[PATCH v2 3/4] x86: serial: Add a coreboot serial driver

[Simon Glass]

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 <sjg at chromium.org>
Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
---

Changes in v2: None

 drivers/serial/Kconfig           | 11 ++++++++
 drivers/serial/Makefile          |  1 +
 drivers/serial/serial_coreboot.c | 46 ++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+)
 create mode 100644 drivers/serial/serial_coreboot.c

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 472a9f0929..c403c2fc25 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -539,6 +539,17 @@ config BCM6345_SERIAL
 	help
 	  Select this to enable UART on BCM6345 SoCs.
 
+config COREBOOT_SERIAL
+	bool "Coreboot UART support"
+	depends on DM_SERIAL
+	default y if SYS_COREBOOT
+	select SYS_NS16550
+	help
+	  Select this to enable a ns16550-style UART where the platform data
+	  comes from the coreboot 'sysinfo' tables. This allows U-Boot to have
+	  a serial console on any platform without needing to change the
+	  device tree, etc.
+
 config FSL_LINFLEXUART
 	bool "Freescale Linflex UART support"
 	depends on DM_SERIAL
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 06ee30697d..76b1811510 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -35,6 +35,7 @@ obj-$(CONFIG_AR933X_UART) += serial_ar933x.o
 obj-$(CONFIG_ARM_DCC) += arm_dcc.o
 obj-$(CONFIG_ATMEL_USART) += atmel_usart.o
 obj-$(CONFIG_BCM6345_SERIAL) += serial_bcm6345.o
+obj-$(CONFIG_COREBOOT_SERIAL) += serial_coreboot.o
 obj-$(CONFIG_EFI_APP) += serial_efi.o
 obj-$(CONFIG_LPC32XX_HSUART) += lpc32xx_hsuart.o
 obj-$(CONFIG_MCFUART) += mcfuart.o
diff --git a/drivers/serial/serial_coreboot.c b/drivers/serial/serial_coreboot.c
new file mode 100644
index 0000000000..ccab347514
--- /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,
+};
-- 
2.24.0.393.g34dc348eaf-goog