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/*
* xen/arch/arm/vuart.c
*
* Virtual UART Emulator.
*
* This emulator uses the information from dtuart. This is not intended to be
* a full emulation of an UART device. Rather it is intended to provide a
* sufficient veneer of one that early code (such as Linux's boot time
* decompressor) which hardcodes output directly to such a device are able to
* make progress.
*
* The minimal register set to emulate an UART are:
* - Single byte transmit register
* - Single status register
*
* /!\ This device is not intended to be enumerable or exposed to the OS
* (e.g. via Device Tree).
*
* Julien Grall <julien.grall@linaro.org>
* Ian Campbell <ian.campbell@citrix.com>
* Copyright (c) 2012 Citrix Systems.
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <xen/config.h>
#include <xen/lib.h>
#include <xen/sched.h>
#include <xen/errno.h>
#include <xen/ctype.h>
#include <xen/serial.h>
#include "vuart.h"
#include "io.h"
#define domain_has_vuart(d) ((d)->arch.vuart.info != NULL)
int domain_vuart_init(struct domain *d)
{
ASSERT( !d->domain_id );
d->arch.vuart.info = serial_vuart_info(SERHND_DTUART);
if ( !d->arch.vuart.info )
return 0;
spin_lock_init(&d->arch.vuart.lock);
d->arch.vuart.idx = 0;
d->arch.vuart.buf = xzalloc_array(char, VUART_BUF_SIZE);
if ( !d->arch.vuart.buf )
return -ENOMEM;
return 0;
}
void domain_vuart_free(struct domain *d)
{
if ( !domain_has_vuart(d) )
return;
xfree(d->arch.vuart.buf);
}
static void vuart_print_char(struct vcpu *v, char c)
{
struct domain *d = v->domain;
struct vuart *uart = &d->arch.vuart;
/* Accept only printable characters, newline, and horizontal tab. */
if ( !isprint(c) && (c != '\n') && (c != '\t') )
return ;
spin_lock(&uart->lock);
uart->buf[uart->idx++] = c;
if ( (uart->idx == (VUART_BUF_SIZE - 2)) || (c == '\n') )
{
if ( c != '\n' )
uart->buf[uart->idx++] = '\n';
uart->buf[uart->idx] = '\0';
printk(XENLOG_G_DEBUG "DOM%u: %s", d->domain_id, uart->buf);
uart->idx = 0;
}
spin_unlock(&uart->lock);
}
static int vuart_mmio_check(struct vcpu *v, paddr_t addr)
{
const struct vuart_info *info = v->domain->arch.vuart.info;
return (domain_has_vuart(v->domain) && addr >= info->base_addr &&
addr <= (info->base_addr + info->size));
}
static int vuart_mmio_read(struct vcpu *v, mmio_info_t *info)
{
struct domain *d = v->domain;
struct hsr_dabt dabt = info->dabt;
struct cpu_user_regs *regs = guest_cpu_user_regs();
register_t *r = select_user_reg(regs, dabt.reg);
paddr_t offset = info->gpa - d->arch.vuart.info->base_addr;
/* By default zeroed the register */
*r = 0;
if ( offset == d->arch.vuart.info->status_off )
/* All holding registers empty, ready to send etc */
*r = d->arch.vuart.info->status;
return 1;
}
static int vuart_mmio_write(struct vcpu *v, mmio_info_t *info)
{
struct domain *d = v->domain;
struct hsr_dabt dabt = info->dabt;
struct cpu_user_regs *regs = guest_cpu_user_regs();
register_t *r = select_user_reg(regs, dabt.reg);
paddr_t offset = info->gpa - d->arch.vuart.info->base_addr;
if ( offset == d->arch.vuart.info->data_off )
/* ignore any status bits */
vuart_print_char(v, *r & 0xFF);
return 1;
}
const struct mmio_handler vuart_mmio_handler = {
.check_handler = vuart_mmio_check,
.read_handler = vuart_mmio_read,
.write_handler = vuart_mmio_write,
};
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* indent-tabs-mode: nil
* End:
*/
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