openwrt/target/linux/ramips/patches-3.3/101-rt288x_serial_driver_hack.patch

--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -258,6 +258,14 @@ config SERIAL_8250_ACORN
 	  system, say Y to this option.  The driver can handle 1, 2, or 3 port
 	  cards.  If unsure, say N.
 
+config SERIAL_8250_RT288X
+	bool "Ralink RT288x/RT305x/RT3662/RT3883 serial port support"
+	depends on SERIAL_8250 != n && (SOC_RT288X || SOC_RT305X || SOC_RT3883)
+	help
+	  If you have a Ralink RT288x/RT305x SoC based board and want to use the
+	  serial port, say Y to this option. The driver can handle up to 2 serial
+	  ports. If unsure, say N.
+
 config SERIAL_8250_RM9K
 	bool "Support for MIPS RM9xxx integrated serial port"
 	depends on SERIAL_8250 != n && SERIAL_RM9000
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -321,7 +321,7 @@ struct uart_port {
 #define UPIO_HUB6		(1)
 #define UPIO_MEM		(2)
 #define UPIO_MEM32		(3)
-#define UPIO_AU			(4)			/* Au1x00 type IO */
+#define UPIO_AU			(4)			/* Au1x00 and RT288x type IO */
 #define UPIO_TSI		(5)			/* Tsi108/109 type IO */
 #define UPIO_RM9000		(6)			/* RM9000 type IO */
 
--- a/drivers/tty/serial/8250/8250.c
+++ b/drivers/tty/serial/8250/8250.c
@@ -292,9 +292,9 @@ static const struct serial8250_config ua
 	},
 };
 
-#if defined(CONFIG_MIPS_ALCHEMY)
+#if defined(CONFIG_MIPS_ALCHEMY) || defined (CONFIG_SERIAL_8250_RT288X)
 
-/* Au1x00 UART hardware has a weird register layout */
+/* Au1x00 and RT288x UART hardware has a weird register layout */
 static const u8 au_io_in_map[] = {
 	[UART_RX]  = 0,
 	[UART_IER] = 2,
@@ -516,8 +516,8 @@ static inline void _serial_dl_write(stru
 	serial_outp(up, UART_DLM, value >> 8 & 0xff);
 }
 
-#if defined(CONFIG_MIPS_ALCHEMY)
-/* Au1x00 haven't got a standard divisor latch */
+#if defined(CONFIG_MIPS_ALCHEMY) || defined (CONFIG_SERIAL_8250_RT288X)
+/* Au1x00 and RT288x haven't got a standard divisor latch */
 static int serial_dl_read(struct uart_8250_port *up)
 {
 	if (up->port.iotype == UPIO_AU)
@@ -724,22 +724,19 @@ static int size_fifo(struct uart_8250_po
  */
 static unsigned int autoconfig_read_divisor_id(struct uart_8250_port *p)
 {
-	unsigned char old_dll, old_dlm, old_lcr;
+	unsigned char old_lcr;
+	unsigned int old_dl;
 	unsigned int id;
 
 	old_lcr = serial_inp(p, UART_LCR);
 	serial_outp(p, UART_LCR, UART_LCR_CONF_MODE_A);
 
-	old_dll = serial_inp(p, UART_DLL);
-	old_dlm = serial_inp(p, UART_DLM);
+	old_dl = serial_dl_read(p);
 
-	serial_outp(p, UART_DLL, 0);
-	serial_outp(p, UART_DLM, 0);
+	serial_dl_write(p, 0);
+	id = serial_dl_read(p);
 
-	id = serial_inp(p, UART_DLL) | serial_inp(p, UART_DLM) << 8;
-
-	serial_outp(p, UART_DLL, old_dll);
-	serial_outp(p, UART_DLM, old_dlm);
+	serial_dl_write(p, old_dl);
 	serial_outp(p, UART_LCR, old_lcr);
 
 	return id;
@@ -865,7 +862,7 @@ static int broken_efr(struct uart_8250_p
 	/*
 	 * Exar ST16C2550 "A2" devices incorrectly detect as
 	 * having an EFR, and report an ID of 0x0201.  See
-	 * http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-11/4812.html 
+	 * http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-11/4812.html
 	 */
 	if (autoconfig_read_divisor_id(up) == 0x0201 && size_fifo(up) == 16)
 		return 1;