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/*
* 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;
}
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