net: spacemit: Add K1 Ethernet MAC

The Ethernet MACs found on SpacemiT K1 appears to be a custom design
that only superficially resembles some other embedded MACs. SpacemiT
refers to them as "EMAC", so let's just call the driver "k1_emac".

Supports RGMII and RMII interfaces. Includes support for MAC hardware
statistics counters. PTP support is not implemented.

Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Reviewed-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Tested-by: Junhui Liu <junhui.liu@pigmoral.tech>
Tested-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Link: https://patch.msgid.link/20250914-net-k1-emac-v12-2-65b31b398f44@iscas.ac.cn
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: dramforever

drivers/net/ethernet/Kconfig

@@ -188,6 +188,7 @@ source "drivers/net/ethernet/sis/Kconfig"
 source "drivers/net/ethernet/sfc/Kconfig"
 source "drivers/net/ethernet/smsc/Kconfig"
 source "drivers/net/ethernet/socionext/Kconfig"
+source "drivers/net/ethernet/spacemit/Kconfig"
 source "drivers/net/ethernet/stmicro/Kconfig"
 source "drivers/net/ethernet/sun/Kconfig"
 source "drivers/net/ethernet/sunplus/Kconfig"

drivers/net/ethernet/Makefile

@@ -91,6 +91,7 @@ obj-$(CONFIG_NET_VENDOR_SOLARFLARE) += sfc/
 obj-$(CONFIG_NET_VENDOR_SGI) += sgi/
 obj-$(CONFIG_NET_VENDOR_SMSC) += smsc/
 obj-$(CONFIG_NET_VENDOR_SOCIONEXT) += socionext/
+obj-$(CONFIG_NET_VENDOR_SPACEMIT) += spacemit/
 obj-$(CONFIG_NET_VENDOR_STMICRO) += stmicro/
 obj-$(CONFIG_NET_VENDOR_SUN) += sun/
 obj-$(CONFIG_NET_VENDOR_SUNPLUS) += sunplus/

drivers/net/ethernet/spacemit/Kconfig

@@ -0,0 +1,29 @@
+config NET_VENDOR_SPACEMIT
+	bool "SpacemiT devices"
+	default y
+	depends on ARCH_SPACEMIT || COMPILE_TEST
+	help
+	  If you have a network (Ethernet) device belonging to this class,
+	  say Y.
+
+	  Note that the answer to this question does not directly affect
+	  the kernel: saying N will just cause the configurator to skip all
+	  the questions regarding SpacemiT devices. If you say Y, you will
+	  be asked for your specific chipset/driver in the following questions.
+
+if NET_VENDOR_SPACEMIT
+
+config SPACEMIT_K1_EMAC
+	tristate "SpacemiT K1 Ethernet MAC driver"
+	depends on ARCH_SPACEMIT || COMPILE_TEST
+	depends on MFD_SYSCON
+	depends on OF
+	default m if ARCH_SPACEMIT
+	select PHYLIB
+	help
+	  This driver supports the Ethernet MAC in the SpacemiT K1 SoC.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called k1_emac.
+
+endif # NET_VENDOR_SPACEMIT

drivers/net/ethernet/spacemit/Makefile

@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the SpacemiT network device drivers.
+#
+
+obj-$(CONFIG_SPACEMIT_K1_EMAC) += k1_emac.o