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 <nhan.h.mai@intel.com>
Cc: Colin Cross <ccross@android.com>
Cc: Olof Johansson <olof@lixom.net>
[stephen: kill CONFIG_SERIAL_TEGRA in favor just using CONFIG_ARCH_TEGRA]
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Sudhakar Mamillapalli <sudhakar@fb.com>
Reported-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
index e8c9cee07d00..5410c0637266 100644
--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c
@@ -12,10 +12,13 @@
 #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>
 
@@ -24,6 +27,26 @@ struct of_serial_info {
 	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
  */
@@ -84,6 +107,9 @@ static int __devinit of_platform_serial_setup(struct platform_device *ofdev,
 		| UPF_FIXED_PORT | UPF_FIXED_TYPE;
 	port->dev = &ofdev->dev;
 
+	if (type == PORT_TEGRA)
+		port->handle_break = tegra_serial_handle_break;
+
 	return 0;
 }