amba-pl011: do not disable RTS during shutdown

[firefly-linux-kernel-4.4.55.git] / drivers / tty / serial / amba-pl011.c

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 9ae024025ff356618221717d3fae6b5d296e32db..ce843d058e02a1d9fc81e6f3f7a1b3989ce7ea0c 100644 (file)
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -159,6 +159,7 @@ struct uart_amba_port {
        unsigned int            fifosize;       /* vendor-specific */
        unsigned int            lcrh_tx;        /* vendor-specific */
        unsigned int            lcrh_rx;        /* vendor-specific */
+       unsigned int            old_cr;         /* state during shutdown */
        bool                    autorts;
        char                    type[12];
        bool                    interrupt_may_hang; /* vendor-specific */
@@ -1411,7 +1412,9 @@ static int pl011_startup(struct uart_port *port)
        while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_BUSY)
                barrier();
 
-       cr = UART01x_CR_UARTEN | UART011_CR_RXE | UART011_CR_TXE;
+       /* restore RTS and DTR */
+       cr = uap->old_cr & (UART011_CR_RTS | UART011_CR_DTR);
+       cr |= UART01x_CR_UARTEN | UART011_CR_RXE | UART011_CR_TXE;
        writew(cr, uap->port.membase + UART011_CR);
 
        /* Clear pending error interrupts */
@@ -1469,6 +1472,7 @@ static void pl011_shutdown_channel(struct uart_amba_port *uap,
 static void pl011_shutdown(struct uart_port *port)
 {
        struct uart_amba_port *uap = (struct uart_amba_port *)port;
+       unsigned int cr;
 
        /*
         * disable all interrupts
@@ -1488,9 +1492,16 @@ static void pl011_shutdown(struct uart_port *port)
 
        /*
         * disable the port
+        * disable the port. It should not disable RTS and DTR.
+        * Also RTS and DTR state should be preserved to restore
+        * it during startup().
         */
        uap->autorts = false;
-       writew(UART01x_CR_UARTEN | UART011_CR_TXE, uap->port.membase + UART011_CR);
+       cr = readw(uap->port.membase + UART011_CR);
+       uap->old_cr = cr;
+       cr &= UART011_CR_RTS | UART011_CR_DTR;
+       cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
+       writew(cr, uap->port.membase + UART011_CR);
 
        /*
         * disable break condition and fifos
@@ -1905,6 +1916,7 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
        uap->vendor = vendor;
        uap->lcrh_rx = vendor->lcrh_rx;
        uap->lcrh_tx = vendor->lcrh_tx;
+       uap->old_cr = 0;
        uap->fifosize = vendor->fifosize;
        uap->interrupt_may_hang = vendor->interrupt_may_hang;
        uap->port.dev = &dev->dev;