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/*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2022 Ventana Micro Systems Inc.
*
* Authors:
* Anup Patel <apatel@ventanamicro.com>
* Kautuk Consul <kconsul@ventanamicro.com>
*/
#include <sbi/sbi_console.h>
#include <sbi/sbi_string.h>
#include <sbi/sbi_error.h>
#include <sbi_utils/serial/semihosting.h>
#define SYSOPEN 0x01
#define SYSWRITEC 0x03
#define SYSWRITE 0x05
#define SYSREAD 0x06
#define SYSREADC 0x07
#define SYSERRNO 0x13
static long semihosting_trap(int sysnum, void *addr)
{
register int ret asm ("a0") = sysnum;
register void *param0 asm ("a1") = addr;
asm volatile (
" .align 4\n"
" .option push\n"
" .option norvc\n"
" slli zero, zero, 0x1f\n"
" ebreak\n"
" srai zero, zero, 7\n"
" .option pop\n"
: "+r" (ret) : "r" (param0) : "memory");
return ret;
}
static bool _semihosting_enabled = true;
static bool try_semihosting = true;
bool semihosting_enabled(void)
{
register int ret asm ("a0") = SYSERRNO;
register void *param0 asm ("a1") = NULL;
unsigned long tmp = 0;
if (!try_semihosting)
return _semihosting_enabled;
asm volatile (
" .align 4\n"
" .option push\n"
" .option norvc\n"
" j _semihost_test_vector_next\n"
" .align 4\n"
"_semihost_test_vector:\n"
" csrr %[en], mepc\n"
" addi %[en], %[en], 4\n"
" csrw mepc, %[en]\n"
" add %[en], zero, zero\n"
" mret\n"
"_semihost_test_vector_next:\n"
" la %[tmp], _semihost_test_vector\n"
" csrrw %[tmp], mtvec, %[tmp]\n"
" .align 4\n"
" slli zero, zero, 0x1f\n"
" ebreak\n"
" srai zero, zero, 7\n"
" csrw mtvec, %[tmp]\n"
" .option pop\n"
: [tmp] "+r" (tmp), [en] "+r" (_semihosting_enabled),
[ret] "+r" (ret)
: "r" (param0) : "memory");
try_semihosting = false;
return _semihosting_enabled;
}
static int semihosting_errno(void)
{
long ret = semihosting_trap(SYSERRNO, NULL);
if (ret > 0)
return -ret;
return SBI_EIO;
}
static int semihosting_infd = SBI_ENODEV;
static int semihosting_outfd = SBI_ENODEV;
static long semihosting_open(const char *fname, enum semihosting_open_mode mode)
{
long fd;
struct semihosting_open_s {
const char *fname;
unsigned long mode;
size_t len;
} open;
open.fname = fname;
open.len = sbi_strlen(fname);
open.mode = mode;
/* Open the file on the host */
fd = semihosting_trap(SYSOPEN, &open);
if (fd == -1)
return semihosting_errno();
return fd;
}
/**
* struct semihosting_rdwr_s - Arguments for read and write
* @fd: A file descriptor returned from semihosting_open()
* @memp: Pointer to a buffer of memory of at least @len bytes
* @len: The number of bytes to read or write
*/
struct semihosting_rdwr_s {
long fd;
void *memp;
size_t len;
};
static long semihosting_read(long fd, void *memp, size_t len)
{
long ret;
struct semihosting_rdwr_s read;
read.fd = fd;
read.memp = memp;
read.len = len;
ret = semihosting_trap(SYSREAD, &read);
if (ret < 0)
return semihosting_errno();
return len - ret;
}
static long semihosting_write(long fd, const void *memp, size_t len)
{
long ret;
struct semihosting_rdwr_s write;
write.fd = fd;
write.memp = (void *)memp;
write.len = len;
ret = semihosting_trap(SYSWRITE, &write);
if (ret < 0)
return semihosting_errno();
return len - ret;
}
/* clang-format on */
static void semihosting_putc(char ch)
{
semihosting_trap(SYSWRITEC, &ch);
}
static unsigned long semihosting_puts(const char *str, unsigned long len)
{
char ch;
long ret;
unsigned long i;
if (semihosting_outfd < 0) {
for (i = 0; i < len; i++) {
ch = str[i];
semihosting_trap(SYSWRITEC, &ch);
}
ret = len;
} else
ret = semihosting_write(semihosting_outfd, str, len);
return (ret < 0) ? 0 : ret;
}
static int semihosting_getc(void)
{
char ch = 0;
int ret;
if (semihosting_infd < 0) {
ret = semihosting_trap(SYSREADC, NULL);
ret = ret < 0 ? -1 : ret;
} else
ret = semihosting_read(semihosting_infd, &ch, 1) > 0 ? ch : -1;
return ret;
}
static struct sbi_console_device semihosting_console = {
.name = "semihosting",
.console_putc = semihosting_putc,
.console_puts = semihosting_puts,
.console_getc = semihosting_getc
};
int semihosting_init(void)
{
semihosting_infd = semihosting_open(":tt", MODE_READ);
semihosting_outfd = semihosting_open(":tt", MODE_WRITE);
sbi_console_set_device(&semihosting_console);
return 0;
}
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