misc: Add simple driver to enable the legacy UART on Winbond Super IO chips

On most x86 boards, the legacy serial ports (io address 0x3f8/0x2f8)
are provided by a superio chip connected to the LPC bus. We must
program the superio chip so that serial ports are available for us.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

drivers/misc/Kconfig

@@ -130,4 +130,12 @@ config RESET
 	  effect a reset. The uclass will try all available drivers when
 	  reset_walk() is called.
 
+config WINBOND_W83627
+	bool "Enable Winbond Super I/O driver"
+	help
+	  If you say Y here, you will get support for the Winbond
+	  W83627 Super I/O driver. This can be used to enable the
+	  legacy UART or other devices in the Winbond Super IO chips
+	  on X86 platforms.
+
 endmenu

drivers/misc/Makefile

@@ -41,3 +41,4 @@ obj-$(CONFIG_FSL_SEC_MON) += fsl_sec_mon.o
 obj-$(CONFIG_PCA9551_LED) += pca9551_led.o
 obj-$(CONFIG_RESET) += reset-uclass.o
 obj-$(CONFIG_FSL_DEVICE_DISABLE) += fsl_devdis.o
+obj-$(CONFIG_WINBOND_W83627) += winbond_w83627.o

drivers/misc/winbond_w83627.c

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2016 Stefan Roese <sr@denx.de>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/pnp_def.h>
+
+#define WINBOND_ENTRY_KEY	0x87
+#define WINBOND_EXIT_KEY	0xaa
+
+/* Enable configuration: pass entry key '0x87' into index port dev twice */
+static void pnp_enter_conf_state(u16 dev)
+{
+	u16 port = dev >> 8;
+
+	outb(WINBOND_ENTRY_KEY, port);
+	outb(WINBOND_ENTRY_KEY, port);
+}
+
+/* Disable configuration: pass exit key '0xAA' into index port dev */
+static void pnp_exit_conf_state(u16 dev)
+{
+	u16 port = dev >> 8;
+
+	outb(WINBOND_EXIT_KEY, port);
+}
+
+/* Bring up early serial debugging output before the RAM is initialized */
+void winbond_enable_serial(uint dev, uint iobase, uint irq)
+{
+	pnp_enter_conf_state(dev);
+	pnp_set_logical_device(dev);
+	pnp_set_enable(dev, 0);
+	pnp_set_iobase(dev, PNP_IDX_IO0, iobase);
+	pnp_set_irq(dev, PNP_IDX_IRQ0, irq);
+	pnp_set_enable(dev, 1);
+	pnp_exit_conf_state(dev);
+}

include/winbond_w83627.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2016 Stefan Roese <sr@denx.de>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _WINBOND_W83627_H_
+#define _WINBOND_W83627_H_
+
+/* I/O address of Winbond Super IO chip */
+#define WINBOND_IO_PORT		0x2e
+
+/* Logical device number */
+#define W83627DHG_FDC		0	/* Floppy */
+#define W83627DHG_PP		1	/* Parallel port */
+#define W83627DHG_SP1		2	/* Com1 */
+#define W83627DHG_SP2		3	/* Com2 */
+#define W83627DHG_KBC		5	/* PS/2 keyboard & mouse */
+#define W83627DHG_SPI		6	/* Serial peripheral interface */
+#define W83627DHG_WDTO_PLED	8	/* WDTO#, PLED */
+#define W83627DHG_ACPI		10	/* ACPI */
+#define W83627DHG_HWM		11	/* Hardware monitor */
+#define W83627DHG_PECI_SST	12	/* PECI, SST */
+
+/**
+ * Configure the base I/O port of the specified serial device and enable the
+ * serial device.
+ *
+ * @dev: high 8 bits = super I/O port, low 8 bits = logical device number
+ * @iobase: processor I/O port address to assign to this serial device
+ * @irq: processor IRQ number to assign to this serial device
+ */
+void winbond_enable_serial(uint dev, uint iobase, uint irq);
+
+#endif /* _WINBOND_W83627_H_ */