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

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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>
This commit is contained in:
Vijay Rai 2015-01-05 21:14:42 +05:30 • committed by Greg Kroah-Hartman
commit fddceb8b53
3 changed files with 26 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

23
drivers/tty/serial/8250/8250_core.c
View file

@ -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;

3
include/uapi/linux/serial_core.h
View file

@ -55,7 +55,8 @@
#define PORT_ALTR_16550_F64 27 /* Altera 16550 UART with 64 FIFOs */
#define PORT_ALTR_16550_F128 28 /* Altera 16550 UART with 128 FIFOs */
#define PORT_RT2880 29 /* Ralink RT2880 internal UART */
#define PORT_MAX_8250 29 /* max port ID */
#define PORT_16550A_FSL64 30 /* Freescale 16550 UART with 64 FIFOs */
#define PORT_MAX_8250 30 /* max port ID */
/*
* ARM specific type numbers. These are not currently guaranteed

3
include/uapi/linux/serial_reg.h
View file

@ -86,7 +86,8 @@
#define UART_FCR6_T_TRIGGER_8 0x10 /* Mask for transmit trigger set at 8 */
#define UART_FCR6_T_TRIGGER_24 0x20 /* Mask for transmit trigger set at 24 */
#define UART_FCR6_T_TRIGGER_30 0x30 /* Mask for transmit trigger set at 30 */
#define UART_FCR7_64BYTE 0x20 /* Go into 64 byte mode (TI16C750) */
#define UART_FCR7_64BYTE 0x20 /* Go into 64 byte mode (TI16C750 and
some Freescale UARTs) */
#define UART_FCR_R_TRIG_SHIFT 6
#define UART_FCR_R_TRIG_BITS(x) \