tegra, serial8250: add ->handle_break() uart_port op

The "KT" serial port has another use case for a "received break" quirk,
so before adding another special case to the 8250 core take this
opportunity to push such quirks out of the core and into a uart_port op.

Stephen says:
"If the callback function is to no longer live in 8250.c itself,
arch/arm/mach-tegra/devices.c isn't logically a good place to put it,
and that file will be going away once we get rid of all the board files
and move solely to device tree."

...so since 8250_pci.c houses all the quirks for pci serial devices this
quirk is similarly housed in of_serial.c. Once the open firmware
conversion completes the infrastructure details
(include/linux/of_serial.h, and the export) can all be removed to make
this self contained to of_serial.c.

Cc: Nhan H Mai <[e-mail]>
Cc: Colin Cross <[e-mail]>
Cc: Olof Johansson <[e-mail]>
[stephen: kill CONFIG_SERIAL_TEGRA in favor just using CONFIG_ARCH_TEGRA]
Cc: Grant Likely <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Acked-by: Sudhakar Mamillapalli <[e-mail]>
Reported-by: Alan Cox <[e-mail]>
Acked-by: Alan Cox <[e-mail]>
Signed-off-by: Dan Williams <[e-mail]>
Acked-by: Stephen Warren <[e-mail]>
Tested-by: Stephen Warren <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

arch/arm/mach-tegra/board-harmony.c

···
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/serial_8250.h>
+#include <linux/of_serial.h>
 #include <linux/clk.h>
 #include <linux/dma-mapping.h>
 #include <linux/pda_power.h>
···
 		.irq		= INT_UARTD,
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,

arch/arm/mach-tegra/board-paz00.c

···
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/serial_8250.h>
+#include <linux/of_serial.h>
 #include <linux/clk.h>
 #include <linux/dma-mapping.h>
 #include <linux/gpio_keys.h>
···
 		.irq		= INT_UARTA,
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,
···
 		.irq		= INT_UARTC,
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,

arch/arm/mach-tegra/board-seaboard.c

···
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/serial_8250.h>
+#include <linux/of_serial.h>
 #include <linux/i2c.h>
 #include <linux/delay.h>
 #include <linux/input.h>
···
 		/* Memory and IRQ filled in before registration */
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,

arch/arm/mach-tegra/board-trimslice.c

···
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/serial_8250.h>
+#include <linux/of_serial.h>
 #include <linux/io.h>
 #include <linux/i2c.h>
 #include <linux/gpio.h>
···
 		.irq		= INT_UARTA,
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,

drivers/tty/serial/8250/8250.c

···
 }
 
 /*
- * Clear the Tegra rx fifo after a break
- *
- * FIXME: This needs to become a port specific callback once we have a
- * framework for this
- */
-static void clear_rx_fifo(struct uart_8250_port *up)
-{
-	unsigned int status, tmout = 10000;
-	do {
-		status = serial_in(up, UART_LSR);
-		if (status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS))
-			status = serial_in(up, UART_RX);
-		else
-			break;
-		if (--tmout == 0)
-			break;
-		udelay(1);
-	} while (1);
-}
-
-/*
  * serial8250_rx_chars: processes according to the passed in LSR
  * value, and returns the remaining LSR bits not handled
  * by this Rx routine.
···
 		up->lsr_saved_flags = 0;
 
 		if (unlikely(lsr & UART_LSR_BRK_ERROR_BITS)) {
-			/*
-			 * For statistics only
-			 */
 			if (lsr & UART_LSR_BI) {
 				lsr &= ~(UART_LSR_FE | UART_LSR_PE);
 				port->icount.brk++;
-				/*
-				 * If tegra port then clear the rx fifo to
-				 * accept another break/character.
-				 */
-				if (port->type == PORT_TEGRA)
-					clear_rx_fifo(up);
-
 				/*
 				 * We do the SysRQ and SAK checking
 				 * here because otherwise the break
···
 		port.serial_in		= p->serial_in;
 		port.serial_out		= p->serial_out;
 		port.handle_irq		= p->handle_irq;
+		port.handle_break	= p->handle_break;
 		port.set_termios	= p->set_termios;
 		port.pm			= p->pm;
 		port.dev		= &dev->dev;
···
 			uart->port.set_termios = port->set_termios;
 		if (port->pm)
 			uart->port.pm = port->pm;
+		if (port->handle_break)
+			uart->port.handle_break = port->handle_break;
 
 		if (serial8250_isa_config != NULL)
 			serial8250_isa_config(0, &uart->port,

drivers/tty/serial/of_serial.c

···
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/delay.h>
 #include <linux/serial_core.h>
 #include <linux/serial_8250.h>
+#include <linux/serial_reg.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
+#include <linux/of_serial.h>
 #include <linux/of_platform.h>
 #include <linux/nwpserial.h>
 
···
 	int type;
 	int line;
 };
+
+#ifdef CONFIG_ARCH_TEGRA
+void tegra_serial_handle_break(struct uart_port *p)
+{
+	unsigned int status, tmout = 10000;
+
+	do {
+		status = p->serial_in(p, UART_LSR);
+		if (status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS))
+			status = p->serial_in(p, UART_RX);
+		else
+			break;
+		if (--tmout == 0)
+			break;
+		udelay(1);
+	} while (1);
+}
+/* FIXME remove this export when tegra finishes conversion to open firmware */
+EXPORT_SYMBOL_GPL(tegra_serial_handle_break);
+#endif
 
 /*
  * Fill a struct uart_port for a given device node
···
 	port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP
 		| UPF_FIXED_PORT | UPF_FIXED_TYPE;
 	port->dev = &ofdev->dev;
+
+	if (type == PORT_TEGRA)
+		port->handle_break = tegra_serial_handle_break;
 
 	return 0;
 }

include/linux/of_serial.h

···
+#ifndef __LINUX_OF_SERIAL_H
+#define __LINUX_OF_SERIAL_H
+
+/*
+ * FIXME remove this file when tegra finishes conversion to open firmware,
+ * expectation is that all quirks will then be self-contained in
+ * drivers/tty/serial/of_serial.c.
+ */
+#ifdef CONFIG_ARCH_TEGRA
+extern void tegra_serial_handle_break(struct uart_port *port);
+#else
+static inline void tegra_serial_handle_break(struct uart_port *port)
+{
+}
+#endif
+
+#endif /* __LINUX_OF_SERIAL */

include/linux/serial_8250.h

···
 	int		(*handle_irq)(struct uart_port *);
 	void		(*pm)(struct uart_port *, unsigned int state,
 			      unsigned old);
+	void		(*handle_break)(struct uart_port *);
 };
 
 /*

include/linux/serial_core.h

···
 	int			(*handle_irq)(struct uart_port *);
 	void			(*pm)(struct uart_port *, unsigned int state,
 				      unsigned int old);
+	void			(*handle_break)(struct uart_port *);
 	unsigned int		irq;			/* irq number */
 	unsigned long		irqflags;		/* irq flags  */
 	unsigned int		uartclk;		/* base uart clock */
···
 static inline int uart_handle_break(struct uart_port *port)
 {
 	struct uart_state *state = port->state;
+
+	if (port->handle_break)
+		port->handle_break(port);
+
 #ifdef SUPPORT_SYSRQ
 	if (port->cons && port->cons->index == port->line) {
 		if (!port->sysrq) {