serial: Support the EFR-register of XR1715x uarts.

The EFR (Enhenced-Features-Register) is located at a different offset
than the other devices supporting UART_CAP_EFR. This change add a special
setup quick to set UPF_EXAR_EFR on the port. UPF_EXAR_EFR is then used to
the port type to PORT_XR17D15X since it is for sure a XR17D15X uart.

Signed-off-by: Søren Holm <sgh@sgh.dk>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 19 insertions, 1 deletions

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index 435ce14e676c..82ca71aa9d10 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -309,6 +309,13 @@ static const struct serial8250_config uart_config[] = {
                                   UART_FCR_T_TRIG_01,
                 .flags          = UART_CAP_FIFO | UART_CAP_RTOIE,
         },
+        [PORT_XR17D15X] = {
+                .name           = "XR17D15X",
+                .fifo_size      = 64,
+                .tx_loadsz      = 64,
+                .fcr            = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
+                .flags          = UART_CAP_FIFO | UART_CAP_AFE | UART_CAP_EFR,
+        },
 };
 
 #if defined(CONFIG_MIPS_ALCHEMY)
@@ -1075,6 +1082,14 @@ static void autoconfig_16550a(struct uart_8250_port *up)
         serial_outp(up, UART_IER, iersave);
 
         /*
+         * Exar uarts have EFR in a weird location
+         */
+        if (up->port.flags & UPF_EXAR_EFR) {
+                up->port.type = PORT_XR17D15X;
+                up->capabilities |= UART_CAP_AFE | UART_CAP_EFR;
+        }
+
+        /*
          * We distinguish between 16550A and U6 16550A by counting
          * how many bytes are in the FIFO.
          */
@@ -2417,7 +2432,10 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
                         efr |= UART_EFR_CTS;
 
                 serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
-                serial_outp(up, UART_EFR, efr);
+                if (up->port.flags & UPF_EXAR_EFR)
+                        serial_outp(up, UART_XR_EFR, efr);
+                else
+                        serial_outp(up, UART_EFR, efr);
         }
 
 #ifdef CONFIG_ARCH_OMAP