[arm/tegra]serial: Power control api for bluesleep power management.

Adding apis for following function to hooking up tegra serial driver with
bluesleep power management:
- Clock off.
- Clock on.
- Setting flow control to desired state.
- Checking for tx fifo status.

Following 4 state of uart state machine is developed to achieve this:
UART_CLOSED, UART_OPENED, UART_SUSPEND, UART_CLOCK_OFF.

The transitions of states are as follows:
UART_CLOSED: the init state  on which resource is allocated but not
             opened by client or when device is closed.

UART_OPENED: Able to do data transfer.
             CLOSED  to  OPENED by opening the port.
             CLOCK_OFF to OPENED by calling function tegra_uart_request_clock_on().
             SUSPEND to OPENED by calling resume().

UART_CLOCK_OFF: The controller clock is disabled and so no data transfer
                can happen. At this state, controller is not ready for
                deep power down.
             OPENED to CLOCK_OFF by calling tegra_uart_request_clock_off().
             Can not go to this state from CLOSED and SUSPEND.

UART_SUSPEND: The controller is in suspended state and ready for deep power down.
             UART_CLOCK_OFF to SUSPEND:
             OPENED to SUSPEND.

Change-Id: Ib0c40547665181cadd172840be9aed2cc18ba448
Reviewed-on: http://git-master/r/2819
Reviewed-by: Anantha Idapalapati <aidapalapati@nvidia.com>
Tested-by: Anantha Idapalapati <aidapalapati@nvidia.com>
Reviewed-by: Udaykumar Rameshchan Raval <uraval@nvidia.com>
Reviewed-by: Gary King <gking@nvidia.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/include/mach/serial.h b/arch/arm/mach-tegra/include/mach/serial.h
index c77afa190998..fb4c92a9902c 100644
--- a/arch/arm/mach-tegra/include/mach/serial.h
+++ b/arch/arm/mach-tegra/include/mach/serial.h
@@ -24,6 +24,7 @@
 
 #include <linux/types.h>
 #include <linux/serial_8250.h>
+#include <linux/serial_core.h>
 
 #include <mach/pinmux.h>
 
@@ -33,4 +34,18 @@ struct tegra_serial_platform_data {
 	int nr_pins;
 };
 
+/* Switch off the clock of the uart controller. */
+void tegra_uart_request_clock_off(struct uart_port *uport);
+
+/* Switch on the clock of the uart controller */
+void tegra_uart_request_clock_on(struct uart_port *uport);
+
+/* Set the modem control signals state of uart controller. */
+void tegra_uart_set_mctrl(struct uart_port *uport, unsigned int mctrl);
+
+/* Return the status of the transmit fifo whether empty or not.
+ * Return 0 if tx fifo is not empty.
+ * Return TIOCSER_TEMT if tx fifo is empty */
+int tegra_uart_is_tx_empty(struct uart_port *uport);
+
 #endif