staging: qlge: add documentation for debugging qlge

Instructions and examples on kernel data structures dumping and
coredump.

Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
Link: https://lore.kernel.org/r/20210123104613.38359-9-coiby.xu@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/networking/device_drivers/index.rst

@@ -15,6 +15,7 @@ Contents:
    ethernet/index
    fddi/index
    hamradio/index
+   qlogic/index
    wan/index
    wifi/index
 

Documentation/networking/device_drivers/qlogic/index.rst

@@ -0,0 +1,18 @@
+.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+
+QLogic QLGE Device Drivers
+===============================================
+
+Contents:
+
+.. toctree::
+   :maxdepth: 2
+
+   qlge
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`

Documentation/networking/device_drivers/qlogic/qlge.rst

@@ -0,0 +1,118 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================================
+QLogic QLGE 10Gb Ethernet device driver
+=======================================
+
+This driver use drgn and devlink for debugging.
+
+Dump kernel data structures in drgn
+-----------------------------------
+
+To dump kernel data structures, the following Python script can be used
+in drgn:
+
+.. code-block:: python
+
+	def align(x, a):
+	    """the alignment a should be a power of 2
+	    """
+	    mask = a - 1
+	    return (x+ mask) & ~mask
+
+	def struct_size(struct_type):
+	    struct_str = "struct {}".format(struct_type)
+	    return sizeof(Object(prog, struct_str, address=0x0))
+
+	def netdev_priv(netdevice):
+	    NETDEV_ALIGN = 32
+	    return netdevice.value_() + align(struct_size("net_device"), NETDEV_ALIGN)
+
+	name = 'xxx'
+	qlge_device = None
+	netdevices = prog['init_net'].dev_base_head.address_of_()
+	for netdevice in list_for_each_entry("struct net_device", netdevices, "dev_list"):
+	    if netdevice.name.string_().decode('ascii') == name:
+	        print(netdevice.name)
+
+	ql_adapter = Object(prog, "struct ql_adapter", address=netdev_priv(qlge_device))
+
+The struct ql_adapter will be printed in drgn as follows,
+
+    >>> ql_adapter
+    (struct ql_adapter){
+            .ricb = (struct ricb){
+                    .base_cq = (u8)0,
+                    .flags = (u8)120,
+                    .mask = (__le16)26637,
+                    .hash_cq_id = (u8 [1024]){ 172, 142, 255, 255 },
+                    .ipv6_hash_key = (__le32 [10]){},
+                    .ipv4_hash_key = (__le32 [4]){},
+            },
+            .flags = (unsigned long)0,
+            .wol = (u32)0,
+            .nic_stats = (struct nic_stats){
+                    .tx_pkts = (u64)0,
+                    .tx_bytes = (u64)0,
+                    .tx_mcast_pkts = (u64)0,
+                    .tx_bcast_pkts = (u64)0,
+                    .tx_ucast_pkts = (u64)0,
+                    .tx_ctl_pkts = (u64)0,
+                    .tx_pause_pkts = (u64)0,
+                    ...
+            },
+            .active_vlans = (unsigned long [64]){
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 52780853100545, 18446744073709551615,
+                    18446619461681283072, 0, 42949673024, 2147483647,
+            },
+            .rx_ring = (struct rx_ring [17]){
+                    {
+                            .cqicb = (struct cqicb){
+                                    .msix_vect = (u8)0,
+                                    .reserved1 = (u8)0,
+                                    .reserved2 = (u8)0,
+                                    .flags = (u8)0,
+                                    .len = (__le16)0,
+                                    .rid = (__le16)0,
+                                    ...
+                            },
+                            .cq_base = (void *)0x0,
+                            .cq_base_dma = (dma_addr_t)0,
+                    }
+                    ...
+            }
+    }
+
+coredump via devlink
+--------------------
+
+
+And the coredump obtained via devlink in json format looks like,
+
+.. code:: shell
+
+	$ devlink health dump show DEVICE reporter coredump -p -j
+	{
+	    "Core Registers": {
+	        "segment": 1,
+	        "values": [ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ]
+	    },
+	    "Test Logic Regs": {
+	        "segment": 2,
+	        "values": [ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ]
+	    },
+	    "RMII Registers": {
+	        "segment": 3,
+	        "values": [ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ]
+	    },
+	    ...
+	    "Sem Registers": {
+	        "segment": 50,
+	        "values": [ 0,0,0,0 ]
+	    }
+	}
+
+When the module parameter qlge_force_coredump is set to be true, the MPI
+RISC reset before coredumping. So coredumping will much longer since
+devlink tool has to wait for 5 secs for the resetting to be
+finished.

MAINTAINERS

@@ -14616,6 +14616,12 @@ L:	netdev@vger.kernel.org
 S:	Supported
 F:	drivers/staging/qlge/
 
+QLOGIC QLGE 10Gb ETHERNET DRIVER
+M:	Coiby Xu <coiby.xu@gmail.com>
+L:	netdev@vger.kernel.org
+S:	Maintained
+F:	Documentation/networking/device_drivers/qlogic/qlge.rst
+
 QM1D1B0004 MEDIA DRIVER
 M:	Akihiro Tsukada <tskd08@gmail.com>
 L:	linux-media@vger.kernel.org