ARM: 6092/1: atmel_serial: support for RS485 communications

Final version of the patch that adds support for RS485 communications to the atmel_serial driver.

The patch has been already sent and discussed on both linux-kernel and linux-arm-kernel mailing lists several times.

Many people collaborated to improve and test the code:
Tested-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
Tested-by: Bernhard Roth <br@pwrnet.de>
Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
Signed-off-by: Rick Bronson <rick@efn.org>
Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/ioctls.h

@@ -53,6 +53,9 @@
 #define TIOCGPTN	_IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux device) */
 #define TIOCSPTLCK	_IOW('T',0x31, int)  /* Lock/unlock Pty */
 
+#define TIOCGRS485      0x542E
+#define TIOCSRS485      0x542F
+
 #define FIONCLEX	0x5450  /* these numbers need to be adjusted. */
 #define FIOCLEX		0x5451
 #define FIOASYNC	0x5452

arch/arm/mach-at91/include/mach/board.h

@@ -39,6 +39,7 @@
 #include <linux/usb/atmel_usba_udc.h>
 #include <linux/atmel-mci.h>
 #include <sound/atmel-ac97c.h>
+#include <linux/serial.h>
 
  /* USB Device */
 struct at91_udc_data {
@@ -143,9 +144,10 @@ extern struct platform_device *atmel_default_console_device;
 extern void __init __deprecated at91_init_serial(struct at91_uart_config *config);
 
 struct atmel_uart_data {
-	short		use_dma_tx;	/* use transmit DMA? */
-	short		use_dma_rx;	/* use receive DMA? */
-	void __iomem	*regs;		/* virtual base address, if any */
+	short			use_dma_tx;	/* use transmit DMA? */
+	short			use_dma_rx;	/* use receive DMA? */
+	void __iomem		*regs;		/* virt. base address, if any */
+	struct serial_rs485	rs485;		/* rs485 settings */
 };
 extern void __init at91_add_device_serial(void);