x86: serial: Add a coreboot serial driver

Coreboot can provide information about the serial device in use on a
platform. Add a driver that uses this information to produce a working
UART.

Signed-off-by: Simon Glass <[email protected]>
Reviewed-by: Bin Meng <[email protected]>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/serial/serial_coreboot.c b/drivers/serial/serial_coreboot.c
new file mode 100644
index 00000000000..ccab347514c
--- /dev/null
+++ b/drivers/serial/serial_coreboot.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * UART support for U-Boot when launched from Coreboot
+ *
+ * Copyright 2019 Google LLC
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <ns16550.h>
+#include <serial.h>
+#include <asm/arch/sysinfo.h>
+
+static int coreboot_ofdata_to_platdata(struct udevice *dev)
+{
+	struct ns16550_platdata *plat = dev_get_platdata(dev);
+	struct cb_serial *cb_info = lib_sysinfo.serial;
+
+	plat->base = cb_info->baseaddr;
+	plat->reg_shift = cb_info->regwidth == 4 ? 2 : 0;
+	plat->reg_width = cb_info->regwidth;
+	plat->clock = cb_info->input_hertz;
+	plat->fcr = UART_FCR_DEFVAL;
+	plat->flags = 0;
+	if (cb_info->type == CB_SERIAL_TYPE_IO_MAPPED)
+		plat->flags |= NS16550_FLAG_IO;
+
+	return 0;
+}
+
+static const struct udevice_id coreboot_serial_ids[] = {
+	{ .compatible = "coreboot-serial" },
+	{ },
+};
+
+U_BOOT_DRIVER(coreboot_uart) = {
+	.name	= "coreboot_uart",
+	.id	= UCLASS_SERIAL,
+	.of_match	= coreboot_serial_ids,
+	.priv_auto_alloc_size = sizeof(struct NS16550),
+	.platdata_auto_alloc_size = sizeof(struct ns16550_platdata),
+	.ofdata_to_platdata  = coreboot_ofdata_to_platdata,
+	.probe	= ns16550_serial_probe,
+	.ops	= &ns16550_serial_ops,
+	.flags	= DM_FLAG_PRE_RELOC,
+};