tty: 8250: Add 64byte UART support for FSL platforms

Some of FSL SoCs like T1040 has new version of UART controller which
can support 64byte FiFo.
To enable 64 byte support, following needs to be done:
-FCR[EN64] needs to be programmed to 1 to enable it.
-Also, when FCR[EN64]==1, RTL bits to be used as below
to define various Receive Trigger Levels:
        -FCR[RTL] = 00  1 byte
        -FCR[RTL] = 01  16 bytes
        -FCR[RTL] = 10  32 bytes
        -FCR[RTL] = 11  56 bytes
-tx_loadsz is set to 63-bytes instead of 64-bytes to implement
 workaround of errata A-008006 which states that tx_loadsz should
 be configured less than Maximum supported fifo bytes

Signed-off-by: Vijay Rai <vijay.rai@freescale.com>
Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
Signed-off-by: Poonam Aggrwal <poonam.aggrwal@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 22 insertions, 1 deletions

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 3bfcfdb57d05..689169c11f0f 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -329,6 +329,17 @@ static const struct serial8250_config uart_config[] = {
                 .fcr            = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
                 .flags          = UART_CAP_FIFO | UART_CAP_AFE,
         },
+/* tx_loadsz is set to 63-bytes instead of 64-bytes to implement
+workaround of errata A-008006 which states that tx_loadsz should  be
+configured less than Maximum supported fifo bytes */
+        [PORT_16550A_FSL64] = {
+                .name           = "16550A_FSL64",
+                .fifo_size      = 64,
+                .tx_loadsz      = 63,
+                .fcr            = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10 |
+                                  UART_FCR7_64BYTE,
+                .flags          = UART_CAP_FIFO,
+        },
 };
 
 /* Uart divisor latch read */
@@ -956,7 +967,17 @@ static void autoconfig_16550a(struct uart_8250_port *up)
                         up->port.type = PORT_16650;
                         up->capabilities |= UART_CAP_EFR | UART_CAP_SLEEP;
                 } else {
-                        DEBUG_AUTOCONF("Motorola 8xxx DUART ");
+                        serial_out(up, UART_LCR, 0);
+                        serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO |
+                                   UART_FCR7_64BYTE);
+                        status1 = serial_in(up, UART_IIR) >> 5;
+                        serial_out(up, UART_FCR, 0);
+                        serial_out(up, UART_LCR, 0);
+
+                        if (status1 == 7)
+                                up->port.type = PORT_16550A_FSL64;
+                        else
+                                DEBUG_AUTOCONF("Motorola 8xxx DUART ");
                 }
                 serial_out(up, UART_EFR, 0);
                 return;