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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* 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.
*/
#include <xen/lib.h>
#include <xen/sched.h>
#include <xen/errno.h>
#include <xen/ctype.h>
#include <xen/serial.h>
#include <asm/mmio.h>
#include <xen/perfc.h>
#include "vuart.h"
#define domain_has_vuart(d) ((d)->arch.vuart.info != NULL)
static int vuart_mmio_read(struct vcpu *v, mmio_info_t *info,
register_t *r, void *priv);
static int vuart_mmio_write(struct vcpu *v, mmio_info_t *info,
register_t r, void *priv);
static const struct mmio_handler_ops vuart_mmio_handler = {
.read = vuart_mmio_read,
.write = vuart_mmio_write,
};
int domain_vuart_init(struct domain *d)
{
ASSERT( is_hardware_domain(d) );
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;
register_mmio_handler(d, &vuart_mmio_handler,
d->arch.vuart.info->base_addr,
d->arch.vuart.info->size,
NULL);
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_read(struct vcpu *v, mmio_info_t *info,
register_t *r, void *priv)
{
struct domain *d = v->domain;
paddr_t offset = info->gpa - d->arch.vuart.info->base_addr;
perfc_incr(vuart_reads);
/* 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,
register_t r, void *priv)
{
struct domain *d = v->domain;
paddr_t offset = info->gpa - d->arch.vuart.info->base_addr;
perfc_incr(vuart_writes);
if ( offset == d->arch.vuart.info->data_off )
/* ignore any status bits */
vuart_print_char(v, r & 0xFF);
return 1;
}
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* indent-tabs-mode: nil
* End:
*/
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