Commit 6b1a98d1 authored by Jamie Iles's avatar Jamie Iles Committed by Greg Kroah-Hartman
Browse files

tty: serial8250: add helpers for the DesignWare 8250 



The Synopsys DesignWare 8250 is an 8250 that has an extra interrupt that
gets raised when writing to the LCR when busy.  To handle this we need
special serial_out, serial_in and handle_irq methods.  Add a new
function serial8250_use_designware_io() that configures a uart_port with
these accessors.

Cc: Alan Cox <alan@linux.intel.com>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarJamie Iles <jamie@jamieiles.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 4834d028

drivers/tty/serial/8250_dw.c

0 → 100644
+99 −0
Original line number Diff line number Diff line 
/*

 * Synopsys DesignWare specific 8250 operations.

 *

 * Copyright 2011 Picochip, Jamie Iles.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * The Synopsys DesignWare 8250 has an extra feature whereby it detects if the

 * LCR is written whilst busy.  If it is, then a busy detect interrupt is

 * raised, the LCR needs to be rewritten and the uart status register read.

 */

#include <linux/io.h>

#include <linux/serial_8250.h>

#include <linux/serial_core.h>

#include <linux/serial_reg.h>

#include <linux/slab.h>



struct dw8250_data {

	int	last_lcr;

};



static void dw8250_serial_out(struct uart_port *p, int offset, int value)

{

	struct dw8250_data *d = p->private_data;



	if (offset == UART_LCR)

		d->last_lcr = value;



	offset <<= p->regshift;

	writeb(value, p->membase + offset);

}



static unsigned int dw8250_serial_in(struct uart_port *p, int offset)

{

	offset <<= p->regshift;



	return readb(p->membase + offset);

}



static void dw8250_serial_out32(struct uart_port *p, int offset,

				int value)

{

	struct dw8250_data *d = p->private_data;



	if (offset == UART_LCR)

		d->last_lcr = value;



	offset <<= p->regshift;

	writel(value, p->membase + offset);

}



static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)

{

	offset <<= p->regshift;



	return readl(p->membase + offset);

}



/* Offset for the DesignWare's UART Status Register. */

#define UART_USR	0x1f



static int dw8250_handle_irq(struct uart_port *p)

{

	struct dw8250_data *d = p->private_data;

	unsigned int iir = p->serial_in(p, UART_IIR);



	if (serial8250_handle_irq(p, iir)) {

		return 1;

	} else if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) {

		/* Clear the USR and write the LCR again. */

		(void)p->serial_in(p, UART_USR);

		p->serial_out(p, d->last_lcr, UART_LCR);



		return 1;

	}



	return 0;

}



int serial8250_use_designware_io(struct uart_port *up)

{

	up->private_data = kzalloc(sizeof(struct dw8250_data), GFP_KERNEL);

	if (!up->private_data)

		return -ENOMEM;



	if (up->iotype == UPIO_MEM32) {

		up->serial_out = dw8250_serial_out32;

		up->serial_in = dw8250_serial_in32;

	} else {

		up->serial_out = dw8250_serial_out;

		up->serial_in = dw8250_serial_in;

	}

	up->handle_irq = dw8250_handle_irq;



	return 0;

}

drivers/tty/serial/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -267,6 +267,13 @@ config SERIAL_8250_RM9K 
	  port hardware found on MIPS RM9122 and similar processors.

	  If unsure, say N.



config SERIAL_8250_DW

	bool "Support for Synopsys DesignWare 8250 quirks"

	depends on SERIAL_8250

	help

	  Selecting this option will enable handling of the extra features

	  present in the Synopsys DesignWare APB UART.



comment "Non-8250 serial port support"



config SERIAL_AMBA_PL010

drivers/tty/serial/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ obj-$(CONFIG_SERIAL_8250_BOCA) += 8250_boca.o 
obj-$(CONFIG_SERIAL_8250_EXAR_ST16C554) += 8250_exar_st16c554.o

obj-$(CONFIG_SERIAL_8250_HUB6) += 8250_hub6.o

obj-$(CONFIG_SERIAL_8250_MCA) += 8250_mca.o

obj-$(CONFIG_SERIAL_8250_DW) += 8250_dw.o

obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o

obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o

obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o

include/linux/serial_8250.h

+8 −0
Original line number Diff line number Diff line
@@ -86,5 +86,13 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir); 
extern void serial8250_set_isa_configurator(void (*v)

					(int port, struct uart_port *up,

						unsigned short *capabilities));

#ifndef SERIAL_8250_DW

extern int serial8250_use_designware_io(struct uart_port *up);

#else

static inline int serial8250_use_designware_io(struct uart_port *up)

{

	return -EIO;

}

#endif



#endif