6b1a98d1c4
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: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Jamie Iles <jamie@jamieiles.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
100 lines
2.4 KiB
C
100 lines
2.4 KiB
C
/*
|
|
* 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;
|
|
}
|