ethernet: fix PTP_1588_CLOCK dependencies

The 'imply' keyword does not do what most people think it does, it only
politely asks Kconfig to turn on another symbol, but does not prevent
it from being disabled manually or built as a loadable module when the
user is built-in. In the ICE driver, the latter now causes a link failure:

aarch64-linux-ld: drivers/net/ethernet/intel/ice/ice_main.o: in function `ice_eth_ioctl':
ice_main.c:(.text+0x13b0): undefined reference to `ice_ptp_get_ts_config'
ice_main.c:(.text+0x13b0): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ice_ptp_get_ts_config'
aarch64-linux-ld: ice_main.c:(.text+0x13bc): undefined reference to `ice_ptp_set_ts_config'
ice_main.c:(.text+0x13bc): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ice_ptp_set_ts_config'
aarch64-linux-ld: drivers/net/ethernet/intel/ice/ice_main.o: in function `ice_prepare_for_reset':
ice_main.c:(.text+0x31fc): undefined reference to `ice_ptp_release'
ice_main.c:(.text+0x31fc): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ice_ptp_release'
aarch64-linux-ld: drivers/net/ethernet/intel/ice/ice_main.o: in function `ice_rebuild':

This is a recurring problem in many drivers, and we have discussed
it several times befores, without reaching a consensus. I'm providing
a link to the previous email thread for reference, which discusses
some related problems.

To solve the dependency issue better than the 'imply' keyword, introduce a
separate Kconfig symbol "CONFIG_PTP_1588_CLOCK_OPTIONAL" that any driver
can depend on if it is able to use PTP support when available, but works
fine without it. Whenever CONFIG_PTP_1588_CLOCK=m, those drivers are
then prevented from being built-in, the same way as with a 'depends on
PTP_1588_CLOCK || !PTP_1588_CLOCK' dependency that does the same trick,
but that can be rather confusing when you first see it.

Since this should cover the dependencies correctly, the IS_REACHABLE()
hack in the header is no longer needed now, and can be turned back
into a normal IS_ENABLED() check. Any driver that gets the dependency
wrong will now cause a link time failure rather than being unable to use
PTP support when that is in a loadable module.

However, the two recently added ptp_get_vclocks_index() and
ptp_convert_timestamp() interfaces are only called from builtin code with
ethtool and socket timestamps, so keep the current behavior by stubbing
those out completely when PTP is in a loadable module. This should be
addressed properly in a follow-up.

As Richard suggested, we may want to actually turn PTP support into a
'bool' option later on, preventing it from being a loadable module
altogether, which would be one way to solve the problem with the ethtool
interface.

Fixes: 06c16d89 ("ice: register 1588 PTP clock device object for E810 devices")
Link: https://lore.kernel.org/netdev/20210804121318.337276-1-arnd@kernel.org/
Link: https://lore.kernel.org/netdev/CAK8P3a06enZOf=XyZ+zcAwBczv41UuCTz+=0FMf2gBz1_cOnZQ@mail.gmail.com/
Link: https://lore.kernel.org/netdev/CAK8P3a3=eOxE-K25754+fB_-i_0BZzf9a9RfPTX3ppSwu9WZXw@mail.gmail.com/
Link: https://lore.kernel.org/netdev/20210726084540.3282344-1-arnd@kernel.org/


Acked-by: Shannon Nelson <snelson@pensando.io>
Acked-by: Jacob Keller <jacob.e.keller@intel.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210812183509.1362782-1-arnd@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/mv88e6xxx/Kconfig

@@ -2,6 +2,7 @@
 config NET_DSA_MV88E6XXX
 	tristate "Marvell 88E6xxx Ethernet switch fabric support"
 	depends on NET_DSA
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select IRQ_DOMAIN
 	select NET_DSA_TAG_EDSA
 	select NET_DSA_TAG_DSA

drivers/net/dsa/ocelot/Kconfig

@@ -5,6 +5,7 @@ config NET_DSA_MSCC_FELIX
 	depends on NET_VENDOR_MICROSEMI
 	depends on NET_VENDOR_FREESCALE
 	depends on HAS_IOMEM
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select MSCC_OCELOT_SWITCH_LIB
 	select NET_DSA_TAG_OCELOT_8021Q
 	select NET_DSA_TAG_OCELOT
@@ -19,6 +20,7 @@ config NET_DSA_MSCC_SEVILLE
 	depends on NET_DSA
 	depends on NET_VENDOR_MICROSEMI
 	depends on HAS_IOMEM
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select MSCC_OCELOT_SWITCH_LIB
 	select NET_DSA_TAG_OCELOT_8021Q
 	select NET_DSA_TAG_OCELOT

drivers/net/dsa/sja1105/Kconfig

@@ -2,6 +2,7 @@
 config NET_DSA_SJA1105
 tristate "NXP SJA1105 Ethernet switch family support"
 	depends on NET_DSA && SPI
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select NET_DSA_TAG_SJA1105
 	select PCS_XPCS
 	select PACKING

drivers/net/ethernet/amd/Kconfig

@@ -170,11 +170,11 @@ config AMD_XGBE
 	tristate "AMD 10GbE Ethernet driver"
 	depends on ((OF_NET && OF_ADDRESS) || ACPI || PCI) && HAS_IOMEM
 	depends on X86 || ARM64 || COMPILE_TEST
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select BITREVERSE
 	select CRC32
 	select PHYLIB
 	select AMD_XGBE_HAVE_ECC if X86
-	imply PTP_1588_CLOCK
 	help
 	  This driver supports the AMD 10GbE Ethernet device found on an
 	  AMD SoC.

drivers/net/ethernet/broadcom/Kconfig

@@ -122,8 +122,8 @@ config SB1250_MAC
 config TIGON3
 	tristate "Broadcom Tigon3 support"
 	depends on PCI
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select PHYLIB
-	imply PTP_1588_CLOCK
 	help
 	  This driver supports Broadcom Tigon3 based gigabit Ethernet cards.
 
@@ -140,7 +140,7 @@ config TIGON3_HWMON
 config BNX2X
 	tristate "Broadcom NetXtremeII 10Gb support"
 	depends on PCI
-	imply PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select FW_LOADER
 	select ZLIB_INFLATE
 	select LIBCRC32C
@@ -206,7 +206,7 @@ config SYSTEMPORT
 config BNXT
 	tristate "Broadcom NetXtreme-C/E support"
 	depends on PCI
-	imply PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select FW_LOADER
 	select LIBCRC32C
 	select NET_DEVLINK

drivers/net/ethernet/cadence/Kconfig

@@ -22,6 +22,7 @@ if NET_VENDOR_CADENCE
 config MACB
 	tristate "Cadence MACB/GEM support"
 	depends on HAS_DMA && COMMON_CLK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select PHYLINK
 	select CRC32
 	help

drivers/net/ethernet/cavium/Kconfig

@@ -66,7 +66,7 @@ config LIQUIDIO
 	tristate "Cavium LiquidIO support"
 	depends on 64BIT && PCI
 	depends on PCI
-	imply PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select FW_LOADER
 	select LIBCRC32C
 	select NET_DEVLINK
@@ -91,7 +91,7 @@ config OCTEON_MGMT_ETHERNET
 config LIQUIDIO_VF
 	tristate "Cavium LiquidIO VF support"
 	depends on 64BIT && PCI_MSI
-	imply PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	help
 	  This driver supports Cavium LiquidIO Intelligent Server Adapter
 	  based on CN23XX chips.

drivers/net/ethernet/chelsio/Kconfig

@@ -69,6 +69,7 @@ config CHELSIO_T3
 config CHELSIO_T4
 	tristate "Chelsio Communications T4/T5/T6 Ethernet support"
 	depends on PCI && (IPV6 || IPV6=n) && (TLS || TLS=n)
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select FW_LOADER
 	select MDIO
 	select ZLIB_DEFLATE

drivers/net/ethernet/freescale/Kconfig

@@ -25,10 +25,10 @@ config FEC
 	depends on (M523x || M527x || M5272 || M528x || M520x || M532x || \
 		   ARCH_MXC || SOC_IMX28 || COMPILE_TEST)
 	default ARCH_MXC || SOC_IMX28 if ARM
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select CRC32
 	select PHYLIB
 	imply NET_SELFTESTS
-	imply PTP_1588_CLOCK
 	help
 	  Say Y here if you want to use the built-in 10/100 Fast ethernet
 	  controller on some Motorola ColdFire and Freescale i.MX processors.

drivers/net/ethernet/hisilicon/Kconfig

@@ -104,7 +104,7 @@ config HNS3_HCLGE
 	tristate "Hisilicon HNS3 HCLGE Acceleration Engine & Compatibility Layer Support"
 	default m
 	depends on PCI_MSI
-	imply PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	help
 	  This selects the HNS3_HCLGE network acceleration engine & its hardware
 	  compatibility layer. The engine would be used in Hisilicon hip08 family of

drivers/net/ethernet/intel/Kconfig

@@ -58,8 +58,8 @@ config E1000
 config E1000E
 	tristate "Intel(R) PRO/1000 PCI-Express Gigabit Ethernet support"
 	depends on PCI && (!SPARC32 || BROKEN)
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select CRC32
-	imply PTP_1588_CLOCK
 	help
 	  This driver supports the PCI-Express Intel(R) PRO/1000 gigabit
 	  ethernet family of adapters. For PCI or PCI-X e1000 adapters,
@@ -87,7 +87,7 @@ config E1000E_HWTS
 config IGB
 	tristate "Intel(R) 82575/82576 PCI-Express Gigabit Ethernet support"
 	depends on PCI
-	imply PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select I2C
 	select I2C_ALGOBIT
 	help
@@ -159,9 +159,9 @@ config IXGB
 config IXGBE
 	tristate "Intel(R) 10GbE PCI Express adapters support"
 	depends on PCI
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select MDIO
 	select PHYLIB
-	imply PTP_1588_CLOCK
 	help
 	  This driver supports Intel(R) 10GbE PCI Express family of
 	  adapters.  For more information on how to identify your adapter, go
@@ -239,7 +239,7 @@ config IXGBEVF_IPSEC
 
 config I40E
 	tristate "Intel(R) Ethernet Controller XL710 Family support"
-	imply PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	depends on PCI
 	select AUXILIARY_BUS
 	help
@@ -295,11 +295,11 @@ config ICE
 	tristate "Intel(R) Ethernet Connection E800 Series Support"
 	default n
 	depends on PCI_MSI
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select AUXILIARY_BUS
 	select DIMLIB
 	select NET_DEVLINK
 	select PLDMFW
-	imply PTP_1588_CLOCK
 	help
 	  This driver supports Intel(R) Ethernet Connection E800 Series of
 	  devices.  For more information on how to identify your adapter, go
@@ -317,7 +317,7 @@ config FM10K
 	tristate "Intel(R) FM10000 Ethernet Switch Host Interface Support"
 	default n
 	depends on PCI_MSI
-	imply PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	help
 	  This driver supports Intel(R) FM10000 Ethernet Switch Host
 	  Interface.  For more information on how to identify your adapter,

drivers/net/ethernet/marvell/octeontx2/Kconfig

@@ -12,6 +12,7 @@ config OCTEONTX2_AF
 	select NET_DEVLINK
 	depends on (64BIT && COMPILE_TEST) || ARM64
 	depends on PCI
+	depends on PTP_1588_CLOCK_OPTIONAL
 	help
 	  This driver supports Marvell's OcteonTX2 Resource Virtualization
 	  Unit's admin function manager which manages all RVU HW resources
@@ -32,6 +33,7 @@ config OCTEONTX2_PF
 	select OCTEONTX2_MBOX
 	depends on (64BIT && COMPILE_TEST) || ARM64
 	depends on PCI
+	depends on PTP_1588_CLOCK_OPTIONAL
 	help
 	  This driver supports Marvell's OcteonTX2 NIC physical function.
 

drivers/net/ethernet/mellanox/mlx4/Kconfig

@@ -6,8 +6,8 @@
 config MLX4_EN
 	tristate "Mellanox Technologies 1/10/40Gbit Ethernet support"
 	depends on PCI && NETDEVICES && ETHERNET && INET
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select MLX4_CORE
-	imply PTP_1588_CLOCK
 	help
 	  This driver supports Mellanox Technologies ConnectX Ethernet
 	  devices.

drivers/net/ethernet/mellanox/mlx5/core/Kconfig

@@ -10,7 +10,7 @@ config MLX5_CORE
 	select NET_DEVLINK
 	depends on VXLAN || !VXLAN
 	depends on MLXFW || !MLXFW
-	depends on PTP_1588_CLOCK || !PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	depends on PCI_HYPERV_INTERFACE || !PCI_HYPERV_INTERFACE
 	help
 	  Core driver for low level functionality of the ConnectX-4 and

drivers/net/ethernet/mellanox/mlxsw/Kconfig

@@ -58,10 +58,10 @@ config MLXSW_SPECTRUM
 	depends on NET_IPGRE || NET_IPGRE=n
 	depends on IPV6_GRE || IPV6_GRE=n
 	depends on VXLAN || VXLAN=n
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select GENERIC_ALLOCATOR
 	select PARMAN
 	select OBJAGG
-	imply PTP_1588_CLOCK
 	select NET_PTP_CLASSIFY if PTP_1588_CLOCK
 	default m
 	help

drivers/net/ethernet/microchip/Kconfig

@@ -45,6 +45,7 @@ config ENCX24J600
 config LAN743X
 	tristate "LAN743x support"
 	depends on PCI
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select PHYLIB
 	select CRC16
 	select CRC32

drivers/net/ethernet/mscc/Kconfig

@@ -24,6 +24,7 @@ config MSCC_OCELOT_SWITCH_LIB
 
 config MSCC_OCELOT_SWITCH
 	tristate "Ocelot switch driver"
+	depends on PTP_1588_CLOCK_OPTIONAL
 	depends on BRIDGE || BRIDGE=n
 	depends on NET_SWITCHDEV
 	depends on HAS_IOMEM

drivers/net/ethernet/oki-semi/pch_gbe/Kconfig

@@ -6,6 +6,7 @@
 config PCH_GBE
 	tristate "OKI SEMICONDUCTOR IOH(ML7223/ML7831) GbE"
 	depends on PCI && (X86_32 || COMPILE_TEST)
+	depends on PTP_1588_CLOCK
 	select MII
 	select PTP_1588_CLOCK_PCH
 	select NET_PTP_CLASSIFY

drivers/net/ethernet/pensando/Kconfig

@@ -20,7 +20,7 @@ if NET_VENDOR_PENSANDO
 config IONIC
 	tristate "Pensando Ethernet IONIC Support"
 	depends on 64BIT && PCI
-	depends on PTP_1588_CLOCK || !PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	select NET_DEVLINK
 	select DIMLIB
 	help

drivers/net/ethernet/qlogic/Kconfig

@@ -99,7 +99,7 @@ config QED_SRIOV
 config QEDE
 	tristate "QLogic QED 25/40/100Gb Ethernet NIC"
 	depends on QED
-	imply PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK_OPTIONAL
 	help
 	  This enables the support for Marvell FastLinQ adapters family,
 	  ethernet driver.