net: dwc_eth_qos: add Kconfig option to select supported configuration

Add configuration flag to select the supported dwc driver configuration:
- CONFIG_DWC_ETH_QOS_TEGRA186
- CONFIG_DWC_ETH_QOS_IMX
- CONFIG_DWC_ETH_QOS_STM32

See Linux driver ethernet/stmicro/stmmac and associated glue layers
for other configuration examples.

This patch removes the not-selected compatibles and lets the linker remove
the unused functions to reduce the size of the driver.
Signed-off-by: NPatrick Delaunay <patrick.delaunay@st.com>

drivers/net/Kconfig

@@ -156,9 +156,30 @@ config DWC_ETH_QOS
 	help
 	  This driver supports the Synopsys Designware Ethernet QOS (Quality
 	  Of Service) IP block. The IP supports many options for bus type,
-	  clocking/reset structure, and feature list. This driver currently
-	  supports the specific configuration used in NVIDIA's Tegra186 chip,
-	  but should be extensible to other combinations quite easily.
+	  clocking/reset structure, and feature list.
+
+config DWC_ETH_QOS_IMX
+	bool "Synopsys DWC Ethernet QOS device support for IMX"
+	depends on DWC_ETH_QOS
+	help
+	  The Synopsys Designware Ethernet QOS IP block with the specific
+	  configuration used in IMX soc.
+
+config DWC_ETH_QOS_STM32
+	bool "Synopsys DWC Ethernet QOS device support for STM32"
+	depends on DWC_ETH_QOS
+	default y if ARCH_STM32MP
+	help
+	  The Synopsys Designware Ethernet QOS IP block with the specific
+	  configuration used in STM32MP soc.
+
+config DWC_ETH_QOS_TEGRA186
+	bool "Synopsys DWC Ethernet QOS device support for TEGRA186"
+	depends on DWC_ETH_QOS
+	default y if TEGRA186
+	help
+	  The Synopsys Designware Ethernet QOS IP block with specific
+	  configuration used in NVIDIA's Tegra186 chip.
 
 config E1000
 	bool "Intel PRO/1000 Gigabit Ethernet support"

drivers/net/dwc_eth_qos.c

@@ -2100,7 +2100,7 @@ static struct eqos_ops eqos_tegra186_ops = {
 	.eqos_get_tick_clk_rate = eqos_get_tick_clk_rate_tegra186
 };
 
-static const struct eqos_config eqos_tegra186_config = {
+static const struct eqos_config __maybe_unused eqos_tegra186_config = {
 	.reg_access_always_ok = false,
 	.mdio_wait = 10,
 	.swr_wait = 10,
@@ -2127,7 +2127,7 @@ static struct eqos_ops eqos_stm32_ops = {
 	.eqos_get_tick_clk_rate = eqos_get_tick_clk_rate_stm32
 };
 
-static const struct eqos_config eqos_stm32_config = {
+static const struct eqos_config __maybe_unused eqos_stm32_config = {
 	.reg_access_always_ok = false,
 	.mdio_wait = 10000,
 	.swr_wait = 50,
@@ -2154,7 +2154,7 @@ static struct eqos_ops eqos_imx_ops = {
 	.eqos_get_tick_clk_rate = eqos_get_tick_clk_rate_imx
 };
 
-struct eqos_config eqos_imx_config = {
+struct eqos_config __maybe_unused eqos_imx_config = {
 	.reg_access_always_ok = false,
 	.mdio_wait = 10000,
 	.swr_wait = 50,
@@ -2165,18 +2165,24 @@ struct eqos_config eqos_imx_config = {
 };
 
 static const struct udevice_id eqos_ids[] = {
+#if IS_ENABLED(CONFIG_DWC_ETH_QOS_TEGRA186)
 	{
 		.compatible = "nvidia,tegra186-eqos",
 		.data = (ulong)&eqos_tegra186_config
 	},
+#endif
+#if IS_ENABLED(CONFIG_DWC_ETH_QOS_STM32)
 	{
 		.compatible = "st,stm32mp1-dwmac",
 		.data = (ulong)&eqos_stm32_config
 	},
+#endif
+#if IS_ENABLED(CONFIG_DWC_ETH_QOS_IMX)
 	{
 		.compatible = "fsl,imx-eqos",
 		.data = (ulong)&eqos_imx_config
 	},
+#endif
 
 	{ }
 };