x86: ivybridge: Add early LPC init so that serial works

The PCH (Platform Controller Hub) includes an LPC (Low Pin Count) device
which provides a serial port. This is accessible on Chromebooks, so enable
it early in the boot process.

Signed-off-by: Simon Glass <sjg@chromium.org>

3 files changed, 61 insertions, 0 deletions

diff --git a/arch/x86/cpu/ivybridge/Makefile b/arch/x86/cpu/ivybridge/Makefile
index 6d0a78d25d..4b77c9cd83 100644
--- a/arch/x86/cpu/ivybridge/Makefile
+++ b/arch/x86/cpu/ivybridge/Makefile
@@ -6,5 +6,6 @@
 
 obj-y += car.o
 obj-y += cpu.o
+obj-y += lpc.o
 obj-y += pci.o
 obj-y += sdram.o
diff --git a/arch/x86/cpu/ivybridge/cpu.c b/arch/x86/cpu/ivybridge/cpu.c
index ff6b7b3e7a..5d7640b526 100644
--- a/arch/x86/cpu/ivybridge/cpu.c
+++ b/arch/x86/cpu/ivybridge/cpu.c
@@ -11,16 +11,21 @@
  */
 
 #include <common.h>
+#include <errno.h>
+#include <fdtdec.h>
 #include <asm/cpu.h>
 #include <asm/pci.h>
 #include <asm/post.h>
 #include <asm/processor.h>
+#include <asm/arch/pch.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
 int arch_cpu_init(void)
 {
+	const void *blob = gd->fdt_blob;
 	struct pci_controller *hose;
+	int node;
 	int ret;
 
 	post_code(POST_CPU_INIT);
@@ -34,6 +39,13 @@ int arch_cpu_init(void)
 	if (ret)
 		return ret;
 
+	node = fdtdec_next_compatible(blob, 0, COMPAT_INTEL_LPC);
+	if (node < 0)
+		return -ENOENT;
+	ret = lpc_early_init(gd->fdt_blob, node, PCH_LPC_DEV);
+	if (ret)
+		return ret;
+
 	return 0;
 }
 
diff --git a/arch/x86/cpu/ivybridge/lpc.c b/arch/x86/cpu/ivybridge/lpc.c
new file mode 100644
index 0000000000..621ef2cee6
--- /dev/null
+++ b/arch/x86/cpu/ivybridge/lpc.c
@@ -0,0 +1,48 @@
+/*
+ * From coreboot southbridge/intel/bd82x6x/lpc.c
+ *
+ * Copyright (C) 2008-2009 coresystems GmbH
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#include <common.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <pci.h>
+#include <asm/pci.h>
+#include <asm/arch/pch.h>
+
+int lpc_early_init(const void *blob, int node, pci_dev_t dev)
+{
+	struct reg_info {
+		u32 base;
+		u32 size;
+	} values[4], *ptr;
+	int count;
+	int i;
+
+	count = fdtdec_get_int_array_count(blob, node, "gen-dec",
+			(u32 *)values, sizeof(values) / sizeof(u32));
+	if (count < 0)
+		return -EINVAL;
+
+	/* Set COM1/COM2 decode range */
+	pci_write_config16(dev, LPC_IO_DEC, 0x0010);
+
+	/* Enable PS/2 Keyboard/Mouse, EC areas and COM1 */
+	pci_write_config16(dev, LPC_EN, KBC_LPC_EN | MC_LPC_EN |
+			   GAMEL_LPC_EN | COMA_LPC_EN);
+
+	/* Write all registers but use 0 if we run out of data */
+	count = count * sizeof(u32) / sizeof(values[0]);
+	for (i = 0, ptr = values; i < ARRAY_SIZE(values); i++, ptr++) {
+		u32 reg = 0;
+
+		if (i < count)
+			reg = ptr->base | PCI_COMMAND_IO | (ptr->size << 16);
+		pci_write_config32(dev, LPC_GENX_DEC(i), reg);
+	}
+
+	return 0;
+}