s390/net: Remove LCS driver

JIRA: https://issues.redhat.com/browse/RHEL-73487

commit 6cccb3b
Author: Aswin Karuvally <aswin@linux.ibm.com>
Date:   Tue Feb 4 11:31:35 2025 +0100

    s390/net: Remove LCS driver

    The original Open Systems Adapter (OSA) was introduced by IBM in the
    mid-90s. These were then superseded by OSA-Express in 1999 which used
    Queued Direct IO to greatly improve throughput. The newer cards
    retained the older, slower non-QDIO (OSE) modes for compatibility with
    older systems. In Linux, the lcs driver was responsible for cards
    operating in the older OSE mode and the qeth driver was introduced to
    allow the OSA-Express cards to operate in the newer QDIO (OSD) mode.

    For an S390 machine from 1998 or later, there is no reason to use the
    OSE mode and lcs driver as all OSA cards since 1999 provide the faster
    OSD mode. As a result, it's been years since we have heard of a
    customer configuration involving the lcs driver.

    This patch removes the lcs driver. The technology it supports has been
    obsolete for past 25+ years and is irrelevant for current use cases.

    Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
    Acked-by: Heiko Carstens <hca@linux.ibm.com>
    Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
    Signed-off-by: Aswin Karuvally <aswin@linux.ibm.com>
    Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
    Reviewed-by: Simon Horman <horms@kernel.org>
    Link: https://patch.msgid.link/20250204103135.1619097-1-wintera@linux.ibm.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Mete Durlu <mdurlu@redhat.com>

Author: Mete Durlu

Documentation/arch/s390/driver-model.rst

@@ -244,7 +244,7 @@ information about the interrupt from the irb parameter.
 --------------------
 
 The ccwgroup mechanism is designed to handle devices consisting of multiple ccw
-devices, like lcs or ctc.
+devices, like qeth or ctc.
 
 The ccw driver provides a 'group' attribute. Piping bus ids of ccw devices to
 this attributes creates a ccwgroup device consisting of these ccw devices (if

arch/s390/include/asm/irq.h

@@ -54,7 +54,6 @@ enum interruption_class {
 	IRQIO_C70,
 	IRQIO_TAP,
 	IRQIO_VMR,
-	IRQIO_LCS,
 	IRQIO_CTC,
 	IRQIO_ADM,
 	IRQIO_CSC,

arch/s390/kernel/irq.c

@@ -84,7 +84,6 @@ static const struct irq_class irqclass_sub_desc[] = {
 	{.irq = IRQIO_C70,  .name = "C70", .desc = "[I/O] 3270"},
 	{.irq = IRQIO_TAP,  .name = "TAP", .desc = "[I/O] Tape"},
 	{.irq = IRQIO_VMR,  .name = "VMR", .desc = "[I/O] Unit Record Devices"},
-	{.irq = IRQIO_LCS,  .name = "LCS", .desc = "[I/O] LCS"},
 	{.irq = IRQIO_CTC,  .name = "CTC", .desc = "[I/O] CTC"},
 	{.irq = IRQIO_ADM,  .name = "ADM", .desc = "[I/O] EADM Subchannel"},
 	{.irq = IRQIO_CSC,  .name = "CSC", .desc = "[I/O] CHSC Subchannel"},

drivers/s390/net/Kconfig

@@ -2,15 +2,6 @@
 menu "S/390 network device drivers"
 	depends on NETDEVICES && S390
 
-config LCS
-	def_tristate m
-	prompt "Lan Channel Station Interface"
-	depends on CCW && NETDEVICES && ETHERNET
-	help
-	  Select this option if you want to use LCS networking on IBM System z.
-	  To compile as a module, choose M. The module name is lcs.
-	  If you do not use LCS, choose N.
-
 config CTCM
 	def_tristate m
 	prompt "CTC and MPC SNA device support"
@@ -98,7 +89,7 @@ config QETH_OSX
 
 config CCWGROUP
 	tristate
-	default (LCS || CTCM || QETH || SMC)
+	default (CTCM || QETH || SMC)
 
 config ISM
 	tristate "Support for ISM vPCI Adapter"

drivers/s390/net/Makefile

@@ -8,7 +8,6 @@ obj-$(CONFIG_CTCM) += ctcm.o fsm.o
 obj-$(CONFIG_NETIUCV) += netiucv.o fsm.o
 obj-$(CONFIG_SMSGIUCV) += smsgiucv.o
 obj-$(CONFIG_SMSGIUCV_EVENT) += smsgiucv_app.o
-obj-$(CONFIG_LCS) += lcs.o
 qeth-y += qeth_core_sys.o qeth_core_main.o qeth_core_mpc.o qeth_ethtool.o
 obj-$(CONFIG_QETH) += qeth.o
 qeth_l2-y += qeth_l2_main.o qeth_l2_sys.o