cpm_uart: Modem control lines support

This patch replaces the get_mctrl/set_mctrl stubs with modem control line
read/write access through the GPIO lib.

Available modem control lines are described in the device tree using GPIO
bindings. The driver expect a GPIO pin for each of the CTS, RTS, DCD, DSR,
DTR and RI signals. Unused control lines can be left out.

Signed-off-by: Laurent Pinchart <laurentp@cse-semaphore.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/drivers/serial/cpm_uart/cpm_uart.h b/drivers/serial/cpm_uart/cpm_uart.h
index 5c76e0a..5999ef5 100644
--- a/drivers/serial/cpm_uart/cpm_uart.h
+++ b/drivers/serial/cpm_uart/cpm_uart.h
@@ -50,6 +50,15 @@
 
 #define SCC_WAIT_CLOSING 100
 
+#define GPIO_CTS	0
+#define GPIO_RTS	1
+#define GPIO_DCD	2
+#define GPIO_DSR	3
+#define GPIO_DTR	4
+#define GPIO_RI		5
+
+#define NUM_GPIOS	(GPIO_RI+1)
+
 struct uart_cpm_port {
 	struct uart_port	port;
 	u16			rx_nrfifos;
@@ -82,6 +91,7 @@
 	int			wait_closing;
 	/* value to combine with opcode to form cpm command */
 	u32			command;
+	int			gpios[NUM_GPIOS];
 };
 
 extern int cpm_uart_nr;