net: mana: Add support for auxiliary device

In preparation for supporting MANA RDMA driver, add support for auxiliary
device in the Ethernet driver. The RDMA device is modeled as an auxiliary
device to the Ethernet device.

Reviewed-by: Dexuan Cui <[e-mail]>
Signed-off-by: Long Li <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Acked-by: Haiyang Zhang <[e-mail]>
Signed-off-by: Leon Romanovsky <[e-mail]>

drivers/net/ethernet/microsoft/Kconfig

···
 	tristate "Microsoft Azure Network Adapter (MANA) support"
 	depends on PCI_MSI && X86_64
 	depends on PCI_HYPERV
+	select AUXILIARY_BUS
 	help
 	  This driver supports Microsoft Azure Network Adapter (MANA).
 	  So far, the driver is only supported on X86_64.

drivers/net/ethernet/microsoft/mana/gdma.h

···
 
 	/* GDMA driver specific pointer */
 	void *driver_data;
+
+	struct auxiliary_device *adev;
 };
 
 #define MINIMUM_SUPPORTED_PAGE_SIZE PAGE_SIZE

drivers/net/ethernet/microsoft/mana/mana_auxiliary.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (c) 2022, Microsoft Corporation. */
+
+#include "mana.h"
+#include <linux/auxiliary_bus.h>
+
+struct mana_adev {
+	struct auxiliary_device adev;
+	struct gdma_dev *mdev;
+};

drivers/net/ethernet/microsoft/mana/mana_en.c

···
 #include <net/ip6_checksum.h>
 
 #include "mana.h"
+#include "mana_auxiliary.h"
+
+static DEFINE_IDA(mana_adev_ida);
+
+static int mana_adev_idx_alloc(void)
+{
+	return ida_alloc(&mana_adev_ida, GFP_KERNEL);
+}
+
+static void mana_adev_idx_free(int idx)
+{
+	ida_free(&mana_adev_ida, idx);
+}
 
 /* Microsoft Azure Network Adapter (MANA) functions */
 
···
 	return err;
 }
 
+static void adev_release(struct device *dev)
+{
+	struct mana_adev *madev = container_of(dev, struct mana_adev, adev.dev);
+
+	kfree(madev);
+}
+
+static void remove_adev(struct gdma_dev *gd)
+{
+	struct auxiliary_device *adev = gd->adev;
+	int id = adev->id;
+
+	auxiliary_device_delete(adev);
+	auxiliary_device_uninit(adev);
+
+	mana_adev_idx_free(id);
+	gd->adev = NULL;
+}
+
+static int add_adev(struct gdma_dev *gd)
+{
+	struct auxiliary_device *adev;
+	struct mana_adev *madev;
+	int ret;
+
+	madev = kzalloc(sizeof(*madev), GFP_KERNEL);
+	if (!madev)
+		return -ENOMEM;
+
+	adev = &madev->adev;
+	ret = mana_adev_idx_alloc();
+	if (ret < 0)
+		goto idx_fail;
+	adev->id = ret;
+
+	adev->name = "rdma";
+	adev->dev.parent = gd->gdma_context->dev;
+	adev->dev.release = adev_release;
+	madev->mdev = gd;
+
+	ret = auxiliary_device_init(adev);
+	if (ret)
+		goto init_fail;
+
+	ret = auxiliary_device_add(adev);
+	if (ret)
+		goto add_fail;
+
+	gd->adev = adev;
+	return 0;
+
+add_fail:
+	auxiliary_device_uninit(adev);
+
+init_fail:
+	mana_adev_idx_free(adev->id);
+
+idx_fail:
+	kfree(madev);
+
+	return ret;
+}
+
 int mana_probe(struct gdma_dev *gd, bool resuming)
 {
 	struct gdma_context *gc = gd->gdma_context;
···
 				break;
 		}
 	}
+
+	err = add_adev(gd);
 out:
 	if (err)
 		mana_remove(gd, false);
···
 	struct net_device *ndev;
 	int err;
 	int i;
+
+	/* adev currently doesn't support suspending, always remove it */
+	if (gd->adev)
+		remove_adev(gd);
 
 	for (i = 0; i < ac->num_ports; i++) {
 		ndev = ac->ports[i];
···
 	}
 
 	mana_destroy_eq(ac);
-
 out:
 	mana_gd_deregister_device(gd);