/net/ethernet/pensando/Kconfig
@@ -24,6 +24,7 @@ config IONIC
 	select NET_DEVLINK
 	select DIMLIB
 	select PAGE_POOL
+	select AUXILIARY_BUS
 	help
 	  This enables the support for the Pensando family of Ethernet
 	  adapters.  More specific information on this driver can be
diff --git a/drivers/net/ethernet/pensando/ionic/Makefile b/drivers/net/ethernet/pensando/ionic/Makefile
index 4e7642a2d25f..a598972fef41 100644
--- a/drivers/net/ethernet/pensando/ionic/Makefile
+++ b/drivers/net/ethernet/pensando/ionic/Makefile
@@ -5,5 +5,5 @@ obj-$(CONFIG_IONIC) := ionic.o
 
 ionic-y := ionic_main.o ionic_bus_pci.o ionic_devlink.o ionic_dev.o \
 	   ionic_debugfs.o ionic_lif.o ionic_rx_filter.o ionic_ethtool.o \
-	   ionic_txrx.o ionic_stats.o ionic_fw.o
+	   ionic_txrx.o ionic_stats.o ionic_fw.o ionic_aux.o
 ionic-$(CONFIG_PTP_1588_CLOCK) += ionic_phc.o
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_api.h b/drivers/net/ethernet/pensando/ionic/ionic_api.h
new file mode 100644
index 000000000000..f9fcd1b67b35
--- /dev/null
+++ b/drivers/net/ethernet/pensando/ionic/ionic_api.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2018-2025, Advanced Micro Devices, Inc. */
+
+#ifndef _IONIC_API_H_
+#define _IONIC_API_H_
+
+#include <linux/auxiliary_bus.h>
+
+/**
+ * struct ionic_aux_dev - Auxiliary device information
+ * @lif:        Logical interface
+ * @idx:        Index identifier
+ * @adev:       Auxiliary device
+ */
+struct ionic_aux_dev {
+	struct ionic_lif *lif;
+	int idx;
+	struct auxiliary_device adev;
+};
+
+#endif /* _IONIC_API_H_ */
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_aux.c b/drivers/net/ethernet/pensando/ionic/ionic_aux.c
new file mode 100644
index 000000000000..f3c2a5227b36
--- /dev/null
+++ b/drivers/net/ethernet/pensando/ionic/ionic_aux.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2018-2025, Advanced Micro Devices, Inc. */
+
+#include <linux/kernel.h>
+#include "ionic.h"
+#include "ionic_lif.h"
+#include "ionic_aux.h"
+
+static DEFINE_IDA(aux_ida);
+
+static void ionic_auxbus_release(struct device *dev)
+{
+	struct ionic_aux_dev *ionic_adev;
+
+	ionic_adev = container_of(dev, struct ionic_aux_dev, adev.dev);
+	ida_free(&aux_ida, ionic_adev->adev.id);
+	kfree(ionic_adev);
+}
+
+int ionic_auxbus_register(struct ionic_lif *lif)
+{
+	struct ionic_aux_dev *ionic_adev;
+	struct auxiliary_device *aux_dev;
+	int err, id;
+
+	if (!(le64_to_cpu(lif->ionic->ident.lif.capabilities) & IONIC_LIF_CAP_RDMA))
+		return 0;
+
+	ionic_adev = kzalloc(sizeof(*ionic_adev), GFP_KERNEL);
+	if (!ionic_adev)
+		return -ENOMEM;
+
+	aux_dev = &ionic_adev->adev;
+
+	id = ida_alloc(&aux_ida, GFP_KERNEL);
+	if (id < 0) {
+		dev_err(lif->ionic->dev, "Failed to allocate aux id: %d\n", id);
+		kfree(ionic_adev);
+		return id;
+	}
+
+	aux_dev->id = id;
+	aux_dev->name = "rdma";
+	aux_dev->dev.parent = &lif->ionic->pdev->dev;
+	aux_dev->dev.release = ionic_auxbus_release;
+	ionic_adev->lif = lif;
+	err = auxiliary_device_init(aux_dev);
+	if (err) {
+		dev_err(lif->ionic->dev, "Failed to initialize %s aux device: %d\n",
+			aux_dev->name, err);
+		ida_free(&aux_ida, id);
+		kfree(ionic_adev);
+		return err;
+	}
+
+	err = auxiliary_device_add(aux_dev);
+	if (err) {
+		dev_err(lif->ionic->dev, "Failed to add %s aux device: %d\n",
+			aux_dev->name, err);
+		auxiliary_device_uninit(aux_dev);
+		return err;
+	}
+
+	lif->ionic_adev = ionic_adev;
+	return 0;
+}
+
+void ionic_auxbus_unregister(struct ionic_lif *lif)
+{
+	mutex_lock(&lif->adev_lock);
+	if (!lif->ionic_adev)
+		goto out;
+
+	auxiliary_device_delete(&lif->ionic_adev->adev);
+	auxiliary_device_uninit(&lif->ionic_adev->adev);
+
+	lif->ionic_adev = NULL;
+out:
+	mutex_unlock(&lif->adev_lock);
+}
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_aux.h b/drivers/net/ethernet/pensando/ionic/ionic_aux.h
new file mode 100644
index 000000000000..f5528a9f187d
--- /dev/null
+++ b/drivers/net/ethernet/pensando/ionic/ionic_aux.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2018-2025, Advanced Micro Devices, Inc. */
+
+#ifndef _IONIC_AUX_H_
+#define _IONIC_AUX_H_
+
+int ionic_auxbus_register(struct ionic_lif *lif);
+void ionic_auxbus_unregister(struct ionic_lif *lif);
+
+#endif /* _IONIC_AUX_H_ */
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_bus_pci.c b/drivers/net/ethernet/pensando/ionic/ionic_bus_pci.c
index 136bfa3516d0..f8752b1d2790 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_bus_pci.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_bus_pci.c
@@ -9,6 +9,7 @@
 #include "ionic.h"
 #include "ionic_bus.h"
 #include "ionic_lif.h"
+#include "ionic_aux.h"
 #include "ionic_debugfs.h"
 
 /* Supported devices */
@@ -375,6 +376,8 @@ static int ionic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto err_out_deregister_devlink;
 	}
 
+	ionic_auxbus_register(ionic->lif);
+
 	mod_timer(&ionic->watchdog_timer,
 		  round_jiffies(jiffies + ionic->watchdog_period));
 	ionic_queue_doorbell_check(ionic, IONIC_NAPI_DEADLINE);
@@ -416,6 +419,7 @@ static void ionic_remove(struct pci_dev *pdev)
 
 		if (ionic->lif->doorbell_wa)
 			cancel_delayed_work_sync(&ionic->doorbell_check_dwork);
+		ionic_auxbus_unregister(ionic->lif);
 		ionic_lif_unregister(ionic->lif);
 		ionic_devlink_unregister(ionic);
 		ionic_lif_deinit(ionic->lif);
@@ -445,6 +449,7 @@ static void ionic_reset_prepare(struct pci_dev *pdev)
 	timer_delete_sync(&ionic->watchdog_timer);
 	cancel_work_sync(&lif->deferred.work);
 
+	ionic_auxbus_unregister(ionic->lif);
 	mutex_lock(&lif->queue_lock);
 	ionic_stop_queues_reconfig(lif);
 	ionic_txrx_free(lif);
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.c b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
index 48cb5d30b5f6..8ed5d2e5fde4 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
@@ -19,6 +19,7 @@
 #include "ionic_bus.h"
 #include "ionic_dev.h"
 #include "ionic_lif.h"
+#include "ionic_aux.h"
 #include "ionic_txrx.h"
 #include "ionic_ethtool.h"
 #include "ionic_debugfs.h"
@@ -3293,6 +3294,7 @@ int ionic_lif_alloc(struct ionic *ionic)
 
 	mutex_init(&lif->queue_lock);
 	mutex_init(&lif->config_lock);
+	mutex_init(&lif->adev_lock);
 
 	spin_lock_init(&lif->adminq_lock);
 
@@ -3349,6 +3351,7 @@ int ionic_lif_alloc(struct ionic *ionic)
 	lif->info = NULL;
 	lif->info_pa = 0;
 err_out_free_mutex:
+	mutex_destroy(&lif->adev_lock);
 	mutex_destroy(&lif->config_lock);
 	mutex_destroy(&lif->queue_lock);
 err_out_free_netdev:
@@ -3384,6 +3387,7 @@ static void ionic_lif_handle_fw_down(struct ionic_lif *lif)
 
 	netif_device_detach(lif->netdev);
 
+	ionic_auxbus_unregister(ionic->lif);
 	mutex_lock(&lif->queue_lock);
 	if (test_bit(IONIC_LIF_F_UP, lif->state)) {
 		dev_info(ionic->dev, "Surprise FW stop, stopping queues\n");
@@ -3446,6 +3450,8 @@ int ionic_restart_lif(struct ionic_lif *lif)
 	netif_device_attach(lif->netdev);
 	ionic_queue_doorbell_check(ionic, IONIC_NAPI_DEADLINE);
 
+	ionic_auxbus_register(ionic->lif);
+
 	return 0;
 
 err_txrx_free:
@@ -3528,6 +3534,7 @@ void ionic_lif_free(struct ionic_lif *lif)
 
 	mutex_destroy(&lif->config_lock);
 	mutex_destroy(&lif->queue_lock);
+	mutex_destroy(&lif->adev_lock);
 
 	/* free netdev & lif */
 	ionic_debugfs_del_lif(lif);
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.h b/drivers/net/ethernet/pensando/ionic/ionic_lif.h
index e01756fb7fdd..43bdd0fb8733 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.h
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.h
@@ -10,6 +10,7 @@
 #include <linux/dim.h>
 #include <linux/pci.h>
 #include "ionic_rx_filter.h"
+#include "ionic_api.h"
 
 #define IONIC_ADMINQ_LENGTH	16	/* must be a power of two */
 #define IONIC_NOTIFYQ_LENGTH	64	/* must be a power of two */
@@ -225,6 +226,8 @@ struct ionic_lif {
 	dma_addr_t info_pa;
 	u32 info_sz;
 	struct ionic_qtype_info qtype_info[IONIC_QTYPE_MAX];
+	struct ionic_aux_dev *ionic_adev;
+	struct mutex adev_lock;	/* lock for aux_dev actions */
 
 	u8 rss_hash_key[IONIC_RSS_HASH_KEY_SIZE];
 	u8 *rss_ind_tbl;
-- 
2.43.0