Add a subdev driver to probe the subdev devices and create fake
netdevice for it.

Signed-off-by: Parav Pandit <redacted>
---
 drivers/net/ethernet/mellanox/mlx5/core/Makefile   |  2 +-
 drivers/net/ethernet/mellanox/mlx5/core/main.c     |  8 +-
 .../net/ethernet/mellanox/mlx5/core/mlx5_core.h    |  3 +
 .../ethernet/mellanox/mlx5/core/subdev_driver.c    | 93
++++++++++++++++++++++
 4 files changed, 104 insertions(+), 2 deletions(-)
 create mode 100644
drivers/net/ethernet/mellanox/mlx5/core/subdev_driver.c

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/Makefile

b/drivers/net/ethernet/mellanox/mlx5/core/Makefile
index f218789..c8aeaf1 100644

--- a/drivers/net/ethernet/mellanox/mlx5/core/Makefile
+++ b/drivers/net/ethernet/mellanox/mlx5/core/Makefile

@@ -16,7 +16,7 @@ mlx5_core-y :=	main.o cmd.o debugfs.o fw.o

eq.o uar.o pagealloc.o \
 		transobj.o vport.o sriov.o fs_cmd.o fs_core.o \
 		fs_counters.o rl.o lag.o dev.o events.o wq.o lib/gid.o
\
 		lib/devcom.o diag/fs_tracepoint.o diag/fw_tracer.o
-mlx5_core-$(CONFIG_SUBDEV) += subdev.o
+mlx5_core-$(CONFIG_SUBDEV) += subdev.o subdev_driver.o
 
 #
 # Netdev basic

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c

b/drivers/net/ethernet/mellanox/mlx5/core/main.c
index 5f8cf0d..7dfa8c4 100644

--- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c

@@ -1548,7 +1548,11 @@ static int __init init(void)
 	mlx5e_init();
 #endif
 
-	return 0;
+	err = subdev_register_driver(&mlx5_subdev_driver);
+	if (err)
+		pci_unregister_driver(&mlx5_core_driver);
+
+	return err;
 
 err_debug:
 	mlx5_unregister_debugfs();

@@ -1557,6 +1561,8 @@ static int __init init(void)
 
 static void __exit cleanup(void)
 {
+	subdev_unregister_driver(&mlx5_subdev_driver);
+
 #ifdef CONFIG_MLX5_CORE_EN
 	mlx5e_cleanup();
 #endif

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.h

b/drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.h
index 2a54148..1b733c7 100644

--- a/drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.h

@@ -41,12 +41,15 @@
 #include <linux/ptp_clock_kernel.h>
 #include <linux/mlx5/cq.h>
 #include <linux/mlx5/fs.h>
+#include <linux/subdev_bus.h>
 
 #define DRIVER_NAME "mlx5_core"
 #define DRIVER_VERSION "5.0-0"
 
 extern uint mlx5_core_debug_mask;
 
+extern struct subdev_driver mlx5_subdev_driver;
+
 #define mlx5_core_dbg(__dev, format, ...)				

\
 	dev_dbg(&(__dev)->pdev->dev, "%s:%d:(pid %d): " format,		
\
 		 __func__, __LINE__, current->pid,			
\

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/subdev_driver.c

b/drivers/net/ethernet/mellanox/mlx5/core/subdev_driver.c
new file mode 100644
index 0000000..880aa4f

--- /dev/null
+++ b/drivers/net/ethernet/mellanox/mlx5/core/subdev_driver.c

@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018-19 Mellanox Technologies
+
+#include <linux/module.h>
+#include <linux/dma-mapping.h>
+#include <linux/subdev_bus.h>
+#include <linux/subdev_ids.h>
+#include <linux/etherdevice.h>
+
+struct mlx5_subdev_ndev {
+	struct net_device ndev;
+};
+
+static void mlx5_dma_test(struct device *dev)
+{
+	dma_addr_t pa;
+	void *va;
+
+	va = dma_alloc_coherent(dev, 4096, &pa, GFP_KERNEL);
+	if (va)
+		dma_free_coherent(dev, 4096, va, pa);
+}
+
+static struct net_device *ndev;
+
+static int mlx5e_subdev_open(struct net_device *netdev)
+{
+	return 0;
+}
+
+static int mlx5e_subdev_close(struct net_device *netdev)
+{
+	return 0;
+}
+
+static netdev_tx_t
+mlx5e_subdev_xmit(struct sk_buff *skb, struct net_device *netdev)
+{
+	return NETDEV_TX_BUSY;
+}
+
+const struct net_device_ops mlx5e_subdev_netdev_ops = {
+	.ndo_open                = mlx5e_subdev_open,
+	.ndo_stop                = mlx5e_subdev_close,
+	.ndo_start_xmit          = mlx5e_subdev_xmit,
+};
+
+static int mlx5_subdev_probe(struct device *dev)
+{
+	int err;
+
+	mlx5_dma_test(dev);