1 files changed, 77 insertions, 0 deletions
diff --git a/arch/x86/cpu/baytrail/early_uart.c b/arch/x86/cpu/baytrail/early_uart.c
new file mode 100644
index 0000000000..41992105fe
--- /dev/null
+++ b/arch/x86/cpu/baytrail/early_uart.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2015 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <errno.h>
+#include <asm/io.h>
+
+#define PCI_DEV_CONFIG(segbus, dev, fn) ( \
+		(((segbus) & 0xfff) << 20) | \
+		(((dev) & 0x1f) << 15) | \
+		(((fn)  & 0x07) << 12))
+
+/* Platform Controller Unit */
+#define LPC_DEV			0x1f
+#define LPC_FUNC		0
+
+/* Enable UART */
+#define UART_CONT		0x80
+
+/* SCORE Pad definitions */
+#define UART_RXD_PAD			82
+#define UART_TXD_PAD			83
+
+/* Pad base: PAD_CONF0[n]= PAD_BASE + 16 * n */
+#define GPSCORE_PAD_BASE	(IO_BASE_ADDRESS + IO_BASE_OFFSET_GPSCORE)
+
+/* IO Memory */
+#define IO_BASE_ADDRESS			0xfed0c000
+#define  IO_BASE_OFFSET_GPSCORE		0x0000
+#define  IO_BASE_OFFSET_GPNCORE		0x1000
+#define  IO_BASE_OFFSET_GPSSUS		0x2000
+#define IO_BASE_SIZE			0x4000
+
+static inline unsigned int score_pconf0(int pad_num)
+{
+	return GPSCORE_PAD_BASE + pad_num * 16;
+}
+
+static void score_select_func(int pad, int func)
+{
+	uint32_t reg;
+	uint32_t pconf0_addr = score_pconf0(pad);
+
+	reg = readl(pconf0_addr);
+	reg &= ~0x7;
+	reg |= func & 0x7;
+	writel(reg, pconf0_addr);
+}
+
+static void pci_write_config32(int dev, unsigned int where, u32 value)
+{
+	unsigned long addr;
+
+	addr = CONFIG_PCIE_ECAM_BASE | dev | (where & ~3);
+	writel(value, addr);
+}
+
+/* This can be called after memory-mapped PCI is working */
+int setup_early_uart(void)
+{
+	/* Enable the legacy UART hardware. */
+	pci_write_config32(PCI_DEV_CONFIG(0, LPC_DEV, LPC_FUNC), UART_CONT, 1);
+
+	/*
+	 * Set up the pads to the UART function. This allows the signals to
+	 * leave the chip
+	 */
+	score_select_func(UART_RXD_PAD, 1);
+	score_select_func(UART_TXD_PAD, 1);
+
+	/* TODO(sjg@chromium.org): Call debug_uart_init() */
+
+	return 0;
+}