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Commit 129a45b1 authored by Matt Redfearn's avatar Matt Redfearn Committed by Greg Kroah-Hartman
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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: default avatarMatt Redfearn <matt.redfearn@imgtec.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 20b5af93

drivers/tty/serial/8250/8250_ingenic.c

+41 −0
Original line number Diff line number Diff line
@@ -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;