riscv: sifive: fu540: add SPL configuration

Add a support for SPL which will boot from L2 LIM (0x0800_0000) and
then SPL will boot U-Boot FIT image (OpenSBI FW_DYNAMIC + u-boot.bin)
from MMC boot devices.

SPL related code is leveraged from FSBL
(https://github.com/sifive/freedom-u540-c000-bootloader.git)

Signed-off-by: Pragnesh Patel <pragnesh.patel@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/board/sifive/fu540/spl.c b/board/sifive/fu540/spl.c
new file mode 100644
index 0000000..55325cf
--- /dev/null
+++ b/board/sifive/fu540/spl.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2019 SiFive, Inc
+ *
+ * Authors:
+ *   Pragnesh Patel <pragnesh.patel@sifive.com>
+ */
+
+#include <init.h>
+#include <spl.h>
+#include <misc.h>
+#include <log.h>
+#include <linux/delay.h>
+#include <asm/gpio.h>
+#include <asm/arch/gpio.h>
+#include <asm/arch/spl.h>
+
+#define GEM_PHY_RESET	SIFIVE_GENERIC_GPIO_NR(0, 12)
+
+int init_clk_and_ddr(void)
+{
+	int ret;
+
+	ret = soc_spl_init();
+	if (ret) {
+		debug("FU540 SPL init failed: %d\n", ret);
+		return ret;
+	}
+
+	/*
+	 * GEMGXL init VSC8541 PHY reset sequence;
+	 * leave pull-down active for 2ms
+	 */
+	udelay(2000);
+	ret = gpio_request(GEM_PHY_RESET, "gem_phy_reset");
+	if (ret) {
+		debug("gem_phy_reset gpio request failed: %d\n", ret);
+		return ret;
+	}
+
+	/* Set GPIO 12 (PHY NRESET) */
+	ret = gpio_direction_output(GEM_PHY_RESET, 1);
+	if (ret) {
+		debug("gem_phy_reset gpio direction set failed: %d\n", ret);
+		return ret;
+	}
+
+	udelay(1);
+
+	/* Reset PHY again to enter unmanaged mode */
+	gpio_set_value(GEM_PHY_RESET, 0);
+	udelay(1);
+	gpio_set_value(GEM_PHY_RESET, 1);
+	mdelay(15);
+
+	return 0;
+}
+
+void board_init_f(ulong dummy)
+{
+	int ret;
+
+	ret = spl_early_init();
+	if (ret)
+		panic("spl_early_init() failed: %d\n", ret);
+
+	arch_cpu_init_dm();
+
+	preloader_console_init();
+
+	ret = init_clk_and_ddr();
+	if (ret)
+		panic("init_clk_and_ddr() failed: %d\n", ret);
+}