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>

1 files changed, 41 insertions, 0 deletions

diff --git a/drivers/misc/winbond_w83627.c b/drivers/misc/winbond_w83627.c
new file mode 100644
index 0000000000..59db7d971c
--- /dev/null
+++ b/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);
+}