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serial: 8250_ingenic: Enable hardware flow control 

The Ingenic UART is similar to a standard 16550, but hardware flow control
requires setting a couple of additional, non-standard bits in the MCR.

The non-standard "modem control enable" and "hardware flow control
mode" bits are set when writing to the MCR register, based
on whether the modem control interrupt is active.

Additionally the non-16550 compliant parts of the uart need to be
masked from higher layers.

Tested on Ingenic JZ4780 on MIPS Creator Ci20 board

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Matt Redfearn 2015-09-08 16:55:34 +01:00 committed by Greg Kroah-Hartman
parent 20b5af9350
commit 129a45b1a9
1 changed files with 41 additions and 0 deletions
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41
drivers/tty/serial/8250/8250_ingenic.c
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@ -34,6 +34,9 @@ struct ingenic_uart_data {
#define UART_FCR_UME BIT(4)
#define UART_MCR_MDCE BIT(7)
#define UART_MCR_FCM BIT(6)
static struct earlycon_device *early_device;
static uint8_t __init early_in(struct uart_port *port, int offset)
@ -129,6 +132,8 @@ OF_EARLYCON_DECLARE(jz4780_uart, "ingenic,jz4780-uart",
static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value)
{
int ier;
switch (offset) {
case UART_FCR:
/* UART module enable */
@ -136,9 +141,22 @@ static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value)
break;
case UART_IER:
/* Enable receive timeout interrupt with the
* receive line status interrupt */
value |= (value & 0x4) << 2;
break;
case UART_MCR:
/* If we have enabled modem status IRQs we should enable modem
* mode. */
ier = p->serial_in(p, UART_IER);
if (ier & UART_IER_MSI)
value |= UART_MCR_MDCE | UART_MCR_FCM;
else
value &= ~(UART_MCR_MDCE | UART_MCR_FCM);
break;
default:
break;
}
@ -146,6 +164,28 @@ static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value)
writeb(value, p->membase + (offset << p->regshift));
}
static unsigned int ingenic_uart_serial_in(struct uart_port *p, int offset)
{
unsigned int value;
value = readb(p->membase + (offset << p->regshift));
/* Hide non-16550 compliant bits from higher levels */
switch (offset) {
case UART_FCR:
value &= ~UART_FCR_UME;
break;
case UART_MCR:
value &= ~(UART_MCR_MDCE | UART_MCR_FCM);
break;
default:
break;
}
return value;
}
static int ingenic_uart_probe(struct platform_device *pdev)
{
struct uart_8250_port uart = {};
@ -170,6 +210,7 @@ static int ingenic_uart_probe(struct platform_device *pdev)
uart.port.mapbase = regs->start;
uart.port.regshift = 2;
uart.port.serial_out = ingenic_uart_serial_out;
uart.port.serial_in = ingenic_uart_serial_in;
uart.port.irq = irq->start;
uart.port.dev = &pdev->dev;